[PATCH v4 5/9] trace.c: add GIT_TRACE_INDEX_STATS for index statistics

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 Documentation/git.txt |  1 +
 cache.h               |  1 +
 read-cache.c          | 16 ++++++++++++++++
 trace.c               |  5 ++++-
 4 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/Documentation/git.txt b/Documentation/git.txt
index 1086ced..f2078aa 100644
--- a/Documentation/git.txt
+++ b/Documentation/git.txt
@@ -1046,6 +1046,7 @@ of clones and fetches.
 	See 'GIT_TRACE' for available trace output options.
 
 'GIT_TRACE_PACK_STATS'::
+'GIT_TRACE_INDEX_STATS'::
 	Print various statistics.
 
 'GIT_TRACE_SETUP'::
diff --git a/cache.h b/cache.h
index 30a3a77..69c2365 100644
--- a/cache.h
+++ b/cache.h
@@ -1754,5 +1754,6 @@ int versioncmp(const char *s1, const char *s2);
 void sleep_millisec(int millisec);
 
 void report_pack_stats(struct trace_key *key);
+void report_index_stats(struct trace_key *key);
 
 #endif /* CACHE_H */
diff --git a/read-cache.c b/read-cache.c
index 6c98e98..6ae50c7 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -50,6 +50,10 @@ static struct cache_entry *refresh_cache_entry(struct cache_entry *ce,
 struct index_state the_index;
 static const char *alternate_index_output;
 
+static unsigned int nr_read_index;
+static unsigned int nr_read_shm_index;
+static unsigned int nr_write_index;
+
 static void set_index_entry(struct index_state *istate, int nr, struct cache_entry *ce)
 {
 	istate->cache[nr] = ce;
@@ -1592,6 +1596,7 @@ static int try_shm(struct index_state *istate)
 	istate->mmap = new_mmap;
 	istate->mmap_size = new_length;
 	istate->from_shm = 1;
+	nr_read_shm_index++;
 	return 0;
 }
 
@@ -1689,6 +1694,7 @@ int do_read_index(struct index_state *istate, const char *path, int must_exist)
 	}
 	if (!istate->keep_mmap)
 		munmap(mmap, mmap_size);
+	nr_read_index++;
 	return istate->cache_nr;
 
 unmap:
@@ -2174,6 +2180,7 @@ static int do_write_index(struct index_state *istate, int newfd,
 		return -1;
 	istate->timestamp.sec = (unsigned int)st.st_mtime;
 	istate->timestamp.nsec = ST_MTIME_NSEC(st);
+	nr_write_index++;
 	return 0;
 }
 
@@ -2400,3 +2407,12 @@ void stat_validity_update(struct stat_validity *sv, int fd)
 		fill_stat_data(sv->sd, &st);
 	}
 }
+
+void report_index_stats(struct trace_key *key)
+{
+	trace_printf_key(key, "\n"
+			 "index stats: file reads        = %10u\n"
+			 "index stats: cache reads       = %10u\n"
+			 "index stats: file writes       = %10u\n",
+			 nr_read_index, nr_read_shm_index, nr_write_index);
+}
diff --git a/trace.c b/trace.c
index b1d0885..eea1fa8 100644
--- a/trace.c
+++ b/trace.c
@@ -434,14 +434,17 @@ void trace_command_performance(const char **argv)
 }
 
 static struct trace_key trace_pack_stats = TRACE_KEY_INIT(PACK_STATS);
+static struct trace_key trace_index_stats = TRACE_KEY_INIT(INDEX_STATS);
 
 static void print_stats_atexit(void)
 {
 	report_pack_stats(&trace_pack_stats);
+	report_index_stats(&trace_index_stats);
 }
 
 void trace_stats(void)
 {
-	if (trace_want(&trace_pack_stats))
+	if (trace_want(&trace_pack_stats) ||
+	    trace_want(&trace_index_stats))
 		atexit(print_stats_atexit);
 }
-- 
2.2.0.513.g477eb31