From a9e32767f717e7454e86fdf73772edab28d5453d Mon Sep 17 00:00:00 2001
From: Harkrishn Patro <harkrisp@amazon.com>
Date: Tue, 13 Jun 2023 08:16:32 -0700
Subject: [PATCH] Allow cluster slots/shards api to respond during loading
 (#12269)

It would be helpful for clients to get cluster slots/shards information during a node failover and is loading data.
---
 src/commands.def                          | 4 ++--
 src/commands/cluster-shards.json          | 1 +
 src/commands/cluster-slots.json           | 1 +
 tests/cluster/tests/28-cluster-shards.tcl | 4 ++++
 4 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/commands.def b/src/commands.def
index ab2891394..95bdacbad 100644
--- a/src/commands.def
+++ b/src/commands.def
@@ -970,9 +970,9 @@ struct COMMAND_STRUCT CLUSTER_Subcommands[] = {
 {MAKE_CMD("saveconfig","Forces a node to save the cluster configuration to disk.","O(1)","3.0.0",CMD_DOC_NONE,NULL,NULL,"cluster",COMMAND_GROUP_CLUSTER,CLUSTER_SAVECONFIG_History,0,CLUSTER_SAVECONFIG_Tips,0,clusterCommand,2,CMD_NO_ASYNC_LOADING|CMD_ADMIN|CMD_STALE,0,CLUSTER_SAVECONFIG_Keyspecs,0,NULL,0)},
 {MAKE_CMD("set-config-epoch","Sets the configuration epoch for a new node.","O(1)","3.0.0",CMD_DOC_NONE,NULL,NULL,"cluster",COMMAND_GROUP_CLUSTER,CLUSTER_SET_CONFIG_EPOCH_History,0,CLUSTER_SET_CONFIG_EPOCH_Tips,0,clusterCommand,3,CMD_NO_ASYNC_LOADING|CMD_ADMIN|CMD_STALE,0,CLUSTER_SET_CONFIG_EPOCH_Keyspecs,0,NULL,1),.args=CLUSTER_SET_CONFIG_EPOCH_Args},
 {MAKE_CMD("setslot","Binds a hash slot to a node.","O(1)","3.0.0",CMD_DOC_NONE,NULL,NULL,"cluster",COMMAND_GROUP_CLUSTER,CLUSTER_SETSLOT_History,0,CLUSTER_SETSLOT_Tips,0,clusterCommand,-4,CMD_NO_ASYNC_LOADING|CMD_ADMIN|CMD_STALE,0,CLUSTER_SETSLOT_Keyspecs,0,NULL,2),.args=CLUSTER_SETSLOT_Args},
-{MAKE_CMD("shards","Returns the mapping of cluster slots to shards.","O(N) where N is the total number of cluster nodes","7.0.0",CMD_DOC_NONE,NULL,NULL,"cluster",COMMAND_GROUP_CLUSTER,CLUSTER_SHARDS_History,0,CLUSTER_SHARDS_Tips,1,clusterCommand,2,CMD_STALE,0,CLUSTER_SHARDS_Keyspecs,0,NULL,0)},
+{MAKE_CMD("shards","Returns the mapping of cluster slots to shards.","O(N) where N is the total number of cluster nodes","7.0.0",CMD_DOC_NONE,NULL,NULL,"cluster",COMMAND_GROUP_CLUSTER,CLUSTER_SHARDS_History,0,CLUSTER_SHARDS_Tips,1,clusterCommand,2,CMD_LOADING|CMD_STALE,0,CLUSTER_SHARDS_Keyspecs,0,NULL,0)},
 {MAKE_CMD("slaves","Lists the replica nodes of a master node.","O(1)","3.0.0",CMD_DOC_DEPRECATED,"`CLUSTER REPLICAS`","5.0.0","cluster",COMMAND_GROUP_CLUSTER,CLUSTER_SLAVES_History,0,CLUSTER_SLAVES_Tips,1,clusterCommand,3,CMD_ADMIN|CMD_STALE,0,CLUSTER_SLAVES_Keyspecs,0,NULL,1),.args=CLUSTER_SLAVES_Args},
-{MAKE_CMD("slots","Returns the mapping of cluster slots to nodes.","O(N) where N is the total number of Cluster nodes","3.0.0",CMD_DOC_DEPRECATED,"`CLUSTER SHARDS`","7.0.0","cluster",COMMAND_GROUP_CLUSTER,CLUSTER_SLOTS_History,2,CLUSTER_SLOTS_Tips,1,clusterCommand,2,CMD_STALE,0,CLUSTER_SLOTS_Keyspecs,0,NULL,0)},
+{MAKE_CMD("slots","Returns the mapping of cluster slots to nodes.","O(N) where N is the total number of Cluster nodes","3.0.0",CMD_DOC_DEPRECATED,"`CLUSTER SHARDS`","7.0.0","cluster",COMMAND_GROUP_CLUSTER,CLUSTER_SLOTS_History,2,CLUSTER_SLOTS_Tips,1,clusterCommand,2,CMD_LOADING|CMD_STALE,0,CLUSTER_SLOTS_Keyspecs,0,NULL,0)},
 {0}
 };
 
diff --git a/src/commands/cluster-shards.json b/src/commands/cluster-shards.json
index cfc7250b0..dcaad3ea3 100644
--- a/src/commands/cluster-shards.json
+++ b/src/commands/cluster-shards.json
@@ -9,6 +9,7 @@
         "function": "clusterCommand",
         "history": [],
         "command_flags": [
+            "LOADING",
             "STALE"
         ],
         "command_tips": [
diff --git a/src/commands/cluster-slots.json b/src/commands/cluster-slots.json
index fc98ba79a..b00cc60f4 100644
--- a/src/commands/cluster-slots.json
+++ b/src/commands/cluster-slots.json
@@ -23,6 +23,7 @@
             ]
         ],
         "command_flags": [
+            "LOADING",
             "STALE"
         ],
         "command_tips": [
diff --git a/tests/cluster/tests/28-cluster-shards.tcl b/tests/cluster/tests/28-cluster-shards.tcl
index ef4067ff0..f24b91729 100644
--- a/tests/cluster/tests/28-cluster-shards.tcl
+++ b/tests/cluster/tests/28-cluster-shards.tcl
@@ -182,6 +182,10 @@ test "Test the replica reports a loading state while it's loading" {
         fail "Replica never transitioned to loading"
     }
 
+    # Verify cluster shards and cluster slots (deprecated) API responds while the node is loading data.
+    R $replica_id CLUSTER SHARDS
+    R $replica_id CLUSTER SLOTS
+
     # Speed up the key loading and verify everything resumes
     R $replica_id config set key-load-delay 0