lib-index: Fixed another transaction log read optimization.

Buffer's size should always be the same as sync_offset, otherwise some
optimizations could think that the data doesn't have to be re-read even
though it was updated in disk already.

diff --git a/src/lib-index/mail-transaction-log-file.c b/src/lib-index/mail-transaction-log-file.c
index 823812a983ab4bfc26b4672d9a8a222238c6578b..621bbc6b2c85dd887c64efe5c393afb76d4565be 100644 (file)
--- a/src/lib-index/mail-transaction-log-file.c
+++ b/src/lib-index/mail-transaction-log-file.c
@@ -16,6 +16,9 @@
 #define MEMORY_LOG_NAME "(in-memory transaction log file)"
 #define LOG_NEW_DOTLOCK_SUFFIX ".newlock"
 
+static int
+mail_transaction_log_file_sync(struct mail_transaction_log_file *file);
+
 static int
 log_file_set_syscall_error(struct mail_transaction_log_file *file,
                           const char *function)
@@ -186,6 +189,14 @@ mail_transaction_log_file_add_to_list(struct mail_transaction_log_file *file)
 
        file->next = *p;
        *p = file;
+
+       if (file->buffer != NULL) {
+               /* if we read any unfinished data, make sure the buffer gets
+                  truncated. */
+               (void)mail_transaction_log_file_sync(file);
+               buffer_set_used_size(file->buffer,
+                                    file->sync_offset - file->buffer_offset);
+       }
 }
 
 static int
@@ -399,7 +410,9 @@ mail_transaction_log_file_read_header(struct mail_transaction_log_file *file)
 
        memset(&file->hdr, 0, sizeof(file->hdr));
        if (file->last_size < mmap_get_page_size() && file->last_size > 0) {
-               /* just read the entire transaction log to memory */
+               /* just read the entire transaction log to memory.
+                  note that if some of the data hasn't been fully committed
+                  yet (hdr.size=0), the buffer must be truncated later */
                file->buffer = buffer_create_dynamic(default_pool, 4096);
                file->buffer_offset = 0;
                dest_size = file->last_size;
@@ -1403,23 +1416,19 @@ mail_transaction_log_file_read(struct mail_transaction_log_file *file,
        }
 
        if ((ret = mail_transaction_log_file_read_more(file)) <= 0)
-               return ret;
-
-       if (file->log->nfs_flush && !nfs_flush &&
-           mail_transaction_log_file_need_nfs_flush(file)) {
+               ;
+       else if (file->log->nfs_flush && !nfs_flush &&
+                mail_transaction_log_file_need_nfs_flush(file)) {
                /* we didn't read enough data. flush and try again. */
                return mail_transaction_log_file_read(file, start_offset, TRUE);
+       } else if ((ret = mail_transaction_log_file_sync(file)) <= 0) {
+               i_assert(ret != 0); /* ret=0 happens only with mmap */
+       } else {
+               i_assert(file->sync_offset >= file->buffer_offset);
        }
-
-       if ((ret = mail_transaction_log_file_sync(file)) <= 0) {
-               i_assert(ret != 0); /* happens only with mmap */
-               return -1;
-       }
-
-       i_assert(file->sync_offset >= file->buffer_offset);
        buffer_set_used_size(file->buffer,
                             file->sync_offset - file->buffer_offset);
-       return 1;
+       return ret;
 }
 
 static int
@@ -1553,6 +1562,8 @@ int mail_transaction_log_file_map(struct mail_transaction_log_file *file,
 
        i_assert(start_offset >= file->hdr.hdr_size);
        i_assert(start_offset <= end_offset);
+       i_assert(file->buffer == NULL || file->mmap_base != NULL ||
+                file->sync_offset >= file->buffer_offset + file->buffer->used);
 
        if (file->locked_sync_offset_updated && file == file->log->head &&
            end_offset == (uoff_t)-1) {
@@ -1606,6 +1617,9 @@ int mail_transaction_log_file_map(struct mail_transaction_log_file *file,
                ret = mail_transaction_log_file_read(file, start_offset, FALSE);
        }
 
+       i_assert(file->buffer == NULL || file->mmap_base != NULL ||
+                file->sync_offset >= file->buffer_offset + file->buffer->used);
+
        return ret <= 0 ? ret :
                log_file_map_check_offsets(file, start_offset, end_offset);
 }