Commit Graph

341 Commits

Author SHA1 Message Date
Junio C Hamano
89563ec379 Merge branch 'jk/incore-lockfile-removal'
The long-standing rule that an in-core lockfile instance, once it
is used, must not be freed, has been lifted and the lockfile and
tempfile APIs have been updated to reduce the chance of programming
errors.

* jk/incore-lockfile-removal:
  stop leaking lock structs in some simple cases
  ref_lock: stop leaking lock_files
  lockfile: update lifetime requirements in documentation
  tempfile: auto-allocate tempfiles on heap
  tempfile: remove deactivated list entries
  tempfile: use list.h for linked list
  tempfile: release deactivated strbufs instead of resetting
  tempfile: robustify cleanup handler
  tempfile: factor out deactivation
  tempfile: factor out activation
  tempfile: replace die("BUG") with BUG()
  tempfile: handle NULL tempfile pointers gracefully
  tempfile: prefer is_tempfile_active to bare access
  lockfile: do not rollback lock on failed close
  tempfile: do not delete tempfile on failed close
  always check return value of close_tempfile
  verify_signed_buffer: prefer close_tempfile() to close()
  setup_temporary_shallow: move tempfile struct into function
  setup_temporary_shallow: avoid using inactive tempfile
  write_index_as_tree: cleanup tempfile on error
2017-09-19 10:47:53 +09:00
Junio C Hamano
8a044c7f1d Merge branch 'nd/prune-in-worktree'
"git gc" and friends when multiple worktrees are used off of a
single repository did not consider the index and per-worktree refs
of other worktrees as the root for reachability traversal, making
objects that are in use only in other worktrees to be subject to
garbage collection.

* nd/prune-in-worktree:
  refs.c: reindent get_submodule_ref_store()
  refs.c: remove fallback-to-main-store code get_submodule_ref_store()
  rev-list: expose and document --single-worktree
  revision.c: --reflog add HEAD reflog from all worktrees
  files-backend: make reflog iterator go through per-worktree reflog
  revision.c: --all adds HEAD from all worktrees
  refs: remove dead for_each_*_submodule()
  refs.c: move for_each_remote_ref_submodule() to submodule.c
  revision.c: use refs_for_each*() instead of for_each_*_submodule()
  refs: add refs_head_ref()
  refs: move submodule slash stripping code to get_submodule_ref_store
  refs.c: refactor get_submodule_ref_store(), share common free block
  revision.c: --indexed-objects add objects from all worktrees
  revision.c: refactor add_index_objects_to_pending()
  refs.c: use is_dir_sep() in resolve_gitlink_ref()
  revision.h: new flag in struct rev_info wrt. worktree-related refs
2017-09-19 10:47:53 +09:00
Junio C Hamano
dafbe1993e Merge branch 'ma/split-symref-update-fix'
A leakfix.

* ma/split-symref-update-fix:
  refs/files-backend: add `refname`, not "HEAD", to list
  refs/files-backend: correct return value in lock_ref_for_update
  refs/files-backend: fix memory leak in lock_ref_for_update
  refs/files-backend: add longer-scoped copy of string to list
2017-09-19 10:47:53 +09:00
Michael Haggerty
a8811695e3 read_packed_refs(): make parsing of the header line more robust
The old code parsed the traits in the `packed-refs` header by looking
for the string " trait " (i.e., the name of the trait with a space on
either side) in the header line. This is fragile, because if any other
implementation of Git forgets to write the trailing space, the last
trait would silently be ignored (and the error might never be
noticed).

So instead, use `string_list_split_in_place()` to split the traits
into tokens then use `unsorted_string_list_has_string()` to look for
the tokens we are interested in. This means that we can read the
traits correctly even if the header line is missing a trailing
space (or indeed, if it is missing the space after the colon, or if it
has multiple spaces somewhere).

However, older Git clients (and perhaps other Git implementations)
still require the surrounding spaces, so we still have to output the
header with a trailing space.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-14 15:19:07 +09:00
Michael Haggerty
36f23534ae read_packed_refs(): only check for a header at the top of the file
This tightens up the parsing a bit; previously, stray header-looking
lines would have been processed.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-14 15:19:07 +09:00
Michael Haggerty
49a03ef466 read_packed_refs(): use mmap to read the packed-refs file
It's still done in a pretty stupid way, involving more data copying
than necessary. That will improve in future commits.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-14 15:19:07 +09:00
Michael Haggerty
735267aa10 die_unterminated_line(), die_invalid_line(): new functions
Extract some helper functions for reporting errors. While we're at it,
prevent them from spewing unlimited output to the terminal. These
functions will soon have more callers.

These functions accept the problematic line as a `(ptr, len)` pair
rather than a NUL-terminated string, and `die_invalid_line()` checks
for an EOL itself, because these calling conventions will be
convenient for future callers. (Efficiency is not a concern here
because these functions are only ever called if the `packed-refs` file
is corrupt.)

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-14 15:19:07 +09:00
Michael Haggerty
f0a7dc86d2 packed_ref_cache: add a backlink to the associated packed_ref_store
It will prove convenient in upcoming patches.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-14 15:19:07 +09:00
Jeff King
157113c614 prefix_ref_iterator: break when we leave the prefix
If the underlying iterator is ordered, then `prefix_ref_iterator` can
stop as soon as it sees a refname that comes after the prefix. This
will rarely make a big difference now, because `ref_cache_iterator`
only iterates over the directory containing the prefix (and usually
the prefix will span a whole directory anyway). But if *hint, hint* a
future reference backend doesn't itself know where to stop the
iteration, then this optimization will be a big win.

Note that there is no guarantee that the underlying iterator doesn't
include output preceding the prefix, so we have to skip over any
unwanted references before we get to the ones that we want.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-14 15:19:07 +09:00
Michael Haggerty
8738a8a4df ref_iterator: keep track of whether the iterator output is ordered
References are iterated over in order by refname, but reflogs are not.
Some consumers of reference iteration care about the difference. Teach
each `ref_iterator` to keep track of whether its output is ordered.

`overlay_ref_iterator` is one of the picky consumers. Add a sanity
check in `overlay_ref_iterator_begin()` to verify that its inputs are
ordered.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-14 15:19:07 +09:00
Jeff King
564bde9ae6 convert less-trivial versions of "write_in_full() != len"
The prior commit converted many sites to check the return
value of write_in_full() for negativity, rather than a
mismatch with the input length. This patch covers similar
cases, but where the return value is stored in an
intermediate variable. These should get the same treatment,
but they need to be reviewed more carefully since it would
be a bug if the return value is stored in an unsigned type
(which indeed, it is in one of the cases).

Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-14 15:17:59 +09:00
Jeff King
06f46f237a avoid "write_in_full(fd, buf, len) != len" pattern
The return value of write_in_full() is either "-1", or the
requested number of bytes[1]. If we make a partial write
before seeing an error, we still return -1, not a partial
value. This goes back to f6aa66cb95 (write_in_full: really
write in full or return error on disk full., 2007-01-11).

So checking anything except "was the return value negative"
is pointless. And there are a couple of reasons not to do
so:

  1. It can do a funny signed/unsigned comparison. If your
     "len" is signed (e.g., a size_t) then the compiler will
     promote the "-1" to its unsigned variant.

     This works out for "!= len" (unless you really were
     trying to write the maximum size_t bytes), but is a
     bug if you check "< len" (an example of which was fixed
     recently in config.c).

     We should avoid promoting the mental model that you
     need to check the length at all, so that new sites are
     not tempted to copy us.

  2. Checking for a negative value is shorter to type,
     especially when the length is an expression.

  3. Linus says so. In d34cf19b89 (Clean up write_in_full()
     users, 2007-01-11), right after the write_in_full()
     semantics were changed, he wrote:

       I really wish every "write_in_full()" user would just
       check against "<0" now, but this fixes the nasty and
       stupid ones.

     Appeals to authority aside, this makes it clear that
     writing it this way does not have an intentional
     benefit. It's a historical curiosity that we never
     bothered to clean up (and which was undoubtedly
     cargo-culted into new sites).

So let's convert these obviously-correct cases (this
includes write_str_in_full(), which is just a wrapper for
write_in_full()).

[1] A careful reader may notice there is one way that
    write_in_full() can return a different value. If we ask
    write() to write N bytes and get a return value that is
    _larger_ than N, we could return a larger total. But
    besides the fact that this would imply a totally broken
    version of write(), it would already invoke undefined
    behavior. Our internal remaining counter is an unsigned
    size_t, which means that subtracting too many byte will
    wrap it around to a very large number. So we'll instantly
    begin reading off the end of the buffer, trying to write
    gigabytes (or petabytes) of data.

Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-14 15:17:59 +09:00
Martin Ågren
276d0e35c0 refs/files-backend: add refname, not "HEAD", to list
An earlier patch rewrote `split_symref_update()` to add a copy of a
string to a string list instead of adding the original string. That was
so that the original string could be freed in a later patch, but it is
also conceptually cleaner, since now all calls to `string_list_insert()`
and `string_list_append()` add `update->refname`. --- Except a literal
"HEAD" is added in `split_head_update()`.

Restructure `split_head_update()` in the same way as the earlier patch
did for `split_symref_update()`. This does not correct any practical
problem, but makes things conceptually cleaner. The downside is a call
to `string_list_has_string()`, which should be relatively cheap.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-10 16:36:58 +09:00
Martin Ågren
3f5ef95b5e refs/files-backend: correct return value in lock_ref_for_update
In one code path we return a literal -1 and not a symbolic constant. The
value -1 would be interpreted as TRANSACTION_NAME_CONFLICT, which is
wrong. Use TRANSACTION_GENERIC_ERROR instead (that is the only other
return value we have to choose from).

Noticed-by: Michael Haggerty <mhagger@alum.mit.edu>
Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-10 16:36:58 +09:00
Martin Ågren
851e1fbd01 refs/files-backend: fix memory leak in lock_ref_for_update
After the previous patch, none of the functions we call hold on to
`referent.buf`, so we can safely release the string buffer before
returning.

Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-10 16:36:58 +09:00
Martin Ågren
c299468bd7 refs/files-backend: add longer-scoped copy of string to list
split_symref_update() receives a string-pointer `referent` and adds it
to the list of `affected_refnames`. The list simply holds on to the
pointers it is given, it does not copy the strings and it does not ever
free them. The `referent` string in split_symref_update() belongs to a
string buffer in the caller. After we return, the string will be leaked.

In the next patch, we want to properly release the string buffer in the
caller, but we can't safely do so until we've made sure that
`affected_refnames` will not be holding on to a pointer to the string.
We could configure the list to handle its own resources, but it would
mean some alloc/free-churning. The list is already handling other
strings (through other code paths) which we do not need to worry about,
and we'd be memory-churning those strings too, completely unnecessary.

Observe that split_symref_update() creates a `new_update`-object through
ref_transaction_add_update(), after which `new_update->refname` is a
copy of `referent`. The difference is, this copy will be freed, and it
will be freed *after* `affected_refnames` has been cleared.

Rearrange the handling of `referent`, so that we don't add it directly
to `affected_refnames`. Instead, first just check whether `referent`
exists in the string list, and later add `new_update->refname`.

Helped-by: Michael Haggerty <mhagger@alum.mit.edu>
Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-10 16:36:58 +09:00
Michael Haggerty
5e00a6c873 files_transaction_finish(): delete reflogs before references
If the deletion steps unexpectedly fail, it is less bad to leave a
reference without its reflog than it is to leave a reflog without its
reference, since the latter is an invalid repository state.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-09 03:18:04 +09:00
Michael Haggerty
9939b33d6a packed-backend: rip out some now-unused code
Now the outside world interacts with the packed ref store only via the
generic refs API plus a few lock-related functions. This allows us to
delete some functions that are no longer used, thereby completing the
encapsulation of the packed ref store.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-09 03:18:04 +09:00
Michael Haggerty
dc39e09942 files_ref_store: use a transaction to update packed refs
When processing a `files_ref_store` transaction, it is sometimes
necessary to delete some references from the "packed-refs" file. Do
that using a reference transaction conducted against the
`packed_ref_store`.

This change further decouples `files_ref_store` from
`packed_ref_store`. It also fixes multiple problems, including the two
revealed by test cases added in the previous commit.

First, the old code didn't obtain the `packed-refs` lock until
`files_transaction_finish()`. This means that a failure to acquire the
`packed-refs` lock (e.g., due to contention with another process)
wasn't detected until it was too late (problems like this are supposed
to be detected in the "prepare" phase). The new code acquires the
`packed-refs` lock in `files_transaction_prepare()`, the same stage of
the processing when the loose reference locks are being acquired,
removing another reason why the "prepare" phase might succeed and the
"finish" phase might nevertheless fail.

Second, the old code deleted the loose version of a reference before
deleting any packed version of the same reference. This left a moment
when another process might think that the packed version of the
reference is current, which is incorrect. (Even worse, the packed
version of the reference can be arbitrarily old, and might even point
at an object that has since been garbage-collected.)

Third, if a reference deletion fails to acquire the `packed-refs` lock
altogether, then the old code might leave the repository in the
incorrect state (possibly corrupt) described in the previous
paragraph.

Now we activate the new "packed-refs" file (sans any references that
are being deleted) *before* deleting the corresponding loose
references. But we hold the "packed-refs" lock until after the loose
references have been finalized, thus preventing a simultaneous
"pack-refs" process from packing the loose version of the reference in
the time gap, which would otherwise defeat our attempt to delete it.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-09 03:18:04 +09:00
Michael Haggerty
1444bfe027 files_initial_transaction_commit(): use a transaction for packed refs
Use a `packed_ref_store` transaction in the implementation of
`files_initial_transaction_commit()` rather than using internal
features of the packed ref store. This further decouples
`files_ref_store` from `packed_ref_store`.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-09 03:18:04 +09:00
Michael Haggerty
22b09cdfad prune_refs(): also free the linked list
At least since v1.7, the elements of the `refs_to_prune` linked list
have been leaked. Fix the leak by teaching `prune_refs()` to free the
list elements as it processes them.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-09 03:18:04 +09:00
Michael Haggerty
27d03d04d5 files_pack_refs(): use a reference transaction to write packed refs
Now that the packed reference store supports transactions, we can use
a transaction to write the packed versions of references that we want
to pack. This decreases the coupling between `files_ref_store` and
`packed_ref_store`.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-09 03:18:04 +09:00
Michael Haggerty
2fb330ca72 packed_delete_refs(): implement method
Implement `packed_delete_refs()` using a reference transaction. This
means that `files_delete_refs()` can use `refs_delete_refs()` instead
of `repack_without_refs()` to delete any packed references, decreasing
the coupling between the classes.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-09 03:18:04 +09:00
Michael Haggerty
2775d8724d packed_ref_store: implement reference transactions
Implement the methods needed to support reference transactions for
the packed-refs backend. The new methods are not yet used.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-09 03:18:03 +09:00
Michael Haggerty
3bf4f56134 struct ref_transaction: add a place for backends to store data
`packed_ref_store` is going to want to store some transaction-wide
data, so make a place for it.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-09 03:18:03 +09:00
Michael Haggerty
39c8df0cfe packed-backend: don't adjust the reference count on lock/unlock
The old code incremented the packed ref cache reference count when
acquiring the packed-refs lock, and decremented the count when
releasing the lock. This is unnecessary because:

* Another process cannot change the packed-refs file because it is
  locked.

* When we ourselves change the packed-refs file, we do so by first
  modifying the packed ref-cache, and then writing the data from the
  ref-cache to disk. So the packed ref-cache remains fresh because any
  changes that we plan to make to the file are made in the cache first
  anyway.

So there is no reason for the cache to become stale.

Moreover, the extra reference count causes a problem if we
intentionally clear the packed refs cache, as we sometimes need to do
if we change the cache in anticipation of writing a change to disk,
but then the write to disk fails. In that case, `packed_refs_unlock()`
would have no easy way to find the cache whose reference count it
needs to decrement.

This whole issue will soon become moot due to upcoming changes that
avoid changing the in-memory cache as part of updating the packed-refs
on disk, but this change makes that transition easier.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-09 03:18:03 +09:00
Jeff King
ee4d8e455c ref_lock: stop leaking lock_files
Since the tempfile code recently relaxed the rule that
tempfile structs (and thus locks) need to hang around
forever, we no longer have to leak our lock_file structs.

In fact, we don't even need to heap-allocate them anymore,
since their lifetime can just match that of the surrounding
ref_lock (and if we forget to delete a lock, the effect is
the same as before: it will eventually go away at program
exit).

Note that there is a check in unlock_ref() to only rollback
a lock file if it has been allocated. We don't need that
check anymore; we zero the ref_lock (and thus the
lock_file), so at worst we pass a NULL pointer to
delete_tempfile(), which considers that a noop.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-06 17:19:54 +09:00
Jeff King
076aa2cbda tempfile: auto-allocate tempfiles on heap
The previous commit taught the tempfile code to give up
ownership over tempfiles that have been renamed or deleted.
That makes it possible to use a stack variable like this:

  struct tempfile t;

  create_tempfile(&t, ...);
  ...
  if (!err)
          rename_tempfile(&t, ...);
  else
          delete_tempfile(&t);

But doing it this way has a high potential for creating
memory errors. The tempfile we pass to create_tempfile()
ends up on a global linked list, and it's not safe for it to
go out of scope until we've called one of those two
deactivation functions.

Imagine that we add an early return from the function that
forgets to call delete_tempfile(). With a static or heap
tempfile variable, the worst case is that the tempfile hangs
around until the program exits (and some functions like
setup_shallow_temporary rely on this intentionally, creating
a tempfile and then leaving it for later cleanup).

But with a stack variable as above, this is a serious memory
error: the variable goes out of scope and may be filled with
garbage by the time the tempfile code looks at it.  Let's
see if we can make it harder to get this wrong.

Since many callers need to allocate arbitrary numbers of
tempfiles, we can't rely on static storage as a general
solution. So we need to turn to the heap. We could just ask
all callers to pass us a heap variable, but that puts the
burden on them to call free() at the right time.

Instead, let's have the tempfile code handle the heap
allocation _and_ the deallocation (when the tempfile is
deactivated and removed from the list).

This changes the return value of all of the creation
functions. For the cleanup functions (delete and rename),
we'll add one extra bit of safety: instead of taking a
tempfile pointer, we'll take a pointer-to-pointer and set it
to NULL after freeing the object. This makes it safe to
double-call functions like delete_tempfile(), as the second
call treats the NULL input as a noop. Several callsites
follow this pattern.

The resulting patch does have a fair bit of noise, as each
caller needs to be converted to handle:

  1. Storing a pointer instead of the struct itself.

  2. Passing the pointer instead of taking the struct
     address.

  3. Handling a "struct tempfile *" return instead of a file
     descriptor.

We could play games to make this less noisy. For example, by
defining the tempfile like this:

  struct tempfile {
	struct heap_allocated_part_of_tempfile {
                int fd;
                ...etc
        } *actual_data;
  }

Callers would continue to have a "struct tempfile", and it
would be "active" only when the inner pointer was non-NULL.
But that just makes things more awkward in the long run.
There aren't that many callers, so we can simply bite
the bullet and adjust all of them. And the compiler makes it
easy for us to find them all.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-06 17:19:54 +09:00
Jeff King
83a3069a38 lockfile: do not rollback lock on failed close
Since the lockfile code is based on the tempfile code, it
has some of the same problems, including that close_lock_file()
erases the tempfile's filename buf, making it hard for the
caller to write a good error message.

In practice this comes up less for lockfiles than for
straight tempfiles, since we usually just report the
refname. But there is at least one buggy case in
write_ref_to_lockfile(). Besides, given the coupling between
the lockfile and tempfile modules, it's less confusing if
their close() functions have the same semantics.

Just as the previous commit did for close_tempfile(), let's
teach close_lock_file() and its wrapper close_ref() not to
rollback on error. And just as before, we'll give them new
"gently" names to catch any new callers that are added.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-06 17:19:53 +09:00
Junio C Hamano
f2dd90fc1c Merge branch 'mh/ref-lock-entry'
The code to acquire a lock on a reference (e.g. while accepting a
push from a client) used to immediately fail when the reference is
already locked---now it waits for a very short while and retries,
which can make it succeed if the lock holder was holding it during
a read-only operation.

* mh/ref-lock-entry:
  refs: retry acquiring reference locks for 100ms
2017-08-26 22:55:09 -07:00
Nguyễn Thái Ngọc Duy
944b4e3013 files-backend: make reflog iterator go through per-worktree reflog
refs/bisect is unfortunately per-worktree, so we need to look in
per-worktree logs/refs/bisect in addition to per-repo logs/refs. The
current iterator only goes through per-repo logs/refs.

Use merge iterator to walk two ref stores at the same time and pick
per-worktree refs from the right iterator.

PS. Note the unsorted order of for_each_reflog in the test. This is
supposed to be OK, for now. If we enforce order on for_each_reflog()
then some more work will be required.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-08-24 14:57:56 -07:00
Michael Haggerty
4ff0f01cb7 refs: retry acquiring reference locks for 100ms
The philosophy of reference locking has been, "if another process is
changing a reference, then whatever I'm trying to do to it will
probably fail anyway because my old-SHA-1 value is probably no longer
current". But this argument falls down if the other process has locked
the reference to do something that doesn't actually change the value
of the reference, such as `pack-refs` or `reflog expire`. There
actually *is* a decent chance that a planned reference update will
still be able to go through after the other process has released the
lock.

So when trying to lock an individual reference (e.g., when creating
"refs/heads/master.lock"), if it is already locked, then retry the
lock acquisition for approximately 100 ms before giving up. This
should eliminate some unnecessary lock conflicts without wasting a lot
of time.

Add a configuration setting, `core.filesRefLockTimeout`, to allow this
setting to be tweaked.

Note: the function `get_files_ref_lock_timeout_ms()` cannot be private
to the files backend because it is also used by `write_pseudoref()`
and `delete_pseudoref()`, which are defined in `refs.c` so that they
can be used by other reference backends.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-08-23 10:37:21 -07:00
Junio C Hamano
44c2339e55 Merge branch 'mh/packed-ref-store'
The "ref-store" code reorganization continues.

* mh/packed-ref-store: (32 commits)
  files-backend: cheapen refname_available check when locking refs
  packed_ref_store: handle a packed-refs file that is a symlink
  read_packed_refs(): die if `packed-refs` contains bogus data
  t3210: add some tests of bogus packed-refs file contents
  repack_without_refs(): don't lock or unlock the packed refs
  commit_packed_refs(): remove call to `packed_refs_unlock()`
  clear_packed_ref_cache(): don't protest if the lock is held
  packed_refs_unlock(), packed_refs_is_locked(): new functions
  packed_refs_lock(): report errors via a `struct strbuf *err`
  packed_refs_lock(): function renamed from lock_packed_refs()
  commit_packed_refs(): use a staging file separate from the lockfile
  commit_packed_refs(): report errors rather than dying
  packed_ref_store: make class into a subclass of `ref_store`
  packed-backend: new module for handling packed references
  packed_read_raw_ref(): new function, replacing `resolve_packed_ref()`
  packed_ref_store: support iteration
  packed_peel_ref(): new function, extracted from `files_peel_ref()`
  repack_without_refs(): take a `packed_ref_store *` parameter
  get_packed_ref(): take a `packed_ref_store *` parameter
  rollback_packed_refs(): take a `packed_ref_store *` parameter
  ...
2017-08-22 10:29:16 -07:00
Michael Haggerty
8ec617c80c files-backend: cheapen refname_available check when locking refs
When locking references in preparation for updating them, we need to
check that none of the newly added references D/F conflict with
existing references (e.g., we don't allow `refs/foo` to be added if
`refs/foo/bar` already exists, or vice versa).

Prior to 524a9fdb51 (refs_verify_refname_available(): use function in
more places, 2017-04-16), conflicts with existing loose references
were checked by looking directly in the filesystem, and then conflicts
with existing packed references were checked by running
`verify_refname_available_dir()` against the packed-refs cache.

But that commit changed the final check to call
`refs_verify_refname_available()` against the *whole* files ref-store,
including both loose and packed references, with the following
comment:

> This means that those callsites now check for conflicts with all
> references rather than just packed refs, but the performance cost
> shouldn't be significant (and will be regained later).

That comment turned out to be too sanguine. User s@kazlauskas.me
reported that fetches involving a very large number of references in
neighboring directories were slowed down by that change.

The problem is that when fetching, each reference is updated
individually, within its own reference transaction. This is done
because some reference updates might succeed even though others fail.
But every time a reference update transaction is finished,
`clear_loose_ref_cache()` is called. So when it is time to update the
next reference, part of the loose ref cache has to be repopulated for
the `refs_verify_refname_available()` call. If the references are all
in neighboring directories, then the cost of repopulating the
reference cache increases with the number of references, resulting in
O(N²) effort.

The comment above also claims that the performance cost "will be
regained later". The idea was that once the packed-refs were finished
being split out into a separate ref-store, we could limit the
`refs_verify_refname_available()` call to the packed references again.
That is what we do now.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-08-17 14:32:23 -07:00
Michael Haggerty
198b808e20 packed_ref_store: handle a packed-refs file that is a symlink
One of the tricks that `contrib/workdir/git-new-workdir` plays is to
making `packed-refs` in the new workdir a symlink to the `packed-refs`
file in the original repository. Before
42dfa7ecef ("commit_packed_refs(): use a staging file separate from
the lockfile", 2017-06-23), a lockfile was used as the staging file,
and because the `LOCK_NO_DEREF` was not used, the pointed-to file was
locked and modified.

But after that commit, the staging file was created using a tempfile,
with the end result that rewriting the `packed-refs` file in the
workdir overwrote the symlink rather than the original `packed-refs`
file.

Change `commit_packed_refs()` to use `get_locked_file_path()` to find
the path of the file that it should overwrite. Since that path was
properly resolved when the lockfile was created, this restores the
pre-42dfa7ecef behavior.

Also add a test case to document this use case and prevent a
regression like this from recurring.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-07-27 10:19:56 -07:00
Michael Haggerty
9308b7f3ca read_packed_refs(): die if packed-refs contains bogus data
The old code ignored any lines that it didn't understand, including
unterminated lines. This is dangerous. Instead, `die()` if the
`packed-refs` file contains any unterminated lines or lines that we
don't know how to handle.

This fixes the tests added in the last commit.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-07-03 10:01:57 -07:00
Michael Haggerty
e5cc7d7d2b repack_without_refs(): don't lock or unlock the packed refs
Change `repack_without_refs()` to expect the packed-refs lock to be
held already, and not to release the lock before returning. Change the
callers to deal with lock management.

This change makes it possible for callers to hold the packed-refs lock
for a longer span of time, a possibility that will eventually make it
possible to fix some longstanding races.

The only semantic change here is that `repack_without_refs()` used to
forget to release the lock in the `if (!removed)` exit path. That
omission is now fixed.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-07-03 10:01:56 -07:00
Junio C Hamano
5c83d850d0 Merge branch 'mh/packed-ref-store-prep'
Bugfix for a topic that is (only) in 'master'.

* mh/packed-ref-store-prep:
  for_each_bisect_ref(): don't trim refnames
  lock_packed_refs(): fix cache validity check
2017-06-26 14:09:29 -07:00
Junio C Hamano
50f03c6676 Merge branch 'ab/free-and-null'
A common pattern to free a piece of memory and assign NULL to the
pointer that used to point at it has been replaced with a new
FREE_AND_NULL() macro.

* ab/free-and-null:
  *.[ch] refactoring: make use of the FREE_AND_NULL() macro
  coccinelle: make use of the "expression" FREE_AND_NULL() rule
  coccinelle: add a rule to make "expression" code use FREE_AND_NULL()
  coccinelle: make use of the "type" FREE_AND_NULL() rule
  coccinelle: add a rule to make "type" code use FREE_AND_NULL()
  git-compat-util: add a FREE_AND_NULL() wrapper around free(ptr); ptr = NULL
2017-06-24 14:28:41 -07:00
Junio C Hamano
f31d23a399 Merge branch 'bw/config-h'
Fix configuration codepath to pay proper attention to commondir
that is used in multi-worktree situation, and isolate config API
into its own header file.

* bw/config-h:
  config: don't implicitly use gitdir or commondir
  config: respect commondir
  setup: teach discover_git_directory to respect the commondir
  config: don't include config.h by default
  config: remove git_config_iter
  config: create config.h
2017-06-24 14:28:41 -07:00
Michael Haggerty
42c7f7ff96 commit_packed_refs(): remove call to packed_refs_unlock()
Instead, change the callers of `commit_packed_refs()` to call
`packed_refs_unlock()`.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:33 -07:00
Michael Haggerty
9051198214 clear_packed_ref_cache(): don't protest if the lock is held
The existing callers already check that the lock isn't held just
before calling `clear_packed_ref_cache()`, and in the near future we
want to be able to call this function when the lock is held.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:33 -07:00
Michael Haggerty
49aebcf432 packed_refs_unlock(), packed_refs_is_locked(): new functions
Add two new public functions, `packed_refs_unlock()` and
`packed_refs_is_locked()`, with which callers can manage and query the
`packed-refs` lock externally.

Call `packed_refs_unlock()` from `commit_packed_refs()` and
`rollback_packed_refs()`.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:33 -07:00
Michael Haggerty
c8bed835c2 packed_refs_lock(): report errors via a struct strbuf *err
That way the callers don't have to come up with error messages
themselves.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:33 -07:00
Michael Haggerty
b7de57d8d1 packed_refs_lock(): function renamed from lock_packed_refs()
Rename `lock_packed_refs()` to `packed_refs_lock()` for consistency
with how other methods are named. Also, it's about to get some
companions.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:33 -07:00
Michael Haggerty
42dfa7ecef commit_packed_refs(): use a staging file separate from the lockfile
We will want to be able to hold the lockfile for `packed-refs` even
after we have activated the new values. So use a separate tempfile,
`packed-refs.new`, as a place to stage the new contents of the
`packed-refs` file. For now this is all done within
`commit_packed_refs()`, but that will change shortly.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:33 -07:00
Michael Haggerty
3478983b51 commit_packed_refs(): report errors rather than dying
Report errors via a `struct strbuf *err` rather than by calling
`die()`. To enable this goal, change `write_packed_entry()` to report
errors via a return value and `errno` rather than dying.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:33 -07:00
Michael Haggerty
e0cc8ac820 packed_ref_store: make class into a subclass of ref_store
Add the infrastructure to make `packed_ref_store` implement
`ref_store`, at least formally (few of the methods are actually
implemented yet). Change the functions in its interface to take
`ref_store *` arguments. Change `files_ref_store` to store a pointer
to `ref_store *` and to call functions via the virtual `ref_store`
interface where possible. This also means that a few
`packed_ref_store` functions can become static.

This is a work in progress. Some more `ref_store` methods will soon be
implemented (e.g., those having to do with reference transactions).
But some of them will never be implemented (e.g., those having to do
with symrefs or reflogs).

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:33 -07:00
Michael Haggerty
67be7c5a59 packed-backend: new module for handling packed references
Now that the interface between `files_ref_store` and
`packed_ref_store` is relatively narrow, move the latter into a new
module, "refs/packed-backend.h" and "refs/packed-backend.c". It still
doesn't quite implement the `ref_store` interface, but it will soon.

This commit moves code around and adjusts its visibility, but doesn't
change anything.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:32 -07:00
Michael Haggerty
d13fa1a9ba packed_read_raw_ref(): new function, replacing resolve_packed_ref()
Add a new function, `packed_read_raw_ref()`, which is nearly a
`read_raw_ref_fn`. Use it in place of `resolve_packed_ref()`.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:32 -07:00
Michael Haggerty
38b86e81ae packed_ref_store: support iteration
Add the infrastructure to iterate over a `packed_ref_store`. It's a
lot of boilerplate, but it's all part of a campaign to make
`packed_ref_store` implement `ref_store`. In the future, this iterator
will work much differently.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:32 -07:00
Michael Haggerty
6dc6ba7092 packed_peel_ref(): new function, extracted from files_peel_ref()
This will later become a method of `packed_ref_store`.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:32 -07:00
Michael Haggerty
0f199b1ee0 repack_without_refs(): take a packed_ref_store * parameter
It only cares about the packed-refs part of the reference store.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:32 -07:00
Michael Haggerty
f3f9724940 get_packed_ref(): take a packed_ref_store * parameter
It only cares about the packed-refs part of the reference store.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:32 -07:00
Michael Haggerty
38e3fe6dec rollback_packed_refs(): take a packed_ref_store * parameter
It only cares about the packed-refs part of the reference store.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:32 -07:00
Michael Haggerty
cf30b3e88b commit_packed_refs(): take a packed_ref_store * parameter
It only cares about the packed-refs part of the reference store.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:32 -07:00
Michael Haggerty
f512f0f32c lock_packed_refs(): take a packed_ref_store * parameter
It only cares about the packed-refs part of the reference store.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:32 -07:00
Michael Haggerty
e70b70294e add_packed_ref(): take a packed_ref_store * parameter
It only cares about the packed-refs part of the reference store.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:32 -07:00
Michael Haggerty
a9169f5dc2 get_packed_refs(): take a packed_ref_store * parameter
It only cares about the packed-refs part of the reference store.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:32 -07:00
Michael Haggerty
8e821c38f7 get_packed_ref_cache(): take a packed_ref_store * parameter
It only cares about the packed-refs part of the reference store.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:32 -07:00
Michael Haggerty
25e0c5faf2 validate_packed_ref_cache(): take a packed_ref_store * parameter
It only cares about the packed-refs part of the reference store.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:32 -07:00
Michael Haggerty
9c4fe0ff95 clear_packed_ref_cache(): take a packed_ref_store * parameter
It only cares about the packed-refs part of the reference store.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:32 -07:00
Michael Haggerty
139c4596ad packed_ref_store: move packed_refs_lock member here
Move the `packed_refs_lock` member from `files_ref_store` to
`packed_ref_store`, and rename it to `lock` since it's now more
obvious what it is locking.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:32 -07:00
Michael Haggerty
e0d483970b packed_ref_store: move packed_refs_path here
Move `packed_refs_path` from `files_ref_store` to `packed_ref_store`,
and rename it to `path` since its meaning is clear from its new
context.

Inline `files_packed_refs_path()`.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:32 -07:00
Michael Haggerty
bdf55fa6b2 packed_ref_store: new struct
Start extracting the packed-refs-related data structures into a new
class, `packed_ref_store`. It doesn't yet implement `ref_store`, but
it will.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:32 -07:00
Michael Haggerty
2f10882166 add_packed_ref(): teach function to overwrite existing refs
Teach `add_packed_ref()` to overwrite an existing entry if one already
exists for the specified `refname`. This means that we can call it
from `files_pack_refs()`, thereby reducing the amount that the latter
function needs to know about the internals of packed-reference
handling.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-23 13:27:32 -07:00
Sahil Dua
52d59cc645 branch: add a --copy (-c) option to go with --move (-m)
Add the ability to --copy a branch and its reflog and configuration,
this uses the same underlying machinery as the --move (-m) option
except the reflog and configuration is copied instead of being moved.

This is useful for e.g. copying a topic branch to a new version,
e.g. work to work-2 after submitting the work topic to the list, while
preserving all the tracking info and other configuration that goes
with the branch, and unlike --move keeping the other already-submitted
branch around for reference.

Like --move, when the source branch is the currently checked out
branch the HEAD is moved to the destination branch. In the case of
--move we don't really have a choice (other than remaining on a
detached HEAD) and in order to keep the functionality consistent, we
are doing it in similar way for --copy too.

The most common usage of this feature is expected to be moving to a
new topic branch which is a copy of the current one, in that case
moving to the target branch is what the user wants, and doesn't
unexpectedly behave differently than --move would.

One outstanding caveat of this implementation is that:

    git checkout maint &&
    git checkout master &&
    git branch -c topic &&
    git checkout -

Will check out 'maint' instead of 'master'. This is because the @{-N}
feature (or its -1 shorthand "-") relies on HEAD reflogs created by
the checkout command, so in this case we'll checkout maint instead of
master, as the user might expect. What to do about that is left to a
future change.

Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Sahil Dua <sahildua2305@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-18 21:47:59 -07:00
Ævar Arnfjörð Bjarmason
88ce3ef636 *.[ch] refactoring: make use of the FREE_AND_NULL() macro
Replace occurrences of `free(ptr); ptr = NULL` which weren't caught by
the coccinelle rule. These fall into two categories:

 - free/NULL assignments one after the other which coccinelle all put
   on one line, which is functionally equivalent code, but very ugly.

 - manually spotted occurrences where the NULL assignment isn't right
   after the free() call.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-16 12:44:09 -07:00
Ævar Arnfjörð Bjarmason
6a83d90207 coccinelle: make use of the "type" FREE_AND_NULL() rule
Apply the result of the just-added coccinelle rule. This manually
excludes a few occurrences, mostly things that resulted in many
FREE_AND_NULL() on one line, that'll be manually fixed in a subsequent
change.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-16 12:44:03 -07:00
Brandon Williams
b2141fc1d2 config: don't include config.h by default
Stop including config.h by default in cache.h.  Instead only include
config.h in those files which require use of the config system.

Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-15 12:56:22 -07:00
Michael Haggerty
fed6ebebf1 lock_packed_refs(): fix cache validity check
Commit 28ed9830b1 (get_packed_ref_cache(): assume "packed-refs" won't
change while locked, 2017-05-22) assumes that the "packed-refs" file
cannot change while we hold the lock. That assumption is
justified *if* the lock has been held the whole time since the
"packed-refs" file was last read.

But in `lock_packed_refs()`, we ourselves lock the "packed-refs" file
and then call `get_packed_ref_cache()` to ensure that the cache agrees
with the file. The intent is to guard against the possibility that
another process changed the "packed-refs" file the moment before we
locked it.

This check was defeated because `get_packed_ref_cache()` saw that the
file was locked, and therefore didn't do the `stat_validity_check()`
that we want.

The mistake was compounded with a misleading comment in
`lock_packed_refs()` claiming that it was doing the right thing. That
comment came from an earlier draft of the mh/packed-ref-store-prep
patch series when the commits were in a different order.

So instead:

* Extract a function `validate_packed_ref_cache()` that does the
  validity check independent of whether the lock is held.

* Change `get_packed_ref_cache()` to call the new function, but only
  if the lock *isn't* held.

* Change `lock_packed_refs()` to call the new function in any case
  before calling `get_packed_ref_cache()`.

* Fix the comment in `lock_packed_refs()`.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-12 10:11:36 -07:00
Michael Haggerty
f23092f19e cache_ref_iterator_begin(): avoid priming unneeded directories
When iterating over references, reference priming is used to make sure
that loose references are read into the ref-cache before packed
references, to avoid races. It used to be that the prefix passed to
reference iterators almost always ended in `/`, for example
`refs/heads/`. In that case, the priming code would read all loose
references under `find_containing_dir("refs/heads/")`, which is
"refs/heads/". That's just what we want.

But now that `ref-filter` knows how to pass refname prefixes to
`for_each_fullref_in()`, the prefix might come from user input; for
example,

    git for-each-ref refs/heads

Since the argument doesn't include a trailing slash, the reference
iteration code would prime all of the loose references under
`find_containing_dir("refs/heads")`, which is "refs/". Thus we would
unnecessarily read tags, remote-tracking references, etc., when the
user is only interested in branches.

It is a bit awkward to get around this problem. We can't just append a
slash to the argument, because we don't know ab initio whether an
argument like `refs/tags/release` corresponds to a single tag or to a
directory containing tags.

Moreover, until now a `prefix_ref_iterator` was used to make the final
decision about which references fall within the prefix (the
`cache_ref_iterator` only did a rough cut). This is also inefficient,
because the `prefix_ref_iterator` can't know, for example, that while
you are in a subdirectory that is completely within the prefix, you
don't have to do the prefix check.

So:

* Move the responsibility for doing the prefix check directly to
  `cache_ref_iterator`. This means that `cache_ref_iterator_begin()`
  never has to wrap its return value in a `prefix_ref_iterator`.

* Teach `cache_ref_iterator_begin()` (and `prime_ref_dir()`) to be
  stricter about what they iterate over and what directories they
  prime.

* Teach `cache_ref_iterator` to keep track of whether the current
  `cache_ref_iterator_level` is fully within the prefix. If so, skip
  the prefix checks entirely.

The main benefit of these optimizations is for loose references, since
packed references are always read all at once.

Note that after this change, `prefix_ref_iterator` is only ever used
for its trimming feature and not for its "prefix" feature. But I'm not
ripping out the latter yet, because it might be useful for another
patch series that I'm working on.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-24 21:21:21 +09:00
Michael Haggerty
c1da06c6f1 create_ref_entry(): remove check_name option
Only one caller was using it, so move the check to that caller.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-23 14:29:56 +09:00
Michael Haggerty
0a0865b8f1 refs_ref_iterator_begin(): handle GIT_REF_PARANOIA
Instead of handling `GIT_REF_PARANOIA` in
`files_ref_iterator_begin()`, handle it in
`refs_ref_iterator_begin()`, where it will cover all reference stores.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-23 14:29:56 +09:00
Michael Haggerty
89c571da56 read_packed_refs(): report unexpected fopen() failures
The old code ignored any errors encountered when trying to fopen the
"packed-refs" file, treating all such failures as if the file didn't
exist. But it could be that there is some other error opening the
file (e.g., permissions problems), and we don't want to silently
ignore such problems. So report any failures that are not due to
ENOENT.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-23 14:29:56 +09:00
Michael Haggerty
099a912a27 read_packed_refs(): do more of the work of reading packed refs
Teach `read_packed_refs()` to also

* Allocate and initialize the new `packed_ref_cache`
* Open and close the `packed-refs` file
* Update the `validity` field of the new object

This decreases the coupling between `packed_refs_cache` and
`files_ref_store` by a little bit.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-23 14:29:55 +09:00
Michael Haggerty
28ed9830b1 get_packed_ref_cache(): assume "packed-refs" won't change while locked
If we've got the "packed-refs" file locked, then it can't change;
there's no need to keep calling `stat_validity_check()` on it.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-23 14:29:55 +09:00
Michael Haggerty
531cc4a56d should_pack_ref(): new function, extracted from files_pack_refs()
Extract a function for deciding whether a reference should be packed.
It is a self-contained bit of logic, so splitting it out improves
readability.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-23 14:29:55 +09:00
Michael Haggerty
2ced105cb1 ref_update_reject_duplicates(): expose function to whole refs module
It will soon have some other users.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-23 14:29:55 +09:00
Michael Haggerty
30173b8851 ref_transaction_prepare(): new optional step for reference updates
In the future, compound reference stores will sometimes need to modify
references in two different reference stores at the same time, meaning
that a single logical reference transaction might have to be
implemented as two internal sub-transactions. They won't want to call
`ref_transaction_commit()` for the two sub-transactions one after the
other, because that wouldn't be atomic (the first commit could succeed
and the second one fail). Instead, they will want to prepare both
sub-transactions (i.e., obtain any necessary locks and do any
pre-checks), and only if both prepare steps succeed, then commit both
sub-transactions.

Start preparing for that day by adding a new, optional
`ref_transaction_prepare()` step to the reference transaction
sequence, which obtains the locks and does any prechecks, reporting
any errors that occur. Also add a `ref_transaction_abort()` function
that can be used to abort a sub-transaction even if it has already
been prepared.

That is on the side of the public-facing API. On the side of the
`ref_store` VTABLE, get rid of `transaction_commit` and instead add
methods `transaction_prepare`, `transaction_finish`, and
`transaction_abort`. A `ref_transaction_commit()` now basically calls
methods `transaction_prepare` then `transaction_finish`.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-23 14:29:55 +09:00
Michael Haggerty
8d4240d3c8 ref_transaction_commit(): check for valid transaction->state
Move the check that `transaction->state` is valid from
`files_transaction_commit()` to `ref_transaction_commit()`, where
other future reference backends can benefit from it as well.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-23 14:29:55 +09:00
Michael Haggerty
c0ca935764 files_transaction_cleanup(): new helper function
Extract the cleanup functionality from `files_transaction_commit()`
into a new function. It will soon have another caller.

Use the common cleanup code even on early exit if the transaction is
empty, to reduce code duplication.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-23 14:29:55 +09:00
Michael Haggerty
00d174489e files_ref_store: put the packed files lock directly in this struct
Instead of using a global `lock_file` instance for the main
"packed-refs" file and using a pointer in `files_ref_store` to keep
track of whether it is locked, embed the `lock_file` instance directly
in the `files_ref_store` struct and use the new
`is_lock_file_locked()` function to keep track of whether it is
locked. This keeps related data together and makes the main reference
store less of a special case.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-23 14:29:54 +09:00
Michael Haggerty
55c6bc37c9 files-backend: move lock member to files_ref_store
Move the `lock` member from `packed_ref_cache` to `files_ref_store`,
since at most one cache can have a locked "packed-refs" file
associated with it. Rename it to `packed_refs_lock` to make its
purpose clearer in its new home. More changes are coming here shortly.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-23 14:29:54 +09:00
Michael Haggerty
64da41993a ref_store: take a msg parameter when deleting references
Just because the files backend can't retain reflogs for deleted
references is no reason that they shouldn't be supported by the
virtual method interface. Also, `delete_ref()` and `refs_delete_ref()`
have already gained `msg` parameters. Now let's add them to
`delete_refs()` and `refs_delete_refs()`.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-23 14:29:53 +09:00
Michael Haggerty
43a2dfde76 refs: use size_t indexes when iterating over ref transaction updates
Eliminate any chance of integer overflow on platforms where the two
types have different sizes.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-23 14:29:53 +09:00
Michael Haggerty
b9c8e7f2fb prefix_ref_iterator: don't trim too much
The `trim` parameter can be set independently of `prefix`. So if some
caller were to set `trim` to be greater than `strlen(prefix)`, we
could end up pointing the `refname` field of the iterator past the NUL
of the actual reference name string.

That can't happen currently, because `trim` is always set either to
zero or to `strlen(prefix)`. But even the latter could lead to
confusion, if a refname is exactly equal to the prefix, because then
we would set the outgoing `refname` to the empty string.

And we're about to decouple the `prefix` and `trim` arguments even
more, so let's be cautious here. Report a bug if ever asked to trim a
reference whose name is not longer than `trim`.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-23 14:29:52 +09:00
Michael Haggerty
04aea8d4df files-backend: use die("BUG: ..."), not die("internal error: ...")
The former is by far more common in our codebase.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-23 14:29:52 +09:00
Michael Haggerty
e186057138 ref_iterator_begin_fn(): fix docstring
The iterator returned by this function only includes references whose
names start with the whole prefix, not all of those in
`find_containing_dir(prefix)` as the old docstring claimed. This
docstring was probably copy-pasted from old ref-cache code, which had
the old specification. But now, `cache_ref_iterator_begin()`
(from which the files reference iterator gets its values)
automatically wraps its output using `prefix_ref_iterator_begin()`
when necessary, so it has the stricter behavior.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-23 14:29:52 +09:00
Junio C Hamano
ca7b2ab07d Merge branch 'bc/object-id'
* bc/object-id: (53 commits)
  object: convert parse_object* to take struct object_id
  tree: convert parse_tree_indirect to struct object_id
  sequencer: convert do_recursive_merge to struct object_id
  diff-lib: convert do_diff_cache to struct object_id
  builtin/ls-tree: convert to struct object_id
  merge: convert checkout_fast_forward to struct object_id
  sequencer: convert fast_forward_to to struct object_id
  builtin/ls-files: convert overlay_tree_on_cache to object_id
  builtin/read-tree: convert to struct object_id
  sha1_name: convert internals of peel_onion to object_id
  upload-pack: convert remaining parse_object callers to object_id
  revision: convert remaining parse_object callers to object_id
  revision: rename add_pending_sha1 to add_pending_oid
  http-push: convert process_ls_object and descendants to object_id
  refs/files-backend: convert many internals to struct object_id
  refs: convert struct ref_update to use struct object_id
  ref-filter: convert some static functions to struct object_id
  Convert struct ref_array_item to struct object_id
  Convert the verify_pack callback to struct object_id
  Convert lookup_tag to struct object_id
  ...
2017-05-23 14:29:19 +09:00
Junio C Hamano
b15667bbdc Merge branch 'js/larger-timestamps'
Some platforms have ulong that is smaller than time_t, and our
historical use of ulong for timestamp would mean they cannot
represent some timestamp that the platform allows.  Invent a
separate and dedicated timestamp_t (so that we can distingiuish
timestamps and a vanilla ulongs, which along is already a good
move), and then declare uintmax_t is the type to be used as the
timestamp_t.

* js/larger-timestamps:
  archive-tar: fix a sparse 'constant too large' warning
  use uintmax_t for timestamps
  date.c: abort if the system time cannot handle one of our timestamps
  timestamp_t: a new data type for timestamps
  PRItime: introduce a new "printf format" for timestamps
  parse_timestamp(): specify explicitly where we parse timestamps
  t0006 & t5000: skip "far in the future" test when time_t is too limited
  t0006 & t5000: prepare for 64-bit timestamps
  ref-filter: avoid using `unsigned long` for catch-all data type
2017-05-16 11:51:59 +09:00
Junio C Hamano
4b44b7b1df Merge branch 'nd/worktree-kill-parse-ref'
"git gc" did not interact well with "git worktree"-managed
per-worktree refs.

* nd/worktree-kill-parse-ref:
  refs: kill set_worktree_head_symref()
  worktree.c: kill parse_ref() in favor of refs_resolve_ref_unsafe()
  refs: introduce get_worktree_ref_store()
  refs: add REFS_STORE_ALL_CAPS
  refs.c: make submodule ref store hashmap generic
  environment.c: fix potential segfault by get_git_common_dir()
2017-05-16 11:51:51 +09:00
brian m. carlson
c251c83df2 object: convert parse_object* to take struct object_id
Make parse_object, parse_object_or_die, and parse_object_buffer take a
pointer to struct object_id.  Remove the temporary variables inserted
earlier, since they are no longer necessary.  Transform all of the
callers using the following semantic patch:

@@
expression E1;
@@
- parse_object(E1.hash)
+ parse_object(&E1)

@@
expression E1;
@@
- parse_object(E1->hash)
+ parse_object(E1)

@@
expression E1, E2;
@@
- parse_object_or_die(E1.hash, E2)
+ parse_object_or_die(&E1, E2)

@@
expression E1, E2;
@@
- parse_object_or_die(E1->hash, E2)
+ parse_object_or_die(E1, E2)

@@
expression E1, E2, E3, E4, E5;
@@
- parse_object_buffer(E1.hash, E2, E3, E4, E5)
+ parse_object_buffer(&E1, E2, E3, E4, E5)

@@
expression E1, E2, E3, E4, E5;
@@
- parse_object_buffer(E1->hash, E2, E3, E4, E5)
+ parse_object_buffer(E1, E2, E3, E4, E5)

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-08 15:12:58 +09:00
brian m. carlson
4417df8c49 refs/files-backend: convert many internals to struct object_id
Convert many of the internals of the files backend to use struct
object_id.  Avoid converting public APIs (except one change to
refs/ref-cache.c) to limit the scope of the changes.

Convert one use of get_sha1_hex to parse_oid_hex, and rely on the fact
that a strbuf will be NUL-terminated and that parse_oid_hex will fail on
truncated input to avoid the need to check the length.

This is a requirement to convert parse_object later on.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-08 15:12:58 +09:00
brian m. carlson
984912989d refs: convert struct ref_update to use struct object_id
Convert struct ref_array_item to use struct object_id by changing the
definition and applying the following semantic patch, plus the standard
object_id transforms:

@@
struct ref_update E1;
@@
- E1.new_sha1
+ E1.new_oid.hash

@@
struct ref_update *E1;
@@
- E1->new_sha1
+ E1->new_oid.hash

@@
struct ref_update E1;
@@
- E1.old_sha1
+ E1.old_oid.hash

@@
struct ref_update *E1;
@@
- E1->old_sha1
+ E1->old_oid.hash

This transformation allows us to convert write_ref_to_lockfile, which is
required to convert parse_object.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-08 15:12:58 +09:00
brian m. carlson
4322478a49 reflog_expire: convert to struct object_id
Adjust the callback functions to take struct object_id * instead of
unsigned char *, and modify related static functions accordingly.

Introduce a temporary object_id instance into files_reflog_expire and
copy the SHA-1 value passed in.  This is necessary because the sha1
parameter can come indirectly from get_sha1.  Without the temporary, it
would require much more refactoring to be able to convert this function.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-08 15:12:57 +09:00
Johannes Schindelin
dddbad728c timestamp_t: a new data type for timestamps
Git's source code assumes that unsigned long is at least as precise as
time_t. Which is incorrect, and causes a lot of problems, in particular
where unsigned long is only 32-bit (notably on Windows, even in 64-bit
versions).

So let's just use a more appropriate data type instead. In preparation
for this, we introduce the new `timestamp_t` data type.

By necessity, this is a very, very large patch, as it has to replace all
timestamps' data type in one go.

As we will use a data type that is not necessarily identical to `time_t`,
we need to be very careful to use `time_t` whenever we interact with the
system functions, and `timestamp_t` everywhere else.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-04-27 13:07:39 +09:00
Junio C Hamano
77b34eaa07 Merge branch 'mh/separate-ref-cache'
The internals of the refs API around the cached refs has been
streamlined.

* mh/separate-ref-cache:
  do_for_each_entry_in_dir(): delete function
  files_pack_refs(): use reference iteration
  commit_packed_refs(): use reference iteration
  cache_ref_iterator_begin(): make function smarter
  get_loose_ref_cache(): new function
  get_loose_ref_dir(): function renamed from get_loose_refs()
  do_for_each_entry_in_dir(): eliminate `offset` argument
  refs: handle "refs/bisect/" in `loose_fill_ref_dir()`
  ref-cache: use a callback function to fill the cache
  refs: record the ref_store in ref_cache, not ref_dir
  ref-cache: introduce a new type, ref_cache
  refs: split `ref_cache` code into separate files
  ref-cache: rename `remove_entry()` to `remove_entry_from_dir()`
  ref-cache: rename `find_ref()` to `find_ref_entry()`
  ref-cache: rename `add_ref()` to `add_ref_entry()`
  refs_verify_refname_available(): use function in more places
  refs_verify_refname_available(): implement once for all backends
  refs_ref_iterator_begin(): new function
  refs_read_raw_ref(): new function
  get_ref_dir(): don't call read_loose_refs() for "refs/bisect"
2017-04-26 15:39:13 +09:00
Nguyễn Thái Ngọc Duy
d026a25657 refs: kill set_worktree_head_symref()
70999e9cec (branch -m: update all per-worktree HEADs - 2016-03-27)
added this function in order to update HEADs of all relevant
worktrees, when a branch is renamed.

It, as a public ref api, kind of breaks abstraction when it uses
internal functions of files backend. With the introduction of
refs_create_symref(), we can move back pretty close to the code before
70999e9cec, where create_symref() was used for updating HEAD.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-04-24 21:28:55 -07:00
Nguyễn Thái Ngọc Duy
0d8a814d8a refs: add REFS_STORE_ALL_CAPS
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-04-24 21:28:55 -07:00