Fix gen_write_load error on MOVED/ASK during atomic-slot-migration tests (#15016)

tests/helpers/gen_write_load.tcl

@@ -18,7 +18,9 @@ set ::tlsdir "tests/tls"
 
 # Continuously sends SET commands to the server. If key is omitted, a random key
 # is used for every SET command. The value is always random.
-proc gen_write_load {host port seconds tls {key ""} {size 0} {sleep 0}} {
+# ignore_error_reply (default 0): when non-zero, MOVED/ASK replies are tolerated
+# while draining pipelined responses (periodic 500-reply batches and final drain).
+proc gen_write_load {host port seconds tls {key ""} {size 0} {sleep 0} {ignore_error_reply 0}} {
     set start_time [clock seconds]
     set r [redis $host $port 1 $tls]
     $r client setname LOAD_HANDLER
@@ -44,12 +46,19 @@ proc gen_write_load {host port seconds tls {key ""} {size 0} {sleep 0}} {
         } else {
             $r set $key $value
         }
-        
+
         incr count
         if {$count % 500 == 0} {
             for {set i 0} {$i < 500} {incr i} {
-                $r read
+                # Capture opts to preserve original errorInfo/errorCode on re-raise.
+                if {[catch {$r read} err opts]} {
+                    if {$ignore_error_reply && ([string match {MOVED*} $err] || [string match {ASK*} $err])} {
+                        continue
+                    }
+                    return -options $opts $err
+                }
             }
+            set count 0
         }
 
         if {[clock seconds]-$start_time > $seconds} {
@@ -59,12 +68,17 @@ proc gen_write_load {host port seconds tls {key ""} {size 0} {sleep 0}} {
             after $sleep
         }
     }
-    
+
     # Read remaining replies
     for {set i 0} {$i < $count} {incr i} {
-        $r read
+        if {[catch {$r read} err opts]} {
+            if {$ignore_error_reply && ([string match {MOVED*} $err] || [string match {ASK*} $err])} {
+                continue
+            }
+            return -options $opts $err
+        }
     }
     exit 0
 }
 
-gen_write_load [lindex $argv 0] [lindex $argv 1] [lindex $argv 2] [lindex $argv 3] [lindex $argv 4] [lindex $argv 5] [lindex $argv 6]
+gen_write_load [lindex $argv 0] [lindex $argv 1] [lindex $argv 2] [lindex $argv 3] [lindex $argv 4] [lindex $argv 5] [lindex $argv 6] [lindex $argv 7]

tests/support/util.tcl

@@ -604,9 +604,11 @@ proc find_valgrind_errors {stderr on_termination} {
 # Execute a background process writing random data for the specified number
 # of seconds to the specified Redis instance. If key is omitted, a random key
 # is used for every SET command.
-proc start_write_load {host port seconds {key ""} {size 0} {sleep 0}} {
+# ignore_error_reply (default 0): set non-zero in cluster slot-migration tests to tolerate
+# MOVED/ASK replies while draining pipelined writes in the load helper.
+proc start_write_load {host port seconds {key ""} {size 0} {sleep 0} {ignore_error_reply 0}} {
     set tclsh [info nameofexecutable]
-    exec $tclsh tests/helpers/gen_write_load.tcl $host $port $seconds $::tls $key $size $sleep &
+    exec $tclsh tests/helpers/gen_write_load.tcl $host $port $seconds $::tls $key $size $sleep $ignore_error_reply &
 }
 
 # Stop a process generating write load executed with start_write_load.

tests/unit/cluster/atomic-slot-migration.tcl

@@ -577,23 +577,16 @@ start_cluster 3 3 {tags {external:skip cluster} overrides {cluster-node-timeout
         R 1 debug asm-trim-method none
         populate_slot 10000 -idx 1 -slot 6000
 
-        # Start write traffic on node-0
-        # Throws -MOVED error once asm is completed, catch block will ignore it.
-        catch {
-            # Start the slot 0 write load on the R 0
-            set port [get_port 0]
-            set key [slot_key 0 mykey]
-            set load_handle0 [start_write_load "127.0.0.1" $port 100 $key 0 5]
-        }
+        # Start write traffic on node-0 (ignore_error_reply=1 tolerates MOVED/ASK
+        # replies while slots are being migrated).
+        set port [get_port 0]
+        set key [slot_key 0 mykey]
+        set load_handle0 [start_write_load "127.0.0.1" $port 100 $key 0 5 1]
 
-        # Start write traffic on node-1
-        # Throws -MOVED error once asm is completed, catch block will ignore it.
-        catch {
-            # Start the slot 6000 write load on the R 1
-            set port [get_port 1]
-            set key [slot_key 6000 mykey]
-            set load_handle1 [start_write_load "127.0.0.1" $port 100 $key 0 5]
-        }
+        # Start write traffic on node-1 (ignore_error_reply=1 for migration redirects).
+        set port [get_port 1]
+        set key [slot_key 6000 mykey]
+        set load_handle1 [start_write_load "127.0.0.1" $port 100 $key 0 5 1]
 
         # Migrate keys
         R 1 CLUSTER MIGRATION IMPORT 0 100
@@ -801,8 +794,9 @@ start_cluster 3 3 {tags {external:skip cluster} overrides {cluster-node-timeout
         # we set a delay to write incremental data
         R 1 config set rdb-key-save-delay 1000000
 
-        # Start the slot 0 write load on the R 1
-        set load_handle [start_write_load "127.0.0.1" [get_port 1] 100 $slot0_key]
+        # Start slot 0 write load on R1. ignore_error_reply=1 tolerates MOVED/ASK
+        # replies that can appear while slot 0 is being migrated.
+        set load_handle [start_write_load "127.0.0.1" [get_port 1] 100 $slot0_key 0 0 1]
 
         # Clear all fail points
         assert_equal {OK} [R 0 debug asm-failpoint "" ""]