From dd53453e8fa7b8c2fc2821488b8692bea30a8f60 Mon Sep 17 00:00:00 2001
From: antirez <antirez@gmail.com>
Date: Mon, 1 Jun 2020 16:40:32 +0200
Subject: Threaded core commands: clients wait queue WIP.

---
 src/blocked.c | 21 ++++++++++++++-------
 src/server.c  |  5 +++++
 src/server.h  |  3 ++-
 3 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/src/blocked.c b/src/blocked.c
index 92f1cee65..a14330b5c 100644
--- a/src/blocked.c
+++ b/src/blocked.c
@@ -144,13 +144,15 @@ void queueClientForReprocessing(client *c) {
 /* Unblock a client calling the right function depending on the kind
  * of operation the client is blocking for. */
 void unblockClient(client *c) {
-    if (c->btype == BLOCKED_LIST ||
-        c->btype == BLOCKED_ZSET ||
-        c->btype == BLOCKED_STREAM) {
+    int btype = c->btype;
+
+    if (btype == BLOCKED_LIST ||
+        btype == BLOCKED_ZSET ||
+        btype == BLOCKED_STREAM) {
         unblockClientWaitingData(c);
-    } else if (c->btype == BLOCKED_WAIT) {
+    } else if (btype == BLOCKED_WAIT) {
         unblockClientWaitingReplicas(c);
-    } else if (c->btype == BLOCKED_MODULE) {
+    } else if (btype == BLOCKED_MODULE) {
         if (moduleClientIsBlockedOnKeys(c)) unblockClientWaitingData(c);
         unblockClientFromModule(c);
     } else {
@@ -159,11 +161,15 @@ void unblockClient(client *c) {
     /* Clear the flags, and put the client in the unblocked list so that
      * we'll process new commands in its query buffer ASAP. */
     server.blocked_clients--;
-    server.blocked_clients_by_type[c->btype]--;
+    server.blocked_clients_by_type[btype]--;
     c->flags &= ~CLIENT_BLOCKED;
     c->btype = BLOCKED_NONE;
     removeClientFromTimeoutTable(c);
     queueClientForReprocessing(c);
+
+    /* Re-execute the command if it was not executed at all since the
+     * client was blocked because of key locks. */
+    if (btype == BLOCKED_LOCK) processCommand(c);
 }
 
 /* This function gets called when a blocked client timed out in order to
@@ -172,7 +178,8 @@ void unblockClient(client *c) {
 void replyToBlockedClientTimedOut(client *c) {
     if (c->btype == BLOCKED_LIST ||
         c->btype == BLOCKED_ZSET ||
-        c->btype == BLOCKED_STREAM) {
+        c->btype == BLOCKED_STREAM ||
+        c->btype == BLOCKED_LOCK) {
         addReplyNullArray(c);
     } else if (c->btype == BLOCKED_WAIT) {
         addReplyLongLong(c,replicationCountAcksByOffset(c->bpop.reploffset));
diff --git a/src/server.c b/src/server.c
index 6ce40c4cf..15863335c 100644
--- a/src/server.c
+++ b/src/server.c
@@ -3500,6 +3500,11 @@ int processCommand(client *c) {
         }
     }
 
+    /* We want to block this client if the keys it is going to access
+     * are locked. */
+    if (dictSize(c->db->locked_keys)) {
+    }
+
     /* Handle the maxmemory directive.
      *
      * Note that we do not want to reclaim memory if we are here re-entering
diff --git a/src/server.h b/src/server.h
index f60ca38d3..f33225bcb 100644
--- a/src/server.h
+++ b/src/server.h
@@ -265,7 +265,8 @@ typedef long long ustime_t; /* microsecond time type. */
 #define BLOCKED_MODULE 3  /* Blocked by a loadable module. */
 #define BLOCKED_STREAM 4  /* XREAD. */
 #define BLOCKED_ZSET 5    /* BZPOP et al. */
-#define BLOCKED_NUM 6     /* Number of blocked states. */
+#define BLOCKED_LOCK 6    /* Waiting for locked keys. */
+#define BLOCKED_NUM 7     /* Number of blocked states. */
 
 /* Client request types */
 #define PROTO_REQ_INLINE 1
-- 
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