Make use of a single listNode pointer for blocking utility lists (val…

…key-io#919) Saves some memory (one pointer) in the client struct. Since a client cannot be blocked multiple times, we can assume it will be held in only one extra utility list, so it is ok to maintain a union of these listNode references. Signed-off-by: Ran Shidlansik <ranshid@amazon.com> Signed-off-by: ranshid <88133677+ranshid@users.noreply.github.com> Signed-off-by: Binbin <binloveplay1314@qq.com> Co-authored-by: Viktor Söderqvist <viktor.soderqvist@est.tech> Co-authored-by: Binbin <binloveplay1314@qq.com> Signed-off-by: Ping Xie <pingxie@google.com>
PingXie · Sep 14, 2024 · ce08e2b · ce08e2b
1 parent 072dc74
commit ce08e2b
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Showing 2 changed files with 12 additions and 5 deletions.
diff --git a/src/blocked.c b/src/blocked.c
@@ -81,7 +81,7 @@ void initClientBlockingState(client *c) {
     c->bstate.numreplicas = 0;
     c->bstate.numlocal = 0;
     c->bstate.reploffset = 0;
-    c->bstate.client_waiting_acks_list_node = NULL;
+    c->bstate.generic_blocked_list_node = NULL;
     c->bstate.module_blocked_handle = NULL;
     c->bstate.async_rm_call_handle = NULL;
 }

diff --git a/src/server.h b/src/server.h
@@ -1011,15 +1011,22 @@ typedef struct blockingState {
                            * is > timeout then the operation timed out. */
     int unblock_on_nokey; /* Whether to unblock the client when at least one of the keys
                              is deleted or does not exist anymore */
+    union {
+        listNode *client_waiting_acks_list_node; /* list node in server.clients_waiting_acks list. */
+        listNode *postponed_list_node;           /* list node in server.postponed_clients */
+        listNode *generic_blocked_list_node;     /* generic placeholder for blocked clients utility lists.
+                                                    Since a client cannot be blocked multiple times, we can assume
+                                                    it will be held in only one extra utility list, so it is ok to maintain
+                                                    a union of these listNode references. */
+    };
 
     /* BLOCKED_LIST, BLOCKED_ZSET and BLOCKED_STREAM or any other Keys related blocking */
     dict *keys; /* The keys we are blocked on */
 
     /* BLOCKED_WAIT and BLOCKED_WAITAOF */
-    int numreplicas;                         /* Number of replicas we are waiting for ACK. */
-    int numlocal;                            /* Indication if WAITAOF is waiting for local fsync. */
-    long long reploffset;                    /* Replication offset to reach. */
-    listNode *client_waiting_acks_list_node; /* list node in server.clients_waiting_acks list. */
+    int numreplicas;      /* Number of replicas we are waiting for ACK. */
+    int numlocal;         /* Indication if WAITAOF is waiting for local fsync. */
+    long long reploffset; /* Replication offset to reach. */
 
     /* BLOCKED_MODULE */
     void *module_blocked_handle; /* ValkeyModuleBlockedClient structure.