From 225ea22046a1193bd934a8ea308fa4a7788c9796 Mon Sep 17 00:00:00 2001 From: Ramsay Jones Date: Sun, 13 Jul 2014 02:41:41 -0400 Subject: [PATCH 1/8] alloc.c: remove the alloc_raw_commit_node() function In order to encapsulate the setting of the unique commit index, commit 969eba63 ("commit: push commit_index update into alloc_commit_node", 10-06-2014) introduced a (logically private) intermediary allocator function. However, this function (alloc_raw_commit_node()) was declared as a public function, which undermines its entire purpose. Introduce an inline function, alloc_node(), which implements the main logic of the allocator used by DEFINE_ALLOCATOR, and redefine the macro in terms of the new function. In addition, use the new function in the implementation of the alloc_commit_node() allocator, rather than the intermediary allocator, which can now be removed. Noticed by sparse ("symbol 'alloc_raw_commit_node' was not declared. Should it be static?"). Signed-off-by: Ramsay Jones Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- alloc.c | 47 +++++++++++++++++++++++++++++------------------ 1 file changed, 29 insertions(+), 18 deletions(-) diff --git a/alloc.c b/alloc.c index eb22a45c9d..d7c3605fd6 100644 --- a/alloc.c +++ b/alloc.c @@ -19,22 +19,10 @@ #define BLOCKING 1024 #define DEFINE_ALLOCATOR(name, type) \ -static unsigned int name##_allocs; \ +static struct alloc_state name##_state; \ void *alloc_##name##_node(void) \ { \ - static int nr; \ - static type *block; \ - void *ret; \ - \ - if (!nr) { \ - nr = BLOCKING; \ - block = xmalloc(BLOCKING * sizeof(type)); \ - } \ - nr--; \ - name##_allocs++; \ - ret = block++; \ - memset(ret, 0, sizeof(type)); \ - return ret; \ + return alloc_node(&name##_state, sizeof(type)); \ } union any_object { @@ -45,16 +33,39 @@ union any_object { struct tag tag; }; +struct alloc_state { + int count; /* total number of nodes allocated */ + int nr; /* number of nodes left in current allocation */ + void *p; /* first free node in current allocation */ +}; + +static inline void *alloc_node(struct alloc_state *s, size_t node_size) +{ + void *ret; + + if (!s->nr) { + s->nr = BLOCKING; + s->p = xmalloc(BLOCKING * node_size); + } + s->nr--; + s->count++; + ret = s->p; + s->p = (char *)s->p + node_size; + memset(ret, 0, node_size); + return ret; +} + DEFINE_ALLOCATOR(blob, struct blob) DEFINE_ALLOCATOR(tree, struct tree) -DEFINE_ALLOCATOR(raw_commit, struct commit) DEFINE_ALLOCATOR(tag, struct tag) DEFINE_ALLOCATOR(object, union any_object) +static struct alloc_state commit_state; + void *alloc_commit_node(void) { static int commit_count; - struct commit *c = alloc_raw_commit_node(); + struct commit *c = alloc_node(&commit_state, sizeof(struct commit)); c->index = commit_count++; return c; } @@ -66,13 +77,13 @@ static void report(const char *name, unsigned int count, size_t size) } #define REPORT(name, type) \ - report(#name, name##_allocs, name##_allocs * sizeof(type) >> 10) + report(#name, name##_state.count, name##_state.count * sizeof(type) >> 10) void alloc_report(void) { REPORT(blob, struct blob); REPORT(tree, struct tree); - REPORT(raw_commit, struct commit); + REPORT(commit, struct commit); REPORT(tag, struct tag); REPORT(object, union any_object); } From 600e2a69df6dfde134aba0ca88cfe1bd2c88ecbb Mon Sep 17 00:00:00 2001 From: Jeff King Date: Sun, 13 Jul 2014 02:41:51 -0400 Subject: [PATCH 2/8] alloc: write out allocator definitions Because the allocator functions for tree, blobs, etc are all very similar, we originally used a macro to avoid repeating ourselves. Since the prior commit, though, the heavy lifting is done by an inline helper function. The macro does still save us a few lines, but at some readability cost. It obfuscates the function definitions (and makes them hard to find via grep). Much worse, though, is the fact that it isn't used consistently for all allocators. Somebody coming later may be tempted to modify DEFINE_ALLOCATOR, but they would miss alloc_commit_node, which is treated specially. Let's just drop the macro and write everything out explicitly. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- alloc.c | 38 +++++++++++++++++++++++++++----------- 1 file changed, 27 insertions(+), 11 deletions(-) diff --git a/alloc.c b/alloc.c index d7c3605fd6..03e458bad0 100644 --- a/alloc.c +++ b/alloc.c @@ -18,13 +18,6 @@ #define BLOCKING 1024 -#define DEFINE_ALLOCATOR(name, type) \ -static struct alloc_state name##_state; \ -void *alloc_##name##_node(void) \ -{ \ - return alloc_node(&name##_state, sizeof(type)); \ -} - union any_object { struct object object; struct blob blob; @@ -55,10 +48,33 @@ static inline void *alloc_node(struct alloc_state *s, size_t node_size) return ret; } -DEFINE_ALLOCATOR(blob, struct blob) -DEFINE_ALLOCATOR(tree, struct tree) -DEFINE_ALLOCATOR(tag, struct tag) -DEFINE_ALLOCATOR(object, union any_object) +static struct alloc_state blob_state; +void *alloc_blob_node(void) +{ + struct blob *b = alloc_node(&blob_state, sizeof(struct blob)); + return b; +} + +static struct alloc_state tree_state; +void *alloc_tree_node(void) +{ + struct tree *t = alloc_node(&tree_state, sizeof(struct tree)); + return t; +} + +static struct alloc_state tag_state; +void *alloc_tag_node(void) +{ + struct tag *t = alloc_node(&tag_state, sizeof(struct tag)); + return t; +} + +static struct alloc_state object_state; +void *alloc_object_node(void) +{ + struct object *obj = alloc_node(&object_state, sizeof(union any_object)); + return obj; +} static struct alloc_state commit_state; From d36f51c13b54a872cdaf08a1765a23afab26ae51 Mon Sep 17 00:00:00 2001 From: Jeff King Date: Sun, 13 Jul 2014 02:41:55 -0400 Subject: [PATCH 3/8] move setting of object->type to alloc_* functions The "struct object" type implements basic object polymorphism. Individual instances are allocated as concrete types (or as a union type that can store any object), and a "struct object *" can be cast into its real type after examining its "type" enum. This means it is dangerous to have a type field that does not match the allocation (e.g., setting the type field of a "struct blob" to "OBJ_COMMIT" would mean that a reader might read past the allocated memory). In most of the current code this is not a problem; the first thing we do after allocating an object is usually to set its type field by passing it to create_object. However, the virtual commits we create in merge-recursive.c do not ever get their type set. This does not seem to have caused problems in practice, though (presumably because we always pass around a "struct commit" pointer and never even look at the type). We can fix this oversight and also make it harder for future code to get it wrong by setting the type directly in the object allocation functions. This will also make it easier to fix problems with commit index allocation, as we know that any object allocated by alloc_commit_node will meet the invariant that an object with an OBJ_COMMIT type field will have a unique index number. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- alloc.c | 5 +++++ blob.c | 2 +- builtin/blame.c | 1 - commit.c | 6 ++---- object.c | 5 ++--- object.h | 2 +- tag.c | 2 +- tree.c | 2 +- 8 files changed, 13 insertions(+), 12 deletions(-) diff --git a/alloc.c b/alloc.c index 03e458bad0..fd2e32df8c 100644 --- a/alloc.c +++ b/alloc.c @@ -52,6 +52,7 @@ static struct alloc_state blob_state; void *alloc_blob_node(void) { struct blob *b = alloc_node(&blob_state, sizeof(struct blob)); + b->object.type = OBJ_BLOB; return b; } @@ -59,6 +60,7 @@ static struct alloc_state tree_state; void *alloc_tree_node(void) { struct tree *t = alloc_node(&tree_state, sizeof(struct tree)); + t->object.type = OBJ_TREE; return t; } @@ -66,6 +68,7 @@ static struct alloc_state tag_state; void *alloc_tag_node(void) { struct tag *t = alloc_node(&tag_state, sizeof(struct tag)); + t->object.type = OBJ_TAG; return t; } @@ -73,6 +76,7 @@ static struct alloc_state object_state; void *alloc_object_node(void) { struct object *obj = alloc_node(&object_state, sizeof(union any_object)); + obj->type = OBJ_NONE; return obj; } @@ -82,6 +86,7 @@ void *alloc_commit_node(void) { static int commit_count; struct commit *c = alloc_node(&commit_state, sizeof(struct commit)); + c->object.type = OBJ_COMMIT; c->index = commit_count++; return c; } diff --git a/blob.c b/blob.c index ae320bd8fa..5720a38ca2 100644 --- a/blob.c +++ b/blob.c @@ -7,7 +7,7 @@ struct blob *lookup_blob(const unsigned char *sha1) { struct object *obj = lookup_object(sha1); if (!obj) - return create_object(sha1, OBJ_BLOB, alloc_blob_node()); + return create_object(sha1, alloc_blob_node()); if (!obj->type) obj->type = OBJ_BLOB; if (obj->type != OBJ_BLOB) { diff --git a/builtin/blame.c b/builtin/blame.c index d3b256e545..8f3e311123 100644 --- a/builtin/blame.c +++ b/builtin/blame.c @@ -2287,7 +2287,6 @@ static struct commit *fake_working_tree_commit(struct diff_options *opt, commit = alloc_commit_node(); commit->object.parsed = 1; commit->date = now; - commit->object.type = OBJ_COMMIT; parent_tail = &commit->parents; if (!resolve_ref_unsafe("HEAD", head_sha1, 1, NULL)) diff --git a/commit.c b/commit.c index 4ff8077dbf..eb24add866 100644 --- a/commit.c +++ b/commit.c @@ -61,10 +61,8 @@ struct commit *lookup_commit_or_die(const unsigned char *sha1, const char *ref_n struct commit *lookup_commit(const unsigned char *sha1) { struct object *obj = lookup_object(sha1); - if (!obj) { - struct commit *c = alloc_commit_node(); - return create_object(sha1, OBJ_COMMIT, c); - } + if (!obj) + return create_object(sha1, alloc_commit_node()); if (!obj->type) obj->type = OBJ_COMMIT; return check_commit(obj, sha1, 0); diff --git a/object.c b/object.c index 9c31e9a5e0..a950b85146 100644 --- a/object.c +++ b/object.c @@ -141,13 +141,12 @@ static void grow_object_hash(void) obj_hash_size = new_hash_size; } -void *create_object(const unsigned char *sha1, int type, void *o) +void *create_object(const unsigned char *sha1, void *o) { struct object *obj = o; obj->parsed = 0; obj->used = 0; - obj->type = type; obj->flags = 0; hashcpy(obj->sha1, sha1); @@ -163,7 +162,7 @@ struct object *lookup_unknown_object(const unsigned char *sha1) { struct object *obj = lookup_object(sha1); if (!obj) - obj = create_object(sha1, OBJ_NONE, alloc_object_node()); + obj = create_object(sha1, alloc_object_node()); return obj; } diff --git a/object.h b/object.h index 6e12f2c7f4..8020ace566 100644 --- a/object.h +++ b/object.h @@ -79,7 +79,7 @@ extern struct object *get_indexed_object(unsigned int); */ struct object *lookup_object(const unsigned char *sha1); -extern void *create_object(const unsigned char *sha1, int type, void *obj); +extern void *create_object(const unsigned char *sha1, void *obj); /* * Returns the object, having parsed it to find out what it is. diff --git a/tag.c b/tag.c index 7b07921b30..79552c716c 100644 --- a/tag.c +++ b/tag.c @@ -40,7 +40,7 @@ struct tag *lookup_tag(const unsigned char *sha1) { struct object *obj = lookup_object(sha1); if (!obj) - return create_object(sha1, OBJ_TAG, alloc_tag_node()); + return create_object(sha1, alloc_tag_node()); if (!obj->type) obj->type = OBJ_TAG; if (obj->type != OBJ_TAG) { diff --git a/tree.c b/tree.c index c8c49d7b78..ed66575079 100644 --- a/tree.c +++ b/tree.c @@ -183,7 +183,7 @@ struct tree *lookup_tree(const unsigned char *sha1) { struct object *obj = lookup_object(sha1); if (!obj) - return create_object(sha1, OBJ_TREE, alloc_tree_node()); + return create_object(sha1, alloc_tree_node()); if (!obj->type) obj->type = OBJ_TREE; if (obj->type != OBJ_TREE) { From 5af01caa08700e389d49a81be15c7413abd4aa69 Mon Sep 17 00:00:00 2001 From: Jeff King Date: Sun, 13 Jul 2014 02:42:00 -0400 Subject: [PATCH 4/8] parse_object_buffer: do not set object type The only way that "obj" can be non-NULL is if it came from one of the lookup_* functions. These functions always ensure that the object has the expected type (and return NULL otherwise), so there is no need for us to set the type. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- object.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/object.c b/object.c index a950b85146..472aa8d5be 100644 --- a/object.c +++ b/object.c @@ -213,8 +213,6 @@ struct object *parse_object_buffer(const unsigned char *sha1, enum object_type t warning("object %s has unknown type id %d", sha1_to_hex(sha1), type); obj = NULL; } - if (obj && obj->type == OBJ_NONE) - obj->type = type; return obj; } From 8ff226a9d5ee065fe52752e6032f63cb6e4beccb Mon Sep 17 00:00:00 2001 From: Jeff King Date: Sun, 13 Jul 2014 02:42:03 -0400 Subject: [PATCH 5/8] add object_as_type helper for casting objects 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 Signed-off-by: Junio C Hamano --- blob.c | 9 +-------- commit.c | 19 ++----------------- object.c | 17 +++++++++++++++++ object.h | 2 ++ refs.c | 3 +-- tag.c | 9 +-------- tree.c | 9 +-------- 7 files changed, 25 insertions(+), 43 deletions(-) diff --git a/blob.c b/blob.c index 5720a38ca2..1fcb8e44b0 100644 --- a/blob.c +++ b/blob.c @@ -8,14 +8,7 @@ struct blob *lookup_blob(const unsigned char *sha1) struct object *obj = lookup_object(sha1); if (!obj) return create_object(sha1, alloc_blob_node()); - if (!obj->type) - obj->type = OBJ_BLOB; - if (obj->type != OBJ_BLOB) { - error("Object %s is a %s, not a blob", - sha1_to_hex(sha1), typename(obj->type)); - return NULL; - } - return (struct blob *) obj; + return object_as_type(obj, OBJ_BLOB, 0); } int parse_blob_buffer(struct blob *item, void *buffer, unsigned long size) diff --git a/commit.c b/commit.c index eb24add866..65179f96ee 100644 --- a/commit.c +++ b/commit.c @@ -18,19 +18,6 @@ int save_commit_buffer = 1; const char *commit_type = "commit"; -static struct commit *check_commit(struct object *obj, - const unsigned char *sha1, - int quiet) -{ - if (obj->type != OBJ_COMMIT) { - if (!quiet) - error("Object %s is a %s, not a commit", - sha1_to_hex(sha1), typename(obj->type)); - return NULL; - } - return (struct commit *) obj; -} - struct commit *lookup_commit_reference_gently(const unsigned char *sha1, int quiet) { @@ -38,7 +25,7 @@ struct commit *lookup_commit_reference_gently(const unsigned char *sha1, if (!obj) return NULL; - return check_commit(obj, sha1, quiet); + return object_as_type(obj, OBJ_COMMIT, quiet); } struct commit *lookup_commit_reference(const unsigned char *sha1) @@ -63,9 +50,7 @@ struct commit *lookup_commit(const unsigned char *sha1) struct object *obj = lookup_object(sha1); if (!obj) return create_object(sha1, alloc_commit_node()); - if (!obj->type) - obj->type = OBJ_COMMIT; - return check_commit(obj, sha1, 0); + return object_as_type(obj, OBJ_COMMIT, 0); } struct commit *lookup_commit_reference_by_name(const char *name) diff --git a/object.c b/object.c index 472aa8d5be..b2319f6246 100644 --- a/object.c +++ b/object.c @@ -158,6 +158,23 @@ void *create_object(const unsigned char *sha1, void *o) return obj; } +void *object_as_type(struct object *obj, enum object_type type, int quiet) +{ + if (obj->type == type) + return obj; + else if (obj->type == OBJ_NONE) { + obj->type = type; + return obj; + } + else { + if (!quiet) + error("object %s is a %s, not a %s", + sha1_to_hex(obj->sha1), + typename(obj->type), typename(type)); + return NULL; + } +} + struct object *lookup_unknown_object(const unsigned char *sha1) { struct object *obj = lookup_object(sha1); diff --git a/object.h b/object.h index 8020ace566..5e8d8ee548 100644 --- a/object.h +++ b/object.h @@ -81,6 +81,8 @@ struct object *lookup_object(const unsigned char *sha1); extern void *create_object(const unsigned char *sha1, void *obj); +void *object_as_type(struct object *obj, enum object_type type, int quiet); + /* * Returns the object, having parsed it to find out what it is. * diff --git a/refs.c b/refs.c index dc457742ea..7343565354 100644 --- a/refs.c +++ b/refs.c @@ -1531,9 +1531,8 @@ static enum peel_status peel_object(const unsigned char *name, unsigned char *sh if (o->type == OBJ_NONE) { int type = sha1_object_info(name, NULL); - if (type < 0) + if (type < 0 || !object_as_type(o, type, 0)) return PEEL_INVALID; - o->type = type; } if (o->type != OBJ_TAG) diff --git a/tag.c b/tag.c index 79552c716c..82d841bf2d 100644 --- a/tag.c +++ b/tag.c @@ -41,14 +41,7 @@ struct tag *lookup_tag(const unsigned char *sha1) struct object *obj = lookup_object(sha1); if (!obj) return create_object(sha1, alloc_tag_node()); - if (!obj->type) - obj->type = OBJ_TAG; - if (obj->type != OBJ_TAG) { - error("Object %s is a %s, not a tag", - sha1_to_hex(sha1), typename(obj->type)); - return NULL; - } - return (struct tag *) obj; + return object_as_type(obj, OBJ_TAG, 0); } static unsigned long parse_tag_date(const char *buf, const char *tail) diff --git a/tree.c b/tree.c index ed66575079..bb02c1caa4 100644 --- a/tree.c +++ b/tree.c @@ -184,14 +184,7 @@ struct tree *lookup_tree(const unsigned char *sha1) struct object *obj = lookup_object(sha1); if (!obj) return create_object(sha1, alloc_tree_node()); - if (!obj->type) - obj->type = OBJ_TREE; - if (obj->type != OBJ_TREE) { - error("Object %s is a %s, not a tree", - sha1_to_hex(sha1), typename(obj->type)); - return NULL; - } - return (struct tree *) obj; + return object_as_type(obj, OBJ_TREE, 0); } int parse_tree_buffer(struct tree *item, void *buffer, unsigned long size) From 94d5a22cf651174f91d40a140593628a04fdacf3 Mon Sep 17 00:00:00 2001 From: Jeff King Date: Sun, 13 Jul 2014 02:42:08 -0400 Subject: [PATCH 6/8] alloc: factor out commit index We keep a static counter to set the commit index on newly allocated objects. However, since we also need to set the index on any_objects which are converted to commits, let's make the counter available as a public function. While we're moving it, let's make sure the counter is allocated as an unsigned integer to match the index field in "struct commit". Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- alloc.c | 9 +++++++-- cache.h | 1 + 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/alloc.c b/alloc.c index fd2e32df8c..12afadfacd 100644 --- a/alloc.c +++ b/alloc.c @@ -82,12 +82,17 @@ void *alloc_object_node(void) static struct alloc_state commit_state; +unsigned int alloc_commit_index(void) +{ + static unsigned int count; + return count++; +} + void *alloc_commit_node(void) { - static int commit_count; struct commit *c = alloc_node(&commit_state, sizeof(struct commit)); c->object.type = OBJ_COMMIT; - c->index = commit_count++; + c->index = alloc_commit_index(); return c; } diff --git a/cache.h b/cache.h index df65231ac3..42a5e865b5 100644 --- a/cache.h +++ b/cache.h @@ -1376,6 +1376,7 @@ extern void *alloc_commit_node(void); extern void *alloc_tag_node(void); extern void *alloc_object_node(void); extern void alloc_report(void); +extern unsigned int alloc_commit_index(void); /* trace.c */ __attribute__((format (printf, 1, 2))) From d66bebcbcfa46d72bb5008e1d211c0ea87200d86 Mon Sep 17 00:00:00 2001 From: Jeff King Date: Sun, 13 Jul 2014 02:42:12 -0400 Subject: [PATCH 7/8] object_as_type: set commit index The point of the "index" field of struct commit is that every allocated commit would have one. It is supposed to be an invariant that whenever object->type is set to OBJ_COMMIT, we have a unique index. Commit 969eba6 (commit: push commit_index update into alloc_commit_node, 2014-06-10) covered this case for newly-allocated commits. However, we may also allocate an "unknown" object via lookup_unknown_object, and only later convert it to a commit. We must make sure that we set the commit index when we switch the type field. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- object.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/object.c b/object.c index b2319f6246..69fbbbf504 100644 --- a/object.c +++ b/object.c @@ -163,6 +163,8 @@ void *object_as_type(struct object *obj, enum object_type type, int quiet) if (obj->type == type) return obj; else if (obj->type == OBJ_NONE) { + if (type == OBJ_COMMIT) + ((struct commit *)obj)->index = alloc_commit_index(); obj->type = type; return obj; } From fa96082617e07d988103854fb96c5e92b7587e72 Mon Sep 17 00:00:00 2001 From: Jeff King Date: Sun, 13 Jul 2014 02:42:17 -0400 Subject: [PATCH 8/8] diff-tree: avoid lookup_unknown_object We generally want to avoid lookup_unknown_object, because it results in allocating more memory for the object than may be strictly necessary. In this case, it is used to check whether we have an already-parsed object before calling parse_object, to save us from reading the object from disk. Using lookup_object would be fine for that purpose, but we can take it a step further. Since this code was written, parse_object already learned the "check lookup_object" optimization, so we can simply call parse_object directly. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- builtin/diff-tree.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/builtin/diff-tree.c b/builtin/diff-tree.c index be6417d166..dddd0f9188 100644 --- a/builtin/diff-tree.c +++ b/builtin/diff-tree.c @@ -72,9 +72,7 @@ static int diff_tree_stdin(char *line) line[len-1] = 0; if (get_sha1_hex(line, sha1)) return -1; - obj = lookup_unknown_object(sha1); - if (!obj || !obj->parsed) - obj = parse_object(sha1); + obj = parse_object(sha1); if (!obj) return -1; if (obj->type == OBJ_COMMIT)