From: Timo Sirainen <tss@iki.fi>
Date: Mon, 14 Jun 2004 05:22:51 +0000 (+0300)
Subject: Locking fixes. use less memory
X-Git-Tag: 1.1.alpha1~3985
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d77c309fccbc6a7594f8cb08fb01009fa613c568;p=thirdparty%2Fdovecot%2Fcore.git

Locking fixes. use less memory

--HG--
branch : HEAD
---

diff --git a/src/lib-storage/index/maildir/maildir-sync.c b/src/lib-storage/index/maildir/maildir-sync.c
index 66db21a9c0..8f60cdb1e3 100644
--- a/src/lib-storage/index/maildir/maildir-sync.c
+++ b/src/lib-storage/index/maildir/maildir-sync.c
@@ -424,9 +424,6 @@ static int maildir_scan_dir(struct maildir_sync_context *ctx, int new_dir)
         enum maildir_uidlist_rec_flag flags;
 	int move_new, ret = 1;
 
-	src = t_str_new(1024);
-	dest = t_str_new(1024);
-
 	dir = new_dir ? ctx->new_dir : ctx->cur_dir;
 	dirp = opendir(dir);
 	if (dirp == NULL) {
@@ -435,6 +432,10 @@ static int maildir_scan_dir(struct maildir_sync_context *ctx, int new_dir)
 		return -1;
 	}
 
+	t_push();
+	src = t_str_new(1024);
+	dest = t_str_new(1024);
+
 	move_new = new_dir && !mailbox_is_readonly(&ctx->ibox->box) &&
 		!ctx->ibox->keep_recent;
 	while ((dp = readdir(dirp)) != NULL) {
@@ -507,6 +508,8 @@ static int maildir_scan_dir(struct maildir_sync_context *ctx, int new_dir)
 		mail_storage_set_critical(storage,
 					  "closedir(%s) failed: %m", dir);
 	}
+
+	t_pop();
 	return ret < 0 ? -1 : 0;
 }
 
@@ -835,6 +838,15 @@ static int maildir_sync_context(struct maildir_sync_context *ctx)
 	ctx->uidlist_sync_ctx =
 		maildir_uidlist_sync_init(ctx->ibox->uidlist, ctx->partial);
 
+	/* we have to lock uidlist immediately, otherwise there's race
+	   conditions with other processes who might write older maildir
+	   file list into uidlist.
+
+	   alternative would be to lock it when new files are found, but
+	   the directory scans _must_ be restarted then */
+	if (maildir_uidlist_try_lock(ctx->ibox->uidlist) < 0)
+		return -1;
+
 	if (maildir_scan_dir(ctx, TRUE) < 0)
 		return -1;
 	if (cur_changed) {
diff --git a/src/lib-storage/index/maildir/maildir-uidlist.c b/src/lib-storage/index/maildir/maildir-uidlist.c
index bc51ab463d..f7b9c0145f 100644
--- a/src/lib-storage/index/maildir/maildir-uidlist.c
+++ b/src/lib-storage/index/maildir/maildir-uidlist.c
@@ -91,8 +91,12 @@ int maildir_uidlist_try_lock(struct maildir_uidlist *uidlist)
 			"file_dotlock_open(%s) failed: %m", path);
 		return -1;
 	}
-
 	uidlist->lock_fd = fd;
+
+	/* our view of uidlist must be up-to-date if we plan on changing it */
+	if (maildir_uidlist_update(uidlist) < 0)
+		return -1;
+
 	return 1;
 }
 
@@ -463,8 +467,10 @@ static int maildir_uidlist_rewrite_fd(struct maildir_uidlist *uidlist,
 
 	iter = maildir_uidlist_iter_init(uidlist->ibox->uidlist);
 	while (maildir_uidlist_iter_next(iter, &uid, &flags, &filename)) {
+		/* avoid overflowing str buffer so we don't eat more memory
+		   than we need. */
 		if (str_len(str) + MAX_INT_STRLEN +
-		    strlen(filename) + 2 >= 4096) {
+		    strlen(filename) + 5 + 10 >= 4096) {
 			/* flush buffer */
 			if (write_full(uidlist->lock_fd,
 				       str_data(str), str_len(str)) < 0) {
@@ -592,6 +598,11 @@ static int maildir_uidlist_sync_uidlist(struct maildir_uidlist_sync_ctx *ctx)
 
 	i_assert(!ctx->synced);
 
+	if (UIDLIST_IS_LOCKED(ctx->uidlist)) {
+		ctx->synced = TRUE;
+		return 1;
+	}
+
 	if (!ctx->uidlist->initial_read) {
 		/* first time reading the uidlist,
 		   no locking yet */
@@ -612,10 +623,6 @@ static int maildir_uidlist_sync_uidlist(struct maildir_uidlist_sync_ctx *ctx)
 		ctx->failed = TRUE;
 		return -1;
 	}
-	if (maildir_uidlist_update(ctx->uidlist) < 0) {
-		ctx->failed = TRUE;
-		return -1;
-	}
 
 	ctx->synced = TRUE;
 	return 1;
@@ -842,8 +849,11 @@ int maildir_uidlist_sync_deinit(struct maildir_uidlist_sync_ctx *ctx)
 	if (!ctx->finished)
 		maildir_uidlist_sync_finish(ctx);
 
-	if (ctx->new_files_count != 0 && !ctx->failed && !ctx->locked)
+	if (ctx->new_files_count != 0 && !ctx->failed && !ctx->locked) {
+		t_push();
 		ret = maildir_uidlist_rewrite(ctx->uidlist);
+		t_pop();
+	}
 
 	if (ctx->partial)
 		maildir_uidlist_mark_all(ctx->uidlist, FALSE);