ServerMonitor now only calls buildInfo once for each established connection.

  JAVA-1635

Author: jyemin

src/main/com/mongodb/DBPort.java

@@ -54,6 +54,7 @@
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.List;
 import java.util.Map;
 import java.util.Random;
 import java.util.Set;
@@ -86,7 +87,7 @@ public class DBPort implements Connection {
      */
     @SuppressWarnings("deprecation")
     public DBPort( ServerAddress addr ){
-        this( addr , new MongoOptions());
+        this( addr , null, new MongoOptions());
     }
 
     // Normal usage
@@ -95,8 +96,8 @@ public DBPort( ServerAddress addr ){
     }
 
     // Server monitor usage
-    DBPort( ServerAddress addr, MongoOptions options ) {
-        this(addr, null, null, options, 0);
+    DBPort( ServerAddress addr, Mongo mongo, MongoOptions options ) {
+        this(addr, null, mongo, options, 0);
     }
 
     private DBPort( ServerAddress addr, PooledConnectionProvider pool, Mongo mongo, MongoOptions options, int generation ) {
@@ -291,7 +292,7 @@ private synchronized void ensureOpen(final Mongo mongo) throws IOException {
                 _in = new BufferedInputStream( _socket.getInputStream() );
                 _out = _socket.getOutputStream();
                 if (mongo != null) {
-                    _serverVersion = ServerMonitor.getVersion(runCommand(mongo.getDB("admin"), new BasicDBObject("buildinfo", 1)));
+                    _serverVersion = getVersion(runCommand(mongo.getDB("admin"), new BasicDBObject("buildinfo", 1)));
                 }
                 successfullyConnected = true;
             }
@@ -317,6 +318,11 @@ private synchronized void ensureOpen(final Mongo mongo) throws IOException {
         } while (!successfullyConnected);
     }
 
+    @SuppressWarnings("unchecked")
+    static ServerVersion getVersion(final CommandResult buildInfoResult) {
+        return new ServerVersion(((List<Integer>) buildInfoResult.get("versionArray")).subList(0, 3));
+    }
+
     @Override
     public int hashCode(){
         return _addr.hashCode();

src/main/com/mongodb/ServerMonitor.java

@@ -41,7 +41,7 @@ class ServerMonitor {
 
     private static final Logger LOGGER = Loggers.getLogger("cluster");
 
-    private ServerAddress serverAddress;
+    private final ServerAddress serverAddress;
     private final ChangeListener<ServerDescription> serverStateListener;
     private final SocketSettings socketSettings;
     private final ServerSettings settings;
@@ -85,7 +85,7 @@ public void run() {
                     Throwable previousException = currentException;
                     try {
                         if (connection == null) {
-                            connection = new DBPort(serverAddress, getOptions());
+                            connection = new DBPort(serverAddress, mongo, getOptions());
                         }
                         try {
                             currentServerDescription = lookupServerDescription(connection);
@@ -99,7 +99,7 @@ public void run() {
                                 connection = null;
                                 connectionProvider.invalidate();
                             }
-                            connection = new DBPort(serverAddress, getOptions());
+                            connection = new DBPort(serverAddress, mongo, getOptions());
                             try {
                                 currentServerDescription = lookupServerDescription(connection);
                             } catch (IOException e1) {
@@ -234,16 +234,15 @@ private ServerDescription lookupServerDescription(final DBPort connection) throw
         count++;
         elapsedNanosSum += System.nanoTime() - startNanoTime;
 
-        final CommandResult buildInfoResult = connection.runCommand(mongo.getDB("admin"), new BasicDBObject("buildinfo", 1));
-        return createDescription(isMasterResult, buildInfoResult, elapsedNanosSum / count);
+        return createDescription(isMasterResult, connection.getServerVersion(), elapsedNanosSum / count);
     }
 
     @SuppressWarnings("unchecked")
-    private ServerDescription createDescription(final CommandResult commandResult, final CommandResult buildInfoResult,
+    private ServerDescription createDescription(final CommandResult commandResult, final ServerVersion serverVersion,
                                                 final long averageLatencyNanos) {
         return ServerDescription.builder()
                                 .state(ServerConnectionState.Connected)
-                                .version(getVersion(buildInfoResult))
+                                .version(serverVersion)
                                 .address(commandResult.getServerUsed())
                                 .type(getServerType(commandResult))
                                 .hosts(listToSet((List<String>) commandResult.get("hosts")))
@@ -262,11 +261,6 @@ private ServerDescription createDescription(final CommandResult commandResult, f
                                 .ok(commandResult.ok()).build();
     }
 
-    @SuppressWarnings("unchecked")
-    static ServerVersion getVersion(final CommandResult buildInfoResult) {
-        return new ServerVersion(((List<Integer>) buildInfoResult.get("versionArray")).subList(0, 3));
-    }
-
     private Set<String> listToSet(final List<String> list) {
         if (list == null || list.isEmpty()) {
             return Collections.emptySet();