git/cache.h, branch v2.37.2

Merge branch 'ds/sparse-sparse-checkout'

2022-06-03T21:30:35Z

"sparse-checkout" learns to work well with the sparse-index feature. * ds/sparse-sparse-checkout: sparse-checkout: integrate with sparse index p2000: add test for 'git sparse-checkout [add|set]' sparse-index: complete partial expansion sparse-index: partially expand directories sparse-checkout: --no-sparse-index needs a full index cache-tree: implement cache_tree_find_path() sparse-index: introduce partially-sparse indexes sparse-index: create expand_index() t1092: stress test 'git sparse-checkout set' t1092: refactor 'sparse-index contents' test

Merge branch 'ns/batch-fsync'

2022-06-03T21:30:34Z

Introduce a filesystem-dependent mechanism to optimize the way the bits for many loose object files are ensured to hit the disk platter. * ns/batch-fsync: core.fsyncmethod: performance tests for batch mode t/perf: add iteration setup mechanism to perf-lib core.fsyncmethod: tests for batch mode test-lib-functions: add parsing helpers for ls-files and ls-tree core.fsync: use batch mode and sync loose objects by default on Windows unpack-objects: use the bulk-checkin infrastructure update-index: use the bulk-checkin infrastructure builtin/add: add ODB transaction around add_files_to_cache cache-tree: use ODB transaction around writing a tree core.fsyncmethod: batched disk flushes for loose-objects bulk-checkin: rebrand plug/unplug APIs as 'odb transactions' bulk-checkin: rename 'state' variable and separate 'plugged' boolean

sparse-index: introduce partially-sparse indexes

2022-05-23T18:08:21Z

A future change will present a temporary, in-memory mode where the index can both contain sparse directory entries but also not be completely collapsed to the smallest possible sparse directories. This will be necessary for modifying the sparse-checkout definition while using a sparse index. For now, convert the single-bit member 'sparse_index' in 'struct index_state' to be a an 'enum sparse_index_mode' with three modes: * INDEX_EXPANDED (0): No sparse directories exist. This is always the case for repositories that do not use cone-mode sparse-checkout. * INDEX_COLLAPSED: Sparse directories may exist. Files outside the sparse-checkout cone are reduced to sparse directory entries whenever possible. * INDEX_PARTIALLY_SPARSE: Sparse directories may exist. Some file entries outside the sparse-checkout cone may exist. Running convert_to_sparse() may further reduce those files to sparse directory entries. The main reason to store this extra information is to allow convert_to_sparse() to short-circuit when the index is already in INDEX_EXPANDED mode but to actually do the necessary work when in INDEX_PARTIALLY_SPARSE mode. The INDEX_PARTIALLY_SPARSE mode will be used in an upcoming change. Signed-off-by: Derrick Stolee Signed-off-by: Junio C Hamano

Merge branch 'ds/midx-normalize-pathname-before-comparison'

2022-05-04T16:51:29Z

The path taken by "git multi-pack-index" command from the end user was compared with path internally prepared by the tool withut first normalizing, which lead to duplicated paths not being noticed, which has been corrected. * ds/midx-normalize-pathname-before-comparison: cache: use const char * for get_object_directory() multi-pack-index: use --object-dir real path midx: use real paths in lookup_multi_pack_index()

cache: use const char * for get_object_directory()

2022-04-25T18:31:13Z

The get_object_directory() method returns the exact string stored at the_repository->objects->odb->path. The return type of "char *" implies that the caller must keep track of the buffer and free() it when complete. This causes significant problems later when the ODB is accessed. Use "const char *" as the return type to avoid this confusion. There are no current callers that care about the non-const definition. Signed-off-by: Derrick Stolee Signed-off-by: Junio C Hamano

core.fsync: use batch mode and sync loose objects by default on Windows

2022-04-06T20:13:26Z

Git for Windows has defaulted to core.fsyncObjectFiles=true since September 2017. We turn on syncing of loose object files with batch mode in upstream Git so that we can get broad coverage of the new code upstream. We don't actually do fsyncs in the most of the test suite, since GIT_TEST_FSYNC is set to 0. However, we do exercise all of the surrounding batch mode code since GIT_TEST_FSYNC merely makes the maybe_fsync wrapper always appear to succeed. Signed-off-by: Neeraj Singh Signed-off-by: Junio C Hamano

core.fsyncmethod: batched disk flushes for loose-objects

2022-04-06T20:13:01Z

When adding many objects to a repo with `core.fsync=loose-object`, the cost of fsync'ing each object file can become prohibitive. One major source of the cost of fsync is the implied flush of the hardware writeback cache within the disk drive. This commit introduces a new `core.fsyncMethod=batch` option that batches up hardware flushes. It hooks into the bulk-checkin odb-transaction functionality, takes advantage of tmp-objdir, and uses the writeout-only support code. When the new mode is enabled, we do the following for each new object: 1a. Create the object in a tmp-objdir. 2a. Issue a pagecache writeback request and wait for it to complete. At the end of the entire transaction when unplugging bulk checkin: 1b. Issue an fsync against a dummy file to flush the log and hardware writeback cache, which should by now have seen the tmp-objdir writes. 2b. Rename all of the tmp-objdir files to their final names. 3b. When updating the index and/or refs, we assume that Git will issue another fsync internal to that operation. This is not the default today, but the user now has the option of syncing the index and there is a separate patch series to implement syncing of refs. On a filesystem with a singular journal that is updated during name operations (e.g. create, link, rename, etc), such as NTFS, HFS+, or XFS we would expect the fsync to trigger a journal writeout so that this sequence is enough to ensure that the user's data is durable by the time the git command returns. This sequence also ensures that no object files appear in the main object store unless they are fsync-durable. Batch mode is only enabled if core.fsync includes loose-objects. If the legacy core.fsyncObjectFiles setting is enabled, but core.fsync does not include loose-objects, we will use file-by-file fsyncing. In step (1a) of the sequence, the tmp-objdir is created lazily to avoid work if no loose objects are ever added to the ODB. We use a tmp-objdir to maintain the invariant that no loose-objects are visible in the main ODB unless they are properly fsync-durable. This is important since future ODB operations that try to create an object with specific contents will silently drop the new data if an object with the target hash exists without checking that the loose-object contents match the hash. Only a full git-fsck would restore the ODB to a functional state where dataloss doesn't occur. In step (1b) of the sequence, we issue a fsync against a dummy file created specifically for the purpose. This method has a little higher cost than using one of the input object files, but makes adding new callers of this mechanism easier, since we don't need to figure out which object file is "last" or risk sharing violations by caching the fd of the last object file. _Performance numbers_: Linux - Hyper-V VM running Kernel 5.11 (Ubuntu 20.04) on a fast SSD. Mac - macOS 11.5.1 running on a Mac mini on a 1TB Apple SSD. Windows - Same host as Linux, a preview version of Windows 11. Adding 500 files to the repo with 'git add' Times reported in seconds. object file syncing | Linux | Mac | Windows --------------------|-------|-------|-------- disabled | 0.06 | 0.35 | 0.61 fsync | 1.88 | 11.18 | 2.47 batch | 0.15 | 0.41 | 1.53 Signed-off-by: Neeraj Singh Signed-off-by: Junio C Hamano

Merge branch 'ns/core-fsyncmethod' into ns/batch-fsync

2022-04-06T20:01:54Z

* ns/core-fsyncmethod: configure.ac: fix HAVE_SYNC_FILE_RANGE definition core.fsyncmethod: correctly camel-case warning message core.fsync: fix incorrect expression for default configuration core.fsync: documentation and user-friendly aggregate options core.fsync: new option to harden the index core.fsync: add configuration parsing core.fsync: introduce granular fsync control infrastructure core.fsyncmethod: add writeout-only mode wrapper: make inclusion of Windows csprng header tightly scoped

Merge branch 'jh/builtin-fsmonitor-part2'

2022-04-04T17:56:24Z

Built-in fsmonitor (part 2). * jh/builtin-fsmonitor-part2: (30 commits) t7527: test status with untracked-cache and fsmonitor--daemon fsmonitor: force update index after large responses fsmonitor--daemon: use a cookie file to sync with file system fsmonitor--daemon: periodically truncate list of modified files t/perf/p7519: add fsmonitor--daemon test cases t/perf/p7519: speed up test on Windows t/perf/p7519: fix coding style t/helper/test-chmtime: skip directories on Windows t/perf: avoid copying builtin fsmonitor files into test repo t7527: create test for fsmonitor--daemon t/helper/fsmonitor-client: create IPC client to talk to FSMonitor Daemon help: include fsmonitor--daemon feature flag in version info fsmonitor--daemon: implement handle_client callback compat/fsmonitor/fsm-listen-darwin: implement FSEvent listener on MacOS compat/fsmonitor/fsm-listen-darwin: add MacOS header files for FSEvent compat/fsmonitor/fsm-listen-win32: implement FSMonitor backend on Windows fsmonitor--daemon: create token-based changed path cache fsmonitor--daemon: define token-ids fsmonitor--daemon: add pathname classification fsmonitor--daemon: implement 'start' command ...

Merge branch 'ns/core-fsyncmethod'

2022-04-04T17:56:22Z

A couple of fix-up to a topic that is now in 'master'. * ns/core-fsyncmethod: core.fsyncmethod: correctly camel-case warning message core.fsync: fix incorrect expression for default configuration