Using FindFirstFileExW() requires the OS to allocate a 64K buffer for each
directory and then free it when we call FindClose(). Update fscache to call
the underlying kernel API NtQueryDirectoryFile so that we can do the buffer
management ourselves. That allows us to allocate a single buffer for the
lifetime of the cache and reuse it for each directory.
This change improves performance of 'git status' by 18% in a repo with ~200K
files and 30k folders.
Documentation for NtQueryDirectoryFile can be found at:
https://docs.microsoft.com/en-us/windows-hardware/drivers/ddi/content/ntifs/nf-ntifs-ntquerydirectoryfilehttps://docs.microsoft.com/en-us/windows/desktop/FileIO/file-attribute-constantshttps://docs.microsoft.com/en-us/windows/desktop/fileio/reparse-point-tags
To determine if the specified directory is a symbolic link, inspect the
FileAttributes member to see if the FILE_ATTRIBUTE_REPARSE_POINT flag is
set. If so, EaSize will contain the reparse tag (this is a so far
undocumented feature, but confirmed by the NTFS developers). To
determine if the reparse point is a symbolic link (and not some other
form of reparse point), test whether the tag value equals the value
IO_REPARSE_TAG_SYMLINK.
Signed-off-by: Ben Peart <benpeart@microsoft.com>
We cannot rely on `uname -m` in Git for Windows' SDK to tell us what
architecture we are compiling for, as we can compile both 32-bit and
64-bit `git.exe` from a 64-bit SDK, but the `uname -m` in that SDK will
always report `x86_64`.
So let's go back to our original design. And make it explicitly
Windows-specific.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
The recent change to make fscache thread specific relied on fscache_enable()
being called first from the primary thread before being called in parallel
from worker threads. Make that more robust and protect it with a critical
section to avoid any issues.
Helped-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Ben Peart <benpeart@microsoft.com>
To support IPv6, Git provided fall back functions for Windows versions that
did not support IPv6. However, as Git dropped support for Windows XP and
prior, those functions are not needed anymore.
Removed those fallbacks by reverting commit[1] and using the functions
directly (without 'ipv6_' prefix).
[1] fe3b2b7b82.
Signed-off-by: tanushree27 <tanushreetumane@gmail.com>
This brings substantial wins in performance because the FSCache is now
per-thread, being merged to the primary thread only at the end, so we do
not have to lock (except while merging).
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
When debugging Git, the criss-cross spawning of processes can make
things quite a bit difficult, especially when a Unix shell script is
thrown in the mix that calls a `git.exe` that then segfaults.
To help debugging such things, we introduce the `open_in_gdb()` function
which can be called at a code location where the segfault happens (or as
close as one can get); This will open a new MinTTY window with a GDB
that already attached to the current process.
Inspired by Derrick Stolee.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Now that the fscache is single threaded, take advantage of the mem_pool as
the allocator to significantly reduce the cost of allocations and frees.
With the reduced cost of free, in future patches, we can start freeing the
fscache at the end of commands instead of just leaking it.
Signed-off-by: Ben Peart <benpeart@microsoft.com>
The threading model for fscache has been to have a single, global cache.
This puts requirements on it to be thread safe so that callers like
preload-index can call it from multiple threads. This was implemented
with a single mutex and completion events which introduces contention
between the calling threads.
Simplify the threading model by making fscache thread specific. This allows
us to remove the global mutex and synchronization events entirely and instead
associate a fscache with every thread that requests one. This works well with
the current multi-threading which divides the cache entries into blocks with
a separate thread processing each block.
At the end of each worker thread, if there is a fscache on the primary
thread, merge the cached results from the worker into the primary thread
cache. This enables us to reuse the cache later especially when scanning for
untracked files.
In testing, this reduced the time spent in preload_index() by about 25% and
also reduced the CPU utilization significantly. On a repo with ~200K files,
it reduced overall status times by ~12%.
Signed-off-by: Ben Peart <benpeart@microsoft.com>
Update enable_fscache() to take an optional initial size parameter which is
used to initialize the hashmap so that it can avoid having to rehash as
additional entries are added.
Add a separate disable_fscache() macro to make the code clearer and easier
to read.
Signed-off-by: Ben Peart <benpeart@microsoft.com>
Add tracing around initializing and discarding mempools. In discard report
on the amount of memory unused in the current block to help tune setting
the initial_size.
Signed-off-by: Ben Peart <benpeart@microsoft.com>
Track fscache hits and misses for lstat and opendir requests. Reporting of
statistics is done when the cache is disabled for the last time and freed
and is only reported if GIT_TRACE_FSCACHE is set.
Sample output is:
11:33:11.836428 compat/win32/fscache.c:433 fscache: lstat 3775, opendir 263, total requests/misses 4052/269
Signed-off-by: Ben Peart <benpeart@microsoft.com>
At the end of the status command, disable and free the fscache so that we
don't leak the memory and so that we can dump the fscache statistics.
Signed-off-by: Ben Peart <benpeart@microsoft.com>
Use FindFirstFileExW with FindExInfoBasic to avoid forcing NTFS to look up
the short name. Also switch to a larger (64K vs 4K) buffer using
FIND_FIRST_EX_LARGE_FETCH to minimize round trips to the kernel.
In a repo with ~200K files, this drops warm cache status times from 3.19
seconds to 2.67 seconds for a 16% savings.
Signed-off-by: Ben Peart <benpeart@microsoft.com>
To avoid having to play tricks as in earlier rounds, we bit the sour
apple and rebased the `builtin-stash-rebase-v3` branch thicket onto the
commit starting Git for Windows' merging-rebase.
(The merging-rebase pulls in the previous branch thicket via a "fake
merge", i.e. a merge commit that does not actually apply any changes
from the merged commit history. This has the unfortunate side effect of
confusing `merge` into thinking that any branch that was merged into an
earlier round does not need to be merged again.)
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
This fixes the issue identified in
https://github.com/git-for-windows/git/issues/1498
where Git would not fall back to reading credentials from a Win32
Console when the credentials could not be read from the terminal via the
Bash hack (that is necessary to support running in a MinTTY).
Tested in a Powershell window.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
This topic branch brings slightly experimental changes supporting Git
for Windows to use BusyBox-w32 to execute its shell scripts as well as
its test suite.
The test suite can be run by installing the test artifacts into a MinGit
that has busybox.exe (and using Git for Windows' SDK's Perl for now, as
the test suite requires Perl even when NO_PERL is set, go figure) by
using the `install-mingit-test-artifacts` Makefile target with the
DESTDIR variable pointing to the top-level directory of the MinGit
installation.
To facilitate running the test suite (without having `make` available,
as `make.exe` is not part of MinGit), this branch brings an experimental
patch to the `test-run-command` helper to run Git's test suite. It is
still very experimental, though: in this developer's tests it seemed
that the `poll()` emulation required for `run_parallel_processes()` to
work sometimes hiccups on Windows, causing infinite "hangs". It is also
possible that BusyBox itself has problems writing to the pipes opened by
`test-run-command` (and merging this branch will help investigate
further). Caveat emptor.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
When spawning child processes, we do want them to inherit the standard
handles so that we can talk to them. We do *not* want them to inherit
any other handle, as that would hold a lock to the respective files
(preventing them from being renamed, modified or deleted), and the child
process would not know how to access that handle anyway.
Happily, there is an API to make that happen. It is supported in Windows
Vista and later, which is exactly what we promise to support in Git for
Windows for the time being.
This also means that we lift, at long last, the target Windows version
from Windows XP to Windows Vista.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
This branch allows third-party tools to call `git status
--no-lock-index` to avoid lock contention with the interactive Git usage
of the actual human user.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Git for Windows supports the core.longPaths config setting to allow
writing/reading long paths via the \\?\ trick for a long time now.
However, for that support to work, it is absolutely necessary that
git_default_config() is given a chance to parse the config. Otherwise
Git will be non the wiser.
So let's make sure that as many commands that previously failed to
parse the core.* settings now do that, implicitly enabling long path
support in a lot more places.
Note: this is not a perfect solution, and it cannot be, as there is
a chicken-and-egg problem in reading the config itself...
This fixes https://github.com/git-for-windows/git/issues/1218
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
This branch introduces support for reading the "Windows-wide" Git
configuration from `%PROGRAMDATA%\Git\config`. As these settings are
intended to be shared between *all* Git-related software, that config
file takes an even lower precedence than `$(prefix)/etc/gitconfig`.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
