There is code in post_read_index_from() to catch out of order entries
when reading an index file. This order verification is ~13% of the cost
of every call to read_index_from().
Update check_ce_order() so that it skips this verification unless the
"verify_ce_order" global variable is set.
Teach fsck to force this verification.
The effect can be seen using t/perf/p0002-read-cache.sh:
Test HEAD HEAD~1
--------------------------------------------------------------------------------------
0002.1: read_cache/discard_cache 1000 times 0.41(0.04+0.04) 0.50(0.00+0.10) +22.0%
Signed-off-by: Ben Peart <benpeart@xxxxxxxxxxxxx>
---
Notes:
Base Ref:
Web-Diff: https://github.com/benpeart/git/commit/54fa9cf954
Checkout: git fetch https://github.com/benpeart/git verify_ce_order-v1 && git checkout 54fa9cf954
builtin/fsck.c | 1 +
cache.h | 1 +
read-cache.c | 6 ++++++
3 files changed, 8 insertions(+)
diff --git a/builtin/fsck.c b/builtin/fsck.c
index d18244ab54..81cc5ad78d 100644
--- a/builtin/fsck.c
+++ b/builtin/fsck.c
@@ -763,6 +763,7 @@ int cmd_fsck(int argc, const char **argv, const char *prefix)
if (keep_cache_objects) {
verify_index_checksum = 1;
+ verify_ce_order = 1;
read_cache();
for (i = 0; i < active_nr; i++) {
unsigned int mode;
diff --git a/cache.h b/cache.h
index 5e2c9512ff..4a4f879061 100644
--- a/cache.h
+++ b/cache.h
@@ -721,6 +721,7 @@ extern int hold_locked_index(struct lock_file *, int);
extern void set_alternate_index_output(const char *);
extern int verify_index_checksum;
+extern int verify_ce_order;
/* Environment bits from configuration mechanism */
extern int trust_executable_bit;
diff --git a/read-cache.c b/read-cache.c
index b64610c400..32743da157 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -1513,6 +1513,9 @@ struct ondisk_cache_entry_extended {
/* Allow fsck to force verification of the index checksum. */
int verify_index_checksum;
+/* Allow fsck to force verification of the cache entry order. */
+int verify_ce_order;
+
static int verify_hdr(struct cache_header *hdr, unsigned long size)
{
git_SHA_CTX c;
@@ -1698,6 +1701,9 @@ static void check_ce_order(struct index_state *istate)
{
unsigned int i;
+ if (!verify_ce_order)
+ return;
+
for (i = 1; i < istate->cache_nr; i++) {
struct cache_entry *ce = istate->cache[i - 1];
struct cache_entry *next_ce = istate->cache[i];
base-commit: 46309c695b080648f8c0ea5e2d1fd7387ee7f044
--
2.14.1.windows.1.1034.g0776750557
