Merge pull request redis#3244 from dvirsky/optimize_autoMemoryFreed

Optimized autoMemoryFreed loop

src/module.c

@@ -611,14 +611,22 @@ void autoMemoryFreed(RedisModuleCtx *ctx, int type, void *ptr) {
     if (!(ctx->flags & REDISMODULE_CTX_AUTO_MEMORY)) return;
 
     int j;
-    for (j = 0; j < ctx->amqueue_used; j++) {
+    for (j = ctx->amqueue_used - 1; j >= 0; j--) {
         if (ctx->amqueue[j].type == type &&
             ctx->amqueue[j].ptr == ptr)
         {
             ctx->amqueue[j].type = REDISMODULE_AM_FREED;
-            /* Optimization: if this is the last element, we can
-             * reuse it. */
-            if (j == ctx->amqueue_used-1) ctx->amqueue_used--;
+
+            /* Switch the freed element and the top element, to avoid growing
+             * the queue unnecessarily if we allocate/free in a loop */
+            if (j != ctx->amqueue_used-1) {
+                ctx->amqueue[j] = ctx->amqueue[ctx->amqueue_used-1];
+            }
+            /* Reduce the size of the queue because we either moved the top
+             * element elsewhere or freed it */ 
+            ctx->amqueue_used--;
+
+            break;
         }
     }
 }