//

// Redis Sentinel will connect to a Redis Sentinel Instance and create an IRedisClientsManager based off of the first sentinel that returns data

//

// Upon failure of a sentinel, other sentinels will be attempted to be connected to

// Upon a s_down event, the RedisClientsManager will be failed over to the new set of slaves/masters

//

using System;

using System.Collections.Generic;

using System.Linq;

using System.Threading;

using System.Threading.Tasks;

using ServiceStack;

using ServiceStack.Logging;

using ServiceStack.Text;

namespace ServiceStack.Redis

{

public class RedisSentinel : IRedisSentinel

{

protected static readonly ILog Log = LogManager.GetLogger(typeof(RedisSentinel));

public static string DefaultMasterName = "mymaster";

public static string DefaultAddress = "127.0.0.1:26379";

private object oLock = new object();

private bool isDisposed = false;

private readonly string masterName;

public string MasterName

{

get { return masterName; }

}

private int failures = 0;

private int sentinelIndex = -1;

public List<string> SentinelHosts { get; private set; }

internal RedisEndpoint[] SentinelEndpoints { get; private set; }

private RedisSentinelWorker worker;

private static int MaxFailures = 5;

/// <summary>

/// Change to use a different IRedisClientsManager

/// </summary>

public Func<string[], string[], IRedisClientsManager> RedisManagerFactory { get; set; }

/// <summary>

/// Configure the Redis Connection String to use for a Redis Client Host

/// </summary>

public Func<string, string> HostFilter { get; set; }

/// <summary>

/// The configured Redis Client Manager this Sentinel managers

/// </summary>

public IRedisClientsManager RedisManager { get; set; }

/// <summary>

/// Fired when Sentinel fails over the Redis Client Manager to a new master

/// </summary>

public Action<IRedisClientsManager> OnFailover { get; set; }

/// <summary>

/// Fired when the Redis Sentinel Worker connection fails

/// </summary>

public Action<Exception> OnWorkerError { get; set; }

/// <summary>

/// Fired when the Sentinel worker receives a message from the Sentinel Subscription

/// </summary>

public Action<string, string> OnSentinelMessageReceived { get; set; }

/// <summary>

/// Map the internal IP's returned by Sentinels to its external IP

/// </summary>

public Dictionary<string, string> IpAddressMap { get; set; }

/// <summary>

/// Whether to routinely scan for other sentinel hosts (default true)

/// </summary>

public bool ScanForOtherSentinels { get; set; }

/// <summary>

/// What interval to scan for other sentinel hosts (default 10 mins)

/// </summary>

public TimeSpan RefreshSentinelHostsAfter { get; set; }

private DateTime lastSentinelsRefresh;

/// <summary>

/// How long to wait after failing before connecting to next redis instance (default 250ms)

/// </summary>

public TimeSpan WaitBetweenFailedHosts { get; set; }

/// <summary>

/// How long to retry connecting to hosts before throwing (default 60 secs)

/// </summary>

public TimeSpan MaxWaitBetweenFailedHosts { get; set; }

/// <summary>

/// How long to wait after consecutive failed connection attempts to master before forcing

/// a Sentinel to failover the current master (default 60 secs)

/// </summary>

public TimeSpan WaitBeforeForcingMasterFailover { get; set; }

/// <summary>

/// The Max Connection time for Sentinel Worker (default 100ms)

/// </summary>

public int SentinelWorkerConnectTimeoutMs { get; set; }

/// <summary>

/// The Max TCP Socket Receive time for Sentinel Worker (default 100ms)

/// </summary>

public int SentinelWorkerReceiveTimeoutMs { get; set; }

/// <summary>

/// The Max TCP Socket Send time for Sentinel Worker (default 100ms)

/// </summary>

public int SentinelWorkerSendTimeoutMs { get; set; }

/// <summary>

/// Reset client connections when Sentinel reports redis instance is subjectively down (default true)

/// </summary>

public bool ResetWhenSubjectivelyDown { get; set; }

/// <summary>

/// Reset client connections when Sentinel reports redis instance is objectively down (default true)

/// </summary>

public bool ResetWhenObjectivelyDown { get; set; }

public RedisSentinel(string sentinelHost = null, string masterName = null)

: this(new[] { sentinelHost ?? DefaultAddress }, masterName ?? DefaultMasterName) { }

public RedisSentinel(IEnumerable<string> sentinelHosts, string masterName = null)

{

this.SentinelHosts = sentinelHosts != null

? sentinelHosts.ToList()

: null;

if (SentinelHosts == null || SentinelHosts.Count == 0)

throw new ArgumentException("sentinels must have at least one entry");

this.masterName = masterName ?? DefaultMasterName;

IpAddressMap = new Dictionary<string, string>();

RedisManagerFactory = (masters, slaves) => new PooledRedisClientManager(masters, slaves);

ScanForOtherSentinels = true;

RefreshSentinelHostsAfter = TimeSpan.FromMinutes(10);

ResetWhenObjectivelyDown = true;

ResetWhenSubjectivelyDown = true;

SentinelWorkerConnectTimeoutMs = 100;

SentinelWorkerReceiveTimeoutMs = 100;

SentinelWorkerSendTimeoutMs = 100;

WaitBetweenFailedHosts = TimeSpan.FromMilliseconds(250);

MaxWaitBetweenFailedHosts = TimeSpan.FromSeconds(60);

WaitBeforeForcingMasterFailover = TimeSpan.FromSeconds(60);

}

/// <summary>

/// Initialize Sentinel Subscription and Configure Redis ClientsManager

/// </summary>

public IRedisClientsManager Start()

{

lock (oLock)

{

for (int i = 0; i < SentinelHosts.Count; i++)

{

var parts = SentinelHosts[i].SplitOnLast(':');

if (parts.Length == 1)

{

SentinelHosts[i] = parts[0] + ":{0}".Fmt(RedisConfig.DefaultPortSentinel);

}

}

if (ScanForOtherSentinels)

RefreshActiveSentinels();

SentinelEndpoints = SentinelHosts

.Map(x => x.ToRedisEndpoint(defaultPort: RedisConfig.DefaultPortSentinel))

.ToArray();

var sentinelWorker = GetValidSentinelWorker();

if (this.RedisManager == null || sentinelWorker == null)

throw new Exception("Unable to resolve sentinels!");

return this.RedisManager;

}

}

public List<string> GetActiveSentinelHosts(IEnumerable<string> sentinelHosts)

{

var activeSentinelHosts = new List<string>();

foreach (var sentinelHost in sentinelHosts.ToArray())

{

try

{

if (Log.IsDebugEnabled)

Log.Debug("Connecting to all available Sentinels to discover Active Sentinel Hosts...");

var endpoint = sentinelHost.ToRedisEndpoint(defaultPort: RedisConfig.DefaultPortSentinel);

using (var sentinelWorker = new RedisSentinelWorker(this, endpoint))

{

var activeHosts = sentinelWorker.GetSentinelHosts(MasterName);

if (!activeSentinelHosts.Contains(sentinelHost))

activeSentinelHosts.Add(sentinelHost);

foreach (var activeHost in activeHosts)

{

if (!activeSentinelHosts.Contains(activeHost))

activeSentinelHosts.Add(activeHost);

}

}

if (Log.IsDebugEnabled)

Log.Debug("All active Sentinels Found: " + string.Join(", ", activeSentinelHosts));

}

catch (Exception ex)

{

Log.Error("Could not get active Sentinels from: {0}".Fmt(sentinelHost), ex);

}

}

return activeSentinelHosts;

}

public void RefreshActiveSentinels()

{

var activeHosts = GetActiveSentinelHosts(SentinelHosts);

if (activeHosts.Count == 0) return;

lock (SentinelHosts)

{

lastSentinelsRefresh = DateTime.UtcNow;

activeHosts.Each(x =>

{

if (!SentinelHosts.Contains(x))

SentinelHosts.Add(x);

});

SentinelEndpoints = SentinelHosts

.Map(x => x.ToRedisEndpoint(defaultPort: RedisConfig.DefaultPortSentinel))

.ToArray();

}

}

internal string[] ConfigureHosts(IEnumerable<string> hosts)

{

if (hosts == null)

return TypeConstants.EmptyStringArray;

return HostFilter == null

? hosts.ToArray()

: hosts.Map(HostFilter).ToArray();

}

public SentinelInfo ResetClients()

{

var sentinelInfo = GetSentinelInfo();

if (RedisManager == null)

{

if (Log.IsDebugEnabled)

Log.Debug("Configuring initial Redis Clients: {0}".Fmt(sentinelInfo));

RedisManager = CreateRedisManager(sentinelInfo);

}

else

{

if (Log.IsDebugEnabled)

Log.Debug("Failing over to Redis Clients: {0}".Fmt(sentinelInfo));

((IRedisFailover)RedisManager).FailoverTo(

ConfigureHosts(sentinelInfo.RedisMasters),

ConfigureHosts(sentinelInfo.RedisSlaves));

}

return sentinelInfo;

}

private IRedisClientsManager CreateRedisManager(SentinelInfo sentinelInfo)

{

var masters = ConfigureHosts(sentinelInfo.RedisMasters);

var slaves = ConfigureHosts(sentinelInfo.RedisSlaves);

var redisManager = RedisManagerFactory(masters, slaves);

var hasRedisResolver = (IHasRedisResolver)redisManager;

hasRedisResolver.RedisResolver = new RedisSentinelResolver(this, masters, slaves);

var canFailover = redisManager as IRedisFailover;

if (canFailover != null && this.OnFailover != null)

{

canFailover.OnFailover.Add(this.OnFailover);

}

return redisManager;

}

public IRedisClientsManager GetRedisManager()

{

return RedisManager ?? (RedisManager = CreateRedisManager(GetSentinelInfo()));

}

private RedisSentinelWorker GetValidSentinelWorker()

{

if (isDisposed)

throw new ObjectDisposedException(GetType().Name);

if (this.worker != null)

return this.worker;

RedisException lastEx = null;

while (this.worker == null && ShouldRetry())

{

try

{

this.worker = GetNextSentinel();

GetRedisManager();

this.worker.BeginListeningForConfigurationChanges();

this.failures = 0; //reset

return this.worker;

}

catch (RedisException ex)

{

if (OnWorkerError != null)

OnWorkerError(ex);

lastEx = ex;

this.worker = null;

this.failures++;

Interlocked.Increment(ref RedisState.TotalFailedSentinelWorkers);

}

}

this.failures = 0; //reset

TaskUtils.Sleep(WaitBetweenFailedHosts);

throw new RedisException("No Redis Sentinels were available", lastEx);

}

public RedisEndpoint GetMaster()

{

var sentinelWorker = GetValidSentinelWorker();

lock (sentinelWorker)

{

var host = sentinelWorker.GetMasterHost(masterName);

if (ScanForOtherSentinels && DateTime.UtcNow - lastSentinelsRefresh > RefreshSentinelHostsAfter)

{

RefreshActiveSentinels();

}

return host != null

? (HostFilter != null ? HostFilter(host) : host).ToRedisEndpoint()

: null;

}

}

public List<RedisEndpoint> GetSlaves()

{

var sentinelWorker = GetValidSentinelWorker();

lock (sentinelWorker)

{

var hosts = sentinelWorker.GetSlaveHosts(masterName);

return ConfigureHosts(hosts).Map(x => x.ToRedisEndpoint());

}

}

/// <summary>

/// Check if GetValidSentinel should try the next sentinel server

/// </summary>

/// <returns></returns>

/// <remarks>This will be true if the failures is less than either RedisSentinel.MaxFailures or the # of sentinels, whatever is greater</remarks>

private bool ShouldRetry()

{

return this.failures < Math.Max(MaxFailures, this.SentinelEndpoints.Length);

}

private RedisSentinelWorker GetNextSentinel()

{

lock (oLock)

{

if (this.worker != null)

{

this.worker.Dispose();

this.worker = null;

}

if (++sentinelIndex >= SentinelEndpoints.Length)

sentinelIndex = 0;

var sentinelWorker = new RedisSentinelWorker(this, SentinelEndpoints[sentinelIndex])

{

OnSentinelError = OnSentinelError

};

return sentinelWorker;

}

}

private void OnSentinelError(Exception ex)

{

if (this.worker != null)

{

Log.Error("Error on existing SentinelWorker, reconnecting...");

if (OnWorkerError != null)

OnWorkerError(ex);

this.worker = GetNextSentinel();

this.worker.BeginListeningForConfigurationChanges();

}

}

public void ForceMasterFailover()

{

var sentinelWorker = GetValidSentinelWorker();

lock (sentinelWorker)

{

sentinelWorker.ForceMasterFailover(masterName);

}

}

public SentinelInfo GetSentinelInfo()

{

var sentinelWorker = GetValidSentinelWorker();

lock (sentinelWorker)

{

return sentinelWorker.GetSentinelInfo();

}

}

public void Dispose()

{

this.isDisposed = true;

new IDisposable[] { RedisManager, worker }.Dispose();

}

}

}

public class SentinelInfo

{

public string MasterName { get; set; }

public string[] RedisMasters { get; set; }

public string[] RedisSlaves { get; set; }

public SentinelInfo(string masterName, IEnumerable<string> redisMasters, IEnumerable<string> redisSlaves)

{

MasterName = masterName;

RedisMasters = redisMasters != null ? redisMasters.ToArray() : TypeConstants.EmptyStringArray;

RedisSlaves = redisSlaves != null ? redisSlaves.ToArray() : TypeConstants.EmptyStringArray;

}

public override string ToString()

{

return "{0} masters: {1}, slaves: {2}".Fmt(

MasterName,

string.Join(", ", RedisMasters),

string.Join(", ", RedisSlaves));

}

}