dovecot-2.2: expire plugin: If expire_cache=yes, cache the dict ...
dovecot at dovecot.org
dovecot at dovecot.org
Tue Feb 24 16:43:24 UTC 2015
details: http://hg.dovecot.org/dovecot-2.2/rev/c2e46b4df488
changeset: 18273:c2e46b4df488
user: Timo Sirainen <tss at iki.fi>
date: Tue Feb 24 18:42:43 2015 +0200
description:
expire plugin: If expire_cache=yes, cache the dict db value in dovecot.index file.
This avoids all of the dict lookups when mails are being saved to a mailbox
that is tracked for expiring. The only downside is that if the dict is
externally modified, the changes won't reflect the cached value. This isn't
normally a problem (except maybe in initial testing stages).
diffstat:
src/plugins/expire/expire-plugin.c | 161 +++++++++++++++++++++++++++---------
1 files changed, 119 insertions(+), 42 deletions(-)
diffs (247 lines):
diff -r 466596200825 -r c2e46b4df488 src/plugins/expire/expire-plugin.c
--- a/src/plugins/expire/expire-plugin.c Sat Feb 21 11:40:40 2015 +0200
+++ b/src/plugins/expire/expire-plugin.c Tue Feb 24 18:42:43 2015 +0200
@@ -1,5 +1,10 @@
/* Copyright (c) 2006-2015 Dovecot authors, see the included COPYING file */
+/* There are several race conditions in this plugin, but they should be
+ happening pretty rarely and usually it's not a big problem if the results
+ are temporarily wrong. Fixing the races would likely be a lot of work,
+ so it's not really worth it. */
+
#include "lib.h"
#include "ioloop.h"
#include "array.h"
@@ -21,15 +26,21 @@
#define EXPIRE_USER_CONTEXT(obj) \
MODULE_CONTEXT(obj, expire_mail_user_module)
+struct expire_mail_index_header {
+ uint32_t timestamp;
+};
+
struct expire_mail_user {
union mail_user_module_context module_ctx;
struct dict *db;
struct expire_set *set;
+ bool expire_cache;
};
struct expire_mailbox {
union mailbox_module_context module_ctx;
+ uint32_t expire_ext_id;
};
struct expire_transaction_context {
@@ -62,6 +73,108 @@
return t;
}
+static void first_save_timestamp(struct mailbox *box, time_t *stamp_r)
+{
+ struct mailbox_transaction_context *t;
+ const struct mail_index_header *hdr;
+ struct mail *mail;
+
+ *stamp_r = ioloop_time;
+
+ t = mailbox_transaction_begin(box, 0);
+ mail = mail_alloc(t, 0, NULL);
+
+ /* find the first non-expunged mail. we're here because the first
+ mail was expunged, so don't bother checking it. */
+ hdr = mail_index_get_header(box->view);
+ if (hdr->messages_count > 0) {
+ mail_set_seq(mail, 1);
+ (void)mail_get_save_date(mail, stamp_r);
+ }
+ mail_free(&mail);
+ (void)mailbox_transaction_commit(&t);
+}
+
+static uint32_t expire_get_ext_id(struct mailbox *box)
+{
+ struct expire_mailbox *xpr_box = EXPIRE_CONTEXT(box);
+
+ if (xpr_box->expire_ext_id != (uint32_t)-1)
+ return xpr_box->expire_ext_id;
+
+ xpr_box->expire_ext_id =
+ mail_index_ext_register(box->index, "expire",
+ sizeof(struct expire_mail_index_header), 0, 0);
+ return xpr_box->expire_ext_id;
+}
+
+static int expire_lookup(struct mailbox *box, const char *key,
+ time_t *new_stamp_r)
+{
+ struct expire_mail_user *euser =
+ EXPIRE_USER_CONTEXT(box->storage->user);
+ const struct expire_mail_index_header *hdr;
+ const void *data;
+ size_t data_size;
+ const char *value;
+ int ret;
+
+ /* default to ioloop_time for newly saved mails. it may not be exactly
+ the first message's save time, but a few seconds difference doesn't
+ matter */
+ *new_stamp_r = ioloop_time;
+
+ if (euser->expire_cache) {
+ mail_index_get_header_ext(box->view, expire_get_ext_id(box),
+ &data, &data_size);
+ if (data_size == sizeof(*hdr)) {
+ hdr = data;
+ if (hdr->timestamp == 0)
+ return 0;
+ /* preserve the original timestamp */
+ *new_stamp_r = hdr->timestamp;
+ return 1;
+ }
+ /* cache doesn't exist yet */
+ }
+
+ ret = dict_lookup(euser->db, pool_datastack_create(),
+ key, &value);
+ if (ret <= 0) {
+ if (ret < 0)
+ return -1;
+ first_save_timestamp(box, new_stamp_r);
+ return 0;
+ }
+ return strcmp(value, "0") != 0 ? 1 : 0;
+}
+
+static void
+expire_update(struct mailbox *box, const char *key, time_t timestamp)
+{
+ struct expire_mail_user *euser =
+ EXPIRE_USER_CONTEXT(box->storage->user);
+ struct dict_transaction_context *dctx;
+ struct mail_index_transaction *trans;
+ struct expire_mail_index_header hdr;
+
+ dctx = dict_transaction_begin(euser->db);
+ dict_set(dctx, key, dec2str(timestamp));
+ if (dict_transaction_commit(&dctx) < 0)
+ i_error("expire: dict commit failed");
+ else if (euser->expire_cache) {
+ memset(&hdr, 0, sizeof(hdr));
+ hdr.timestamp = timestamp;
+
+ trans = mail_index_transaction_begin(box->view,
+ MAIL_INDEX_TRANSACTION_FLAG_EXTERNAL);
+ mail_index_update_header_ext(trans, expire_get_ext_id(box),
+ 0, &hdr, sizeof(hdr));
+ if (mail_index_transaction_commit(&trans) < 0)
+ i_error("expire: index transaction commit failed");
+ }
+}
+
static void first_nonexpunged_timestamp(struct mailbox_transaction_context *t,
time_t *stamp_r)
{
@@ -90,34 +203,11 @@
}
}
-static void first_save_timestamp(struct mailbox *box, time_t *stamp_r)
-{
- struct mailbox_transaction_context *t;
- const struct mail_index_header *hdr;
- struct mail *mail;
-
- *stamp_r = ioloop_time;
-
- t = mailbox_transaction_begin(box, 0);
- mail = mail_alloc(t, 0, NULL);
-
- /* find the first non-expunged mail. we're here because the first
- mail was expunged, so don't bother checking it. */
- hdr = mail_index_get_header(box->view);
- if (hdr->messages_count > 0) {
- mail_set_seq(mail, 1);
- (void)mail_get_save_date(mail, stamp_r);
- }
- mail_free(&mail);
- (void)mailbox_transaction_commit(&t);
-}
-
static int
expire_mailbox_transaction_commit(struct mailbox_transaction_context *t,
struct mail_transaction_commit_changes *changes_r)
{
struct mail_user *user = t->box->storage->user;
- struct expire_mail_user *euser = EXPIRE_USER_CONTEXT(user);
struct expire_mailbox *xpr_box = EXPIRE_CONTEXT(t->box);
struct expire_transaction_context *xt = EXPIRE_CONTEXT(t);
struct mailbox *box = t->box;
@@ -149,7 +239,7 @@
t = NULL;
if (xt->first_expunged || xt->saves) T_BEGIN {
- const char *key, *value;
+ const char *key;
key = t_strconcat(DICT_EXPIRE_PREFIX,
box->storage->user->username, "/",
@@ -160,8 +250,7 @@
i_assert(xt->saves);
/* saved new mails. dict needs to be updated only if
this is the first mail in the database */
- ret = dict_lookup(euser->db, pool_datastack_create(),
- key, &value);
+ ret = expire_lookup(box, key, &new_stamp);
if (ret <= 0) {
/* first time saving here with expire enabled.
also handle lookup errors by just assuming
@@ -170,14 +259,6 @@
i_warning("expire: dict lookup failed, "
"assuming update is needed");
}
- first_save_timestamp(box, &new_stamp);
- update_dict = TRUE;
- } else if (strcmp(value, "0") == 0) {
- /* we're saving the first mail to this mailbox.
- ioloop_time may not be exactly the first
- message's save time, but a few seconds
- difference doesn't matter */
- new_stamp = ioloop_time;
update_dict = TRUE;
} else {
/* already exists */
@@ -189,14 +270,8 @@
}
}
- if (update_dict) {
- struct dict_transaction_context *dctx;
-
- dctx = dict_transaction_begin(euser->db);
- dict_set(dctx, key, dec2str(new_stamp));
- if (dict_transaction_commit(&dctx) < 0)
- i_error("expire: dict commit failed");
- }
+ if (update_dict)
+ expire_update(box, key, new_stamp);
} T_END;
i_free(xt);
return 0;
@@ -273,6 +348,7 @@
xpr_box = p_new(box->pool, struct expire_mailbox, 1);
xpr_box->module_ctx.super = *v;
box->vlast = &xpr_box->module_ctx.super;
+ xpr_box->expire_ext_id = (uint32_t)-1;
v->transaction_begin = expire_mailbox_transaction_begin;
v->transaction_commit = expire_mailbox_transaction_commit;
@@ -356,6 +432,7 @@
euser->db = db;
euser->set = expire_set_init(expire_get_patterns(user));
+ euser->expire_cache = mail_user_plugin_getenv(user, "expire_cache") != NULL;
MODULE_CONTEXT_SET(user, expire_mail_user_module, euser);
}
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