From aa64a260fc14a6442117ec754e79c1ffe225cb20 Mon Sep 17 00:00:00 2001
From: John Sully <john@csquare.ca>
Date: Thu, 8 Apr 2021 19:52:38 +0000
Subject: [PATCH] Make prefetch configurable

Former-commit-id: 3b660347d70cc25d57119080bd43fb4671e36488
---
 src/config.cpp     | 1 +
 src/networking.cpp | 4 ++--
 src/server.h       | 2 ++
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/config.cpp b/src/config.cpp
index 99505d444..9d7f14007 100644
--- a/src/config.cpp
+++ b/src/config.cpp
@@ -2535,6 +2535,7 @@ standardConfig configs[] = {
     createBoolConfig("use-fork", NULL, IMMUTABLE_CONFIG, cserver.fForkBgSave, 0, NULL, NULL),
     createBoolConfig("allow-write-during-load", NULL, MODIFIABLE_CONFIG, g_pserver->fWriteDuringActiveLoad, 0, NULL, NULL),
     createBoolConfig("io-threads-do-reads", NULL, IMMUTABLE_CONFIG, fDummy, 0, NULL, NULL),
+    createBoolConfig("prefetch-enabled", NULL, MODIFIABLE_CONFIG, g_pserver->prefetch_enabled, 1, NULL, NULL),
 
     /* String Configs */
     createStringConfig("aclfile", NULL, IMMUTABLE_CONFIG, ALLOW_EMPTY_STRING, g_pserver->acl_filename, "", NULL, NULL),
diff --git a/src/networking.cpp b/src/networking.cpp
index 72d08cc80..c6daefe1f 100644
--- a/src/networking.cpp
+++ b/src/networking.cpp
@@ -2353,7 +2353,7 @@ void parseClientCommandBuffer(client *c) {
             }
         }
 
-        size_t cqueries = c->vecqueuedcmd.size();
+        size_t cqueriesStart = c->vecqueuedcmd.size();
         if (c->reqtype == PROTO_REQ_INLINE) {
             if (processInlineBuffer(c) != C_OK) break;
         } else if (c->reqtype == PROTO_REQ_MULTIBULK) {
@@ -2369,7 +2369,7 @@ void parseClientCommandBuffer(client *c) {
         }
 
         /* Prefetch outside the lock for better perf */
-        if (cqueries < c->vecqueuedcmd.size() && !GlobalLocksAcquired()) {
+        if (g_pserver->prefetch_enabled && cqueriesStart < c->vecqueuedcmd.size() && !GlobalLocksAcquired()) {
             auto &query = c->vecqueuedcmd.back();
             if (query.argc > 0 && query.argc == query.argcMax) {
                 c->db->prefetchKeysAsync(c, query);
diff --git a/src/server.h b/src/server.h
index 449bc77ee..9eed26e95 100644
--- a/src/server.h
+++ b/src/server.h
@@ -2391,6 +2391,8 @@ struct redisServer {
     char *aof_rewrite_cpulist; /* cpu affinity list of aof rewrite process. */
     char *bgsave_cpulist; /* cpu affinity list of bgsave process. */
 
+    int prefetch_enabled = 1;
+
     long long repl_batch_offStart = -1;
     long long repl_batch_idxStart = -1;