kmx git

Commit	Date	Message
2766b92d	2019-07-21T15:10:34	config_file: refresh when creating an iterator When creating a new iterator for a config file backend, then we should always make sure that we're up to date by calling `config_refresh`. Otherwise, we might not notice when another process has modified the configuration file and thus will represent outdated values. Add two tests to config::stress that verify that we get up-to-date values when reading configuration entries via `git_config_iterator`.
e54343a4	2019-06-29T09:17:32	fileops: rename to "futils.h" to match function signatures Our file utils functions all have a "futils" prefix, e.g. `git_futils_touch`. One would thus naturally guess that their definitions and implementation would live in files "futils.h" and "futils.c", respectively, but in fact they live in "fileops.h". Rename the files to match expectations.
d7f58eab	2019-06-21T11:55:21	config_file: implement stat cache to avoid repeated rehashing To decide whether a config file has changed, we always hash its complete contents. This is unnecessarily expensive, as well-behaved filesystems will always update stat information for files which have changed. So before computing the hash, we should first check whether the stat info has actually changed for either the configuration file or any of its includes. This avoids having to re-read the configuration file and its includes every time when we check whether it's been modified. Tracing the for-each-ref example previous to this commit, one can see that we repeatedly re-open both the repo configuration as well as the global configuration: $ strace lg2 for-each-ref \|& grep config access("/home/pks/.gitconfig", F_OK) = -1 ENOENT (No such file or directory) access("/home/pks/.config/git/config", F_OK) = 0 access("/etc/gitconfig", F_OK) = -1 ENOENT (No such file or directory) stat("/tmp/repo/.git/config", {st_mode=S_IFREG\|0644, st_size=92, ...}) = 0 access("/tmp/repo/.git/config", F_OK) = 0 stat("/tmp/repo/.git/config", {st_mode=S_IFREG\|0644, st_size=92, ...}) = 0 open("/tmp/repo/.git/config", O_RDONLY\|O_CLOEXEC) = 3 stat("/home/pks/.gitconfig", 0x7ffd15c05290) = -1 ENOENT (No such file or directory) access("/home/pks/.gitconfig", F_OK) = -1 ENOENT (No such file or directory) stat("/home/pks/.config/git/config", {st_mode=S_IFREG\|0644, st_size=1154, ...}) = 0 access("/home/pks/.config/git/config", F_OK) = 0 stat("/home/pks/.config/git/config", {st_mode=S_IFREG\|0644, st_size=1154, ...}) = 0 open("/home/pks/.config/git/config", O_RDONLY\|O_CLOEXEC) = 3 stat("/tmp/repo/.git/config", {st_mode=S_IFREG\|0644, st_size=92, ...}) = 0 open("/tmp/repo/.git/config", O_RDONLY\|O_CLOEXEC) = 3 stat("/home/pks/.gitconfig", 0x7ffd15c051f0) = -1 ENOENT (No such file or directory) stat("/home/pks/.config/git/config", {st_mode=S_IFREG\|0644, st_size=1154, ...}) = 0 open("/home/pks/.config/git/config", O_RDONLY\|O_CLOEXEC) = 3 stat("/tmp/repo/.git/config", {st_mode=S_IFREG\|0644, st_size=92, ...}) = 0 open("/tmp/repo/.git/config", O_RDONLY\|O_CLOEXEC) = 3 stat("/home/pks/.gitconfig", 0x7ffd15c05090) = -1 ENOENT (No such file or directory) stat("/home/pks/.config/git/config", {st_mode=S_IFREG\|0644, st_size=1154, ...}) = 0 open("/home/pks/.config/git/config", O_RDONLY\|O_CLOEXEC) = 3 stat("/tmp/repo/.git/config", {st_mode=S_IFREG\|0644, st_size=92, ...}) = 0 open("/tmp/repo/.git/config", O_RDONLY\|O_CLOEXEC) = 3 stat("/home/pks/.gitconfig", 0x7ffd15c05090) = -1 ENOENT (No such file or directory) stat("/home/pks/.config/git/config", {st_mode=S_IFREG\|0644, st_size=1154, ...}) = 0 open("/home/pks/.config/git/config", O_RDONLY\|O_CLOEXEC) = 3 stat("/tmp/repo/.git/config", {st_mode=S_IFREG\|0644, st_size=92, ...}) = 0 open("/tmp/repo/.git/config", O_RDONLY\|O_CLOEXEC) = 3 stat("/home/pks/.gitconfig", 0x7ffd15c05090) = -1 ENOENT (No such file or directory) stat("/home/pks/.config/git/config", {st_mode=S_IFREG\|0644, st_size=1154, ...}) = 0 open("/home/pks/.config/git/config", O_RDONLY\|O_CLOEXEC) = 3 With the change, we only do stats for those files and open them a single time, only: $ strace lg2 for-each-ref \|& grep config access("/home/pks/.gitconfig", F_OK) = -1 ENOENT (No such file or directory) access("/home/pks/.config/git/config", F_OK) = 0 access("/etc/gitconfig", F_OK) = -1 ENOENT (No such file or directory) stat("/tmp/repo/.git/config", {st_mode=S_IFREG\|0644, st_size=92, ...}) = 0 access("/tmp/repo/.git/config", F_OK) = 0 stat("/tmp/repo/.git/config", {st_mode=S_IFREG\|0644, st_size=92, ...}) = 0 stat("/tmp/repo/.git/config", {st_mode=S_IFREG\|0644, st_size=92, ...}) = 0 open("/tmp/repo/.git/config", O_RDONLY\|O_CLOEXEC) = 3 stat("/home/pks/.gitconfig", 0x7ffe70540d20) = -1 ENOENT (No such file or directory) access("/home/pks/.gitconfig", F_OK) = -1 ENOENT (No such file or directory) stat("/home/pks/.config/git/config", {st_mode=S_IFREG\|0644, st_size=1154, ...}) = 0 access("/home/pks/.config/git/config", F_OK) = 0 stat("/home/pks/.config/git/config", {st_mode=S_IFREG\|0644, st_size=1154, ...}) = 0 stat("/home/pks/.config/git/config", {st_mode=S_IFREG\|0644, st_size=1154, ...}) = 0 open("/home/pks/.config/git/config", O_RDONLY\|O_CLOEXEC) = 3 stat("/tmp/repo/.git/config", {st_mode=S_IFREG\|0644, st_size=92, ...}) = 0 stat("/home/pks/.gitconfig", 0x7ffe70540ca0) = -1 ENOENT (No such file or directory) stat("/home/pks/.gitconfig", 0x7ffe70540c80) = -1 ENOENT (No such file or directory) stat("/home/pks/.config/git/config", {st_mode=S_IFREG\|0644, st_size=1154, ...}) = 0 stat("/tmp/repo/.git/config", {st_mode=S_IFREG\|0644, st_size=92, ...}) = 0 stat("/home/pks/.gitconfig", 0x7ffe70540b40) = -1 ENOENT (No such file or directory) stat("/home/pks/.gitconfig", 0x7ffe70540b20) = -1 ENOENT (No such file or directory) stat("/home/pks/.config/git/config", {st_mode=S_IFREG\|0644, st_size=1154, ...}) = 0 stat("/tmp/repo/.git/config", {st_mode=S_IFREG\|0644, st_size=92, ...}) = 0 stat("/home/pks/.gitconfig", 0x7ffe70540b40) = -1 ENOENT (No such file or directory) stat("/home/pks/.gitconfig", 0x7ffe70540b20) = -1 ENOENT (No such file or directory) stat("/home/pks/.config/git/config", {st_mode=S_IFREG\|0644, st_size=1154, ...}) = 0 stat("/tmp/repo/.git/config", {st_mode=S_IFREG\|0644, st_size=92, ...}) = 0 stat("/home/pks/.gitconfig", 0x7ffe70540b40) = -1 ENOENT (No such file or directory) stat("/home/pks/.gitconfig", 0x7ffe70540b20) = -1 ENOENT (No such file or directory) stat("/home/pks/.config/git/config", {st_mode=S_IFREG\|0644, st_size=1154, ...}) = 0 The following benchmark has been performed with and without the stat cache in a best-of-ten run: ``` int lg2_repro(git_repository repo, int argc, char argv) { git_config cfg; int32_t dummy; int i; UNUSED(argc); UNUSED(argv); check_lg2(git_repository_config(&cfg, repo), "Could not obtain config", NULL); for (i = 1; i < 100000; ++i) git_config_get_int32(&dummy, cfg, "foo.bar"); git_config_free(cfg); return 0; } ``` Without stat cache: $ time lg2 repro real 0m1.528s user 0m0.568s sys 0m0.944s With stat cache: $ time lg2 repro real 0m0.526s user 0m0.268s sys 0m0.258s This benchmark shows a nearly three-fold performance improvement. This change requires that we check our configuration stress tests as we're now in fact becoming more racy. If somebody is writing a configuration file at nearly the same time (there is a window of 100ns on Windows-based systems), then it might be that we realize that this file has actually changed and thus may not re-read it. This will only happen if either an external process is rewriting the configuration file or if the same process has multiple `git_config` structures pointing to the same time, where one of both is being used to write and the other one is used to read values.
ecf4f33a	2018-02-08T11:14:48	Convert usage of `git_buf_free` to new `git_buf_dispose`
9031be18	2015-11-24T14:38:17	tests: config::stress: free `git_config` structs
a2f96479	2015-10-29T20:31:25	config: add failing test for an external modification We currently use the timestamp in order to decide whether a config file has changed since we last read it. This scheme falls down if the file is written twice within the same second, as we fail to detect the file change after the first read in that second.
9a97f49e	2014-12-21T15:31:03	config: borrow refcounted references This changes the get_entry() method to return a refcounted version of the config entry, which you have to free when you're done. This allows us to avoid freeing the memory in which the entry is stored on a refresh, which may happen at any time for a live config. For this reason, get_string() has been forbidden on live configs and a new function get_string_buf() has been added, which stores the string in a git_buf which the user then owns. The functions which parse the string value takea advantage of the borrowing to parse safely and then release the entry.
a447a7e4	2014-10-04T23:28:40	config: Add test cases that have trailing spaces before comment chars
9dac1f95	2014-08-09T10:56:50	config: a multiline var can start immediately In the check for multiline, we traverse the backslashes from the end backwards and int the end assert that we haven't gone past the beginning of the line. We make sure of this in the loop condition, but we also check in the return value. However, for certain configurations, a line in a multiline variable might be empty to aid formatting. In that case, 'end' == 'start', since we ended up looking at the first char which made it a multiline. There is no need for the (end > start) check in the return, since the loop guarantees we won't go further back than the first char in the line, and we do accept the first char to be the final backslash. This fixes #2483.
17820381	2013-11-14T14:05:52	Rename tests-clar to tests

2766b92d

2019-07-21T15:10:34

config_file: refresh when creating an iterator When creating a new iterator for a config file backend, then we should always make sure that we're up to date by calling `config_refresh`. Otherwise, we might not notice when another process has modified the configuration file and thus will represent outdated values. Add two tests to config::stress that verify that we get up-to-date values when reading configuration entries via `git_config_iterator`.

e54343a4

2019-06-29T09:17:32

fileops: rename to "futils.h" to match function signatures Our file utils functions all have a "futils" prefix, e.g. `git_futils_touch`. One would thus naturally guess that their definitions and implementation would live in files "futils.h" and "futils.c", respectively, but in fact they live in "fileops.h". Rename the files to match expectations.

d7f58eab

2019-06-21T11:55:21

config_file: implement stat cache to avoid repeated rehashing To decide whether a config file has changed, we always hash its complete contents. This is unnecessarily expensive, as well-behaved filesystems will always update stat information for files which have changed. So before computing the hash, we should first check whether the stat info has actually changed for either the configuration file or any of its includes. This avoids having to re-read the configuration file and its includes every time when we check whether it's been modified. Tracing the for-each-ref example previous to this commit, one can see that we repeatedly re-open both the repo configuration as well as the global configuration: $ strace lg2 for-each-ref |& grep config access("/home/pks/.gitconfig", F_OK) = -1 ENOENT (No such file or directory) access("/home/pks/.config/git/config", F_OK) = 0 access("/etc/gitconfig", F_OK) = -1 ENOENT (No such file or directory) stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0 access("/tmp/repo/.git/config", F_OK) = 0 stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0 open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3 stat("/home/pks/.gitconfig", 0x7ffd15c05290) = -1 ENOENT (No such file or directory) access("/home/pks/.gitconfig", F_OK) = -1 ENOENT (No such file or directory) stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0 access("/home/pks/.config/git/config", F_OK) = 0 stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0 open("/home/pks/.config/git/config", O_RDONLY|O_CLOEXEC) = 3 stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0 open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3 stat("/home/pks/.gitconfig", 0x7ffd15c051f0) = -1 ENOENT (No such file or directory) stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0 open("/home/pks/.config/git/config", O_RDONLY|O_CLOEXEC) = 3 stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0 open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3 stat("/home/pks/.gitconfig", 0x7ffd15c05090) = -1 ENOENT (No such file or directory) stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0 open("/home/pks/.config/git/config", O_RDONLY|O_CLOEXEC) = 3 stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0 open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3 stat("/home/pks/.gitconfig", 0x7ffd15c05090) = -1 ENOENT (No such file or directory) stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0 open("/home/pks/.config/git/config", O_RDONLY|O_CLOEXEC) = 3 stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0 open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3 stat("/home/pks/.gitconfig", 0x7ffd15c05090) = -1 ENOENT (No such file or directory) stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0 open("/home/pks/.config/git/config", O_RDONLY|O_CLOEXEC) = 3 With the change, we only do stats for those files and open them a single time, only: $ strace lg2 for-each-ref |& grep config access("/home/pks/.gitconfig", F_OK) = -1 ENOENT (No such file or directory) access("/home/pks/.config/git/config", F_OK) = 0 access("/etc/gitconfig", F_OK) = -1 ENOENT (No such file or directory) stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0 access("/tmp/repo/.git/config", F_OK) = 0 stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0 stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0 open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3 stat("/home/pks/.gitconfig", 0x7ffe70540d20) = -1 ENOENT (No such file or directory) access("/home/pks/.gitconfig", F_OK) = -1 ENOENT (No such file or directory) stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0 access("/home/pks/.config/git/config", F_OK) = 0 stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0 stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0 open("/home/pks/.config/git/config", O_RDONLY|O_CLOEXEC) = 3 stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0 stat("/home/pks/.gitconfig", 0x7ffe70540ca0) = -1 ENOENT (No such file or directory) stat("/home/pks/.gitconfig", 0x7ffe70540c80) = -1 ENOENT (No such file or directory) stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0 stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0 stat("/home/pks/.gitconfig", 0x7ffe70540b40) = -1 ENOENT (No such file or directory) stat("/home/pks/.gitconfig", 0x7ffe70540b20) = -1 ENOENT (No such file or directory) stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0 stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0 stat("/home/pks/.gitconfig", 0x7ffe70540b40) = -1 ENOENT (No such file or directory) stat("/home/pks/.gitconfig", 0x7ffe70540b20) = -1 ENOENT (No such file or directory) stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0 stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0 stat("/home/pks/.gitconfig", 0x7ffe70540b40) = -1 ENOENT (No such file or directory) stat("/home/pks/.gitconfig", 0x7ffe70540b20) = -1 ENOENT (No such file or directory) stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0 The following benchmark has been performed with and without the stat cache in a best-of-ten run: ``` int lg2_repro(git_repository *repo, int argc, char **argv) { git_config *cfg; int32_t dummy; int i; UNUSED(argc); UNUSED(argv); check_lg2(git_repository_config(&cfg, repo), "Could not obtain config", NULL); for (i = 1; i < 100000; ++i) git_config_get_int32(&dummy, cfg, "foo.bar"); git_config_free(cfg); return 0; } ``` Without stat cache: $ time lg2 repro real 0m1.528s user 0m0.568s sys 0m0.944s With stat cache: $ time lg2 repro real 0m0.526s user 0m0.268s sys 0m0.258s This benchmark shows a nearly three-fold performance improvement. This change requires that we check our configuration stress tests as we're now in fact becoming more racy. If somebody is writing a configuration file at nearly the same time (there is a window of 100ns on Windows-based systems), then it might be that we realize that this file has actually changed and thus may not re-read it. This will only happen if either an external process is rewriting the configuration file or if the same process has multiple `git_config` structures pointing to the same time, where one of both is being used to write and the other one is used to read values.

ecf4f33a

2018-02-08T11:14:48

Convert usage of `git_buf_free` to new `git_buf_dispose`

9031be18

2015-11-24T14:38:17

tests: config::stress: free `git_config` structs

a2f96479

2015-10-29T20:31:25

config: add failing test for an external modification We currently use the timestamp in order to decide whether a config file has changed since we last read it. This scheme falls down if the file is written twice within the same second, as we fail to detect the file change after the first read in that second.

9a97f49e

2014-12-21T15:31:03

config: borrow refcounted references This changes the get_entry() method to return a refcounted version of the config entry, which you have to free when you're done. This allows us to avoid freeing the memory in which the entry is stored on a refresh, which may happen at any time for a live config. For this reason, get_string() has been forbidden on live configs and a new function get_string_buf() has been added, which stores the string in a git_buf which the user then owns. The functions which parse the string value takea advantage of the borrowing to parse safely and then release the entry.

a447a7e4

2014-10-04T23:28:40

config: Add test cases that have trailing spaces before comment chars

9dac1f95

2014-08-09T10:56:50

config: a multiline var can start immediately In the check for multiline, we traverse the backslashes from the end backwards and int the end assert that we haven't gone past the beginning of the line. We make sure of this in the loop condition, but we also check in the return value. However, for certain configurations, a line in a multiline variable might be empty to aid formatting. In that case, 'end' == 'start', since we ended up looking at the first char which made it a multiline. There is no need for the (end > start) check in the return, since the loop guarantees we won't go further back than the first char in the line, and we do accept the first char to be the final backslash. This fixes #2483.

17820381

2013-11-14T14:05:52

Rename tests-clar to tests

thodg/libgit2/tests/config/stress.c

tests/config/stress.c

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