kernel/git - git - PowerEL Git System

Commit Graph

Author	SHA1	Message	Date
Derrick Stolee	cfd781ea22	maintenance: use 'git fetch --prefetch' The 'prefetch' maintenance task previously forced the following refspec for each remote: +refs/heads/:refs/prefetch/<remote>/ If a user has specified a more strict refspec for the remote, then this prefetch task downloads more objects than necessary. The previous change introduced the '--prefetch' option to 'git fetch' which manipulates the remote's refspec to place all resulting refs into refs/prefetch/, with further partitioning based on the destinations of those refspecs. Update the documentation to be more generic about the destination refs. Do not mention custom refspecs explicitly, as that does not need to be highlighted in this documentation. The important part of placing refs in refs/prefetch/ remains. Reported-by: Tom Saeger <tom.saeger@oracle.com> Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	4 years ago
Derrick Stolee	41abfe15d9	maintenance: add pack-refs task It is valuable to collect loose refs into a more compressed form. This is typically the packed-refs file, although this could be the reftable in the future. Having packed refs can be extremely valuable in repos with many tags or remote branches that are not modified by the local user, but still are necessary for other queries. For instance, with many exploded refs, commands such as git describe --tags --exact-match HEAD can be very slow (multiple seconds). This command in particular is used by terminal prompts to show when a detatched HEAD is pointing to an existing tag, so having it be slow causes significant delays for users. Add a new 'pack-refs' maintenance task. It runs 'git pack-refs --all --prune' to move loose refs into a packed form. For now, that is the packed-refs file, but could adjust to other file formats in the future. This is the first of several sub-tasks of the 'gc' task that could be extracted to their own tasks. In this process, we should not change the behavior of the 'gc' task since that remains the default way to keep repositories maintained. Creating a new task for one of these sub-tasks only provides more customization options for those choosing to not use the 'gc' task. It is certainly possible to have both the 'gc' and 'pack-refs' tasks enabled and run regularly. While they may repeat effort, they do not conflict in a destructive way. The 'auto_condition' function pointer is left NULL for now. We could extend this in the future to have a condition check if pack-refs should be run during 'git maintenance run --auto'. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Reviewed-by: Taylor Blau <me@ttaylorr.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	4 years ago
Derrick Stolee	3797a0a7b7	maintenance: use Windows scheduled tasks Git's background maintenance uses cron by default, but this is not available on Windows. Instead, integrate with Task Scheduler. Tasks can be scheduled using the 'schtasks' command. There are several command-line options that can allow for some advanced scheduling, but unfortunately these seem to all require authenticating using a password. Instead, use the "/xml" option to pass an XML file that contains the configuration for the necessary schedule. These XML files are based on some that I exported after constructing a schedule in the Task Scheduler GUI. These options only run background maintenance when the user is logged in, and more fields are populated with the current username and SID at run-time by 'schtasks'. Since the GIT_TEST_MAINT_SCHEDULER environment variable allows us to specify 'schtasks' as the scheduler, we can test the Windows-specific logic on other platforms. Thus, add a check that the XML file written by Git is valid when xmllint exists on the system. Since we use a temporary file for the XML files sent to 'schtasks', we prefix the random characters with the frequency so it is easier to examine the proper file during tests. Instead of an exact match on the 'args' file, we 'grep' for the arguments other than the filename. There is a deficiency in the current design. Windows has two kinds of applications: GUI applications that start by "winmain()" and console applications that start by "main()". Console applications are attached to a new Console window if they are not already associated with a GUI application. This means that every hour the scheudled task launches a command window for the scheduled tasks. Not only is this visually obtrusive, but it also takes focus from whatever else the user is doing! A simple fix would be to insert a GUI application that acts as a shim between the scheduled task and Git. This is currently possible in Git for Windows by setting the <Command> tag equal to C:\Program Files\Git\git-bash.exe with options "--hide --no-needs-console --command=cmd\git.exe" followed by the arguments currently used. Since git-bash.exe is not included in Windows builds of core Git, I chose to leave out this feature. My plan is to submit a small patch to Git for Windows that converts the use of git.exe with this use of git-bash.exe in the short term. In the long term, we can consider creating this GUI shim application within core Git, perhaps in contrib/. Co-authored-by: Eric Sunshine <sunshine@sunshineco.com> Signed-off-by: Eric Sunshine <sunshine@sunshineco.com> Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	4 years ago
Derrick Stolee	2afe7e3567	maintenance: use launchctl on macOS The existing mechanism for scheduling background maintenance is done through cron. The 'crontab -e' command allows updating the schedule while cron itself runs those commands. While this is technically supported by macOS, it has some significant deficiencies: 1. Every run of 'crontab -e' must request elevated privileges through the user interface. When running 'git maintenance start' from the Terminal app, it presents a dialog box saying "Terminal.app would like to administer your computer. Administration can include modifying passwords, networking, and system settings." This is more alarming than what we are hoping to achieve. If this alert had some information about how "git" is trying to run "crontab" then we would have some reason to believe that this dialog might be fine. However, it also doesn't help that some scenarios just leave Git waiting for a response without presenting anything to the user. I experienced this when executing the command from a Bash terminal view inside Visual Studio Code. 2. While cron initializes a user environment enough for "git config --global --show-origin" to show the correct config file information, it does not set up the environment enough for Git Credential Manager Core to load credentials during a 'prefetch' task. My prefetches against private repositories required re-authenticating through UI pop-ups in a way that should not be required. The solution is to switch from cron to the Apple-recommended [1] 'launchd' tool. [1] https://developer.apple.com/library/archive/documentation/MacOSX/Conceptual/BPSystemStartup/Chapters/ScheduledJobs.html The basics of this tool is that we need to create XML-formatted "plist" files inside "~/Library/LaunchAgents/" and then use the 'launchctl' tool to make launchd aware of them. The plist files include all of the scheduling information, along with the command-line arguments split across an array of <string> tags. For example, here is my plist file for the weekly scheduled tasks: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"><dict> <key>Label</key><string>org.git-scm.git.weekly</string> <key>ProgramArguments</key> <array> <string>/usr/local/libexec/git-core/git</string> <string>--exec-path=/usr/local/libexec/git-core</string> <string>for-each-repo</string> <string>--config=maintenance.repo</string> <string>maintenance</string> <string>run</string> <string>--schedule=weekly</string> </array> <key>StartCalendarInterval</key> <array> <dict> <key>Day</key><integer>0</integer> <key>Hour</key><integer>0</integer> <key>Minute</key><integer>0</integer> </dict> </array> </dict> </plist> The schedules for the daily and hourly tasks are more complicated since we need to use an array for the StartCalendarInterval with an entry for each of the six days other than the 0th day (to avoid colliding with the weekly task), and each of the 23 hours other than the 0th hour (to avoid colliding with the daily task). The "Label" value is currently filled with "org.git-scm.git.X" where X is the frequency. We need a different plist file for each frequency. The launchctl command needs to be aligned with a user id in order to initialize the command environment. This must be done using the 'launchctl bootstrap' subcommand. This subcommand is new as of macOS 10.11, which was released in September 2015. Before that release the 'launchctl load' subcommand was recommended. The best source of information on this transition I have seen is available at [2]. The current design does not preclude a future version that detects the available fatures of 'launchctl' to use the older commands. However, it is best to rely on the newest version since Apple might completely remove the deprecated version on short notice. [2] https://babodee.wordpress.com/2016/04/09/launchctl-2-0-syntax/ To remove a schedule, we must run 'launchctl bootout' with a valid plist file. We also need to 'bootout' a task before the 'bootstrap' subcommand will succeed, if such a task already exists. The need for a user id requires us to run 'id -u' which works on POSIX systems but not Windows. Further, the need for fully-qualitifed path names including $HOME behaves differently in the Git internals and the external test suite. The $HOME variable starts with "C:\..." instead of the "/c/..." that is provided by Git in these subcommands. The test therefore has a prerequisite that we are not on Windows. The cross- platform logic still allows us to test the macOS logic on a Linux machine. We can verify the commands that were run by 'git maintenance start' and 'git maintenance stop' by injecting a script that writes the command-line arguments into GIT_TEST_MAINT_SCHEDULER. An earlier version of this patch accidentally had an opening "<dict>" tag when it should have had a closing "</dict>" tag. This was caught during manual testing with actual 'launchctl' commands, but we do not want to update developers' tasks when running tests. It appears that macOS includes the "xmllint" tool which can verify the XML format. This is useful for any system that might contain the tool, so use it whenever it is available. We strive to make these tests work on all platforms, but Windows caused some headaches. In particular, the value of getuid() called by the C code is not guaranteed to be the same as `$(id -u)` invoked by a test. This is because `git.exe` is a native Windows program, whereas the utility programs run by the test script mostly utilize the MSYS2 runtime, which emulates a POSIX-like environment. Since the purpose of the test is to check that the input to the hook is well-formed, the actual user ID is immaterial, thus we can work around the problem by making the the test UID-agnostic. Another subtle issue is the $HOME environment variable being a Windows-style path instead of a Unix-style path. We can be more flexible here instead of expecting exact path matches. Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Co-authored-by: Eric Sunshine <sunshine@sunshineco.com> Signed-off-by: Eric Sunshine <sunshine@sunshineco.com> Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	4 years ago
Thomas Ackermann	7efc378205	doc: fix some typos Signed-off-by: Thomas Ackermann <th.acker@arcor.de> Acked-by: Martin Ågren <martin.agren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	4 years ago
Martin Ågren	83fcadd636	git-maintenance.txt: add missing word Add a missing "a" before "bunch". Signed-off-by: Martin Ågren <martin.agren@gmail.com> Acked-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	4 years ago
Derrick Stolee	16c5690929	maintenance: include 'cron' details in docs Advanced and expert users may want to know how 'git maintenance start' schedules background maintenance in order to customize their own schedules beyond what the maintenance.* config values allow. Start a new set of sections in git-maintenance.txt that describe how 'cron' is used to run these tasks. This is particularly valuable for users who want to inspect what Git is doing or for users who want to customize the schedule further. Having a baseline can provide a way forward for users who have never worked with cron schedules. Helped-by: Eric Sunshine <sunshine@sunshineco.com> Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	4 years ago
Derrick Stolee	0016b61818	maintenance: add troubleshooting guide to docs The 'git maintenance run' subcommand takes a lock on the object database to prevent concurrent processes from competing for resources. This is an important safety measure to prevent possible repository corruption and data loss. This feature can lead to confusing behavior if a user is not aware of it. Add a TROUBLESHOOTING section to the 'git maintenance' builtin documentation that discusses these tradeoffs. The short version of this section is that Git will not corrupt your repository, but if the list of scheduled tasks takes longer than an hour then some scheduled tasks may be dropped due to this object database collision. For example, a long-running "daily" task at midnight might prevent an "hourly" task from running at 1AM. The opposite is also possible, but less likely as long as the "hourly" tasks are much faster than the "daily" and "weekly" tasks. Helped-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	4 years ago
Derrick Stolee	61f7a383d3	maintenance: use 'incremental' strategy by default The 'git maintenance (register\|start)' subcommands add the current repository to the global Git config so maintenance will operate on that repository. It does not specify what maintenance should occur or how often. To make it simple for users to start background maintenance with a recommended schedlue, update the 'maintenance.strategy' config option in both the 'register' and 'start' subcommands. This allows users to customize beyond the defaults using individual 'maintenance.<task>.schedule' options, but also the user can opt-out of this strategy using 'maintenance.strategy=none'. Helped-by: Martin Ågren <martin.agren@gmail.com> Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	4 years ago
Derrick Stolee	2fec604f8d	maintenance: add start/stop subcommands Add new subcommands to 'git maintenance' that start or stop background maintenance using 'cron', when available. This integration is as simple as I could make it, barring some implementation complications. The schedule is laid out as follows: 0 1-23 * * * $cmd maintenance run --schedule=hourly 0 0 * * 1-6 $cmd maintenance run --schedule=daily 0 0 * * 0 $cmd maintenance run --schedule=weekly where $cmd is a properly-qualified 'git for-each-repo' execution: $cmd=$path/git --exec-path=$path for-each-repo --config=maintenance.repo where $path points to the location of the Git executable running 'git maintenance start'. This is critical for systems with multiple versions of Git. Specifically, macOS has a system version at '/usr/bin/git' while the version that users can install resides at '/usr/local/bin/git' (symlinked to '/usr/local/libexec/git-core/git'). This will also use your locally-built version if you build and run this in your development environment without installing first. This conditional schedule avoids having cron launch multiple 'git for-each-repo' commands in parallel. Such parallel commands would likely lead to the 'hourly' and 'daily' tasks competing over the object database lock. This could lead to to some tasks never being run! Since the --schedule=<frequency> argument will run all tasks with _at least_ the given frequency, the daily runs will also run the hourly tasks. Similarly, the weekly runs will also run the daily and hourly tasks. The GIT_TEST_CRONTAB environment variable is not intended for users to edit, but instead as a way to mock the 'crontab [-l]' command. This variable is set in test-lib.sh to avoid a future test from accidentally running anything with the cron integration from modifying the user's schedule. We use GIT_TEST_CRONTAB='test-tool crontab <file>' in our tests to check how the schedule is modified in 'git maintenance (start\|stop)' commands. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	4 years ago
Derrick Stolee	0c18b70081	maintenance: add [un]register subcommands In preparation for launching background maintenance from the 'git maintenance' builtin, create register/unregister subcommands. These commands update the new 'maintenance.repos' config option in the global config so the background maintenance job knows which repositories to maintain. These commands allow users to add a repository to the background maintenance list without disrupting the actual maintenance mechanism. For example, a user can run 'git maintenance register' when no background maintenance is running and it will not start the background maintenance. A later update to start running background maintenance will then pick up this repository automatically. The opposite example is that a user can run 'git maintenance unregister' to remove the current repository from background maintenance without halting maintenance for other repositories. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	4 years ago
Derrick Stolee	b08ff1fee0	maintenance: add --schedule option and config Maintenance currently triggers when certain data-size thresholds are met, such as number of pack-files or loose objects. Users may want to run certain maintenance tasks based on frequency instead. For example, a user may want to perform a 'prefetch' task every hour, or 'gc' task every day. To help these users, update the 'git maintenance run' command to include a '--schedule=<frequency>' option. The allowed frequencies are 'hourly', 'daily', and 'weekly'. These values are also allowed in a new config value 'maintenance.<task>.schedule'. The 'git maintenance run --schedule=<frequency>' checks the '.schedule' config value for each enabled task to see if the configured frequency is at least as frequent as the frequency from the '--schedule' argument. We use the following order, for full clarity: 'hourly' > 'daily' > 'weekly' Use new 'enum schedule_priority' to track these values numerically. The following cron table would run the scheduled tasks with the correct frequencies: 0 1-23 * * git -C <repo> maintenance run --schedule=hourly 0 0 * * 1-6 git -C <repo> maintenance run --schedule=daily 0 0 * * 0 git -C <repo> maintenance run --schedule=weekly This cron schedule will run --schedule=hourly every hour except at midnight. This avoids a concurrent run with the --schedule=daily that runs at midnight every day except the first day of the week. This avoids a concurrent run with the --schedule=weekly that runs at midnight on the first day of the week. Since --schedule=daily also runs the 'hourly' tasks and --schedule=weekly runs the 'hourly' and 'daily' tasks, we will still see all tasks run with the proper frequencies. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	4 years ago
Derrick Stolee	52fe41ff1c	maintenance: add incremental-repack task The previous change cleaned up loose objects using the 'loose-objects' that can be run safely in the background. Add a similar job that performs similar cleanups for pack-files. One issue with running 'git repack' is that it is designed to repack all pack-files into a single pack-file. While this is the most space-efficient way to store object data, it is not time or memory efficient. This becomes extremely important if the repo is so large that a user struggles to store two copies of the pack on their disk. Instead, perform an "incremental" repack by collecting a few small pack-files into a new pack-file. The multi-pack-index facilitates this process ever since 'git multi-pack-index expire' was added in `19575c7` (multi-pack-index: implement 'expire' subcommand, 2019-06-10) and 'git multi-pack-index repack' was added in `ce1e4a1` (midx: implement midx_repack(), 2019-06-10). The 'incremental-repack' task runs the following steps: 1. 'git multi-pack-index write' creates a multi-pack-index file if one did not exist, and otherwise will update the multi-pack-index with any new pack-files that appeared since the last write. This is particularly relevant with the background fetch job. When the multi-pack-index sees two copies of the same object, it stores the offset data into the newer pack-file. This means that some old pack-files could become "unreferenced" which I will use to mean "a pack-file that is in the pack-file list of the multi-pack-index but none of the objects in the multi-pack-index reference a location inside that pack-file." 2. 'git multi-pack-index expire' deletes any unreferenced pack-files and updaes the multi-pack-index to drop those pack-files from the list. This is safe to do as concurrent Git processes will see the multi-pack-index and not open those packs when looking for object contents. (Similar to the 'loose-objects' job, there are some Git commands that open pack-files regardless of the multi-pack-index, but they are rarely used. Further, a user that self-selects to use background operations would likely refrain from using those commands.) 3. 'git multi-pack-index repack --bacth-size=<size>' collects a set of pack-files that are listed in the multi-pack-index and creates a new pack-file containing the objects whose offsets are listed by the multi-pack-index to be in those objects. The set of pack- files is selected greedily by sorting the pack-files by modified time and adding a pack-file to the set if its "expected size" is smaller than the batch size until the total expected size of the selected pack-files is at least the batch size. The "expected size" is calculated by taking the size of the pack-file divided by the number of objects in the pack-file and multiplied by the number of objects from the multi-pack-index with offset in that pack-file. The expected size approximates how much data from that pack-file will contribute to the resulting pack-file size. The intention is that the resulting pack-file will be close in size to the provided batch size. The next run of the incremental-repack task will delete these repacked pack-files during the 'expire' step. In this version, the batch size is set to "0" which ignores the size restrictions when selecting the pack-files. It instead selects all pack-files and repacks all packed objects into a single pack-file. This will be updated in the next change, but it requires doing some calculations that are better isolated to a separate change. These steps are based on a similar background maintenance step in Scalar (and VFS for Git) [1]. This was incredibly effective for users of the Windows OS repository. After using the same VFS for Git repository for over a year, some users had _thousands_ of pack-files that combined to up to 250 GB of data. We noticed a few users were running into the open file descriptor limits (due in part to a bug in the multi-pack-index fixed by `af96fe3` (midx: add packs to packed_git linked list, 2019-04-29). These pack-files were mostly small since they contained the commits and trees that were pushed to the origin in a given hour. The GVFS protocol includes a "prefetch" step that asks for pre-computed pack- files containing commits and trees by timestamp. These pack-files were grouped into "daily" pack-files once a day for up to 30 days. If a user did not request prefetch packs for over 30 days, then they would get the entire history of commits and trees in a new, large pack-file. This led to a large number of pack-files that had poor delta compression. By running this pack-file maintenance step once per day, these repos with thousands of packs spanning 200+ GB dropped to dozens of pack- files spanning 30-50 GB. This was done all without removing objects from the system and using a constant batch size of two gigabytes. Once the work was done to reduce the pack-files to small sizes, the batch size of two gigabytes means that not every run triggers a repack operation, so the following run will not expire a pack-file. This has kept these repos in a "clean" state. [1] https://github.com/microsoft/scalar/blob/master/Scalar.Common/Maintenance/PackfileMaintenanceStep.cs Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	4 years ago
Derrick Stolee	252cfb7cb8	maintenance: add loose-objects task One goal of background maintenance jobs is to allow a user to disable auto-gc (gc.auto=0) but keep their repository in a clean state. Without any cleanup, loose objects will clutter the object database and slow operations. In addition, the loose objects will take up extra space because they are not stored with deltas against similar objects. Create a 'loose-objects' task for the 'git maintenance run' command. This helps clean up loose objects without disrupting concurrent Git commands using the following sequence of events: 1. Run 'git prune-packed' to delete any loose objects that exist in a pack-file. Concurrent commands will prefer the packed version of the object to the loose version. (Of course, there are exceptions for commands that specifically care about the location of an object. These are rare for a user to run on purpose, and we hope a user that has selected background maintenance will not be trying to do foreground maintenance.) 2. Run 'git pack-objects' on a batch of loose objects. These objects are grouped by scanning the loose object directories in lexicographic order until listing all loose objects -or- reaching 50,000 objects. This is more than enough if the loose objects are created only by a user doing normal development. We noticed users with _millions_ of loose objects because VFS for Git downloads blobs on-demand when a file read operation requires populating a virtual file. This step is based on a similar step in Scalar [1] and VFS for Git. [1] https://github.com/microsoft/scalar/blob/master/Scalar.Common/Maintenance/LooseObjectsStep.cs Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	4 years ago
Derrick Stolee	28cb5e66dd	maintenance: add prefetch task When working with very large repositories, an incremental 'git fetch' command can download a large amount of data. If there are many other users pushing to a common repo, then this data can rival the initial pack-file size of a 'git clone' of a medium-size repo. Users may want to keep the data on their local repos as close as possible to the data on the remote repos by fetching periodically in the background. This can break up a large daily fetch into several smaller hourly fetches. The task is called "prefetch" because it is work done in advance of a foreground fetch to make that 'git fetch' command much faster. However, if we simply ran 'git fetch <remote>' in the background, then the user running a foreground 'git fetch <remote>' would lose some important feedback when a new branch appears or an existing branch updates. This is especially true if a remote branch is force-updated and this isn't noticed by the user because it occurred in the background. Further, the functionality of 'git push --force-with-lease' becomes suspect. When running 'git fetch <remote> <options>' in the background, use the following options for careful updating: 1. --no-tags prevents getting a new tag when a user wants to see the new tags appear in their foreground fetches. 2. --refmap= removes the configured refspec which usually updates refs/remotes/<remote>/* with the refs advertised by the remote. While this looks confusing, this was documented and tested by `b40a50264a` (fetch: document and test --refmap="", 2020-01-21), including this sentence in the documentation: Providing an empty `<refspec>` to the `--refmap` option causes Git to ignore the configured refspecs and rely entirely on the refspecs supplied as command-line arguments. 3. By adding a new refspec "+refs/heads/:refs/prefetch/<remote>/" we can ensure that we actually load the new values somewhere in our refspace while not updating refs/heads or refs/remotes. By storing these refs here, the commit-graph job will update the commit-graph with the commits from these hidden refs. 4. --prune will delete the refs/prefetch/<remote> refs that no longer appear on the remote. 5. --no-write-fetch-head prevents updating FETCH_HEAD. We've been using this step as a critical background job in Scalar [1] (and VFS for Git). This solved a pain point that was showing up in user reports: fetching was a pain! Users do not like waiting to download the data that was created while they were away from their machines. After implementing background fetch, the foreground fetch commands sped up significantly because they mostly just update refs and download a small amount of new data. The effect is especially dramatic when paried with --no-show-forced-udpates (through fetch.showForcedUpdates=false). [1] https://github.com/microsoft/scalar/blob/master/Scalar.Common/Maintenance/FetchStep.cs Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	4 years ago
Derrick Stolee	65d655b52d	maintenance: create maintenance.<task>.enabled config Currently, a normal run of "git maintenance run" will only run the 'gc' task, as it is the only one enabled. This is mostly for backwards- compatible reasons since "git maintenance run --auto" commands replaced previous "git gc --auto" commands after some Git processes. Users could manually run specific maintenance tasks by calling "git maintenance run --task=<task>" directly. Allow users to customize which steps are run automatically using config. The 'maintenance.<task>.enabled' option then can turn on these other tasks (or turn off the 'gc' task). Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	4 years ago
Derrick Stolee	090511bc0b	maintenance: add --task option A user may want to only run certain maintenance tasks in a certain order. Add the --task=<task> option, which allows a user to specify an ordered list of tasks to run. These cannot be run multiple times, however. Here is where our array of maintenance_task pointers becomes critical. We can sort the array of pointers based on the task order, but we do not want to move the struct data itself in order to preserve the hashmap references. We use the hashmap to match the --task=<task> arguments into the task struct data. Keep in mind that the 'enabled' member of the maintenance_task struct is a placeholder for a future 'maintenance.<task>.enabled' config option. Thus, we use the 'enabled' member to specify which tasks are run when the user does not specify any --task=<task> arguments. The 'enabled' member should be ignored if --task=<task> appears. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	4 years ago
Derrick Stolee	663b2b1b90	maintenance: add commit-graph task The first new task in the 'git maintenance' builtin is the 'commit-graph' task. This updates the commit-graph file incrementally with the command git commit-graph write --reachable --split By writing an incremental commit-graph file using the "--split" option we minimize the disruption from this operation. The default behavior is to merge layers until the new "top" layer is less than half the size of the layer below. This provides quick writes most of the time, with the longer writes following a power law distribution. Most importantly, concurrent Git processes only look at the commit-graph-chain file for a very short amount of time, so they will verly likely not be holding a handle to the file when we try to replace it. (This only matters on Windows.) If a concurrent process reads the old commit-graph-chain file, but our job expires some of the .graph files before they can be read, then those processes will see a warning message (but not fail). This could be avoided by a future update to use the --expire-time argument when writing the commit-graph. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	4 years ago
Derrick Stolee	3ddaad0e06	maintenance: add --quiet option Maintenance activities are commonly used as steps in larger scripts. Providing a '--quiet' option allows those scripts to be less noisy when run on a terminal window. Turn this mode on by default when stderr is not a terminal. Pipe the option to the 'git gc' child process. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	4 years ago
Derrick Stolee	2057d75038	maintenance: create basic maintenance runner The 'gc' builtin is our current entrypoint for automatically maintaining a repository. This one tool does many operations, such as repacking the repository, packing refs, and rewriting the commit-graph file. The name implies it performs "garbage collection" which means several different things, and some users may not want to use this operation that rewrites the entire object database. Create a new 'maintenance' builtin that will become a more general- purpose command. To start, it will only support the 'run' subcommand, but will later expand to add subcommands for scheduling maintenance in the background. For now, the 'maintenance' builtin is a thin shim over the 'gc' builtin. In fact, the only option is the '--auto' toggle, which is handed directly to the 'gc' builtin. The current change is isolated to this simple operation to prevent more interesting logic from being lost in all of the boilerplate of adding a new builtin. Use existing builtin/gc.c file because we want to share code between the two builtins. It is possible that we will have 'maintenance' replace the 'gc' builtin entirely at some point, leaving 'git gc' as an alias for some specific arguments to 'git maintenance run'. Create a new test_subcommand helper that allows us to test if a certain subcommand was run. It requires storing the GIT_TRACE2_EVENT logs in a file. A negation mode is available that will be used in later tests. Helped-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	4 years ago

21 Commits (cfba19618f61d8dce247160d3e9516b041bb98cf)