CONFIG REWRITE: don't add the signature if it already exists.

At the end of the file, CONFIG REWRITE adds a comment line that:

    # Generated by CONFIG REWRITE

Followed by the additional config options required. However this was
added again and again at every rewrite in praticular conditions (when a
given set of options change in a given time during the time).

Now if it was alrady encountered, it is not added a second time.

This is especially important for Sentinel that rewrites the config at
every state change.

1 files changed, 5 insertions, 1 deletions

diff --git a/src/config.c b/src/config.c
index 29e1893b6..0d8376e5a 100644
--- a/src/config.c
+++ b/src/config.c
@@ -1102,6 +1102,8 @@ void configGetCommand(redisClient *c) {
  * CONFIG REWRITE implementation
  *----------------------------------------------------------------------------*/
 
+#define REDIS_CONFIG_REWRITE_SIGNATURE "# Generated by CONFIG REWRITE"
+
 /* We use the following dictionary type to store where a configuration
  * option is mentioned in the old configuration file, so it's
  * like "maxmemory" -> list of line numbers (first line is zero). */
@@ -1178,6 +1180,8 @@ struct rewriteConfigState *rewriteConfigReadOldFile(char *path) {
 
         /* Handle comments and empty lines. */
         if (line[0] == '#' || line[0] == '\0') {
+            if (!state->has_tail && !strcmp(line,REDIS_CONFIG_REWRITE_SIGNATURE))
+                state->has_tail = 1;
             rewriteConfigAppendLine(state,line);
             continue;
         }
@@ -1249,7 +1253,7 @@ void rewriteConfigRewriteLine(struct rewriteConfigState *state, char *option, sd
         /* Append a new line. */
         if (!state->has_tail) {
             rewriteConfigAppendLine(state,
-                sdsnew("# Generated by CONFIG REWRITE"));
+                sdsnew(REDIS_CONFIG_REWRITE_SIGNATURE));
             state->has_tail = 1;
         }
         rewriteConfigAppendLine(state,line);