When a reflog is deleted, e.g. when "git stash" clears its stashes,
"git rev-parse --verify --quiet" dies:
fatal: Log for refs/stash is empty.
The reason is that the get_sha1() code path does not allow us
to suppress this message.
Pass the flags bitfield through get_sha1_with_context() so that
read_ref_at() can suppress the message.
Use get_sha1_with_context1() instead of get_sha1() in rev-parse
so that the --quiet flag is honored.
Signed-off-by: David Aguilar <davvid@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Our filesystem ref storage does not allow D/F conflicts; so
if "refs/heads/a/b" exists, we do not allow "refs/heads/a"
to exist (and vice versa). This falls out naturally for
loose refs, where the filesystem enforces the condition. But
for packed-refs, we have to make the check ourselves.
We do so by iterating over the entire packed-refs namespace
and checking whether each name creates a conflict. If you
have a very large number of refs, this is quite inefficient,
as you end up doing a large number of comparisons with
uninteresting bits of the ref tree (e.g., we know that all
of "refs/tags" is uninteresting in the example above, yet we
check each entry in it).
Instead, let's take advantage of the fact that we have the
packed refs stored as a trie of ref_entry structs. We can
find each component of the proposed refname as we walk
through the trie, checking for D/F conflicts as we go. For a
refname of depth N (i.e., 4 in the above example), we only
have to visit N nodes. And at each visit, we can binary
search the M names at that level, for a total complexity of
O(N lg M). ("M" is different at each level, of course, but
we can take the worst-case "M" as a bound).
In a pathological case of fetching 30,000 fresh refs into a
repository with 8.5 million refs, this dropped the time to
run "git fetch" from tens of minutes to ~30s.
This may also help smaller cases in which we check against
loose refs (which we do when renaming a ref), as we may
avoid a disk access for unrelated loose directories.
Note that the tests we add appear at first glance to be
redundant with what is already in t3210. However, the early
tests are not robust; they are run with reflogs turned on,
meaning that we are not actually testing
is_refname_available at all! The operations will still fail
because the reflogs will hit D/F conflicts in the
filesystem. To get a true test, we must turn off reflogs
(but we don't want to do so for the entire script, because
the point of turning them on was to cover some other cases).
Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
After "pack-refs --prune" packed refs at the top-level, it failed
to prune them.
* jk/prune-top-level-refs-after-packing:
pack-refs: prune top-level refs like "refs/foo"
The second batch of the transactional ref update series.
* rs/ref-transaction-1: (22 commits)
update-ref --stdin: pass transaction around explicitly
update-ref --stdin: narrow scope of err strbuf
refs.c: make delete_ref use a transaction
refs.c: make prune_ref use a transaction to delete the ref
refs.c: remove lock_ref_sha1
refs.c: remove the update_ref_write function
refs.c: remove the update_ref_lock function
refs.c: make lock_ref_sha1 static
walker.c: use ref transaction for ref updates
fast-import.c: use a ref transaction when dumping tags
receive-pack.c: use a reference transaction for updating the refs
refs.c: change update_ref to use a transaction
branch.c: use ref transaction for all ref updates
fast-import.c: change update_branch to use ref transactions
sequencer.c: use ref transactions for all ref updates
commit.c: use ref transactions for updates
replace.c: use the ref transaction functions for updates
tag.c: use ref transactions when doing updates
refs.c: add transaction.status and track OPEN/CLOSED
refs.c: make ref_transaction_begin take an err argument
...
We write each line of a new packed-refs file individually
using a write() syscall (and sometimes 2, if the ref is
peeled). Since each line is only about 50-100 bytes long,
this creates a lot of system call overhead.
We can instead open a stdio handle around our descriptor and
use fprintf to write to it. The extra buffering is not a
problem for us, because nobody will read our new packed-refs
file until we call commit_lock_file (by which point we have
flushed everything).
On a pathological repository with 8.5 million refs, this
dropped the time to run `git pack-refs` from 20s to 6s.
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Change delete_ref to use a ref transaction for the deletion. At the same time
since we no longer have any callers of repack_without_ref we can now delete
this function.
Change delete_ref to return 0 on success and 1 on failure instead of the
previous 0 on success either 1 or -1 on failure.
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Change prune_ref to delete the ref using a ref transaction. To do this we also
need to add a new flag REF_ISPRUNING that will tell the transaction that we
do not want to delete this ref from the packed refs. This flag is private to
refs.c and not exposed to external callers.
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
lock_ref_sha1 was only called from one place in refs.c and only provided
a check that the refname was sane before adding back the initial "refs/"
part of the ref path name, the initial "refs/" that this caller had already
stripped off before calling lock_ref_sha1.
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Since we only call update_ref_write from a single place and we only call it
with onerr==QUIET_ON_ERR we can just as well get rid of it and just call
write_ref_sha1 directly. This changes the return status for _commit from
1 to -1 on failures when writing to the ref. Eventually we will want
_commit to start returning more detailed error conditions than the current
simple success/failure.
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Since we now only call update_ref_lock with onerr==QUIET_ON_ERR we no longer
need this function and can replace it with just calling lock_any_ref_for_update
directly.
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
No external callers reference lock_ref_sha1 any more so let's declare it
static.
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Change the update_ref helper function to use a ref transaction internally.
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Track the state of a transaction in a new state field. Check the field for
sanity, i.e. that state must be OPEN when _commit/_create/_delete or
_update is called or else die(BUG:...)
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add an err argument to _begin so that on non-fatal failures in future ref
backends we can report a nice error back to the caller.
While _begin can currently never fail for other reasons than OOM, in which
case we die() anyway, we may add other types of backends in the future.
For example, a hypothetical MySQL backend could fail in _begin with
"Can not connect to MySQL server. No route to host".
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Change ref_transaction_delete() to do basic error checking and return
non-zero on error. Update all callers to check the return for
ref_transaction_delete(). There are currently no conditions in _delete that
will return error but there will be in the future. Add an err argument that
will be updated on failure.
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Do basic error checking in ref_transaction_create() and make it return
non-zero on error. Update all callers to check the result of
ref_transaction_create(). There are currently no conditions in _create that
will return error but there will be in the future. Add an err argument that
will be updated on failure.
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
After we have packed all refs, we prune any loose refs that
correspond to what we packed. We do so by first taking a
lock with lock_ref_sha1, and then deleting the loose ref
file.
However, lock_ref_sha1 will refuse to take a lock on any
refs that exist at the top-level of the "refs/" directory,
and we skip pruning the ref. This is almost certainly not
what we want to happen here. The criteria to be pruned
should not differ from that to be packed; if a ref makes it
to prune_ref, it's because we want it both packed and
pruned (if there are refs you do not want to be packed, they
should be omitted much earlier by pack_ref_is_possible,
which we do in this case if --all is not given).
We can fix this by switching to lock_any_ref_for_update.
This behaves exactly the same with the exception of this
top-level check.
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu>
Reviewed-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When we call lookup_commit, lookup_tree, etc, the logic goes
something like:
1. Look for an existing object struct. If we don't have
one, allocate and return a new one.
2. Double check that any object we have is the expected
type (and complain and return NULL otherwise).
3. Convert an object with type OBJ_NONE (from a prior
call to lookup_unknown_object) to the expected type.
We can encapsulate steps 2 and 3 in a helper function which
checks whether we have the expected object type, converts
OBJ_NONE as appropriate, and returns the object.
Not only does this shorten the code, but it also provides
one central location for converting OBJ_NONE objects into
objects of other types. Future patches will use that to
enforce type-specific invariants.
Since this is a refactoring, we would want it to behave
exactly as the current code. It takes a little reasoning to
see that this is the case:
- for lookup_{commit,tree,etc} functions, we are just
pulling steps 2 and 3 into a function that does the same
thing.
- for the call in peel_object, we currently only do step 3
(but we want to consolidate it with the others, as
mentioned above). However, step 2 is a noop here, as the
surrounding conditional makes sure we have OBJ_NONE
(which we want to keep to avoid an extraneous call to
sha1_object_info).
- for the call in lookup_commit_reference_gently, we are
currently doing step 2 but not step 3. However, step 3
is a noop here. The object we got will have just come
from deref_tag, which must have figured out the type for
each object in order to know when to stop peeling.
Therefore the type will never be OBJ_NONE.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Make sure all in-core commit objects are assigned a unique number
so that they can be annotated using the commit-slab API.
* jk/alloc-commit-id:
diff-tree: avoid lookup_unknown_object
object_as_type: set commit index
alloc: factor out commit index
add object_as_type helper for casting objects
parse_object_buffer: do not set object type
move setting of object->type to alloc_* functions
alloc: write out allocator definitions
alloc.c: remove the alloc_raw_commit_node() function
Early part of the "ref transaction" topic.
* rs/ref-transaction-0:
refs.c: change ref_transaction_update() to do error checking and return status
refs.c: remove the onerr argument to ref_transaction_commit
update-ref: use err argument to get error from ref_transaction_commit
refs.c: make update_ref_write update a strbuf on failure
refs.c: make ref_update_reject_duplicates take a strbuf argument for errors
refs.c: log_ref_write should try to return meaningful errno
refs.c: make resolve_ref_unsafe set errno to something meaningful on error
refs.c: commit_packed_refs to return a meaningful errno on failure
refs.c: make remove_empty_directories always set errno to something sane
refs.c: verify_lock should set errno to something meaningful
refs.c: make sure log_ref_setup returns a meaningful errno
refs.c: add an err argument to repack_without_refs
lockfile.c: make lock_file return a meaningful errno on failurei
lockfile.c: add a new public function unable_to_lock_message
refs.c: add a strbuf argument to ref_transaction_commit for error logging
refs.c: allow passing NULL to ref_transaction_free
refs.c: constify the sha arguments for ref_transaction_create|delete|update
refs.c: ref_transaction_commit should not free the transaction
refs.c: remove ref_transaction_rollback
Both refs.c and fsck.c have their own private copies of the is_branch function.
Delete the is_branch function from fsck.c and make the version in refs.c
public.
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
* jk/strip-suffix:
prepare_packed_git_one: refactor duplicate-pack check
verify-pack: use strbuf_strip_suffix
strbuf: implement strbuf_strip_suffix
index-pack: use strip_suffix to avoid magic numbers
use strip_suffix instead of ends_with in simple cases
replace has_extension with ends_with
implement ends_with via strip_suffix
add strip_suffix function
sha1_file: replace PATH_MAX buffer with strbuf in prepare_packed_git_one()
Update ref_transaction_update() do some basic error checking and return
non-zero on error. Update all callers to check ref_transaction_update() for
error. There are currently no conditions in _update that will return error but
there will be in the future. Add an err argument that will be updated on
failure. In future patches we will start doing both locking and checking
for name conflicts in _update instead of _commit at which time this function
will start returning errors for these conditions.
Also check for BUGs during update and die(BUG:...) if we are calling
_update with have_old but the old_sha1 pointer is NULL.
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Acked-by: Michael Haggerty <mhagger@alum.mit.edu>
Since all callers now use QUIET_ON_ERR we no longer need to provide an onerr
argument any more. Remove the onerr argument from the ref_transaction_commit
signature.
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Acked-by: Michael Haggerty <mhagger@alum.mit.edu>
Change update_ref_write to also update an error strbuf on failure.
This makes the error available to ref_transaction_commit callers if the
transaction failed due to update_ref_sha1/write_ref_sha1 failures.
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Acked-by: Michael Haggerty <mhagger@alum.mit.edu>
Make ref_update_reject_duplicates return any error that occurs through a
new strbuf argument. This means that when a transaction commit fails in
this function we will now be able to pass a helpful error message back to the
caller.
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Acked-by: Michael Haggerty <mhagger@alum.mit.edu>
Making errno from write_ref_sha1() meaningful, which should fix
* a bug in "git checkout -b" where it prints strerror(errno)
despite errno possibly being zero or clobbered
* a bug in "git fetch"'s s_update_ref, which trusts the result of an
errno == ENOTDIR check to detect D/F conflicts
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Acked-by: Michael Haggerty <mhagger@alum.mit.edu>
Making errno when returning from resolve_ref_unsafe() meaningful,
which should fix
* a bug in lock_ref_sha1_basic, where it assumes EISDIR
means it failed due to a directory being in the way
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Acked-by: Michael Haggerty <mhagger@alum.mit.edu>
Making errno when returning from commit_packed_refs() meaningful,
which should fix
* a bug in "git clone" where it prints strerror(errno) based on
errno, despite errno possibly being zero and potentially having
been clobbered by that point
* the same kind of bug in "git pack-refs"
and prepares for repack_without_refs() to get a meaningful
error message when commit_packed_refs() fails without falling into
the same bug.
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Acked-by: Michael Haggerty <mhagger@alum.mit.edu>
Making errno when returning from remove_empty_directories() more
obviously meaningful, which should provide some peace of mind for
people auditing lock_ref_sha1_basic.
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Acked-by: Michael Haggerty <mhagger@alum.mit.edu>
Making errno when returning from verify_lock() meaningful, which
should almost but not completely fix
* a bug in "git fetch"'s s_update_ref, which trusts the result of an
errno == ENOTDIR check to detect D/F conflicts
ENOTDIR makes sense as a sign that a file was in the way of a
directory we wanted to create. Should "git fetch" also look for
ENOTEMPTY or EEXIST to catch cases where a directory was in the way
of a file to be created?
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Acked-by: Michael Haggerty <mhagger@alum.mit.edu>
Making errno when returning from log_ref_setup() meaningful,
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Acked-by: Michael Haggerty <mhagger@alum.mit.edu>
Update repack_without_refs to take an err argument and update it if there
is a failure. Pass the err variable from ref_transaction_commit to this
function so that callers can print a meaningful error message if _commit
fails due to this function.
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Acked-by: Michael Haggerty <mhagger@alum.mit.edu>
Making errno when returning from lock_file() meaningful, which should
fix
* an existing almost-bug in lock_ref_sha1_basic where it assumes
errno==ENOENT is meaningful and could waste some work on retries
* an existing bug in repack_without_refs where it prints
strerror(errno) and picks advice based on errno, despite errno
potentially being zero and potentially having been clobbered by
that point
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Acked-by: Michael Haggerty <mhagger@alum.mit.edu>
Add a strbuf argument to _commit so that we can pass an error string back to
the caller. So that we can do error logging from the caller instead of from
_commit.
Longer term plan is to first convert all callers to use onerr==QUIET_ON_ERR
and craft any log messages from the callers themselves and finally remove the
onerr argument completely.
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Acked-by: Michael Haggerty <mhagger@alum.mit.edu>
Allow ref_transaction_free(NULL) as a no-op. This makes ref_transaction_free
easier to use and more similar to plain 'free'.
In particular, it lets us rollback unconditionally as part of cleanup code
after setting 'transaction = NULL' if a transaction has been committed or
rolled back already.
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Acked-by: Michael Haggerty <mhagger@alum.mit.edu>
ref_transaction_create|delete|update has no need to modify the sha1
arguments passed to it so it should use const unsigned char* instead
of unsigned char*.
Some functions, such as fast_forward_to(), already have its old/new
sha1 arguments as consts. This function will at some point need to
use ref_transaction_update() in which case this change is required.
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Acked-by: Michael Haggerty <mhagger@alum.mit.edu>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Acked-by: Michael Haggerty <mhagger@alum.mit.edu>
We do not yet need both a rollback and a free function for transactions.
Remove ref_transaction_rollback and use ref_transaction_free instead.
At a later stage we may reintroduce a rollback function if we want to start
adding reusable transactions and similar.
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Acked-by: Michael Haggerty <mhagger@alum.mit.edu>
When we call lookup_commit, lookup_tree, etc, the logic goes
something like:
1. Look for an existing object struct. If we don't have
one, allocate and return a new one.
2. Double check that any object we have is the expected
type (and complain and return NULL otherwise).
3. Convert an object with type OBJ_NONE (from a prior
call to lookup_unknown_object) to the expected type.
We can encapsulate steps 2 and 3 in a helper function which
checks whether we have the expected object type, converts
OBJ_NONE as appropriate, and returns the object.
Not only does this shorten the code, but it also provides
one central location for converting OBJ_NONE objects into
objects of other types. Future patches will use that to
enforce type-specific invariants.
Since this is a refactoring, we would want it to behave
exactly as the current code. It takes a little reasoning to
see that this is the case:
- for lookup_{commit,tree,etc} functions, we are just
pulling steps 2 and 3 into a function that does the same
thing.
- for the call in peel_object, we currently only do step 3
(but we want to consolidate it with the others, as
mentioned above). However, step 2 is a noop here, as the
surrounding conditional makes sure we have OBJ_NONE
(which we want to keep to avoid an extraneous call to
sha1_object_info).
- for the call in lookup_commit_reference_gently, we are
currently doing step 2 but not step 3. However, step 3
is a noop here. The object we got will have just come
from deref_tag, which must have figured out the type for
each object in order to know when to stop peeling.
Therefore the type will never be OBJ_NONE.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Fixes to a topic that is already in 'master'.
* dt/refs-check-refname-component-sse-fix:
refs: fix valgrind suppression file
refs.c: handle REFNAME_REFSPEC_PATTERN at end of page
When a ref crosses a memory page boundary, we restart the parsing
at the beginning with the bytewise code. Pass the original flags
to that code, rather than the current flags.
Reported-By: Øyvind A. Holm <sunny@sunbase.org>
Signed-off-by: David Turner <dturner@twitter.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
These two are almost the same function, with the exception
that has_extension only matches if there is content before
the suffix. So ends_with(".exe", ".exe") is true, but
has_extension would not be.
This distinction does not matter to any of the callers,
though, and we can just replace uses of has_extension with
ends_with. We prefer the "ends_with" name because it is more
generic, and there is nothing about the function that
requires it to be used for file extensions.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Optimize check_refname_component using SSE2 on x86_64.
git rev-parse HEAD is a good test-case for this, since it does almost
nothing except parse refs. For one particular repo with about 60k
refs, almost all packed, the timings are:
Look up table: 29 ms
SSE2: 23 ms
This cuts about 20% off of the runtime.
Ondřej Bílka <neleai@seznam.cz> suggested an SSE2 approach to the
substring searches, which netted a speed boost over the SSE4.2 code I
had initially written.
Signed-off-by: David Turner <dturner@twitter.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git remote rm" and "git remote prune" can involve removing many
refs at once, which is not a very efficient thing to do when very
many refs exist in the packed-refs file.
* jl/remote-rm-prune:
remote prune: optimize "dangling symref" check/warning
remote: repack packed-refs once when deleting multiple refs
remote rm: delete remote configuration as the last
In a repository with many refs, check_refname_component can be a major
contributor to the runtime of some git commands. One such command is
git rev-parse HEAD
Timings for one particular repo, with about 60k refs, almost all
packed, are:
Old: 35 ms
New: 29 ms
Many other commands which read refs are also sped up.
Signed-off-by: David Turner <dturner@twitter.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
read_ref_at has its own parsing of the reflog file for no really good reason
so lets change this to use the existing reflog iterators. This removes one
instance where we manually unmarshall the reflog file format.
Remove the now redundant ref_msg function.
Log messages for errors are changed slightly. We no longer print the file
name for the reflog, instead we refer to it as 'Log for ref <refname>'.
This might be a minor useability regression, but I don't really think so, since
experienced users would know where the log is anyway and inexperienced users
would not know what to do about/how to repair 'Log ... has gap ...' anyway.
Adapt the t1400 test to handle the change in log messages.
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When 'git remote prune' was used to delete many refs in a repository
with many refs, a lot of time was spent checking for (now) dangling
symbolic refs pointing to the deleted ref, since warn_dangling_symref()
was once per deleted ref to check all other refs in the repository.
Avoid this using the new warn_dangling_symrefs() function which
makes one pass over all refs and checks for all the deleted refs in
one go, after they have all been deleted.
Signed-off-by: Jens Lindström <jl@opera.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When 'git remote rm' or 'git remote prune' were used in a repository
with many refs, and needed to delete many remote-tracking refs, a lot
of time was spent deleting those refs since for each deleted ref,
repack_without_refs() was called to rewrite packed-refs without just
that deleted ref.
To avoid this, call repack_without_refs() first to repack without all
the refs that will be deleted, before calling delete_ref() to delete
each one completely. The call to repack_without_ref() in delete_ref()
then becomes a no-op, since packed-refs already won't contain any of
the deleted refs.
Signed-off-by: Jens Lindström <jl@opera.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add two new functions, reflog_exists and delete_reflog, to hide the internal
reflog implementation (that they are files under .git/logs/...) from callers.
Update checkout.c to use these functions in update_refs_for_switch instead of
building pathnames and calling out to file access functions. Update reflog.c
to use these to check if the reflog exists. Now there are still many places
in reflog.c where we are still leaking the reflog storage implementation but
this at least reduces the number of such dependencies by one. Finally
change two places in refs.c itself to use the new function to check if a ref
exists or not isntead of build-path-and-stat(). Now, this is strictly not all
that important since these are in parts of refs that are implementing the
actual file storage backend but on the other hand it will not hurt either.
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Acked-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Now that we free the transaction when we are done, there is no need to
make a copy of transaction->updates before working with it.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
It used to be that ref_transaction_commit() allocated a temporary
array to hold the types of references while it is working. Instead,
add a type field to ref_update that ref_transaction_commit() can use
as its scratch space.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Now that we manage ref_update objects internally, we can use them to
hold some of the scratch space we need when actually carrying out the
updates. Store the (struct ref_lock *) there.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Use temporary variables in the for-loop blocks to simplify expressions
in the rest of the loop.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This is consistent with the usual nomenclature.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
It has been superseded by reference transactions. This also means
that struct ref_update can become private.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Build out the API for dealing with a bunch of reference checks and
changes within a transaction. Define an opaque ref_transaction type
that is managed entirely within refs.c. Introduce functions for
beginning a transaction, adding updates to a transaction, and
committing/rolling back a transaction.
This API will soon replace update_refs().
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The old signature of update_refs() required a
(const struct ref_update **) for its updates_orig argument. The
"const" is presumably there to promise that the function will not
modify the contents of the structures.
But this declaration does not permit the function to be called with a
(struct ref_update **), which is perfectly legitimate. C's type
system is not powerful enough to express what we'd like. So remove
the first "const" from the declaration.
On the other hand, the function *can* promise not to modify the
pointers within the array that is passed to it without inconveniencing
its callers. So add a "const" that has that effect, making the final
declaration
(struct ref_update * const *).
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Given that these constants are only being used when updating
references, it is inappropriate to give them such generic names as
"DIE_ON_ERR". So prefix their names with "UPDATE_REFS_".
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We invented hashcpy() to keep the abstraction of "object name"
behind it. Use it instead of calling memcpy() with hard-coded
20-byte length when moving object names between pieces of memory.
Leave ppc/sha1.c as-is, because the function is about the SHA-1 hash
algorithm whose output is and will always be 20 bytes.
Helped-by: Michael Haggerty <mhagger@alum.mit.edu>
Helped-by: Duy Nguyen <pclouds@gmail.com>
Signed-off-by: Sun He <sunheehnus@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Make it clear that we don't use fnmatch() anymore.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Code clean-up and protection against concurrent write access to the
ref namespace.
* mh/safe-create-leading-directories:
rename_tmp_log(): on SCLD_VANISHED, retry
rename_tmp_log(): limit the number of remote_empty_directories() attempts
rename_tmp_log(): handle a possible mkdir/rmdir race
rename_ref(): extract function rename_tmp_log()
remove_dir_recurse(): handle disappearing files and directories
remove_dir_recurse(): tighten condition for removing unreadable dir
lock_ref_sha1_basic(): if locking fails with ENOENT, retry
lock_ref_sha1_basic(): on SCLD_VANISHED, retry
safe_create_leading_directories(): add new error value SCLD_VANISHED
cmd_init_db(): when creating directories, handle errors conservatively
safe_create_leading_directories(): introduce enum for return values
safe_create_leading_directories(): always restore slash at end of loop
safe_create_leading_directories(): split on first of multiple slashes
safe_create_leading_directories(): rename local variable
safe_create_leading_directories(): add explicit "slash" pointer
safe_create_leading_directories(): reduce scope of local variable
safe_create_leading_directories(): fix format of "if" chaining
If safe_create_leading_directories() fails because a file along the
path unexpectedly vanished, try again from the beginning. Try at most
4 times.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This doesn't seem to be a likely error, but we've got the counter
anyway, so we might as well use it for an added bit of safety.
Please note that the first call to rename() is optimistic, and it is
normal for it to fail if there is a directory in the way. So bump the
total number of allowed attempts to 4, to be sure that we can still
have at least 3 retries in the case of a race.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If a directory vanishes while renaming the temporary reflog file,
retry (up to 3 times). This could happen if another process deletes
the directory created by safe_create_leading_directories() just before
we rename the file into the directory.
As far as I can tell, this race could not occur internal to git. The
only time that a directory under $GIT_DIR/logs is deleted is if room
has to be made for a log file for a reference with the same name;
for example, in the following sequence:
git branch foo/bar # Creates file .git/logs/refs/heads/foo/bar
git branch -d foo/bar # Deletes file but leaves .git/logs/refs/heads/foo/
git branch foo # Deletes .git/logs/refs/heads/foo/
But the only reason the last command deletes the directory is because
it wants to create a file with the same name. So if another process
(e.g.,
git branch foo/baz
) wants to create that directory, one of the two is doomed to failure
anyway because of a D/F conflict.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If hold_lock_file_for_update() fails with errno==ENOENT, it might be
because somebody else (for example, a pack-refs process) has just
deleted one of the lockfile's ancestor directories. So if this
condition is detected, try again (up to 3 times).
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If safe_create_leading_directories() fails because a file along the
path unexpectedly vanished, try again (up to 3 times).
This can occur if another process is deleting directories at the same
time as we are trying to make them. For example, "git pack-refs
--all" tries to delete the loose refs and any empty directories that
are left behind. If a pack-refs process is running, then it might
delete a directory that we need to put a new loose reference in.
If safe_create_leading_directories() thinks this might have happened,
then take its advice and try again (maximum three attempts).
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We used to use two separate rules for the normal ref resolution
dwimming and dwimming done to decide which remote ref to grab. The
third parameter to refname_match() selected which rules to use.
When these two rules were harmonized in
2011-11-04 dd621df9cd refs DWIMmery: use the same rule for both "git fetch" and others
, ref_fetch_rules was #defined to avoid potential breakages for
in-flight topics.
It is now safe to remove the backwards-compatibility code, so remove
refname_match()'s third parameter, make ref_rev_parse_rules private to
refs.c, and remove ref_fetch_rules entirely.
Suggested-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
* mh/shorten-unambigous-ref:
shorten_unambiguous_ref(): tighten up pointer arithmetic
gen_scanf_fmt(): delete function and use snprintf() instead
shorten_unambiguous_ref(): introduce a new local variable
As long as we're being pathologically stingy with mallocs, we might as
well do the math right and save 6 (!) bytes.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
To replace "%.*s" with "%s", all we have to do is use snprintf()
to interpolate "%s" into the pattern.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When filling the scanf_fmts array, use a separate variable to keep
track of the offset to avoid clobbering total_len (which we will need
in the next commit).
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Leaving only the function definitions and declarations so that any
new topic in flight can still make use of the old functions, replace
existing uses of the prefixcmp() and suffixcmp() with new API
functions.
The change can be recreated by mechanically applying this:
$ git grep -l -e prefixcmp -e suffixcmp -- \*.c |
grep -v strbuf\\.c |
xargs perl -pi -e '
s|!prefixcmp\(|starts_with\(|g;
s|prefixcmp\(|!starts_with\(|g;
s|!suffixcmp\(|ends_with\(|g;
s|suffixcmp\(|!ends_with\(|g;
'
on the result of preparatory changes in this series.
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The function 'invalidate_ref_cache' was introduced in 79c7ca5 (2011-10-17,
invalidate_ref_cache(): rename function from invalidate_cached_refs())
by a rename and elevated to be publicly usable in 8be8bde (2011-10-17,
invalidate_ref_cache(): expose this function in the refs API)
However it is not used anymore, as 8bf90dc (2011-10-17, write_ref_sha1():
only invalidate the loose ref cache) and (much) later 506a760 (2013-04-22,
refs: change how packed refs are deleted) removed any calls to this
function. So it seems as if we don't need that function any more,
good bye!
Signed-off-by: Stefan Beller <stefanbeller@googlemail.com>
Acked-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In shorten_unambiguous_ref, we build and cache a reverse-map of the
rev-parse rules like this:
static char **scanf_fmts;
static int nr_rules;
if (!nr_rules) {
for (; ref_rev_parse_rules[nr_rules]; nr_rules++)
... generate scanf_fmts ...
}
where ref_rev_parse_rules is terminated with a NULL pointer.
Compiling with "gcc -O2 -Wall" does not cause any problems, but
compiling with "-O3 -Wall" generates:
$ make CFLAGS='-O3 -Wall' refs.o
refs.c: In function ‘shorten_unambiguous_ref’:
refs.c:3379:29: warning: array subscript is above array bounds [-Warray-bounds]
for (; ref_rev_parse_rules[nr_rules]; nr_rules++)
Curiously, we can silence this by explicitly nr_rules to 0
in the beginning of the loop, even though the compiler
should be able to tell that we follow this code path only
when nr_rules is already 0.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
A call to update_ref_lock() passes '0' to the 'int *type_p' parameter.
Noticed by sparse. ("Using plain integer as NULL pointer")
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Instead of typing four capital letters "HEAD", you can say "@" now,
e.g. "git log @".
* fc/at-head:
Add new @ shortcut for HEAD
sha1-name: pass len argument to interpret_branch_name()
Give "update-refs" a "--stdin" option to read multiple update
requests and perform them in an all-or-none fashion.
* bk/refs-multi-update:
update-ref: add test cases covering --stdin signature
update-ref: support multiple simultaneous updates
refs: add update_refs for multiple simultaneous updates
refs: add function to repack without multiple refs
refs: factor delete_ref loose ref step into a helper
refs: factor update_ref steps into helpers
refs: report ref type from lock_any_ref_for_update
reset: rename update_refs to reset_refs
Typing 'HEAD' is tedious, especially when we can use '@' instead.
The reason for choosing '@' is that it follows naturally from the
ref@op syntax (e.g. HEAD@{u}), except we have no ref, and no
operation, and when we don't have those, it makes sens to assume
'HEAD'.
So now we can use 'git show @~1', and all that goody goodness.
Until now '@' was a valid name, but it conflicts with this idea, so
let's make it invalid. Probably very few people, if any, used this name.
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Allow a safer "rewind of the remote tip" push than blind "--force",
by requiring that the overwritten remote ref to be unchanged since
the new history to replace it was prepared.
The machinery is more or less ready. The "--force" option is again
the big red button to override any safety, thanks to J6t's sanity
(the original round allowed --lockref to defeat --force).
The logic to choose the default implemented here is fragile
(e.g. "git fetch" after seeing a failure will update the
remote-tracking branch and will make the next "push" pass,
defeating the safety pretty easily). It is suitable only for the
simplest workflows, and it may hurt users more than it helps them.
* jc/push-cas:
push: teach --force-with-lease to smart-http transport
send-pack: fix parsing of --force-with-lease option
t5540/5541: smart-http does not support "--force-with-lease"
t5533: test "push --force-with-lease"
push --force-with-lease: tie it all together
push --force-with-lease: implement logic to populate old_sha1_expect[]
remote.c: add command line option parser for "--force-with-lease"
builtin/push.c: use OPT_BOOL, not OPT_BOOLEAN
cache.h: move remote/connect API out of it
Add 'struct ref_update' to encode the information needed to update or
delete a ref (name, new sha1, optional old sha1, no-deref flag). Add
function 'update_refs' accepting an array of updates to perform. First
sort the input array to order locks consistently everywhere and reject
multiple updates to the same ref. Then acquire locks on all refs with
verified old values. Then update or delete all refs accordingly. Fail
if any one lock cannot be obtained or any one old value does not match.
Though the refs themselves cannot be modified together in a single
atomic transaction, this function does enable some useful semantics.
For example, a caller may create a new branch starting from the head of
another branch and rewind the original branch at the same time. This
transfers ownership of commits between branches without risk of losing
commits added to the original branch by a concurrent process, or risk of
a concurrent process creating the new branch first.
Signed-off-by: Brad King <brad.king@kitware.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Generalize repack_without_ref as repack_without_refs to support a list
of refs and implement the former in terms of the latter.
Signed-off-by: Brad King <brad.king@kitware.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Factor loose ref deletion into helper function delete_ref_loose to allow
later use elsewhere.
Signed-off-by: Brad King <brad.king@kitware.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Factor the lock and write steps and error handling into helper functions
update_ref_lock and update_ref_write to allow later use elsewhere.
Expose lock_any_ref_for_update's type_p to update_ref_lock callers.
While at it, drop "static" from the local "lock" variable as it is not
necessary to keep across invocations.
Signed-off-by: Brad King <brad.king@kitware.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This is useful to make sure we don't step outside the boundaries of what
we are interpreting at the moment. For example while interpreting
foobar@{u}~1, the job of interpret_branch_name() ends right before ~1,
but there's no way to figure that out inside the function, unless the
len argument is passed.
So let's do that.
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Expose lock_ref_sha1_basic's type_p argument to callers of
lock_any_ref_for_update. Update all call sites to ignore it by passing
NULL for now.
Signed-off-by: Brad King <brad.king@kitware.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This reverts commit cdfd94837b, as it
does not just apply to "@" (and forms with modifiers like @{u}
applied to it), but also affects e.g. "refs/heads/@/foo", which it
shouldn't.
The basic idea of giving a short-hand might be good, and the topic
can be retried later, but let's revert to avoid affecting existing
use cases for now for the upcoming release.
Fix a NULL-pointer dereference during nested iterations over
references (for example, when replace references are being used).
* mh/packed-refs-do-one-ref-recursion:
do_one_ref(): save and restore value of current_ref
If do_one_ref() is called recursively, then the inner call should not
permanently overwrite the value stored in current_ref by the outer
call. Aside from the tiny optimization loss, peel_ref() expects the
value of current_ref not to change across a call to peel_entry(). But
in the presence of replace references that assumption could be
violated by a recursive call to do_one_ref:
do_for_each_entry()
do_one_ref()
builtin/describe.c:get_name()
peel_ref()
peel_entry()
peel_object ()
deref_tag_noverify()
parse_object()
lookup_replace_object()
do_lookup_replace_object()
prepare_replace_object()
do_for_each_ref()
do_for_each_entry()
do_for_each_entry_in_dir()
do_one_ref()
The inner call to do_one_ref() was unconditionally setting current_ref
to NULL when it was done, causing peel_ref() to perform an invalid
memory access.
So change do_one_ref() to save the old value of current_ref before
overwriting it, and restore the old value afterward rather than
setting it to NULL.
Reported-by: Mantas Mikulėnas <grawity@gmail.com>
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The definition of "struct ref" in "cache.h", a header file so
central to the system, always confused me. This structure is not
about the local ref used by sha1-name API to name local objects.
It is what refspecs are expanded into, after finding out what refs
the other side has, to define what refs are updated after object
transfer succeeds to what values. It belongs to "remote.h" together
with "struct refspec".
While we are at it, also move the types and functions related to the
Git transport connection to a new header file connect.h
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git pack-refs" that races with new ref creation or deletion have
been susceptible to lossage of refs under right conditions, which
has been tightened up.
* mh/ref-races:
for_each_ref: load all loose refs before packed refs
get_packed_ref_cache: reload packed-refs file when it changes
add a stat_validity struct
Extract a struct stat_data from cache_entry
packed_ref_cache: increment refcount when locked
do_for_each_entry(): increment the packed refs cache refcount
refs: manage lifetime of packed refs cache via reference counting
refs: implement simple transactions for the packed-refs file
refs: wrap the packed refs cache in a level of indirection
pack_refs(): split creation of packed refs and entry writing
repack_without_ref(): split list curation and entry writing
Now that we keep track of the packed-refs file metadata, we can detect
when the packed-refs file has been modified since we last read it, and
we do so automatically every time that get_packed_ref_cache() is
called. So there is no need to invalidate the cache automatically
when lock_packed_refs() is called; usually the old copy will still be
valid.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If we are iterating through the refs using for_each_ref (or
any of its sister functions), we can get into a race
condition with a simultaneous "pack-refs --prune" that looks
like this:
0. We have a large number of loose refs, and a few packed
refs. refs/heads/z/foo is loose, with no matching entry
in the packed-refs file.
1. Process A starts iterating through the refs. It loads
the packed-refs file from disk, then starts lazily
traversing through the loose ref directories.
2. Process B, running "pack-refs --prune", writes out the
new packed-refs file. It then deletes the newly packed
refs, including refs/heads/z/foo.
3. Meanwhile, process A has finally gotten to
refs/heads/z (it traverses alphabetically). It
descends, but finds nothing there. It checks its
cached view of the packed-refs file, but it does not
mention anything in "refs/heads/z/" at all (it predates
the new file written by B in step 2).
The traversal completes successfully without mentioning
refs/heads/z/foo at all (the name, of course, isn't
important; but the more refs you have and the farther down
the alphabetical list a ref is, the more likely it is to hit
the race). If refs/heads/z/foo did exist in the packed refs
file at state 0, we would see an entry for it, but it would
show whatever sha1 the ref had the last time it was packed
(which could be an arbitrarily long time ago).
This can be especially dangerous when process A is "git
prune", as it means our set of reachable tips will be
incomplete, and we may erroneously prune objects reachable
from that tip (the same thing can happen if "repack -ad" is
used, as it simply drops unreachable objects that are
packed).
This patch solves it by loading all of the loose refs for
our traversal into our in-memory cache, and then refreshing
the packed-refs cache. Because a pack-refs writer will
always put the new packed-refs file into place before
starting the prune, we know that any loose refs we fail to
see will either truly be missing, or will have already been
put in the packed-refs file by the time we refresh.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Once we read the packed-refs file into memory, we cache it
to save work on future ref lookups. However, our cache may
be out of date with respect to what is on disk if another
process is simultaneously packing the refs. Normally it
is acceptable for us to be a little out of date, since there
is no guarantee whether we read the file before or after the
simultaneous update. However, there is an important special
case: our packed-refs file must be up to date with respect
to any loose refs we read. Otherwise, we risk the following
race condition:
0. There exists a loose ref refs/heads/master.
1. Process A starts and looks up the ref "master". It
first checks $GIT_DIR/master, which does not exist. It
then loads (and caches) the packed-refs file to see if
"master" exists in it, which it does not.
2. Meanwhile, process B runs "pack-refs --all --prune". It
creates a new packed-refs file which contains
refs/heads/master, and removes the loose copy at
$GIT_DIR/refs/heads/master.
3. Process A continues its lookup, and eventually tries
$GIT_DIR/refs/heads/master. It sees that the loose ref
is missing, and falls back to the packed-refs file. But
it examines its cached version, which does not have
refs/heads/master. After trying a few other prefixes,
it reports master as a non-existent ref.
There are many variants (e.g., step 1 may involve process A
looking up another ref entirely, so even a fully qualified
refname can fail). One of the most interesting ones is if
"refs/heads/master" is already packed. In that case process
A will not see it as missing, but rather will report
whatever value happened to be in the packed-refs file before
process B repacked (which might be an arbitrarily old
value).
We can fix this by making sure we reload the packed-refs
file from disk after looking at any loose refs. That's
unacceptably slow, so we can check its stat()-validity as a
proxy, and read it only when it appears to have changed.
Reading the packed-refs file after performing any loose-ref
system calls is sufficient because we know the ordering of
the pack-refs process: it always makes sure the newly
written packed-refs file is installed into place before
pruning any loose refs. As long as those operations by B
appear in their executed order to process A, by the time A
sees the missing loose ref, the new packed-refs file must be
in place.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Increment the packed_ref_cache reference count while it is locked to
prevent its being freed.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This function calls a user-supplied callback function which could do
something that causes the packed refs cache to be invalidated. So
acquire a reference count on the data structure to prevent our copy
from being freed while we are iterating over it.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In struct packed_ref_cache, keep a count of the number of users of the
data structure. Only free the packed ref cache when the reference
count goes to zero rather than when the packed ref cache is cleared.
This mechanism will be used to prevent the cache data structure from
being freed while it is being iterated over.
So far, only the reference in struct ref_cache::packed is counted;
other users will be adjusted in separate commits.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Handle simple transactions for the packed-refs file at the
packed_ref_cache level via new functions lock_packed_refs(),
commit_packed_refs(), and rollback_packed_refs().
Only allow the packed ref cache to be modified (via add_packed_ref())
while the packed refs file is locked.
Change clone to add the new references within a transaction.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
As we know, we can solve any problem in this manner. In this case,
the problem is to avoid freeing a packed refs cache while somebody is
using it. So add a level of indirection as a prelude to
reference-counting the packed refs cache.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Split pack_refs() into multiple passes:
* Iterate over loose refs. For each one that can be turned into a
packed ref, create a corresponding entry in the packed refs cache.
* Write the packed refs to the packed-refs file.
This change isolates the mutation of the packed-refs file to a single
place.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The repack_without_ref() function first removes the deleted ref from
the internal packed-refs list, then writes the packed-refs list to
disk, omitting any broken or stale entries. This patch splits that
second step into multiple passes:
* collect the list of refnames that should be deleted from packed_refs
* delete those refnames from the cache
* write the remainder to the packed-refs file
The purpose of this change is to make the "write the remainder" part
reusable.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We read loose references in two steps. The code is roughly:
lstat()
if error ENOENT:
loose ref is missing; look for corresponding packed ref
else if S_ISLNK:
readlink()
if error:
report failure
else if S_ISDIR:
report failure
else
open()
if error:
report failure
read()
The problem is that the first filesystem call, to lstat(), is not
atomic with the second filesystem call, to readlink() or open().
Therefore it is possible for another process to change the file
between our two calls, for example:
* If the other process deletes the file, our second call will fail
with ENOENT, which we *should* interpret as "loose ref is missing;
look for corresponding packed ref". This can arise if the other
process is pack-refs; it might have just written a new packed-refs
file containing the old contents of the reference then deleted the
loose ref.
* If the other process changes a symlink into a plain file, our call
to readlink() will fail with EINVAL, which we *should* respond to by
trying to open() and read() the file.
The old code treats the reference as missing in both of these cases,
which is incorrect.
So instead, handle errors more selectively: if the result of
readline()/open() is a failure that is inconsistent with the result of
the previous lstat(), then something is fishy. In this case jump back
and start over again with a fresh call to lstat().
One race is still possible and undetected: another process could
change the file from a regular file into a symlink between the call to
lstat and the call to open(). The open() call would silently follow
the symlink and not know that something is wrong. This situation
could be detected in two ways:
* On systems that support O_NOFOLLOW, pass that option to the open().
* On other systems, call fstat() on the fd returned by open() and make
sure that it agrees with the stat info from the original lstat().
However, we don't use symlinks anymore, so this situation is unlikely.
Moreover, it doesn't appear that treating a symlink as a regular file
would have grave consequences; after all, this is exactly how the code
handles non-relative symlinks. So this commit leaves that race
unaddressed.
Note that this solves only the part of the race within
resolve_ref_unsafe. In the situation described above, we may still be
depending on a cached view of the packed-refs file; that race will be
dealt with in a future patch.
This problem was reported and diagnosed by Jeff King <peff@peff.net>,
and this solution is derived from his patch.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
There is only one "break" statement within the loop, which jumps to
the code after the loop that handles the case of a file that holds a
SHA-1. So move that code from below the loop into the if statement
where the break was previously located. This makes the logic flow
more local.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The nesting was getting a bit out of hand, and it's about to get
worse.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Update reading and updating packed-refs file, correcting corner case
bugs.
* mh/packed-refs-various: (33 commits)
refs: handle the main ref_cache specially
refs: change do_for_each_*() functions to take ref_cache arguments
pack_one_ref(): do some cheap tests before a more expensive one
pack_one_ref(): use write_packed_entry() to do the writing
pack_one_ref(): use function peel_entry()
refs: inline function do_not_prune()
pack_refs(): change to use do_for_each_entry()
refs: use same lock_file object for both ref-packing functions
pack_one_ref(): rename "path" parameter to "refname"
pack-refs: merge code from pack-refs.{c,h} into refs.{c,h}
pack-refs: rename handle_one_ref() to pack_one_ref()
refs: extract a function write_packed_entry()
repack_without_ref(): write peeled refs in the rewritten file
t3211: demonstrate loss of peeled refs if a packed ref is deleted
refs: change how packed refs are deleted
search_ref_dir(): return an index rather than a pointer
repack_without_ref(): silence errors for dangling packed refs
t3210: test for spurious error messages for dangling packed refs
refs: change the internal reference-iteration API
refs: extract a function peel_entry()
...
Typing 'HEAD' is tedious, especially when we can use '@' instead.
The reason for choosing '@' is that it follows naturally from the
ref@op syntax (e.g. HEAD@{u}), except we have no ref, and no
operation, and when we don't have those, it makes sens to assume
'HEAD'.
So now we can use 'git show @~1', and all that goody goodness.
Until now '@' was a valid name, but it conflicts with this idea, so
let's make it invalid. Probably very few people, if any, used this name.
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Hold the ref_cache instance for the main repository in a dedicated,
statically-allocated instance to avoid the need for a function call
and a linked-list traversal when it is needed.
Suggested by: Heiko Voigt <hvoigt@hvoigt.net>
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Change the callers convert submodule names into ref_cache pointers.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Change pack_refs() to work with a file descriptor instead of a FILE*
(making the file-locking code less awkward) and use
write_packed_entry() to do the writing.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Change pack_one_ref() to call peel_entry() rather than using its own
code for peeling references. Aside from sharing code, this lets it
take advantage of the optimization introduced by 6c4a060d7d.
Please note that we *could* use any peeled values that happen to
already be stored in the ref_entries, which would avoid some object
lookups for references that were already packed. But doing so would
also propagate any peeling errors across runs of "git pack-refs" and
give no way to recover from such errors. And "git pack-refs" isn't
run often enough that the performance cost is a problem. So instead,
add a new option to peel_entry() to force the entry to be re-peeled,
and call it with that option set.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Function do_not_prune() was redundantly checking REF_ISSYMREF, which
was already tested at the top of pack_one_ref(), so remove that check.
And the rest was trivial, so inline the function.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
pack_refs() was not using any of the extra features of for_each_ref(),
so change it to use do_for_each_entry(). This also gives it access to
the ref_entry and in particular its peeled field, which will be taken
advantage of in the next commit.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Use a single struct lock_file for both pack_refs() and
repack_without_ref().
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Make this function conform to the naming convention established in
65385ef7d4 for the rest of the refs.c file.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
pack-refs.c doesn't contain much code, and the code it does contain is
closely related to reference handling. Moreover, there is some
duplication between pack_refs() and repack_without_ref(). Therefore,
merge pack-refs.c into refs.c and pack-refs.h into refs.h.
The code duplication will be addressed in future commits.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Extract the I/O code from the "business logic" in repack_ref_fn().
Later there will be another caller for this function.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When a reference that existed in the packed-refs file is deleted, the
packed-refs file must be rewritten. Previously, the file was
rewritten without any peeled refs, even if the file contained peeled
refs when it was read. This was not a bug, because the packed-refs
file header didn't claim that the file contained peeled values. But
it had a performance cost, because the repository would lose the
benefit of having precomputed peeled references until pack-refs was
run again.
Teach repack_without_ref() to write peeled refs to the packed-refs
file (regardless of whether they were present in the old version of
the file).
This means that if the old version of the packed-refs file was not
fully peeled, then repack_without_ref() will have to peel references.
To avoid the expense of reading lots of loose references, we take two
shortcuts relative to pack-refs:
* If the peeled value of a reference is already known (i.e., because
it was read from the old version of the packed-refs file), then
output that peeled value again without any checks. This is the
usual code path and should avoid any noticeable overhead. (This is
different than pack-refs, which always re-peels references.)
* We don't verify that the packed ref is still current. It could be
that a packed references is overridden by a loose reference, in
which case the packed ref is no longer needed and might even refer
to an object that has been garbage collected. But we don't check;
instead, we just try to peel all references. If peeling is
successful, the peeled value is written out (even though it might
not be needed any more); if not, then the reference is silently
omitted from the output.
The extra overhead of peeling references in repack_without_ref()
should only be incurred the first time the packed-refs file is written
by a version of Git that knows about the "fully-peeled" attribute.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a function remove_ref(), which removes a single entry from a
reference cache.
Use this function to reimplement repack_without_ref(). The old
version iterated over all refs, packing all of them except for the one
to be deleted, then discarded the entire packed reference cache. The
new version deletes the doomed reference from the cache *before*
iterating.
This has two advantages:
* the code for writing packed-refs becomes simpler, because it doesn't
have to exclude one of the references.
* it is no longer necessary to discard the packed refs cache after
deleting a reference: symbolic refs cannot be packed, so packed
references cannot depend on each other, so the rest of the packed
refs cache remains valid after a reference is deleted.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Change search_ref_dir() to return the index of the sought entry (or -1
on error) rather than a pointer to the entry. This will make it more
natural to use the function for removing an entry from the list.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Stop emitting an error message when deleting a packed reference if we
find another dangling packed reference that is overridden by a loose
reference. See the previous commit for a longer explanation of the
issue.
We have to be careful to make sure that the invalid packed reference
really *is* overridden by a loose reference; otherwise what we have
found is repository corruption, which we *should* report.
Please note that this approach is vulnerable to a race condition
similar to the race conditions already known to affect packed
references [1]:
* Process 1 tries to peel packed reference X as part of deleting
another packed reference. It discovers that X does not refer to a
valid object (because the object that it referred to has been
garbage collected).
* Process 2 tries to delete reference X. It starts by deleting the
loose reference X.
* Process 1 checks whether there is a loose reference X. There is not
(it has just been deleted by process 2), so process 1 reports a
spurious error "X does not point to a valid object!"
The worst case seems relatively harmless, and the fix is identical to
the fix that will be needed for the other race conditions (namely
holding a lock on the packed-refs file during *all* reference
deletions), so we leave the cleaning up of all of them as a future
project.
[1] http://thread.gmane.org/gmane.comp.version-control.git/211956
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Establish an internal API for iterating over references, which gives
the callback functions direct access to the ref_entry structure
describing the reference. (Do not change the iteration API that is
exposed outside of the module.)
Define a new internal callback signature
int each_ref_entry_fn(struct ref_entry *entry, void *cb_data)
Change do_for_each_ref_in_dir() and do_for_each_ref_in_dirs() to
accept each_ref_entry_fn callbacks, and rename them to
do_for_each_entry_in_dir() and do_for_each_entry_in_dirs(),
respectively. Adapt their callers accordingly.
Add a new function do_for_each_entry() analogous to do_for_each_ref()
but using the new callback style.
Change do_one_ref() into an each_ref_entry_fn that does some
bookkeeping and then calls a wrapped each_ref_fn.
Reimplement do_for_each_ref() in terms of do_for_each_entry(), using
do_one_ref() as an adapter.
Please note that the responsibility for setting current_ref remains in
do_one_ref(), which means that current_ref is *not* set when iterating
over references via the new internal API. This is not a disadvantage,
because current_ref is not needed by callers of the internal API (they
receive a pointer to the current ref_entry anyway). But more
importantly, this change prevents peel_ref() from returning invalid
results in the following scenario:
When iterating via the external API, the iteration always includes
both packed and loose references, and in particular never presents a
packed ref if there is a loose ref with the same name. The internal
API, on the other hand, gives the option to iterate over only the
packed references. During such an iteration, there is no check
whether the packed ref might be hidden by a loose ref of the same
name. But until now the packed ref was recorded in current_ref during
the iteration. So if peel_ref() were called with the reference name
corresponding to current ref, it would return the peeled version of
the packed ref even though there might be a loose ref that peels to a
different value. This scenario doesn't currently occur in the code,
but fix it to prevent things from breaking in a very confusing way in
the future.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Peel the entry, and as a side effect store the peeled value in the
entry. Use this function from two places in peel_ref(); a third
caller will be added soon.
Please note that this change can lead to ref_entries for unpacked refs
being peeled. This has no practical benefit but is harmless.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The old version was inconsistent: when a reference was
REF_KNOWS_PEELED but with a null peeled value, it returned non-zero
for the current reference but zero for other references. Change the
behavior for non-current references to match that of current_ref,
which is what callers expect. Document the behavior.
Current callers only call peel_ref() from within a for_each_ref-style
iteration and only for the current ref; therefore, the buggy code path
was never reached.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Instead of just returning a success/failure bit, return an enumeration
value that explains the reason for any failure. This will come in
handy shortly.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
It is a nice, logical unit of work, and putting it in a function
removes the need to use a goto in peel_ref(). Soon it will also have
other uses.
The algorithm is unchanged.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
It is a nice unit of work and soon will be needed from multiple
locations.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Instead of copying the reference's SHA1 into a caller-supplied
variable, just return the ref_entry itself (or NULL if there is no
such entry). This change will allow the function to be used from
elsewhere.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
There is no way to drop out of the while loop. This code has been
dead since 432ad41e.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
