Add errorstats info section, Add failed_calls and rejected_calls to commandstats (#8217)

This Commit pushes forward the observability on overall error statistics and command statistics within redis-server:

It extends INFO COMMANDSTATS to have
- failed_calls in - so we can keep track of errors that happen from the command itself, broken by command.
- rejected_calls - so we can keep track of errors that were triggered outside the commmand processing per se

Adds a new section to INFO, named ERRORSTATS that enables keeping track of the different errors that
occur within redis ( within processCommand and call ) based on the reply Error Prefix ( The first word
after the "-", up to the first space ).

This commit also fixes RM_ReplyWithError so that it can be correctly identified as an error reply.

1 files changed, 10 insertions, 14 deletions

diff --git a/src/module.c b/src/module.c
index 11f5f4489..913b4de5d 100644
--- a/src/module.c
+++ b/src/module.c
@@ -1368,18 +1368,6 @@ int RM_ReplyWithLongLong(RedisModuleCtx *ctx, long long ll) {
     return REDISMODULE_OK;
 }
 
-/* Reply with an error or simple string (status message). Used to implement
- * ReplyWithSimpleString() and ReplyWithError().
- * The function always returns REDISMODULE_OK. */
-int replyWithStatus(RedisModuleCtx *ctx, const char *msg, char *prefix) {
-    client *c = moduleGetReplyClient(ctx);
-    if (c == NULL) return REDISMODULE_OK;
-    addReplyProto(c,prefix,strlen(prefix));
-    addReplyProto(c,msg,strlen(msg));
-    addReplyProto(c,"\r\n",2);
-    return REDISMODULE_OK;
-}
-
 /* Reply with the error 'err'.
  *
  * Note that 'err' must contain all the error, including
@@ -1395,7 +1383,10 @@ int replyWithStatus(RedisModuleCtx *ctx, const char *msg, char *prefix) {
  * The function always returns REDISMODULE_OK.
  */
 int RM_ReplyWithError(RedisModuleCtx *ctx, const char *err) {
-    return replyWithStatus(ctx,err,"-");
+    client *c = moduleGetReplyClient(ctx);
+    if (c == NULL) return REDISMODULE_OK;
+    addReplyErrorFormat(c,"-%s",err);
+    return REDISMODULE_OK;
 }
 
 /* Reply with a simple string (+... \r\n in RESP protocol). This replies
@@ -1404,7 +1395,12 @@ int RM_ReplyWithError(RedisModuleCtx *ctx, const char *err) {
  *
  * The function always returns REDISMODULE_OK. */
 int RM_ReplyWithSimpleString(RedisModuleCtx *ctx, const char *msg) {
-    return replyWithStatus(ctx,msg,"+");
+    client *c = moduleGetReplyClient(ctx);
+    if (c == NULL) return REDISMODULE_OK;
+    addReplyProto(c,"+",1);
+    addReplyProto(c,msg,strlen(msg));
+    addReplyProto(c,"\r\n",2);
+    return REDISMODULE_OK;
 }
 
 /* Reply with an array type of 'len' elements. However 'len' other calls