diff options
author | Michael Haggerty <mhagger@alum.mit.edu> | 2013-06-20 12:37:51 +0400 |
---|---|---|
committer | Junio C Hamano <gitster@pobox.com> | 2013-06-21 02:50:17 +0400 |
commit | 38612532240ecbe1b12e54ca859fed8410ae6de1 (patch) | |
tree | f712bce08c4130f25bf4ca5717b82018a7b569fb | |
parent | c21d39d7c7eb07eed0be301a72856bff65201256 (diff) |
add a stat_validity struct
It can sometimes be useful to know whether a path in the
filesystem has been updated without going to the work of
opening and re-reading its content. We trust the stat()
information on disk already to handle index updates, and we
can use the same trick here.
This patch introduces a "stat_validity" struct which
encapsulates the concept of checking the stat-freshness of a
file. It is implemented on top of "struct stat_data" to
reuse the logic about which stat entries to trust for a
particular platform, but hides the complexity behind two
simple functions: check and update.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
-rw-r--r-- | cache.h | 27 | ||||
-rw-r--r-- | read-cache.c | 30 |
2 files changed, 57 insertions, 0 deletions
@@ -1360,4 +1360,31 @@ int checkout_fast_forward(const unsigned char *from, int sane_execvp(const char *file, char *const argv[]); +/* + * A struct to encapsulate the concept of whether a file has changed + * since we last checked it. This uses criteria similar to those used + * for the index. + */ +struct stat_validity { + struct stat_data *sd; +}; + +void stat_validity_clear(struct stat_validity *sv); + +/* + * Returns 1 if the path is a regular file (or a symlink to a regular + * file) and matches the saved stat_validity, 0 otherwise. A missing + * or inaccessible file is considered a match if the struct was just + * initialized, or if the previous update found an inaccessible file. + */ +int stat_validity_check(struct stat_validity *sv, const char *path); + +/* + * Update the stat_validity from a file opened at descriptor fd. If + * the file is missing, inaccessible, or not a regular file, then + * future calls to stat_validity_check will match iff one of those + * conditions continues to be true. + */ +void stat_validity_update(struct stat_validity *sv, int fd); + #endif /* CACHE_H */ diff --git a/read-cache.c b/read-cache.c index 5660b37bb2..b15bc096ea 100644 --- a/read-cache.c +++ b/read-cache.c @@ -1950,3 +1950,33 @@ void *read_blob_data_from_index(struct index_state *istate, const char *path, un *size = sz; return data; } + +void stat_validity_clear(struct stat_validity *sv) +{ + free(sv->sd); + sv->sd = NULL; +} + +int stat_validity_check(struct stat_validity *sv, const char *path) +{ + struct stat st; + + if (stat(path, &st) < 0) + return sv->sd == NULL; + if (!sv->sd) + return 0; + return S_ISREG(st.st_mode) && !match_stat_data(sv->sd, &st); +} + +void stat_validity_update(struct stat_validity *sv, int fd) +{ + struct stat st; + + if (fstat(fd, &st) < 0 || !S_ISREG(st.st_mode)) + stat_validity_clear(sv); + else { + if (!sv->sd) + sv->sd = xcalloc(1, sizeof(struct stat_data)); + fill_stat_data(sv->sd, &st); + } +} |