The MongoTimeoutException thrown from BaseCluster methods now includes a short description of the cluster state,

which includes a short description of each server being monitored, which includes a short description of any exception
thrown while monitoring.

JAVA-1477

Conflicts:
	src/main/com/mongodb/ServerDescription.java
	src/test/com/mongodb/ServerDescriptionTest.java

Author: jyemin

src/main/com/mongodb/BaseCluster.java

@@ -79,8 +79,10 @@ public Server getServer(final ServerSelector serverSelector, final long maxWaitT
                 }
 
                 if (curTimeNanos > endTimeNanos) {
-                    throw new MongoTimeoutException(format("Timed out while waiting for a server that matches %s after %d ms",
-                                                           serverSelector, MILLISECONDS.convert(maxWaitTime, timeUnit)));
+                    throw new MongoTimeoutException(format("Timed out after %d ms while waiting for a server that matches %s. " +
+                                                           "Client view of cluster state is %s",
+                                                           MILLISECONDS.convert(maxWaitTime, timeUnit), serverSelector,
+                                                           curDescription.getShortDescription()));
                 }
 
                 if (!selectionFailureLogged) {
@@ -123,8 +125,10 @@ public ClusterDescription getDescription(final long maxWaitTime, final TimeUnit
             while (curDescription.getType() == ClusterType.Unknown) {
 
                 if (curTimeNanos > endTimeNanos) {
-                    throw new MongoTimeoutException(format("Timed out while waiting to connect after %d ms",
-                                                           MILLISECONDS.convert(maxWaitTime, timeUnit)));
+                    throw new MongoTimeoutException(format("Timed out after %d ms while waiting to connect. Client view of cluster state " +
+                                                           "is %s",
+                                                           MILLISECONDS.convert(maxWaitTime, timeUnit),
+                                                           curDescription.getShortDescription()));
                 }
 
                 if (!selectionFailureLogged) {

src/main/com/mongodb/ServerDescription.java

@@ -72,6 +72,8 @@ class ServerDescription {
     private final int minWireVersion;
     private final int maxWireVersion;
 
+    private Throwable exception;
+
     static class Builder {
         private ServerAddress address;
         private ServerType type = Unknown;
@@ -90,6 +92,7 @@ static class Builder {
         private ServerVersion version = new ServerVersion();
         private int minWireVersion = 0;
         private int maxWireVersion = 0;
+        private Throwable exception;
 
         // CHECKSTYLE:OFF
         public Builder address(final ServerAddress address) {
@@ -178,6 +181,11 @@ public Builder maxWireVersion(final int maxWireVersion) {
             return this;
         }
 
+        public Builder exception(final Throwable exception) {
+            this.exception = exception;
+            return this;
+        }
+
         public ServerDescription build() {
             return new ServerDescription(this);
         }
@@ -349,6 +357,10 @@ public long getAverageLatencyNanos() {
         return averageLatencyNanos;
     }
 
+    public Throwable getException() {
+        return exception;
+    }
+
     /**
      * Returns true if this instance is equals to @code{o}.  Note that equality is defined to NOT include the average ping time.
      *
@@ -415,6 +427,19 @@ public boolean equals(final Object o) {
             return false;
         }
 
+        // Compare class equality and message as exceptions rarely override equals
+        Class thisExceptionClass = exception != null ? exception.getClass() : null;
+        Class thatExceptionClass = that.exception != null ? that.exception.getClass() : null;
+        if (thisExceptionClass != null ? !thisExceptionClass.equals(thatExceptionClass) : thatExceptionClass != null) {
+            return false;
+        }
+
+        String thisExceptionMessage = exception != null ? exception.getMessage() : null;
+        String thatExceptionMessage= that.exception != null ? that.exception.getMessage() : null;
+        if (thisExceptionMessage != null ? !thisExceptionMessage.equals(thatExceptionMessage) : thatExceptionMessage != null) {
+            return false;
+        }
+
         return true;
     }
 
@@ -437,6 +462,8 @@ public int hashCode() {
         result = 31 * result + version.hashCode();
         result = 31 * result + minWireVersion;
         result = 31 * result + maxWireVersion;
+        result = 31 * result + (exception == null ? 0 : exception.getClass().hashCode());
+        result = 31 * result + (exception == null ? 0 : exception.getMessage().hashCode());
         return result;
     }
 
@@ -467,12 +494,30 @@ public String getShortDescription() {
         return "{"
                + "address=" + address
                + ", type=" + type
-               + (tags.isEmpty() ? "" : tags)
+               + (tags.isEmpty() ? "" : ", " + tags)
                + (state == Connected ? (", averageLatency=" + getAverageLatencyFormattedInMilliseconds() + " ms") : "")
                + ", state=" + state
+               + (exception == null ? "" : ", exception=" + translateExceptionToString())
                + '}';
     }
 
+    private String translateExceptionToString() {
+        StringBuilder builder = new StringBuilder();
+        builder.append("{");
+        builder.append(exception);
+        builder.append("}");
+        Throwable cur = exception.getCause();
+        while (cur != null) {
+            builder.append(", caused by ");
+            builder.append("{");
+            builder.append(cur);
+            builder.append("}");
+            cur = cur.getCause();
+        }
+
+        return builder.toString();
+    }
+
     private String getAverageLatencyFormattedInMilliseconds() {
         return new DecimalFormat("#0.0").format(averageLatencyNanos / 1000.0 / 1000.0);
     }
@@ -495,5 +540,6 @@ private String getAverageLatencyFormattedInMilliseconds() {
         ok = builder.ok;
         minWireVersion = builder.minWireVersion;
         maxWireVersion = builder.maxWireVersion;
+        exception = builder.exception;
     }
 }

src/main/com/mongodb/ServerMonitor.java

@@ -77,7 +77,7 @@ class ServerMonitorRunnable implements Runnable {
         public void run() {
             DBPort connection = null;
             try {
-                ServerDescription currentServerDescription = getConnectingServerDescription();
+                ServerDescription currentServerDescription = getConnectingServerDescription(null);
                 Throwable currentException = null;
                 while (!isClosed) {
                     ServerDescription previousServerDescription = currentServerDescription;
@@ -109,7 +109,7 @@ public void run() {
                         }
                     } catch (Throwable t) {
                         currentException = t;
-                        currentServerDescription = getConnectingServerDescription();
+                        currentServerDescription = getConnectingServerDescription(t);
                     }
 
                     if (!isClosed) {
@@ -203,7 +203,7 @@ private MongoOptions getOptions() {
     }
 
     static boolean descriptionHasChanged(final ServerDescription previousServerDescription,
-                                          final ServerDescription currentServerDescription) {
+                                         final ServerDescription currentServerDescription) {
         return !previousServerDescription.equals(currentServerDescription);
     }
 
@@ -317,7 +317,11 @@ private static Tags getTagsFromDocument(final DBObject tagsDocuments) {
         return tags;
     }
 
-    private ServerDescription getConnectingServerDescription() {
-        return ServerDescription.builder().type(ServerType.Unknown).state(ServerConnectionState.Connecting).address(serverAddress).build();
+    private ServerDescription getConnectingServerDescription(final Throwable throwable) {
+        return ServerDescription.builder().type(ServerType.Unknown)
+                                .state(ServerConnectionState.Connecting)
+                                .address(serverAddress)
+                                .exception(throwable)
+                                .build();
     }
 }

src/main/com/mongodb/Tags.java

@@ -158,7 +158,7 @@ public int hashCode() {
 
     @Override
     public String toString() {
-        return wrapped.toString();
+        return "TagSet" + wrapped.toString();
     }
 }