Merge pull request #1957 from snicoll/gh-1953

Backport of gh-1910 to fix race condition

Author: gkorland

src/main/java/redis/clients/jedis/JedisSentinelPool.java

@@ -34,6 +34,8 @@ public class JedisSentinelPool extends Pool<Jedis> {
   private volatile JedisFactory factory;
   private volatile HostAndPort currentHostMaster;
 
+  private final Object initPoolLock = new Object();
+
   public JedisSentinelPool(String masterName, Set<String> sentinels,
       final GenericObjectPoolConfig poolConfig) {
     this(masterName, sentinels, poolConfig, Protocol.DEFAULT_TIMEOUT, null,
@@ -110,22 +112,24 @@ public HostAndPort getCurrentHostMaster() {
   }
 
   private void initPool(HostAndPort master) {
-    if (!master.equals(currentHostMaster)) {
-      currentHostMaster = master;
-      if (factory == null) {
-        factory = new JedisFactory(master.getHost(), master.getPort(), connectionTimeout,
-            soTimeout, password, database, clientName, false, null, null, null);
-        initPool(poolConfig, factory);
-      } else {
-        factory.setHostAndPort(currentHostMaster);
-        // although we clear the pool, we still have to check the
-        // returned object
-        // in getResource, this call only clears idle instances, not
-        // borrowed instances
-        internalPool.clear();
-      }
+    synchronized(initPoolLock){
+      if (!master.equals(currentHostMaster)) {
+        currentHostMaster = master;
+        if (factory == null) {
+          factory = new JedisFactory(master.getHost(), master.getPort(), connectionTimeout,
+              soTimeout, password, database, clientName, false, null, null, null);
+          initPool(poolConfig, factory);
+        } else {
+          factory.setHostAndPort(currentHostMaster);
+          // although we clear the pool, we still have to check the
+          // returned object
+          // in getResource, this call only clears idle instances, not
+          // borrowed instances
+          internalPool.clear();
+        }
 
-      log.info("Created JedisPool to master at " + master);
+        log.info("Created JedisPool to master at " + master);
+      }
     }
   }
 

src/test/java/redis/clients/jedis/tests/JedisSentinelPoolTest.java

@@ -42,6 +42,19 @@ public void setUp() throws Exception {
     sentinelJedis1 = new Jedis(sentinel1.getHost(), sentinel1.getPort());
     sentinelJedis2 = new Jedis(sentinel2.getHost(), sentinel2.getPort());
   }
+  
+  @Test
+  public void repeatedSentinelPoolInitialization() {
+
+     for(int i=0; i<20 ; ++i) {
+      GenericObjectPoolConfig config = new GenericObjectPoolConfig();
+
+       JedisSentinelPool pool = new JedisSentinelPool(MASTER_NAME, sentinels, config, 1000,
+          "foobared", 2);
+      pool.getResource().close();
+      pool.destroy();
+    }
+  }
 
   @Test(expected = JedisConnectionException.class)
   public void initializeWithNotAvailableSentinelsShouldThrowException() {