last_found is the last packfile a wanted object was found in. Since
last_found is shared among all searching threads, it might changes while
we're searching. As suggested by @arrbee, put a copy on the stack to fix
the race condition.
Defining the BOM as a string makes the array include the
NUL-terminator, which means that the memcpy is going to check for that
as well and thus never match for a nonempty file.
Define the array as three chars, which makes the size correct.
Wondows has its own HTTP library. Use that one when possible instead of
our own.
As we don't depend on them anymore, remove the http-parser library from
the Windows build, as well as the search for OpenSSL.
There is a bug in building the linked list of line records in the
diff iterator and also an off by one element error in the hunk
counts. This fixes both of these, adds some test data with more
complex sets of hunk and line diffs to exercise this code better.
This reduces the rate of syscalls for the common case of sequences of
object reads from the same pack.
Best of 5 timings for libgit2_clar before this patch:
real 0m5.375s
user 0m0.392s
sys 0m3.564s
After applying this patch:
real 0m5.285s
user 0m0.356s
sys 0m3.544s
0.6% improvement in system time.
9.2% improvement in user time.
1.7% improvement in elapsed time.
Confirmed a 0.6% reduction in number of system calls with strace.
Expect greater improvement for graph-traversal with large packs.
Fixed some minor `git_repository_hashfile` issues:
- Fixed incorrect doc (saying that repo could be NULL)
- Added checking of object type value to acceptable ones
- Added more tests for various parameter permutations
The existing `git_odb_hashfile` does not apply text filtering
rules because it doesn't have a repository context to evaluate
the correct rules to apply. This adds a new hashfile function
that will apply repository-specific filters (based on config,
attributes, and filename) before calculating the hash.
In the process of adding tests for the max file size threshold
(which treats files over a certain size as binary) there seem to
be a number of problems in the new code with detecting binaries.
This should fix those up, as well as add a test for the file
size threshold stuff.
Also, this un-deprecates `GIT_DIFF_LINE_ADD_EOFNL`, since I
finally found a legitimate situation where it would be returned.
Example: a cached node is owned only by the cache (refcount == 1).
Thread A holds the lock and determines that the entry which should get
cached equals the node (git_oid_cmp(&node->oid, &entry->oid) == 0).
It frees the given entry to instead return the cached node to the user
(entry = node). Now, before Thread A happens to increment the refcount
of the node *outside* the cache lock, Thread B tries to store another
entry and hits the slot of the node before, decrements its refcount and
frees it *before* Thread A gets a chance to increment for the user.
git_cached_obj_incref(entry);
git_mutex_lock(&cache->lock);
{
git_cached_obj *node = cache->nodes[hash & cache->size_mask];
if (node == NULL) {
cache->nodes[hash & cache->size_mask] = entry;
} else if (git_oid_cmp(&node->oid, &entry->oid) == 0) {
git_cached_obj_decref(entry, cache->free_obj);
entry = node;
} else {
git_cached_obj_decref(node, cache->free_obj);
// Thread B is here
cache->nodes[hash & cache->size_mask] = entry;
}
}
git_mutex_unlock(&cache->lock);
// Thread A is here
/* increase the refcount again, because we are
* returning it to the user */
git_cached_obj_incref(entry);
Often `git_odb_read_header` will "fail" and have to read the
entire object into memory instead of just the header. When this
happens, the object is loaded and then disposed of immediately,
which makes it difficult to efficiently use the header information
to decide if the object should be loaded (since attempting to do
so will often result in loading the object twice).
This commit takes the existing code and reorganizes it to have
two new functions:
- `git_odb__read_header_or_object` which acts just like the old
read header function except that it returns the object, too, if
it was forced to load the whole thing. It then becomes the
callers responsibility to free the `git_odb_object`.
- `git_object__from_odb_object` which was extracted from the old
`git_object_lookup` and creates a subclass of `git_object` from
an existing `git_odb_object` (separating the ODB lookup from the
`git_object` creation). This allows you to use the first header
reading function efficiently without instantiating the
`git_odb_object` twice.
There is no net change to the behavior of any of the existing
functions, but this allows internal code to tap into the ODB
lookup and object creation to be more efficient.
