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Optimized persisting of retained messages to avoid useless writes to the filesystem

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This commit is contained in:
Christian Kratky
2017-11-08 14:30:13 +01:00
parent 7e48746944
commit d2e481719c
8 changed files with 155 additions and 28 deletions
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MQTTnet.Core/Server/IMqttClientRetainedMessageManager.cs
+1 -1
View File
@@ -10,6 +10,6 @@ namespace MQTTnet.Core.Server
Task HandleMessageAsync(string clientId, MqttApplicationMessage applicationMessage);
List<MqttApplicationMessage> GetMessages(MqttSubscribePacket subscribePacket);
Task<List<MqttApplicationMessage>> GetSubscribedMessagesAsync(MqttSubscribePacket subscribePacket);
}
}
MQTTnet.Core/Server/MqttClientRetainedMessagesManager.cs
+52 -21
View File
@@ -1,6 +1,7 @@
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using MQTTnet.Core.Packets;
using Microsoft.Extensions.Logging;
@@ -11,6 +12,7 @@ namespace MQTTnet.Core.Server
public sealed class MqttClientRetainedMessagesManager : IMqttClientRetainedMessageManager
{
private readonly Dictionary<string, MqttApplicationMessage> _retainedMessages = new Dictionary<string, MqttApplicationMessage>();
private readonly SemaphoreSlim _gate = new SemaphoreSlim(1, 1);
private readonly ILogger<MqttClientRetainedMessagesManager> _logger;
private readonly MqttServerOptions _options;
@@ -27,62 +29,87 @@ namespace MQTTnet.Core.Server
return;
}
await _gate.WaitAsync();
try
{
var retainedMessages = await _options.Storage.LoadRetainedMessagesAsync();
lock (_retainedMessages)
_retainedMessages.Clear();
foreach (var retainedMessage in retainedMessages)
{
_retainedMessages.Clear();
foreach (var retainedMessage in retainedMessages)
{
_retainedMessages[retainedMessage.Topic] = retainedMessage;
}
_retainedMessages[retainedMessage.Topic] = retainedMessage;
}
}
catch (Exception exception)
{
_logger.LogError(new EventId(), exception, "Unhandled exception while loading retained messages.");
}
finally
{
_gate.Release();
}
}
public async Task HandleMessageAsync(string clientId, MqttApplicationMessage applicationMessage)
{
if (applicationMessage == null) throw new ArgumentNullException(nameof(applicationMessage));
List<MqttApplicationMessage> allRetainedMessages;
lock (_retainedMessages)
await _gate.WaitAsync();
try
{
var saveIsRequired = false;
if (applicationMessage.Payload?.Any() == false)
{
_retainedMessages.Remove(applicationMessage.Topic);
saveIsRequired = _retainedMessages.Remove(applicationMessage.Topic);
_logger.LogInformation("Client '{0}' cleared retained message for topic '{1}'.", clientId, applicationMessage.Topic);
}
else
{
_retainedMessages[applicationMessage.Topic] = applicationMessage;
_logger.LogInformation("Client '{0}' updated retained message for topic '{1}'.", clientId, applicationMessage.Topic);
if (!_retainedMessages.ContainsKey(applicationMessage.Topic))
{
_retainedMessages[applicationMessage.Topic] = applicationMessage;
saveIsRequired = true;
}
else
{
var existingMessage = _retainedMessages[applicationMessage.Topic];
if (existingMessage.QualityOfServiceLevel != applicationMessage.QualityOfServiceLevel || !existingMessage.Payload.SequenceEqual(applicationMessage.Payload ?? new byte[0]))
{
_retainedMessages[applicationMessage.Topic] = applicationMessage;
saveIsRequired = true;
}
}
_logger.LogInformation("Client '{0}' set retained message for topic '{1}'.", clientId, applicationMessage.Topic);
}
allRetainedMessages = new List<MqttApplicationMessage>(_retainedMessages.Values);
}
try
{
if (_options.Storage != null)
if (!saveIsRequired)
{
await _options.Storage.SaveRetainedMessagesAsync(allRetainedMessages);
_logger.LogTrace("Skipped saving retained messages because no changes were detected.");
}
if (saveIsRequired && _options.Storage != null)
{
await _options.Storage.SaveRetainedMessagesAsync(_retainedMessages.Values.ToList());
}
}
catch (Exception exception)
{
_logger.LogError(new EventId(), exception, "Unhandled exception while saving retained messages.");
_logger.LogError(new EventId(), exception, "Unhandled exception while handling retained messages.");
}
finally
{
_gate.Release();
}
}
public List<MqttApplicationMessage> GetMessages(MqttSubscribePacket subscribePacket)
public async Task<List<MqttApplicationMessage>> GetSubscribedMessagesAsync(MqttSubscribePacket subscribePacket)
{
var retainedMessages = new List<MqttApplicationMessage>();
lock (_retainedMessages)
await _gate.WaitAsync();
try
{
foreach (var retainedMessage in _retainedMessages.Values)
{
@@ -103,6 +130,10 @@ namespace MQTTnet.Core.Server
}
}
}
finally
{
_gate.Release();
}
return retainedMessages;
}
MQTTnet.Core/Server/MqttClientSession.cs
+4 -3
View File
@@ -191,8 +191,9 @@ namespace MQTTnet.Core.Server
private async Task HandleIncomingSubscribePacketAsync(IMqttCommunicationAdapter adapter, MqttSubscribePacket subscribePacket, CancellationToken cancellationToken)
{
var subscribeResult = _subscriptionsManager.Subscribe(subscribePacket, ClientId);
await adapter.SendPacketsAsync(_options.DefaultCommunicationTimeout, cancellationToken, subscribeResult.ResponsePacket);
EnqueueRetainedMessages(subscribePacket);
await EnqueueSubscribedRetainedMessagesAsync(subscribePacket);
if (subscribeResult.CloseConnection)
{
@@ -201,9 +202,9 @@ namespace MQTTnet.Core.Server
}
}
private void EnqueueRetainedMessages(MqttSubscribePacket subscribePacket)
private async Task EnqueueSubscribedRetainedMessagesAsync(MqttSubscribePacket subscribePacket)
{
var retainedMessages = _clientRetainedMessageManager.GetMessages(subscribePacket);
var retainedMessages = await _clientRetainedMessageManager.GetSubscribedMessagesAsync(subscribePacket);
foreach (var publishPacket in retainedMessages)
{
EnqueuePublishPacket(publishPacket.ToPublishPacket());