config: add new index.threads config setting
Add support for a new index.threads config setting which will be used to
control the threading code in do_read_index(). A value of 0 will tell the
index code to automatically determine the correct number of threads to use.
A value of 1 will make the code single threaded. A value greater than 1
will set the maximum number of threads to use.
For testing purposes, this setting can be overwritten by setting the
GIT_TEST_INDEX_THREADS=<n> environment variable to a value greater than 0.
Signed-off-by: Ben Peart <benpeart@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/Documentation/config.txt b/Documentation/config.txt
index ad0f451..8fd973b 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -2413,6 +2413,13 @@
The configuration variables in the 'imap' section are described
in linkgit:git-imap-send[1].
+index.threads::
+ Specifies the number of threads to spawn when loading the index.
+ This is meant to reduce index load time on multiprocessor machines.
+ Specifying 0 or 'true' will cause Git to auto-detect the number of
+ CPU's and set the number of threads accordingly. Specifying 1 or
+ 'false' will disable multithreading. Defaults to 'true'.
+
index.version::
Specify the version with which new index files should be
initialized. This does not affect existing repositories.
diff --git a/config.c b/config.c
index 3461993..2ee29f6 100644
--- a/config.c
+++ b/config.c
@@ -2289,6 +2289,24 @@ int git_config_get_fsmonitor(void)
return 0;
}
+int git_config_get_index_threads(void)
+{
+ int is_bool, val = 0;
+
+ val = git_env_ulong("GIT_TEST_INDEX_THREADS", 0);
+ if (val)
+ return val;
+
+ if (!git_config_get_bool_or_int("index.threads", &is_bool, &val)) {
+ if (is_bool)
+ return val ? 0 : 1;
+ else
+ return val;
+ }
+
+ return 0; /* auto */
+}
+
NORETURN
void git_die_config_linenr(const char *key, const char *filename, int linenr)
{
diff --git a/config.h b/config.h
index ab46e01..a06027e 100644
--- a/config.h
+++ b/config.h
@@ -250,6 +250,7 @@ extern int git_config_get_untracked_cache(void);
extern int git_config_get_split_index(void);
extern int git_config_get_max_percent_split_change(void);
extern int git_config_get_fsmonitor(void);
+extern int git_config_get_index_threads(void);
/* This dies if the configured or default date is in the future */
extern int git_config_get_expiry(const char *key, const char **output);
diff --git a/t/README b/t/README
index 3ea6c85..8f5c062 100644
--- a/t/README
+++ b/t/README
@@ -327,6 +327,11 @@
be written after every 'git commit' command, and overrides the
'core.commitGraph' setting to true.
+GIT_TEST_INDEX_THREADS=<n> enables exercising the multi-threaded loading
+of the index for the whole test suite by bypassing the default number of
+cache entries and thread minimums. Setting this to 1 will make the
+index loading single threaded.
+
Naming Tests
------------
diff --git a/t/t1700-split-index.sh b/t/t1700-split-index.sh
index 8e17f8e..ef9349b 100755
--- a/t/t1700-split-index.sh
+++ b/t/t1700-split-index.sh
@@ -6,7 +6,12 @@
# We need total control of index splitting here
sane_unset GIT_TEST_SPLIT_INDEX
+
+# Testing a hard coded SHA against an index with an extension
+# that can vary from run to run is problematic so we disable
+# those extensions.
sane_unset GIT_FSMONITOR_TEST
+sane_unset GIT_TEST_INDEX_THREADS
test_expect_success 'enable split index' '
git config splitIndex.maxPercentChange 100 &&
