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>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
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>
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>
This is retry of #1419.
I added flush_fscache macro to flush cached stats after disk writing
with tests for regression reported in #1438 and #1442.
git checkout checks each file path in sorted order, so cache flushing does not
make performance worse unless we have large number of modified files in
a directory containing many files.
Using chromium repository, I tested `git checkout .` performance when I
delete 10 files in different directories.
With this patch:
TotalSeconds: 4.307272
TotalSeconds: 4.4863595
TotalSeconds: 4.2975562
Avg: 4.36372923333333
Without this patch:
TotalSeconds: 20.9705431
TotalSeconds: 22.4867685
TotalSeconds: 18.8968292
Avg: 20.7847136
I confirmed this patch passed all tests in t/ with core_fscache=1.
Signed-off-by: Takuto Ikuta <tikuta@chromium.org>
Make fscache_enabled() function public rather than static.
Remove unneeded fscache_is_enabled() function.
Change is_fscache_enabled() macro to call fscache_enabled().
is_fscache_enabled() now takes a pathname so that the answer
is more precise and mean "is fscache enabled for this pathname",
since fscache only stores repo-relative paths and not absolute
paths, we can avoid attempting lookups for absolute paths.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Teach read_directory_recursive() and add_excludes() to
be aware of optional fscache and avoid trying to open()
and fstat() non-existant ".gitignore" files in every
directory in the worktree.
The current code in add_excludes() calls open() and then
fstat() for a ".gitignore" file in each directory present
in the worktree. Change that when fscache is enabled to
call lstat() first and if present, call open().
This seems backwards because both lstat needs to do more
work than fstat. But when fscache is enabled, fscache will
already know if the .gitignore file exists and can completely
avoid the IO calls. This works because of the lstat diversion
to mingw_lstat when fscache is enabled.
This reduced status times on a 350K file enlistment of the
Windows repo on a NVMe SSD by 0.25 seconds.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Teach FSCACHE to remember "not found" directories.
This is a performance optimization.
FSCACHE is a performance optimization available for Windows. It
intercepts Posix-style lstat() calls into an in-memory directory
using FindFirst/FindNext. It improves performance on Windows by
catching the first lstat() call in a directory, using FindFirst/
FindNext to read the list of files (and attribute data) for the
entire directory into the cache, and short-cut subsequent lstat()
calls in the same directory. This gives a major performance
boost on Windows.
However, it does not remember "not found" directories. When STATUS
runs and there are missing directories, the lstat() interception
fails to find the parent directory and simply return ENOENT for the
file -- it does not remember that the FindFirst on the directory
failed. Thus subsequent lstat() calls in the same directory, each
re-attempt the FindFirst. This completely defeats any performance
gains.
This can be seen by doing a sparse-checkout on a large repo and
then doing a read-tree to reset the skip-worktree bits and then
running status.
This change reduced status times for my very large repo by 60%.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
If multiple threads access a directory that is not yet in the cache, the
directory will be loaded by each thread. Only one of the results is added
to the cache, all others are leaked. This wastes performance and memory.
On cache miss, add a future object to the cache to indicate that the
directory is currently being loaded. Subsequent threads register themselves
with the future object and wait. When the first thread has loaded the
directory, it replaces the future object with the result and notifies
waiting threads.
Signed-off-by: Karsten Blees <blees@dcon.de>
Checking the work tree status is quite slow on Windows, due to slow
`lstat()` emulation (git calls `lstat()` once for each file in the
index). Windows operating system APIs seem to be much better at scanning
the status of entire directories than checking single files.
Add an `lstat()` implementation that uses a cache for lstat data. Cache
misses read the entire parent directory and add it to the cache.
Subsequent `lstat()` calls for the same directory are served directly
from the cache.
Also implement `opendir()`/`readdir()`/`closedir()` so that they create
and use directory listings in the cache.
The cache doesn't track file system changes and doesn't plug into any
modifying file APIs, so it has to be explicitly enabled for git functions
that don't modify the working copy.
Note: in an earlier version of this patch, the cache was always active and
tracked file system changes via ReadDirectoryChangesW. However, this was
much more complex and had negative impact on the performance of modifying
git commands such as 'git checkout'.
Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Add a macro to mark code sections that only read from the file system,
along with a config option and documentation.
This facilitates implementation of relatively simple file system level
caches without the need to synchronize with the file system.
Enable read-only sections for 'git status' and preload_index.
Signed-off-by: Karsten Blees <blees@dcon.de>
Emulating the POSIX lstat API on Windows via GetFileAttributes[Ex] is quite
slow. Windows operating system APIs seem to be much better at scanning the
status of entire directories than checking single files. A caching
implementation may improve performance by bulk-reading entire directories
or reusing data obtained via opendir / readdir.
Make the lstat implementation pluggable so that it can be switched at
runtime, e.g. based on a config option.
Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Emulating the POSIX `dirent` API on Windows via
`FindFirstFile()`/`FindNextFile()` is pretty staightforward, however,
most of the information provided in the `WIN32_FIND_DATA` structure is
thrown away in the process. A more sophisticated implementation may
cache this data, e.g. for later reuse in calls to `lstat()`.
Make the `dirent` implementation pluggable so that it can be switched at
runtime, e.g. based on a config option.
Define a base DIR structure with pointers to `readdir()`/`closedir()`
that match the `opendir()` implementation (similar to vtable pointers in
Object-Oriented Programming). Define `readdir()`/`closedir()` so that
they call the function pointers in the `DIR` structure. This allows to
choose the `opendir()` implementation on a call-by-call basis.
Make the fixed-size `dirent.d_name` buffer a flex array, as `d_name` may
be implementation specific (e.g. a caching implementation may allocate a
`struct dirent` with _just_ the size needed to hold the `d_name` in
question).
Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
We will use them in the upcoming "FSCache" patches (to accelerate
sequential lstat() calls).
Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
This topic branch teaches `git clean` to respect NTFS junctions and Unix
bind mounts: it will now stop at those boundaries.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
In this context, a "feature" is a dependency combined with its own
dependencies.
Signed-off-by: Dennis Ameling <dennis@dennisameling.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Internally, Git expects the environment variable `HOME` to be set, and
to point to the current user's home directory.
This environment variable is not set by default on Windows, and
therefore Git tries its best to construct one if it finds `HOME` unset.
There are actually two different approaches Git tries: first, it looks
at `HOMEDRIVE`/`HOMEPATH` because this is widely used in corporate
environments with roaming profiles, and a user generally wants their
global Git settings to be in a roaming profile.
Only when `HOMEDRIVE`/`HOMEPATH` is either unset or does not point to a
valid location, Git will fall back to using `USERPROFILE` instead.
However, starting with Windows Vista, for secondary logons and services,
the environment variables `HOMEDRIVE`/`HOMEPATH` point to Windows'
system directory (usually `C:\Windows\system32`).
That is undesirable, and that location is usually write-protected anyway.
So let's verify that the `HOMEDRIVE`/`HOMEPATH` combo does not point to
Windows' system directory before using it, falling back to `USERPROFILE`
if it does.
This fixes git-for-windows#2709
Initial-Path-by: Ivan Pozdeev <vano@mail.mipt.ru>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
There is a Win32 API function to resolve symbolic links, and we can use
that instead of resolving them manually. Even better, this function also
resolves NTFS junction points (which are somewhat similar to bind
mounts).
This fixes https://github.com/git-for-windows/git/issues/2481.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Git for Windows wants to add `git.exe` to the users' `PATH`, without
cluttering the latter with unnecessary executables such as `wish.exe`.
To that end, it invented the concept of its "Git wrapper", i.e. a tiny
executable located in `C:\Program Files\Git\cmd\git.exe` (originally a
CMD script) whose sole purpose is to set up a couple of environment
variables and then spawn the _actual_ `git.exe` (which nowadays lives in
`C:\Program Files\Git\mingw64\bin\git.exe` for 64-bit, and the obvious
equivalent for 32-bit installations).
Currently, the following environment variables are set unless already
initialized:
- `MSYSTEM`, to make sure that the MSYS2 Bash and the MSYS2 Perl
interpreter behave as expected, and
- `PLINK_PROTOCOL`, to force PuTTY's `plink.exe` to use the SSH
protocol instead of Telnet,
- `PATH`, to make sure that the `bin` folder in the user's home
directory, as well as the `/mingw64/bin` and the `/usr/bin`
directories are included. The trick here is that the `/mingw64/bin/`
and `/usr/bin/` directories are relative to the top-level installation
directory of Git for Windows (which the included Bash interprets as
`/`, i.e. as the MSYS pseudo root directory).
Using the absence of `MSYSTEM` as a tell-tale, we can detect in
`git.exe` whether these environment variables have been initialized
properly. Therefore we can call `C:\Program Files\Git\mingw64\bin\git`
in-place after this change, without having to call Git through the Git
wrapper.
Obviously, above-mentioned directories must be _prepended_ to the `PATH`
variable, otherwise we risk picking up executables from unrelated Git
installations. We do that by constructing the new `PATH` value from
scratch, appending `$HOME/bin` (if `HOME` is set), then the MSYS2 system
directories, and then appending the original `PATH`.
Side note: this modification of the `PATH` variable is independent of
the modification necessary to reach the executables and scripts in
`/mingw64/libexec/git-core/`, i.e. the `GIT_EXEC_PATH`. That
modification is still performed by Git, elsewhere, long after making the
changes described above.
While we _still_ cannot simply hard-link `mingw64\bin\git.exe` to `cmd`
(because the former depends on a couple of `.dll` files that are only in
`mingw64\bin`, i.e. calling `...\cmd\git.exe` would fail to load due to
missing dependencies), at least we can now avoid that extra process of
running the Git wrapper (which then has to wait for the spawned
`git.exe` to finish) by calling `...\mingw64\bin\git.exe` directly, via
its absolute path.
Testing this is in Git's test suite tricky: we set up a "new" MSYS
pseudo-root and copy the `git.exe` file into the appropriate location,
then verify that `MSYSTEM` is set properly, and also that the `PATH` is
modified so that scripts can be found in `$HOME/bin`, `/mingw64/bin/`
and `/usr/bin/`.
This addresses https://github.com/git-for-windows/git/issues/2283
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
A change between versions 2.4.1 and 2.6.0 of the MSYS2 runtime modified
how Cygwin's runtime (and hence Git for Windows' MSYS2 runtime
derivative) handles locales: d16a56306d (Consolidate wctomb/mbtowc calls
for POSIX-1.2008, 2016-07-20).
An unintended side-effect is that "cold-calling" into the POSIX
emulation will start with a locale based on the current code page,
something that Git for Windows is very ill-prepared for, as it expects
to be able to pass a command-line containing non-ASCII characters to the
shell without having those characters munged.
One symptom of this behavior: when `git clone` or `git fetch` shell out
to call `git-upload-pack` with a path that contains non-ASCII
characters, the shell tried to interpret the entire command-line
(including command-line parameters) as executable path, which obviously
must fail.
This fixes https://github.com/git-for-windows/git/issues/1036
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Update clink.pl to link with either libcurl.lib or libcurl-d.lib
depending on whether DEBUG=1 is set.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
In 1e64d18 (mingw: do resolve symlinks in `getcwd()`) a problem was
introduced that causes git for Windows to stop working with certain
mapped network drives (in particular, drives that are mapped to
locations with long path names). Error message was "fatal: Unable to
read current working directory: No such file or directory". Present
change fixes this issue as discussed in
https://github.com/git-for-windows/git/issues/2480
Signed-off-by: Bjoern Mueller <bjoernm@gmx.de>
As pointed out in https://github.com/git-for-windows/git/issues/1676,
the `git rev-parse --is-inside-work-tree` command currently fails when
the current directory's path contains symbolic links.
The underlying reason for this bug is that `getcwd()` is supposed to
resolve symbolic links, but our `mingw_getcwd()` implementation did not.
We do have all the building blocks for that, though: the
`GetFinalPathByHandleW()` function will resolve symbolic links. However,
we only called that function if `GetLongPathNameW()` failed, for
historical reasons: the latter function was supported for a long time,
but the former API function was introduced only with Windows Vista, and
we used to support also Windows XP. With that support having been
dropped, we are free to call the symbolic link-resolving function right
away.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
The winsock2 library provides functions that work on different data
types than file descriptors, therefore we wrap them.
But that is not the only difference: they also do not set `errno` but
expect the callers to enquire about errors via `WSAGetLastError()`.
Let's translate that into appropriate `errno` values whenever the socket
operations fail so that Git's code base does not have to change its
expectations.
This closes https://github.com/git-for-windows/git/issues/2404
Helped-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
The vcpkg downloads may not succeed. Warn careful readers of the time out.
A simple retry will usually resolve the issue.
Signed-off-by: Philip Oakley <philipoakley@iee.email>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Windows' equivalent to "bind mounts", NTFS junction points, can be
unlinked without affecting the mount target. This is clearly what users
expect to happen when they call `git clean -dfx` in a worktree that
contains NTFS junction points: the junction should be removed, and the
target directory of said junction should be left alone (unless it is
inside the worktree).
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
The vcpkg_install batch file depends on the availability of a
working Git on the CMD path. This may not be present if the user
has selected the 'bash only' option during Git-for-Windows install.
Detect and tell the user about their lack of a working Git in the CMD
window.
Fixes#2348.
A separate PR https://github.com/git-for-windows/build-extra/pull/258
now highlights the recommended path setting during install.
Signed-off-by: Philip Oakley <philipoakley@iee.email>
It seems to be not exactly rare on Windows to install NTFS junction
points (the equivalent of "bind mounts" on Linux/Unix) in worktrees,
e.g. to map some development tools into a subdirectory.
In such a scenario, it is pretty horrible if `git clean -dfx` traverses
into the mapped directory and starts to "clean up".
Let's just not do that. Let's make sure before we traverse into a
directory that it is not a mount point (or junction).
This addresses https://github.com/git-for-windows/git/issues/607
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
From the documentation of said setting:
This boolean will enable fsync() when writing object files.
This is a total waste of time and effort on a filesystem that
orders data writes properly, but can be useful for filesystems
that do not use journalling (traditional UNIX filesystems) or
that only journal metadata and not file contents (OS X’s HFS+,
or Linux ext3 with "data=writeback").
The most common file system on Windows (NTFS) does not guarantee that
order, therefore a sudden loss of power (or any other event causing an
unclean shutdown) would cause corrupt files (i.e. files filled with
NULs). Therefore we need to change the default.
Note that the documentation makes it sound as if this causes really bad
performance. In reality, writing loose objects is something that is done
only rarely, and only a handful of files at a time.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
When specifying an absolute path without a drive prefix, we convert that
path internally. Let's make sure that we handle that case properly, too
;-)
This fixes the command
git clone https://github.com/git-for-windows/git \G4W
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Something changed in `vcpkg` (which we use in our Visual C++ build to
provide the dependencies such as libcurl) and our `vs-build` job started
failing in CI. The reason is that we had a work-around in place to help
CMake find iconv, and this work-around is neither needed nor does it
work anymore.
For the full discussion with the vcpkg project, see this comment:
https://github.com/microsoft/vcpkg/issues/14780#issuecomment-735368280
Signed-off-by: Dennis Ameling <dennis@dennisameling.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In 1af265f0 (compat/bswap.h: simplify MSVC endianness
detection, 2020-11-08) we attempted to simplify code by assuming MSVC
builds will be for little-endian machines, since only unusably old
versions of MSVC supported big-endian MIPS and m68k architectures.
However, it's possible that MSVC could be ported to build for a
big-endian architecture again, so the simplification wasn't as
future-proof as hoped.
So let's go back to the old way of detecting MSVC, and then checking
architecture from a list of little-endian architecture macros.
Note that MSVC does not treat ARM64 as bi-endian, so we can safely treat
it as little-endian.
Helped-by: brian m. carlson <sandals@crustytoothpaste.net>
Helped-by: Jeff King <peff@peff.net>
Helped-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Daniel Gurney <dgurney99@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Modern MSVC or Windows versions don't support big-endian, so it's
unnecessary to consider architectures when using it.
This also makes ARM64 MSVC builds succeed.
Helped-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Daniel Gurney <dgurney99@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In 554544276a (*.[ch]: remove extern from function declarations using
spatch, 2019-04-29), `extern` on function declarations were declared to
be redundant and thus removed from the codebase. An `extern` was
accidentally reintroduced in 08809c09aa (mingw: add a helper function to
attach GDB to the current process, 2020-02-13).
Remove this spurious `extern`.
Signed-off-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
