This change introduces git_odb_write_multi_pack_index(), which creates a
`multi-pack-index` file from all the `.pack` files that have been loaded
in the ODB.
Fixes: #5399
This change fixes a packfile heap corruption that can happen when
interacting with multiple packfiles concurrently across multiple
threads. This is exacerbated by setting a lower mwindow open file limit.
This change:
* Renames most of the internal methods in pack.c to clearly indicate
that they expect to be called with a certain lock held, making
reasoning about the state of locks a bit easier.
* Splits the `git_pack_file` lock in two: the one in `git_pack_file`
only protects the `index_map`. The protection to `git_mwindow_file` is
now in that struct.
* Explicitly checks for freshness of the `git_pack_file` in
`git_packfile_unpack_header`: this allows the mwindow implementation
to close files whenever there is enough cache pressure, and
`git_packfile_unpack_header` will reopen the packfile if needed.
* After a call to `p_munmap()`, the `data` and `len` fields are poisoned
with `NULL` to make use-after-frees more evident and crash rather than
being open to the possibility of heap corruption.
* Adds a test case to prevent this from regressing in the future.
Fixes: #5591
This change adds support for reading multi-pack-index files from the
packfile odb backend. This also makes git_pack_file objects open their
backing failes lazily in more scenarios, since the multi-pack-index can
avoid having to open them in some cases (yay!).
This change also refreshes the documentation found in src/odb_pack.c to
match the updated code.
Part of: #5399
* Change the default of the file limit to 0 (unlimited).
* Changed the heuristic to close files to be the file that contains the
least-recently-used window such that the window is the
most-recently-used in the file, and the file does not have in-use
windows.
* Parameterized the filelimit test to check for a limit of 1 and 100
open windows.
There are some cases in which repositories accrue a large number of
packfiles. The existing mwindow limit applies only to the total size of
mmap'd files, not on their number. This leads to a situation in which
having lots of small packfiles could exhaust the allowed number of open
files, particularly on macOS, where the default ulimit is very low
(256).
This change adds a new configuration parameter
(GIT_OPT_SET_MWINDOW_FILE_LIMIT) that sets the maximum number of open
packfiles, with a default of 128. This is low enough so that even macOS
users should not hit it during normal use.
Based on PR #5386, originally written by @josharian.
Fixes: #2758
Our file utils functions all have a "futils" prefix, e.g.
`git_futils_touch`. One would thus naturally guess that their
definitions and implementation would live in files "futils.h" and
"futils.c", respectively, but in fact they live in "fileops.h".
Rename the files to match expectations.
Currently, our headers need to leak some implementation details of maps due to
their direct use of indices in the implementation of their foreach macros. This
makes it impossible to completely hide the map structures away, and also makes
it impossible to include the khash implementation header in the C files of the
respective map only.
This is now being fixed by providing a high-level iteration interface
`map_iterate`, which takes as inputs the map that shall be iterated over, an
iterator as well as the locations where keys and values shall be put into. For
simplicity's sake, the iterator is a simple `size_t` that shall initialized to
`0` on the first call. All existing foreach macros are then adjusted to make use
of this new function.
There currently exist two different function names for getting the entry count
of maps, where offmaps offset and string maps use `num_entries` and OID maps use
`size`. In most programming languages with built-in map types, this is simply
called `size`, which is also shorter to type. Thus, this commit renames the
other two functions `num_entries` to match the common way and adjusts all
callers.
Instead of using the `khiter_t`, `git_strmap_iter` and `khint_t` types,
simply use `size_t` instead. This decouples code from the khash stuff
and makes it possible to move the khash includes into the implementation
files.
The new connectivity tests are not currently being verified at all due
to being turned off by default. Create two test cases for a pack file
which fails our checks and one which suceeds.
We strive to keep an options structure to many functions to be able to
extend options in the future without breaking the API. `git_indexer_new`
doesn't have one right now, but we want to be able to add an option
for enabling strict packfile verification.
Add a new `git_indexer_options` structure and adjust callers to use
that.
If an element has been cached, but then the call to
packfile_unpack_compressed() fails, the very next thing that happens is
that its data is freed and then the element is not removed from the
cache, which frees the data again.
This change sets obj->data to NULL to avoid the double-free. It also
stops trying to resolve deltas after two continuous failed rounds of
resolution, and adds a test for this.
Initially, the setting has been solely used to enable the use of
`fsync()` when creating objects. Since then, the use has been extended
to also cover references and index files. As the option is not yet part
of any release, we can still correct this by renaming the option to
something more sensible, indicating not only correlation to objects.
This commit renames the option to `GIT_OPT_ENABLE_FSYNC_GITDIR`. We also
move the variable from the object to repository source code.
Upstream git.git has changed the way how packfiles are named.
Previously, they were using a hash of the contained object's OIDs, which
has then been changed to use the hash of the complete packfile instead.
See 1190a1acf (pack-objects: name pack files after trailer hash,
2013-12-05) in the git.git repository for more information on this
change.
This commit changes our logic to match the behavior of core git.
When fsync'ing files, fsync the parent directory in the case where we
rename a file into place, or create a new file, to ensure that the
directory entry is flushed correctly.
Opening the same repository multiple times will currently open the same
file multiple times, as well as map the same region of the file multiple
times. This is not necessary, as the packfile data is immutable.
Instead of opening and closing packfiles directly, introduce an
indirection and allocate packfiles globally. This does mean locking on
each packfile open, but we already use this lock for the global mwindow
list so it doesn't introduce a new contention point.
This adds tests that try canceling an indexer operation from
within the progress callback.
After writing the tests, I wanted to run this under valgrind and
had a number of errors in that situation because mmap wasn't
working. I added a CMake option to force emulation of mmap and
consolidated the Amiga-specific code into that new place (so we
don't actually need separate Amiga code now, just have to turn on
-DNO_MMAP).
Additionally, I made the indexer code propagate error codes more
reliably than it used to.
