diff options
Diffstat (limited to 'subversion/libsvn_subr/io.c')
| -rw-r--r-- | subversion/libsvn_subr/io.c | 38 |
1 files changed, 25 insertions, 13 deletions
diff --git a/subversion/libsvn_subr/io.c b/subversion/libsvn_subr/io.c index f0956e2aa8e94..08f2e326d7fe6 100644 --- a/subversion/libsvn_subr/io.c +++ b/subversion/libsvn_subr/io.c @@ -1243,32 +1243,44 @@ svn_io_sleep_for_timestamps(const char *path, apr_pool_t *pool) { /* Very simplistic but safe approach: If the filesystem has < sec mtime we can be reasonably sure - that the filesystem has <= millisecond precision. + that the filesystem has some sub-second resolution. On Windows + it is likely to be sub-millisecond; on Linux systems it depends + on the filesystem, ext4 is typically 1ms, 4ms or 10ms resolution. ## Perhaps find a better algorithm here. This will fail once - in every 1000 cases on a millisecond precision filesystem. + in every 1000 cases on a millisecond precision filesystem + if the mtime happens to be an exact second. But better to fail once in every thousand cases than every time, like we did before. - (All tested filesystems I know have at least microsecond precision.) Note for further research on algorithm: - FAT32 has < 1 sec precision on ctime, but 2 sec on mtime */ + FAT32 has < 1 sec precision on ctime, but 2 sec on mtime. - /* Sleep for at least 1 millisecond. - (t < 1000 will be round to 0 in apr) */ - apr_sleep(1000); + Linux/ext4 with CONFIG_HZ=250 has high resolution + apr_time_now and although the filesystem timestamps + have similar high precision they are only updated with + a coarser 4ms resolution. */ - return; + /* 10 milliseconds after now. */ +#ifndef SVN_HI_RES_SLEEP_MS +#define SVN_HI_RES_SLEEP_MS 10 +#endif + then = now + apr_time_from_msec(SVN_HI_RES_SLEEP_MS); } - now = apr_time_now(); /* Extract the time used for the path stat */ - - if (now >= then) - return; /* Passing negative values may suspend indefinitely (Windows) */ + /* Remove time taken to do stat() from sleep. */ + now = apr_time_now(); } - apr_sleep(then - now); + if (now >= then) + return; /* Passing negative values may suspend indefinitely (Windows) */ + + /* (t < 1000 will be round to 0 in apr) */ + if (then - now < 1000) + apr_sleep(1000); + else + apr_sleep(then - now); } |