[JAVA-266]: Need to update the IP resolved for hosts frequently enough to pick up dns changes

Author: agirbal

src/main/com/mongodb/DBTCPConnector.java

@@ -441,6 +441,11 @@ public void close(){
         _myPort = null;
     }
 
+    void updatePortPool(ServerAddress addr) {
+        // just remove from map, a new pool will be created lazily
+        _portHolder._pools.remove(addr);
+    }
+
     public boolean isOpen(){
         return ! _closed;
     }

src/main/com/mongodb/ReplicaSetStatus.java

@@ -28,6 +28,7 @@ class ReplicaSetStatus {
         for ( ServerAddress addr : initial ){
             _all.add( new Node( addr ) );
         }
+        _nextResolveTime = System.currentTimeMillis() + inetAddrCacheMS;
 
         _updater = new Updater();
         _updater.start();
@@ -114,6 +115,18 @@ class Node {
             _names.add( addr.toString() );
         }
 
+        private void updateAddr() {
+            try {
+                if (_addr.updateInetAddr()) {
+                    // address changed, need to use new ports
+                    _port = new DBPort(_addr, null, _mongoOptions);
+                    _mongo.getConnector().updatePortPool(_addr);
+                }
+            } catch (UnknownHostException ex) {
+                _logger.log(Level.WARNING, null, ex);
+            }
+        }
+
         synchronized void update(){
             update(null);
         }
@@ -231,7 +244,7 @@ public String toString(){
 
         final ServerAddress _addr;
         final Set<String> _names = Collections.synchronizedSet( new HashSet<String>() );
-        final DBPort _port; // we have our own port so we can set different socket options and don't have to owrry about the pool
+        DBPort _port; // we have our own port so we can set different socket options and don't have to owrry about the pool
 
         boolean _ok = false;        
         long _lastCheck = 0;
@@ -254,6 +267,14 @@ public void run(){
                 try {
                     updateAll();
 
+                    long now = System.currentTimeMillis();
+                    if (inetAddrCacheMS > 0 && _nextResolveTime < now) {
+                        _nextResolveTime = now + inetAddrCacheMS;
+                        for (Node node : _all) {
+                            node.updateAddr();
+                        }
+                    }
+
                     // force check on master
                     // otherwise master change may go unnoticed for a while if no write concern
                     _mongo.getConnector().checkMaster(true, false);
@@ -266,7 +287,6 @@ public void run(){
                     Thread.sleep( updaterIntervalMS );
                 }
                 catch ( InterruptedException ie ){
-                    // TODO: maybe something smarter
                 }
 
             }
@@ -375,15 +395,18 @@ void close(){
     boolean _closed = false;
 
     final Random _random = new Random();
+    long _nextResolveTime;
 
     static int updaterIntervalMS;
     static int slaveAcceptableLatencyMS;
+    static int inetAddrCacheMS;
 
     static final MongoOptions _mongoOptions = new MongoOptions();
 
     static {
         updaterIntervalMS = Integer.parseInt(System.getProperty("com.mongodb.updaterIntervalMS", "5000"));
         slaveAcceptableLatencyMS = Integer.parseInt(System.getProperty("com.mongodb.slaveAcceptableLatencyMS", "15"));
+        inetAddrCacheMS = Integer.parseInt(System.getProperty("com.mongodb.inetAddrCacheMS", "300000"));
         _mongoOptions.connectTimeout = Integer.parseInt(System.getProperty("com.mongodb.updaterConnectTimeoutMS", "20000"));
         _mongoOptions.socketTimeout = Integer.parseInt(System.getProperty("com.mongodb.updaterSocketTimeoutMS", "20000"));
     }

src/main/com/mongodb/ServerAddress.java

@@ -205,8 +205,8 @@ public String toString(){
 
     final String _host;
     final int _port;
-    final InetSocketAddress _addr;
-    final InetAddress[] _all;
+    InetSocketAddress _addr;
+    InetAddress[] _all;
 
     // --------
     // static helpers
@@ -236,5 +236,19 @@ public static String defaultHost(){
     public static int defaultPort(){
         return DBPort.PORT;
     }
+
+    /**
+     * attempts to update the internal InetAddress by resolving the host name.
+     * @return true if host resolved to a new IP that is different from old one, false otherwise
+     * @throws UnknownHostException
+     */
+    boolean updateInetAddr() throws UnknownHostException {
+        InetSocketAddress oldaddr = _addr;
+        _all = _getAddress( _host );
+        _addr = new InetSocketAddress( _all[0] , _port );
+        if (!_addr.equals(oldaddr))
+            return true;
+        return false;
+    }
 
 }