dovecot-1.0: Map the log files only after they've all been found...

[dovecot at dovecot.org]

details:   http://hg.dovecot.org/dovecot-1.0/rev/b55165d5e675
changeset: 5324:b55165d5e675
user:      Timo Sirainen <tss at iki.fi>
date:      Wed Jun 20 23:58:48 2007 +0300
description:
Map the log files only after they've all been found. Otherwise we could have
skipped some transactions from the end of non-head logs.

diffstat:

1 file changed, 39 insertions(+), 25 deletions(-)
src/lib-index/mail-transaction-log-view.c |   64 +++++++++++++++++------------

diffs (106 lines):

diff -r 98cd45935799 -r b55165d5e675 src/lib-index/mail-transaction-log-view.c
--- a/src/lib-index/mail-transaction-log-view.c	Wed Jun 20 20:51:38 2007 +0300
+++ b/src/lib-index/mail-transaction-log-view.c	Wed Jun 20 23:58:48 2007 +0300
@@ -97,9 +97,10 @@ mail_transaction_log_view_set(struct mai
 			      uint32_t max_file_seq, uoff_t max_file_offset,
 			      enum mail_transaction_type type_mask)
 {
-	struct mail_transaction_log_file *file, *first;
+	struct mail_transaction_log_file *file, *const *files;
+	unsigned int i;
 	uint32_t seq;
-	uoff_t end_offset;
+	uoff_t start_offset, end_offset;
 	int ret;
 
 	i_assert(view->log != NULL);
@@ -159,12 +160,8 @@ mail_transaction_log_view_set(struct mai
 		return -1;
 	}
 
-	end_offset = min_file_seq == max_file_seq ?
-		max_file_offset : (uoff_t)-1;
-	ret = mail_transaction_log_file_map(file, min_file_offset, end_offset);
-	if (ret <= 0)
-		return ret;
-	first = file;
+	view->tail = file;
+	view->head = file;
 
 	for (seq = min_file_seq+1; seq <= max_file_seq; seq++) {
 		file = file->next;
@@ -192,40 +189,57 @@ mail_transaction_log_view_set(struct mai
 			/* missing files in the middle */
 			return 0;
 		}
-
+		view->head = file;
+	}
+
+	/* we have all of them. update refcounts. */
+	mail_transaction_log_view_unref_all(view);
+
+	/* reference all used files */
+	for (file = view->tail;; file = file->next) {
+		array_append(&view->file_refs, &file, 1);
+		file->refcount++;
+
+		if (file == view->head)
+			break;
+	}
+
+	/* Map the files only after we've found them all. Otherwise if we map
+	   one file and then another file just happens to get rotated, we could
+	   include both files in the view but skip the last transactions from
+	   the first file.
+
+	   We're mapping the files in reverse order so that _log_file_map()
+	   can verify that prev_file_offset matches how far it actually managed
+	   to sync the file. */
+	files = array_idx(&view->file_refs, 0);
+	for (i = array_count(&view->file_refs); i > 0; i--) {
+		file = files[i-1];
+		start_offset = file->hdr.file_seq == min_file_seq ?
+			min_file_offset : file->hdr.hdr_size;
 		end_offset = file->hdr.file_seq == max_file_seq ?
 			max_file_offset : (uoff_t)-1;
-		ret = mail_transaction_log_file_map(file, file->hdr.hdr_size,
+		ret = mail_transaction_log_file_map(file, start_offset,
 						    end_offset);
 		if (ret <= 0)
 			return ret;
 	}
 
+	i_assert(max_file_seq == (uint32_t)-1 ||
+		 max_file_seq == view->head->hdr.file_seq);
 	i_assert(max_file_offset == (uoff_t)-1 ||
-		 max_file_offset <= file->sync_offset);
-
-	/* we have all of them. update refcounts. */
-	mail_transaction_log_view_unref_all(view);
-
-	view->tail = first;
-	view->head = view->log->head;
-
-	/* reference all used files */
-	for (file = view->tail; file != NULL; file = file->next) {
-		array_append(&view->file_refs, &file, 1);
-		file->refcount++;
-	}
+		 max_file_offset <= view->head->sync_offset);
 
 	view->prev_file_seq = 0;
 	view->prev_file_offset = 0;
 
-	view->cur = first;
+	view->cur = view->tail;
 	view->cur_offset = min_file_offset;
 
 	view->min_file_seq = min_file_seq;
 	view->min_file_offset = min_file_offset;
 	view->max_file_seq = max_file_seq;
-	view->max_file_offset = max_file_offset;
+	view->max_file_offset = I_MIN(max_file_offset, view->head->sync_offset);
 	view->type_mask = type_mask;
 	view->broken = FALSE;