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authorVolker Lendecke <vl@samba.org>2010-03-23 18:36:55 +0100
committerVolker Lendecke <vl@samba.org>2010-03-24 08:57:29 +0100
commitfbdcaa929c7270469cf6c31fd6fcf94ce4e7306e (patch)
treec175b3ef5b4fbd75835ed038c0f1bf41d15b9d48 /source3/lib
parenta599319d0a389ff0c31dae8068cd7a78352aa9e7 (diff)
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s3: Optimize gencache for smbd exit
If thousands of smbds try to gencache_stabilize at the same time because the network died, all of them might be sitting in transaction_start. Don't do the stabilize transaction if nothing has changed in gencache_notrans.tdb. Volker
Diffstat (limited to 'source3/lib')
-rw-r--r--source3/lib/gencache.c89
1 files changed, 75 insertions, 14 deletions
diff --git a/source3/lib/gencache.c b/source3/lib/gencache.c
index 9a4cbc2cd7..577ff12a19 100644
--- a/source3/lib/gencache.c
+++ b/source3/lib/gencache.c
@@ -40,6 +40,13 @@ static struct tdb_context *cache_notrans;
* @brief Generic, persistent and shared between processes cache mechanism
* for use by various parts of the Samba code
*
+ * We have two cache files, one with transactions (gencache.tdb) and
+ * one without (gencache_notrans.tdb) that is CLEAR_IF_FIRST. Normal
+ * writes go to the gencache_notrans.tdb to be fast. Every 100 writes
+ * to the gencache (settable with gencache:stabilize_count) or every 5
+ * minutes (settable with gencache:stabilize_interval) we stabilize
+ * gencache_notrans.tdb with one transaction to gencache.tdb.
+ *
**/
@@ -107,7 +114,8 @@ again:
DEBUG(5, ("Opening cache file at %s\n", cache_fname));
- cache_notrans = tdb_open_log(cache_fname, 0, TDB_CLEAR_IF_FIRST,
+ cache_notrans = tdb_open_log(cache_fname, 0,
+ TDB_CLEAR_IF_FIRST | TDB_SEQNUM,
open_flags, 0644);
if (cache_notrans == NULL) {
DEBUG(5, ("Opening %s failed: %s\n", cache_fname,
@@ -128,6 +136,51 @@ static TDB_DATA last_stabilize_key(void)
return result;
}
+struct gencache_parse_last_stabilize_state {
+ bool found;
+ int last_time;
+ int last_seqnum;
+};
+
+static int gencache_parse_last_stabilize_fn(TDB_DATA key, TDB_DATA data,
+ void *private_data)
+{
+ struct gencache_parse_last_stabilize_state *state =
+ (struct gencache_parse_last_stabilize_state *)private_data;
+
+ if ((data.dptr == NULL) || (data.dsize == 0) ||
+ (data.dptr[data.dsize-1] != '\0')) {
+ return -1;
+ }
+
+ if (sscanf((char *)data.dptr, "%d/%d", &state->last_time,
+ &state->last_seqnum) != 2) {
+ return -1;
+ }
+
+ state->found = true;
+ return 0;
+}
+
+static bool gencache_parse_last_stabilize(time_t *last_time, int *last_seqnum)
+{
+ struct gencache_parse_last_stabilize_state state;
+
+ state.found = false;
+
+ if (tdb_parse_record(cache_notrans, last_stabilize_key(),
+ gencache_parse_last_stabilize_fn,
+ &state) == -1) {
+ return false;
+ }
+ if (!state.found) {
+ return false;
+ }
+ *last_time = state.last_time;
+ *last_seqnum = state.last_seqnum;
+ return true;
+}
+
/**
* Set an entry in the cache file. If there's no such
* one, then add it.
@@ -144,9 +197,9 @@ bool gencache_set_data_blob(const char *keystr, const DATA_BLOB *blob,
time_t timeout)
{
int ret;
- TDB_DATA databuf;
char* val;
time_t last_stabilize;
+ int last_seqnum;
static int writecount;
if (tdb_data_cmp(string_term_tdb_data(keystr),
@@ -206,17 +259,15 @@ bool gencache_set_data_blob(const char *keystr, const DATA_BLOB *blob,
* gencache_notrans.tdb too large.
*/
- last_stabilize = 0;
- databuf = tdb_fetch(cache_notrans, last_stabilize_key());
- if ((databuf.dptr != NULL)
- && (databuf.dptr[databuf.dsize-1] == '\0')) {
- last_stabilize = atoi((char *)databuf.dptr);
- SAFE_FREE(databuf.dptr);
- }
- if ((last_stabilize
- + lp_parm_int(-1, "gencache", "stabilize_interval", 300))
- < time(NULL)) {
- gencache_stabilize();
+ if (gencache_parse_last_stabilize(&last_stabilize, &last_seqnum)) {
+ time_t next;
+
+ next = last_stabilize + lp_parm_int(
+ -1, "gencache", "stabilize_interval", 300);
+
+ if (next < time(NULL)) {
+ gencache_stabilize();
+ }
}
done:
@@ -411,11 +462,19 @@ bool gencache_stabilize(void)
struct stabilize_state state;
int res;
char *now;
+ time_t last_time;
+ int last_seqnum;
if (!gencache_init()) {
return false;
}
+ if (gencache_parse_last_stabilize(&last_time, &last_seqnum)
+ && (last_seqnum == tdb_get_seqnum(cache_notrans))) {
+ /* Nothing changed */
+ return true;
+ }
+
res = tdb_transaction_start(cache);
if (res == -1) {
DEBUG(10, ("Could not start transaction on gencache.tdb: "
@@ -468,7 +527,9 @@ bool gencache_stabilize(void)
return false;
}
- now = talloc_asprintf(talloc_tos(), "%d", (int)time(NULL));
+ now = talloc_asprintf(talloc_tos(), "%d/%d",
+ (int)time(NULL),
+ tdb_get_seqnum(cache_notrans)+1);
if (now != NULL) {
tdb_store(cache_notrans, last_stabilize_key(),
string_term_tdb_data(now), 0);