| Age | Commit message (Collapse) | Author | Files | Lines |
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In http.c, the run_active_slot() function allows the given "slot" to
make progress by calling step_active_slots() in a loop repeatedly,
and the loop is not left until the request held in the slot
completes.
Ages ago, we used to use the slot->in_use member to get out of the
loop, which misbehaved when the request in "slot" completes (at
which time, the result of the request is copied away from the slot,
and the in_use member is cleared, making the slot ready to be
reused), and the "slot" gets reused to service a different request
(at which time, the "slot" becomes in_use again, even though it is
for a different request). The loop terminating condition mistakenly
thought that the original request has yet to be completed.
Today's code, after baa7b67d (HTTP slot reuse fixes, 2006-03-10)
fixed this issue, uses a separate "slot->finished" member that is
set in run_active_slot() to point to an on-stack variable, and the
code that completes the request in finish_active_slot() clears the
on-stack variable via the pointer to signal that the particular
request held by the slot has completed. It also clears the in_use
member (as before that fix), so that the slot itself can safely be
reused for an unrelated request.
One thing that is not quite clean in this arrangement is that,
unless the slot gets reused, at which point the finished member is
reset to NULL, the member keeps the value of &finished, which
becomes a dangling pointer into the stack when run_active_slot()
returns. Clear the finished member before the control leaves the
function, which has a side effect of unconfusing compilers like
recent GCC 12 that is over-eager to warn against such an assignment.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Fix memory leaks in transport_push(), where remote_refs and local_refs
are never freed.
116 bytes in 1 blocks are definitely lost in loss record 56 of 103
at 0x484486F: malloc (vg_replace_malloc.c:381)
by 0x4938D7E: strdup (strdup.c:42)
by 0x628418: xstrdup (wrapper.c:39)
by 0x4FD454: process_capabilities (connect.c:232)
by 0x4FD454: get_remote_heads (connect.c:354)
by 0x610A38: handshake (transport.c:333)
by 0x612B02: transport_push (transport.c:1302)
by 0x4803D6: push_with_options (push.c:357)
by 0x4811D6: do_push (push.c:414)
by 0x4811D6: cmd_push (push.c:650)
by 0x405210: run_builtin (git.c:465)
by 0x405210: handle_builtin (git.c:719)
by 0x406363: run_argv (git.c:786)
by 0x406363: cmd_main (git.c:917)
by 0x404F17: main (common-main.c:56)
5,912 (388 direct, 5,524 indirect) bytes in 2 blocks are definitely lost in loss record 98 of 103
at 0x4849464: calloc (vg_replace_malloc.c:1328)
by 0x628705: xcalloc (wrapper.c:150)
by 0x5C216D: alloc_ref_with_prefix (remote.c:975)
by 0x5C232A: alloc_ref (remote.c:983)
by 0x5C232A: one_local_ref (remote.c:2299)
by 0x5C232A: one_local_ref (remote.c:2289)
by 0x5BDB03: do_for_each_repo_ref_iterator (iterator.c:418)
by 0x5B4C4F: do_for_each_ref (refs.c:1486)
by 0x5B4C4F: refs_for_each_ref (refs.c:1492)
by 0x5B4C4F: for_each_ref (refs.c:1497)
by 0x5C6ADF: get_local_heads (remote.c:2310)
by 0x612A85: transport_push (transport.c:1286)
by 0x4803D6: push_with_options (push.c:357)
by 0x4811D6: do_push (push.c:414)
by 0x4811D6: cmd_push (push.c:650)
by 0x405210: run_builtin (git.c:465)
by 0x405210: handle_builtin (git.c:719)
by 0x406363: run_argv (git.c:786)
by 0x406363: cmd_main (git.c:917)
Signed-off-by: Frantisek Hrbata <frantisek@hrbata.com>
Reviewed-by: Josh Steadmon <steadmon@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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It seems there is no reason to return 1 instead of -1 when push_refs()
is not set in transport vtable. Let's unify the error return values and
use the done label as a single exit point from transport_push().
Suggested-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Frantisek Hrbata <frantisek@hrbata.com>
Reviewed-by: Josh Steadmon <steadmon@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Remove the big indented block for transport_push() check in transport vtable
and let's just return error immediately. Hopefully this makes the code
more readable.
Signed-off-by: Frantisek Hrbata <frantisek@hrbata.com>
Reviewed-by: Josh Steadmon <steadmon@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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A typical "git revert" commit uses the full title of the original
commit in its title, and starts its body of the message with:
This reverts commit 8fa7f667cf61386257c00d6e954855cc3215ae91.
This does not encourage the best practice of describing not just
"what" (i.e. "Revert X" on the title says what we did) but "why"
(i.e. and it does not say why X was undesirable).
We can instead phrase this first line of the body to be more like
This reverts commit 8fa7f667 (do this and that, 2022-04-25)
so that the title does not have to be
Revert "do this and that"
We can instead use the title to describe "why" we are reverting the
original commit.
Introduce the "--reference" option to "git revert", and also the
revert.reference configuration variable, which defaults to false, to
tweak the title and the first line of the draft commit message for
when creating a "revert" commit.
When this option is in use, the first line of the pre-filled editor
buffer becomes a comment line that tells the user to say _why_. If
the user exits the editor without touching this line by mistake,
what we prepare to become the first line of the body, i.e. "This
reverts commit 8fa7f667 (do this and that, 2022-04-25)", ends up to
be the title of the resulting commit. This behaviour is designed to
help such a user to identify such a revert in "git log --oneline"
easily so that it can be further reworded with "git rebase -i" later.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Refactor the tests that exercise implicit shutdown cases
to make them more robust and less racy.
The fsmonitor--daemon will implicitly shutdown in a variety
of situations, such as when the ".git" directory is deleted
or renamed.
The existing tests would delete or rename the directory, sleep
for one second, and then check the status of the daemon. This
is racy, since the client/status command has no way to sync
with the daemon. This was noticed occasionally on very slow
CI build machines where it would cause a random test to fail.
Replace the simple sleep with a sleep-and-retry loop.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Create a test in t7527 to verify that we get a stray warning from
`git fsmonitor--daemon start` when indirectly called from
`git submodule absorbgitdirs`.
Update `git fsmonitor--daemon` to take (and ignore) the `--super-prefix`
argument to suppress the warning.
When we have:
1. a submodule with a `sub/.git/` directory (rather than a `sub/.git`
file).
2. `core.fsmonitor` is turned on in the submodule, but the daemon is
not yet started in the submodule.
3. and someone does a `git submodule absorbgitdirs` in the super.
Git will recursively invoke `git submodule--helper absorb-git-dirs`
in the submodule. This will read the index and may attempt to start
the fsmonitor--daemon with the `--super-prefix` argument.
`git fsmonitor--daemon start` does not accept the `--super-prefix`
argument and causes a warning to be issued.
This does not cause a problem because the `refresh_index()` code
assumes a trivial response if the daemon does not start.
The net-net is a harmelss, but stray warning. Lets eliminate the
warning.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Confirm that the daemon reports events using the on-disk
spelling for Unicode NFC/NFD characters. On APFS we still
have Unicode aliasing, so we cannot create two files that
only differ by NFC/NFD, but the on-disk format preserves
the spelling used to create the file. On HFS+ we also
have aliasing, but the path is always stored on disk in
NFD.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Create a set of prereqs to help understand how file names
are handled by the filesystem when they contain NFC and NFD
Unicode characters.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Co-authored-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Emit NFC or NFC and NFD spellings of pathnames on macOS.
MacOS is Unicode composition insensitive, so NFC and NFD spellings are
treated as aliases and collide. While the spelling of pathnames in
filesystem events depends upon the underlying filesystem, such as
APFS, HFS+ or FAT32, the OS enforces such collisions regardless of
filesystem.
Teach the daemon to always report the NFC spelling and to report
the NFD spelling when stored in that format on the disk.
This is slightly more general than "core.precomposeUnicode".
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Test that FS events from the OS are received using the preserved,
on-disk spelling of files/directories rather than spelling used
to make the change.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Never set CE_FSMONITOR_VALID on the cache-entry of submodule
directories.
During a client command like 'git status', we may need to recurse
into each submodule to compute a status summary for the submodule.
Since the purpose of the ce_flag is to let Git avoid scanning a
cache-entry, setting the flag causes the recursive call to be
avoided and we report incorrect (no status) for the submodule.
We created an OS watch on the root directory of our working
directory and we receive events for everything in the cone
under it. When submodules are present inside our working
directory, we receive events for both our repo (the super) and
any subs within it. Since our index doesn't have any information
for items within the submodules, we can't use those events.
We could try to truncate the paths of those events back to the
submodule boundary and mark the GITLINK as dirty, but that
feels expensive since we would have to prefix compare every FS
event that we receive against a list of submodule roots. And
it still wouldn't be sufficient to correctly report status on
the submodule, since we don't have any space in the cache-entry
to cache the submodule's status (the 'SCMU' bits in porcelain
V2 speak). That is, the CE_FSMONITOR_VALID bit just says that
we don't need to scan/inspect it because we already know the
answer -- it doesn't say that the item is clean -- and we
don't have space in the cache-entry to store those answers.
So we should always do the recursive scan.
Therefore, we should never set the flag on GITLINK cache-entries.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Create unit tests to move a directory. Verify that `git status`
gives the same result with and without FSMonitor enabled.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Teach Git to perform binary search over the cache-entries for a directory
notification and then linearly scan forward to find the immediate children.
Previously, when the FSMonitor reported a modified directory Git would
perform a linear search on the entire cache-entry array for all
entries matching that directory prefix and invalidate them. Since the
cache-entry array is already sorted, we can use a binary search to
find the first matching entry and then only linearly walk forward and
invalidate entries until the prefix changes.
Also, the original code would invalidate anything having the same
directory prefix. Since a directory event should only be received for
items that are immediately within the directory (and not within
sub-directories of it), only invalidate those entries and not the
whole subtree.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Teach the listener thread to shutdown the daemon if the spelling of the
worktree root directory changes.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Force shutdown fsmonitor daemon if the worktree root directory
is moved, renamed, or deleted.
Use Windows low-level GetFileInformationByHandle() to get and
compare the Windows system unique ID for the directory with a
cached version when we started up. This lets us detect the
case where someone renames the directory that we are watching
and then creates a new directory with the original pathname.
This is important because we are listening to a named pipe for
requests and they are stored in the Named Pipe File System (NPFS)
which a kernel-resident pseudo filesystem not associated with
the actual NTFS directory.
For example, if the daemon was watching "~/foo/", it would have
a directory-watch handle on that directory and a named-pipe
handle for "//./pipe/...foo". Moving the directory to "~/bar/"
does not invalidate the directory handle. (So the daemon would
actually be watching "~/bar" but listening on "//./pipe/...foo".
If the user then does "git init ~/foo" and causes another daemon
to start, the first daemon will still have ownership of the pipe
and the second daemon instance will fail to start. "git status"
clients in "~/foo" will ask "//./pipe/...foo" about changes and
the first daemon instance will tell them about "~/bar".
This commit causes the first daemon to shutdown if the system unique
ID for "~/foo" changes (changes from what it was when the daemon
started). Shutdown occurs after a periodic poll. After the
first daemon exits and releases the lock on the named pipe,
subsequent Git commands may cause another daemon to be started
on "~/foo". Similarly, a subsequent Git command may cause another
daemon to be started on "~/bar".
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Extend the Windows version of the "health" thread to periodically
inspect the system and shutdown if warranted.
This commit updates the thread's wait loop to use a timeout and
defines a (currently empty) table of functions to poll the system.
A later commit will add functions to the table to actually
inspect the system.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Create another thread to watch over the daemon process and
automatically shut it down if necessary.
This commit creates the basic framework for a "health" thread
to monitor the daemon and/or the file system. Later commits
will add platform-specific code to do the actual work.
The "health" thread is intended to monitor conditions that
would be difficult to track inside the IPC thread pool and/or
the file system listener threads. For example, when there are
file system events outside of the watched worktree root or if
we want to have an idle-timeout auto-shutdown feature.
This commit creates the health thread itself, defines the thread-proc
and sets up the thread's event loop. It integrates this new thread
into the existing IPC and Listener thread models.
This commit defines the API to the platform-specific code where all of
the monitoring will actually happen.
The platform-specific code for MacOS is just stubs. Meaning that the
health thread will immediately exit on MacOS, but that is OK and
expected. Future work can define MacOS-specific monitoring.
The platform-specific code for Windows sets up enough of the
WaitForMultipleObjects() machinery to watch for system and/or custom
events. Currently, the set of wait handles only includes our custom
shutdown event (sent from our other theads). Later commits in this
series will extend the set of wait handles to monitor other
conditions.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Rename platform-specific listener thread related variables
and data types as we prepare to add another backend thread
type.
[] `struct fsmonitor_daemon_backend_data` becomes `struct fsm_listen_data`
[] `state->backend_data` becomes `state->listen_data`
[] `state->error_code` becomes `state->listen_error_code`
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Refactor daemon thread startup to make it easier to start
a third thread class to monitor the health of the daemon.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Teach the fsmonitor--daemon to CD outside of the worktree
before starting up.
The common Git startup mechanism causes the CWD of the daemon process
to be in the root of the worktree. On Windows, this causes the daemon
process to hold a locked handle on the CWD and prevents other
processes from moving or deleting the worktree while the daemon is
running.
CD to HOME before entering main event loops.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Ignore FSEvents resulting from `xattr` changes. Git does not care about
xattr's or changes to xattr's, so don't waste time collecting these
events in the daemon nor transmitting them to clients.
Various security tools add xattrs to files and/or directories, such as
to mark them as having been downloaded. We should ignore these events
since it doesn't affect the content of the file/directory or the normal
meta-data that Git cares about.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Initialize `o->result.fsmonitor_has_run_once` based upon value
in `o->src_index->fsmonitor_has_run_once` to prevent a second
fsmonitor query during the tree traversal and possibly getting
a skewed view of the working directory.
The checkout code has already talked to the fsmonitor and the
traversal is updating the index as it traverses, so there is
no need to query the fsmonitor.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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On MacOS mark repos on NTFS or FAT32 volumes as incompatible.
The builtin FSMonitor used Unix domain sockets on MacOS for IPC
with clients. These sockets are kept in the .git directory.
Unix sockets are not supported by NTFS and FAT32, so the daemon
cannot start up.
Test for this during our compatibility checking so that client
commands do not keep trying to start the daemon.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Teach Git to detect remote working directories on Windows and mark them as
incompatible with FSMonitor.
With this `git fsmonitor--daemon run` will error out with a message like it
does for bare repos.
Client commands, such as `git status`, will not attempt to start the daemon.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Teach Git to detect remote working directories on macOS and mark them as
incompatible with FSMonitor.
With this, `git fsmonitor--daemon run` will error out with a message
like it does for bare repos.
Client commands, like `git status`, will not attempt to start the daemon.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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VFS for Git virtual repositories are incompatible with FSMonitor.
VFS for Git is a downstream fork of Git. It contains its own custom
file system watcher that is aware of the virtualization. If a working
directory is being managed by VFS for Git, we should not try to watch
it because we may get incomplete results.
We do not know anything about how VFS for Git works, but we do
know that VFS for Git working directories contain a well-defined
config setting. If it is set, mark the working directory as
incompatible.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Extend generic incompatibility checkout with platform-specific
mechanism. Stub in Win32 version.
In the existing fsmonitor-settings code we have a way to mark
types of repos as incompatible with fsmonitor (whether via the
hook and IPC APIs). For example, we do this for bare repos,
since there are no files to watch.
Extend this exclusion mechanism for platform-specific reasons.
This commit just creates the framework and adds a stub for Win32.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Bare repos do not have a worktree, so there is nothing for the
daemon watch.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Create a stress test to hammer on the fsmonitor daemon.
Create a client-side thread pool of n threads and have
each of them make m requests as fast as they can.
We do not currently inspect the contents of the response.
We're only interested in placing a heavy request load on
the daemon.
This test is useful for interactive testing and various
experimentation. For example, to place additional load
on the daemon while another test is running. We currently
do not have a test script that actually uses this helper.
We might add such a test in the future.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Create some test repos with UTF8 characters in the pathname of the
root directory and verify that the builtin FSMonitor can watch them.
This test is mainly for Windows where we need to avoid `*A()`
routines.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Teach FSMonitor daemon on Windows to recognize shortname paths as
aliases of normal longname paths. FSMonitor clients, such as `git
status`, should receive the longname spelling of changed files (when
possible).
Sometimes we receive FS events using the shortname, such as when a CMD
shell runs "RENAME GIT~1 FOO" or "RMDIR GIT~1". The FS notification
arrives using whatever combination of long and shortnames were used by
the other process. (Shortnames do seem to be case normalized,
however.)
Use Windows GetLongPathNameW() to try to map the pathname spelling in
the notification event into the normalized longname spelling. (This
can fail if the file/directory is deleted, moved, or renamed, because
we are asking the FS for the mapping in response to the event and
after it has already happened, but we try.)
Special case the shortname spelling of ".git" to avoid under-reporting
these events.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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We don't bother to freshen objects stored in a cruft pack individually
by updating the `.mtimes` file. This is because we can't portably `mmap`
and write into the middle of a file (i.e., to update the mtime of just
one object). Instead, we would have to rewrite the entire `.mtimes` file
which may incur some wasted effort especially if there a lot of cruft
objects and they are freshened infrequently.
Instead, force the freshening code to avoid an optimizing write by
writing out the object loose and letting it pick up a current mtime.
This works because we prefer the mtime of the loose copy of an object
when both a loose and packed one exist (whether or not the packed copy
comes from a cruft pack or not).
This could certainly do with a test and/or be included earlier in this
series/PR, but I want to wait until after I have a chance to clean up
the overly-repetitive nature of the cruft pack tests in general.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Expose the new `git repack --cruft` mode from `git gc` via a new opt-in
flag. When invoked like `git gc --cruft`, `git gc` will avoid exploding
unreachable objects as loose ones, and instead create a cruft pack and
`.mtimes` file.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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When using cruft packs, the following race can occur when a geometric
repack that writes a MIDX bitmap takes place afterwords:
- First, create an unreachable object and do an all-into-one cruft
repack which stores that object in the repository's cruft pack.
- Then make that object reachable.
- Finally, do a geometric repack and write a MIDX bitmap.
Assuming that we are sufficiently unlucky as to select a commit from the
MIDX which reaches that object for bitmapping, then the `git
multi-pack-index` process will complain that that object is missing.
The reason is because we don't include cruft packs in the MIDX when
doing a geometric repack. Since the "make that object reachable" doesn't
necessarily mean that we'll create a new copy of that object in one of
the packs that will get rolled up as part of a geometric repack, it's
possible that the MIDX won't see any copies of that now-reachable
object.
Of course, it's desirable to avoid including cruft packs in the MIDX
because it causes the MIDX to store a bunch of objects which are likely
to get thrown away. But excluding that pack does open us up to the above
race.
This patch demonstrates the bug, and resolves it by including cruft
packs in the MIDX even when doing a geometric repack.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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We use the `util` pointer for items in the `existing_packs` string list
to indicate which packs are going to be deleted. Since that has so far
been the only use of that `util` pointer, we just set it to 0 or 1.
But we're going to add an additional state to this field in the next
patch, so prepare for that by adding a #define for the first bit so we
can more expressively inspect the flags state.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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In servers which set the pack.window configuration to a large value, we
can wind up spending quite a lot of time finding new bases when breaking
delta chains between reachable and unreachable objects while generating
a cruft pack.
Introduce a handful of `repack.cruft*` configuration variables to
control the parameters used by pack-objects when generating a cruft
pack.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Expose a way to split the contents of a repository into a main and cruft
pack when doing an all-into-one repack with `git repack --cruft -d`, and
a complementary configuration variable.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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In a previous patch, pack-objects learned how to generate a cruft pack
so long as no objects are dropped.
This patch teaches pack-objects to handle the case where a non-never
`--cruft-expiration` value is passed. This case is slightly more
complicated than before, because we want pack-objects to save
unreachable objects which would have been pruned when there is another
recent (i.e., non-prunable) unreachable object which reaches the other.
We'll call these objects "unreachable but reachable-from-recent".
Here is how pack-objects handles `--cruft-expiration`:
- Instead of adding all objects outside of the kept pack(s) into the
packing list, only handle the ones whose mtime is within the grace
period.
- Construct a reachability traversal whose tips are the
unreachable-but-recent objects.
- Then, walk along that traversal, stopping if we reach an object in
the kept pack. At each step along the traversal, we add the object
we are visiting to the packing list.
In the majority of these cases, any object we visit in this traversal
will already be in our packing list. But we will sometimes encounter
reachable-from-recent cruft objects, which we want to retain even if
they aged out of the grace period.
The most subtle point of this process is that we actually don't need to
bother to update the rescued object's mtime. Even though we will write
an .mtimes file with a value that is older than the expiration window,
it will continue to survive cruft repacks so long as any objects which
reach it haven't aged out.
That is, a future repack will also exclude that object from the initial
packing list, only to discover it later on when doing the reachability
traversal.
Finally, stopping early once an object is found in a kept pack is safe
to do because the kept packs ordinarily represent which packs will
survive after repacking. Assuming that it _isn't_ safe to halt a
traversal early would mean that there is some ancestor object which is
missing, which implies repository corruption (i.e., the complete set of
reachable objects isn't present).
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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When generating a cruft pack, the caller within pack-objects will want
to know the precise timestamps of cruft objects (i.e., their
corresponding values in the .mtimes table) rather than the mtime of the
cruft pack itself.
Teach add_recent_packed() to lookup each object's precise mtime from the
.mtimes file if one exists (indicated by the is_cruft bit on the
packed_git structure).
A couple of small things worth noting here:
- load_pack_mtimes() needs to be called before asking for
nth_packed_mtime(), and that call is done lazily here. That function
exits early if the .mtimes file has already been opened and parsed,
so only the first call is slow.
- Checking the is_cruft bit can be done without any extra work on the
caller's behalf, since it is set up for us automatically as a
side-effect of calling add_packed_git() (just like the 'pack_keep'
and 'pack_promisor' bits).
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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This function behaves very similarly to what we will need in
pack-objects in order to implement cruft packs with expiration. But it
is lacking a couple of things. Namely, it needs:
- a mechanism to communicate the timestamps of individual recent
objects to some external caller
- and, in the case of packed objects, our future caller will also want
to know the originating pack, as well as the offset within that pack
at which the object can be found
- finally, it needs a way to skip over packs which are marked as kept
in-core.
To address the first two, add a callback interface in this patch which
reports the time of each recent object, as well as a (packed_git,
off_t) pair for packed objects.
Likewise, add a new option to the packed object iterators to skip over
packs which are marked as kept in core. This option will become
implicitly tested in a future patch.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Teach `pack-objects` how to generate a cruft pack when no objects are
dropped (i.e., `--cruft-expiration=never`). Later patches will teach
`pack-objects` how to generate a cruft pack that prunes objects.
When generating a cruft pack which does not prune objects, we want to
collect all unreachable objects into a single pack (noting and updating
their mtimes as we accumulate them). Ordinary use will pass the result
of a `git repack -A` as a kept pack, so when this patch says "kept
pack", readers should think "reachable objects".
Generating a non-expiring cruft packs works as follows:
- Callers provide a list of every pack they know about, and indicate
which packs are about to be removed.
- All packs which are going to be removed (we'll call these the
redundant ones) are marked as kept in-core.
Any packs the caller did not mention (but are known to the
`pack-objects` process) are also marked as kept in-core. Packs not
mentioned by the caller are assumed to be unknown to them, i.e.,
they entered the repository after the caller decided which packs
should be kept and which should be discarded.
Since we do not want to include objects in these "unknown" packs
(because we don't know which of their objects are or aren't
reachable), these are also marked as kept in-core.
- Then, we enumerate all objects in the repository, and add them to
our packing list if they do not appear in an in-core kept pack.
This results in a new cruft pack which contains all known objects that
aren't included in the kept packs. When the kept pack is the result of
`git repack -A`, the resulting pack contains all unreachable objects.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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A new caller in the next commit will want to immediately modify the
object_entry structure created by create_object_entry(). Instead of
forcing that caller to wastefully look-up the entry we just created,
return it from create_object_entry() instead.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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In the next patch, we will implement and test support for writing a
cruft pack via a special mode of `git pack-objects`. To make sure that
objects are written with the correct timestamps, and a new test-tool
that can dump the object names and corresponding timestamps from a given
`.mtimes` file.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Now that the `.mtimes` format is defined, supplement the pack-write API
to be able to conditionally write an `.mtimes` file along with a pack by
setting an additional flag and passing an oidmap that contains the
timestamps corresponding to each object in the pack.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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There are three definitions of an identical function which converts
`the_hash_algo` into either 1 (for SHA-1) or 2 (for SHA-256). There is a
copy of this function for writing both the commit-graph and
multi-pack-index file, and another inline definition used to write the
.rev header.
Consolidate these into a single definition in chunk-format.h. It's not
clear that this is the best header to define this function in, but it
should do for now.
(Worth noting, the .rev caller expects a 4-byte unsigned, but the other
two callers work with a single unsigned byte. The consolidated version
uses the latter type, and lets the compiler widen it when required).
Another caller will be added in a subsequent patch.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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This structure will be used to communicate the per-object mtimes when
writing a cruft pack. Here, we need the full packing_data structure
because the mtime information is stored in an array there, not on the
individual object_entry's themselves (to avoid paying the overhead in
structure width for operations which do not generate a cruft pack).
We haven't passed this information down before because one of the two
callers (in bulk-checkin.c) does not have a packing_data structure at
all. In that case (where no cruft pack will be generated), NULL is
passed instead.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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