[cherry-pick](branch-2.1)add SessionVariable for enableCooldownReplicaAffinity (#42675)

pick from master：https://github.com/apache/doris/pull/41741

fe/fe-common/src/main/java/org/apache/doris/common/Config.java

@@ -2844,9 +2844,6 @@ public class Config extends ConfigBase {
             "Stream_Load When importing, the maximum length of label is limited"})
     public static int label_regex_length = 128;
 
-    @ConfField(mutable = true)
-    public static boolean enable_cooldown_replica_affinity = true;
-
     //==========================================================================
     //                      end of cloud config
     //==========================================================================

fe/fe-core/src/main/java/org/apache/doris/planner/OlapScanNode.java

@@ -830,7 +830,7 @@ public class OlapScanNode extends ScanNode {
                 }
             }
 
-            if (Config.enable_cooldown_replica_affinity) {
+            if (isEnableCooldownReplicaAffinity()) {
                 final long coolDownReplicaId = tablet.getCooldownReplicaId();
                 // we prefer to query using cooldown replica to make sure the cache is fully utilized
                 // for example: consider there are 3BEs(A,B,C) and each has one replica for tablet X. and X
@@ -932,6 +932,14 @@ public class OlapScanNode extends ScanNode {
         }
     }
 
+    private boolean isEnableCooldownReplicaAffinity() {
+        ConnectContext connectContext = ConnectContext.get();
+        if (connectContext != null) {
+            return connectContext.getSessionVariable().isEnableCooldownReplicaAffinity();
+        }
+        return true;
+    }
+
     private void computePartitionInfo() throws AnalysisException {
         long start = System.currentTimeMillis();
         // Step1: compute partition ids

fe/fe-core/src/main/java/org/apache/doris/qe/SessionVariable.java

@@ -644,6 +644,8 @@ public class SessionVariable implements Serializable, Writable {
 
     public static final String SKIP_CHECKING_ACID_VERSION_FILE = "skip_checking_acid_version_file";
 
+    public static final String ENABLE_COOLDOWN_REPLICA_AFFINITY =
+            "enable_cooldown_replica_affinity";
     /**
      * If set false, user couldn't submit analyze SQL and FE won't allocate any related resources.
      */
@@ -2139,6 +2141,9 @@ public class SessionVariable implements Serializable, Writable {
     })
     public boolean skipCheckingAcidVersionFile = false;
 
+    @VariableMgr.VarAttr(name = ENABLE_COOLDOWN_REPLICA_AFFINITY, needForward = true)
+    public boolean enableCooldownReplicaAffinity = true;
+
     public void setEnableEsParallelScroll(boolean enableESParallelScroll) {
         this.enableESParallelScroll = enableESParallelScroll;
     }
@@ -4297,4 +4302,8 @@ public class SessionVariable implements Serializable, Writable {
                 throw new IllegalArgumentException("Unknown serde dialect: " + serdeDialect);
         }
     }
+
+    public boolean isEnableCooldownReplicaAffinity() {
+        return enableCooldownReplicaAffinity;
+    }
 }

regression-test/suites/show_p0/test_show_variables.groovy

@@ -0,0 +1,38 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+import org.apache.doris.regression.util.Http
+
+suite("test_show_variables", "p0") {
+
+    def result = sql """show variables like "enable_cooldown_replica_affinity%";"""
+    assertTrue(result[0][1]=="true")
+
+    result = sql """set  enable_cooldown_replica_affinity=false;"""
+    result = sql """show variables like "enable_cooldown_replica_affinity%";"""
+    assertTrue(result[0][1]=="false")
+
+    result = sql """set  enable_cooldown_replica_affinity=true;"""
+    result = sql """show variables like "enable_cooldown_replica_affinity%";"""
+    assertTrue(result[0][1]=="true")
+
+    result = sql """set GLOBAL enable_cooldown_replica_affinity=false;"""
+    result = sql """show variables like "enable_cooldown_replica_affinity%";"""
+    assertTrue(result[0][1]=="false")
+    result = sql """set GLOBAL enable_cooldown_replica_affinity=true;"""
+    
+}