From 8b604d19515c4be18403047045faa363d4de217b Mon Sep 17 00:00:00 2001 From: Jeff Hostetler Date: Wed, 6 Sep 2017 15:43:48 +0000 Subject: hashmap: add API to disable item counting when threaded This is to address concerns raised by ThreadSanitizer on the mailing list about threaded unprotected R/W access to map.size with my previous "disallow rehash" change (0607e10009ee4e37cb49b4cec8d28a9dda1656a4). See: https://public-inbox.org/git/adb37b70139fd1e2bac18bfd22c8b96683ae18eb.1502780344.git.martin.agren@gmail.com/ Add API to hashmap to disable item counting and thus automatic rehashing. Also include API to later re-enable them. When item counting is disabled, the map.size field is invalid. So to prevent accidents, the field has been renamed and an accessor function hashmap_get_size() has been added. All direct references to this field have been been updated. And the name of the field changed to map.private_size to communicate this. Here is the relevant output from ThreadSanitizer showing the problem: WARNING: ThreadSanitizer: data race (pid=10554) Read of size 4 at 0x00000082d488 by thread T2 (mutexes: write M16): #0 hashmap_add hashmap.c:209 #1 hash_dir_entry_with_parent_and_prefix name-hash.c:302 #2 handle_range_dir name-hash.c:347 #3 handle_range_1 name-hash.c:415 #4 lazy_dir_thread_proc name-hash.c:471 #5 Previous write of size 4 at 0x00000082d488 by thread T1 (mutexes: write M31): #0 hashmap_add hashmap.c:209 #1 hash_dir_entry_with_parent_and_prefix name-hash.c:302 #2 handle_range_dir name-hash.c:347 #3 handle_range_1 name-hash.c:415 #4 handle_range_dir name-hash.c:380 #5 handle_range_1 name-hash.c:415 #6 lazy_dir_thread_proc name-hash.c:471 #7 Martin gives instructions for running TSan on test t3008 in this post: https://public-inbox.org/git/CAN0heSoJDL9pWELD6ciLTmWf-a=oyxe4EXXOmCKvsG5MSuzxsA@mail.gmail.com/ Signed-off-by: Jeff Hostetler Signed-off-by: Junio C Hamano --- builtin/describe.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'builtin') diff --git a/builtin/describe.c b/builtin/describe.c index 9c13c6817b..e77163e909 100644 --- a/builtin/describe.c +++ b/builtin/describe.c @@ -508,7 +508,7 @@ int cmd_describe(int argc, const char **argv, const char *prefix) hashmap_init(&names, commit_name_cmp, NULL, 0); for_each_rawref(get_name, NULL); - if (!names.size && !always) + if (!hashmap_get_size(&names) && !always) die(_("No names found, cannot describe anything.")); if (argc == 0) { -- cgit v1.2.3