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/* Copyright 2010 10gen Inc.
*
* Licensed 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.
*/
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using MongoDB.Bson;
namespace MongoDB.Driver.Internal {
internal class ReplicaSetConnector {
#region private fields
private MongoUrl url;
private HashSet<MongoServerAddress> queries = new HashSet<MongoServerAddress>();
private Dictionary<MongoServerAddress, QueryNodeResponse> responses = new Dictionary<MongoServerAddress, QueryNodeResponse>();
private MongoConnection primaryConnection;
private List<MongoConnection> secondaryConnections = new List<MongoConnection>();
private List<MongoServerAddress> replicaSet;
#endregion
#region constructors
public ReplicaSetConnector(
MongoUrl url
) {
this.url = url;
}
#endregion
#region public properties
public MongoConnection PrimaryConnection {
get { return primaryConnection; }
}
public List<MongoConnection> SecondaryConnections {
get { return secondaryConnections; }
}
public IEnumerable<MongoServerAddress> ReplicaSet {
get { return replicaSet; }
}
#endregion
#region public methods
public void Connect(
TimeSpan timeout
) {
DateTime deadline = DateTime.UtcNow + timeout;
// query all servers in seed list in parallel (they will report responses back through the responsesQueue)
var responsesQueue = QuerySeedListNodes();
// process the responses as they come back and stop as soon as we find the primary (unless slaveOk is true)
// stragglers will continue to report responses to the responsesQueue but no one will read them
// and eventually it will all get garbage collected
var exceptions = new List<Exception>();
while (responses.Count < queries.Count) {
var response = responsesQueue.Dequeue(deadline);
if (response == null) {
break; // we timed out
}
responses.Add(response.Address, response);
if (response.Exception != null) {
exceptions.Add(response.Exception);
continue;
}
if (response.IsPrimary) {
primaryConnection = response.Connection;
replicaSet = GetHostAddresses(response);
if (!url.SlaveOk) {
break; // if we're not going to use the secondaries no need to wait for their replies
}
} else {
if (url.SlaveOk) {
secondaryConnections.Add(response.Connection);
} else {
response.Connection.Close();
}
}
// look for additional members of the replica set that might not have been in the seed list and query them also
foreach (var address in GetHostAddresses(response)) {
if (!queries.Contains(address)) {
var args = new QueryNodeParameters {
Address = address,
ResponseQueue = responsesQueue
};
ThreadPool.QueueUserWorkItem(QueryNodeWorkItem, args);
queries.Add(address);
}
}
}
if (primaryConnection == null) {
var innerException = exceptions.FirstOrDefault();
var exception = new MongoConnectionException("Unable to connect to server", innerException);
if (exceptions.Count > 1) {
exception.Data.Add("InnerExceptions", exceptions);
}
throw exception;
}
}
#endregion
#region private methods
private List<MongoServerAddress> GetHostAddresses(
QueryNodeResponse response
) {
if (!response.IsMasterResult.Contains("hosts")) {
var message = string.Format("Server is not a member of a replica set: {0}", response.Address);
throw new MongoConnectionException(message);
}
var nodes = new List<MongoServerAddress>();
foreach (BsonString host in response.IsMasterResult["hosts"].AsBsonArray.Values) {
var address = MongoServerAddress.Parse(host.Value);
nodes.Add(address);
}
return nodes;
}
private BlockingQueue<QueryNodeResponse> QuerySeedListNodes() {
var responseQueue = new BlockingQueue<QueryNodeResponse>();
foreach (var address in url.Servers) {
var args = new QueryNodeParameters {
Address = address,
ResponseQueue = responseQueue
};
ThreadPool.QueueUserWorkItem(QueryNodeWorkItem, args);
queries.Add(address);
}
return responseQueue;
}
// note: this method will run on a thread from the ThreadPool
private void QueryNodeWorkItem(
object parameters
) {
// this method has to work at a very low level because the connection pool isn't set up yet
var args = (QueryNodeParameters) parameters;
var response = new QueryNodeResponse { Address = args.Address };
try {
var connection = new MongoConnection(null, args.Address); // no connection pool
try {
var isMasterCommand = new BsonDocument("ismaster", 1);
var isMasterResult = connection.RunCommand("admin.$cmd", QueryFlags.SlaveOk, isMasterCommand);
response.IsMasterResult = isMasterResult;
response.Connection = connection; // might become the first connection in the connection pool
response.IsPrimary = isMasterResult["ismaster", false].ToBoolean();
if (url.ReplicaSetName != null) {
var getStatusCommand = new BsonDocument("replSetGetStatus", 1);
var getStatusResult = connection.RunCommand("admin.$cmd", QueryFlags.SlaveOk, getStatusCommand);
var replicaSetName = getStatusResult["set"].AsString;
if (replicaSetName != url.ReplicaSetName) {
var message = string.Format("Host {0} belongs to a different replica set: {1}", args.Address, replicaSetName);
throw new MongoConnectionException(message);
}
}
} catch {
try { connection.Close(); } catch { } // ignore exceptions
throw;
}
} catch (Exception ex) {
response.Exception = ex;
}
args.ResponseQueue.Enqueue(response);
}
#endregion
#region private nested classes
// note: OK to use automatic properties on private helper class
private class QueryNodeParameters {
public MongoServerAddress Address { get; set; }
public BlockingQueue<QueryNodeResponse> ResponseQueue { get; set; }
}
// note: OK to use automatic properties on private helper class
private class QueryNodeResponse {
public MongoServerAddress Address { get; set; }
public BsonDocument IsMasterResult { get; set; }
public bool IsPrimary { get; set; }
public MongoConnection Connection { get; set; }
public Exception Exception { get; set; }
}
#endregion
}
}