Bron, Ken, did you have time to take a look at this patch ?
By the way, here is an updated patch.
--
Cyril Servant
2009/11/19 Servant Cyril cyril.serv...@atosorigin.com:
Hello,
Here is a patch for optimizing pop. Let me explain : Here we have lots
(millions) of mailboxes. Many people connect to pop every few minutes, doing
LIST, and if there are mails, they do RETR and DELE. Most of time, there is
no mail (for 138770 pop connections, there was no mail 92498 times = 66.6%).
Without the patch, the seen, index, cache and header files are opened. With
this patch, we only read statuscache.db (which is already opened) when there
is no mail.
On the stat image joined, you can see what's happening when we empty
statuscache.db (at 10:51) : pop optimization doesn't work the first time a
client connects to pop (Lots of reads), and then, as the same clients connect
again to pop, reads slowly decrease. Without the patch, reads would stay high.
--
Cyril Servant
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--
Cyril
diff -u -r cyrus-imapd-2.3.15.orig/imap/index.c cyrus-imapd-2.3.15/imap/index.c
--- cyrus-imapd-2.3.15.orig/imap/index.c 2009-09-09 03:22:38.0 +0200
+++ cyrus-imapd-2.3.15/imap/index.c 2009-11-19 11:56:57.0 +0100
@@ -5511,3 +5511,116 @@
l = n;
}
}
+
+int index_statuscache(char *mboxname, char *name, struct auth_state *authstate, unsigned statusitems, struct statuscache_data *scdata)
+{
+int r;
+struct mailbox mailbox;
+int doclose = 0;
+int num_recent = 0;
+int num_unseen = 0;
+int sepchar;
+static struct seq_set seq_set = { NULL, 0, 0, 0 , NULL};
+
+/* Check status cache if possible */
+if (config_getswitch(IMAPOPT_STATUSCACHE)) {
+ /* Do actual lookup of cache item. */
+ r = statuscache_lookup(mboxname, name, statusitems, scdata);
+
+ /* Seen/recent status uses push invalidation events from
+ * seen_db.c. This avoids needing to open cyrus.header to get
+ * the mailbox uniqueid to open the seen db and get the
+ * unseen_mtime and recentuid. */
+
+ if (!r) {
+ syslog(LOG_DEBUG, statuscache, '%s', '%s', '0x%02x', 'yes',
+ mboxname, name, statusitems);
+ goto statusdone;
+ }
+
+ syslog(LOG_DEBUG, statuscache, '%s', '%s', '0x%02x', 'no',
+ mboxname, name, statusitems);
+}
+
+/* Missing or invalid cache entry */
+r = mailbox_open_header(mboxname, authstate, mailbox);
+
+if (!r) {
+ doclose = 1;
+ r = mailbox_open_index(mailbox);
+}
+
+if (!r mailbox.exists != 0
+ (statusitems (STATUS_RECENT | STATUS_UNSEEN))) {
+ /* Read \Seen state */
+ struct seen *status_seendb;
+ time_t last_read, last_change = 0;
+ unsigned last_uid;
+ char *last_seenuids;
+
+ r = seen_open(mailbox,
+ (mailbox.options OPT_IMAP_SHAREDSEEN) ? anyone :
+ name,
+ SEEN_CREATE, status_seendb);
+
+ if (!r) {
+ r = seen_lockread(status_seendb, last_read, last_uid,
+ last_change, last_seenuids);
+ seen_close(status_seendb);
+ }
+
+ if (!r) {
+ const char *base;
+ unsigned long len = 0;
+ unsigned msg, uid;
+
+ map_refresh(mailbox.index_fd, 0, base, len,
+ mailbox.start_offset +
+ mailbox.exists * mailbox.record_size,
+ index, mailbox.name);
+
+ seq_set.len = seq_set.mark = 0;
+ index_parse_sequence(last_seenuids, 0, seq_set);
+
+ for (msg = 0; msg mailbox.exists; msg++) {
+ uid = ntohl(*((bit32 *)(base + mailbox.start_offset +
+msg * mailbox.record_size +
+OFFSET_UID)));
+ /* Always calculate num_recent,
+ * even if only need num_unseen... for caching below */
+ if (uid last_uid) num_recent++;
+ if ((statusitems STATUS_UNSEEN)
+ !index_insequence(uid, seq_set, 1)) num_unseen++;
+ /* NB: The value of the third argument to
