lib-index: If transaction log file is small enough, just read all of it to memory...

diff --git a/src/lib-index/mail-transaction-log-file.c b/src/lib-index/mail-transaction-log-file.c
index f8f023654c7ae1b4e8120dba2da07acf06b80536..d557640674922c838b184abd52136dcc855eed8e 100644 (file)
--- a/src/lib-index/mail-transaction-log-file.c
+++ b/src/lib-index/mail-transaction-log-file.c
@@ -390,21 +390,42 @@ void mail_transaction_log_file_unlock(struct mail_transaction_log_file *file)
 static ssize_t
 mail_transaction_log_file_read_header(struct mail_transaction_log_file *file)
 {
-       ssize_t pos, ret;
+       void *dest;
+       size_t pos, dest_size;
+       ssize_t ret;
+
+       i_assert(file->buffer == NULL && file->mmap_base == NULL);
 
        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 */
+               file->buffer = buffer_create_dynamic(default_pool, 4096);
+               file->buffer_offset = 0;
+               dest_size = file->last_size;
+               dest = buffer_append_space_unsafe(file->buffer, dest_size);
+       } else {
+               /* read only the header */
+               dest = &file->hdr;
+               dest_size = sizeof(file->hdr);
+       }
 
-        /* try to read the whole header, but it's not necessarily an error to
-          read less since the older versions of the log format could be
-          smaller. */
+       /* it's not necessarily an error to read less than wanted header size,
+          since older versions of the log format used smaller headers. */
         pos = 0;
        do {
-               ret = pread(file->fd, PTR_OFFSET(&file->hdr, pos),
-                           sizeof(file->hdr) - pos, pos);
+               ret = pread(file->fd, PTR_OFFSET(dest, pos),
+                           dest_size - pos, pos);
                if (ret > 0)
                        pos += ret;
-       } while (ret > 0 && pos < (ssize_t)sizeof(file->hdr));
-       return ret < 0 ? -1 : pos;
+       } while (ret > 0 && pos < dest_size);
+
+       if (file->buffer != NULL) {
+               buffer_set_used_size(file->buffer, pos);
+               memcpy(&file->hdr, file->buffer->data,
+                      I_MIN(pos, sizeof(file->hdr)));
+       }
+
+       return ret < 0 ? -1 : (ssize_t)pos;
 }
 
 static int
@@ -598,6 +619,7 @@ mail_transaction_log_file_create2(struct mail_transaction_log_file *file,
                        }
                } else {
                        file->fd = fd;
+                       file->last_size = 0;
                        if (mail_transaction_log_file_read_hdr(file,
                                                               FALSE) > 0 &&
                            mail_transaction_log_file_stat(file, FALSE) == 0) {