/*
* Copyright (c) 2023 Vaughn Nugent
*
* Library: VNLib
* Package: VNLib.Plugins.Extensions.VNCache
* File: VnCacheClient.cs
*
* VnCacheClient.cs is part of VNLib.Plugins.Extensions.VNCache which is part of the larger
* VNLib collection of libraries and utilities.
*
* VNLib.Plugins.Extensions.VNCache is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* VNLib.Plugins.Extensions.VNCache is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see https://www.gnu.org/licenses/.
*/
using System;
using System.Net.Http;
using System.Threading;
using System.Threading.Tasks;
using System.Net.Sockets;
using System.Net.WebSockets;
using System.Collections.Generic;
using System.Security.Cryptography;
using VNLib.Utils.Memory;
using VNLib.Utils.Logging;
using VNLib.Utils.Extensions;
using VNLib.Hashing.IdentityUtility;
using VNLib.Data.Caching;
using VNLib.Data.Caching.Extensions;
using VNLib.Data.Caching.ObjectCache;
using VNLib.Net.Messaging.FBM.Client;
using VNLib.Plugins.Extensions.Loading;
namespace VNLib.Plugins.Extensions.VNCache
{
public interface ICacheRefreshPolicy
{
TimeSpan MaxCacheAge { get; }
TimeSpan RefreshInterval { get; }
}
///
/// A base class that manages
///
[ConfigurationName(VNCacheExtensions.CACHE_CONFIG_KEY)]
internal class VnCacheClient : IGlobalCacheProvider, IAsyncBackgroundWork, IAsyncConfigurable
{
private readonly TimeSpan RetryInterval;
///
/// The internal client
///
public FBMClient Client { get; }
///
/// Gets a value that determines if the client is currently connected to a server
///
public bool IsConnected { get; private set; }
public VnCacheClient(PluginBase pbase, IConfigScope config)
{
//Get required configuration variables
int maxMessageSize = config["max_message_size"].GetInt32();
string? brokerAddress = config["broker_address"].GetString() ?? throw new KeyNotFoundException("Missing required configuration variable broker_address");
RetryInterval = config["retry_interval_sec"].GetTimeSpan(TimeParseType.Seconds);
TimeSpan timeout = config["request_timeout_sec"].GetTimeSpan(TimeParseType.Seconds);
Uri brokerUri = new(brokerAddress);
//Setup debug log if the plugin is in debug mode
ILogProvider? debugLog = pbase.IsDebug() ? pbase.Log : null;
//Init the client with default settings
FBMClientConfig conf = FBMDataCacheExtensions.GetDefaultConfig(MemoryUtil.Shared, maxMessageSize, timeout, debugLog);
Client = new(conf);
//Add the configuration to the client
Client.GetCacheConfiguration()
.WithBroker(brokerUri)
.WithTls(brokerUri.Scheme == Uri.UriSchemeHttps);
}
public virtual async Task ConfigureServiceAsync(PluginBase plugin)
{
//Get keys async
Task clientPrivTask = plugin.TryGetSecretAsync("client_private_key").ToJsonWebKey();
Task brokerPubTask = plugin.TryGetSecretAsync("broker_public_key").ToJsonWebKey();
Task cachePubTask = plugin.TryGetSecretAsync("cache_public_key").ToJsonWebKey();
//Wait for all tasks to complete
_ = await Task.WhenAll(clientPrivTask, brokerPubTask, cachePubTask);
ReadOnlyJsonWebKey clientPriv = await clientPrivTask ?? throw new KeyNotFoundException("Missing required secret client_private_key");
ReadOnlyJsonWebKey brokerPub = await brokerPubTask ?? throw new KeyNotFoundException("Missing required secret broker_public_key");
ReadOnlyJsonWebKey cachePub = await cachePubTask ?? throw new KeyNotFoundException("Missing required secret cache_public_key");
//Connection authentication methods
Client.GetCacheConfiguration()
.WithVerificationKey(cachePub)
.WithSigningCertificate(clientPriv)
.WithBrokerVerificationKey(brokerPub);
}
/*
* Background work method manages the remote cache connection
* to the cache cluster
*/
public virtual async Task DoWorkAsync(ILogProvider pluginLog, CancellationToken exitToken)
{
try
{
while (true)
{
//Load the server list
ActiveServer[]? servers;
while (true)
{
try
{
pluginLog.Debug("Discovering cluster nodes in broker");
//Get server list
servers = await Client.DiscoverCacheNodesAsync(exitToken);
break;
}
catch (HttpRequestException re) when (re.InnerException is SocketException)
{
pluginLog.Warn("Broker server is unreachable");
}
catch (Exception ex)
{
pluginLog.Warn("Failed to get server list from broker, reason {r}", ex.Message);
}
//Gen random ms delay
int randomMsDelay = RandomNumberGenerator.GetInt32(1000, 2000);
await Task.Delay(randomMsDelay, exitToken);
}
if (servers?.Length == 0)
{
pluginLog.Warn("No cluster nodes found, retrying");
await Task.Delay(RetryInterval, exitToken);
continue;
}
try
{
pluginLog.Debug("Connecting to random cache server");
//Connect to a random server
ActiveServer selected = await Client.ConnectToRandomCacheAsync(exitToken);
pluginLog.Debug("Connected to cache server {s}", selected.ServerId);
//Set connection status flag
IsConnected = true;
//Wait for disconnect
await Client.WaitForExitAsync(exitToken);
pluginLog.Debug("Cache server disconnected");
}
catch (WebSocketException wse)
{
pluginLog.Warn("Failed to connect to cache server {reason}", wse.Message);
continue;
}
catch (HttpRequestException he) when (he.InnerException is SocketException)
{
pluginLog.Debug("Failed to connect to random cache server server");
//Continue next loop
continue;
}
finally
{
IsConnected = false;
}
}
}
catch (OperationCanceledException)
{
//Normal exit from listening loop
}
catch (KeyNotFoundException e)
{
pluginLog.Error("Missing required configuration variable for VnCache client: {0}", e.Message);
}
catch (FBMServerNegiationException fne)
{
pluginLog.Error("Failed to negotiate connection with cache server {reason}", fne.Message);
}
catch (Exception ex)
{
pluginLog.Error(ex, "Unhandled exception occured in background cache client listening task");
}
finally
{
//Dispose the client on exit
Client.Dispose();
}
pluginLog.Information("Cache client exited");
}
///
public virtual Task AddOrUpdateAsync(string key, string? newKey, T value, CancellationToken cancellation)
{
return !IsConnected
? throw new InvalidOperationException("The underlying client is not connected to a cache node")
: Client!.AddOrUpdateObjectAsync(key, newKey, value, cancellation);
}
///
public virtual Task DeleteAsync(string key, CancellationToken cancellation)
{
return !IsConnected
? throw new InvalidOperationException("The underlying client is not connected to a cache node")
: Client!.DeleteObjectAsync(key, cancellation);
}
///
public virtual Task GetAsync(string key, CancellationToken cancellation)
{
return !IsConnected
? throw new InvalidOperationException("The underlying client is not connected to a cache node")
: Client!.GetObjectAsync(key, cancellation);
}
///
public virtual Task GetAsync(string key, ICacheObjectDeserialzer deserializer, CancellationToken cancellation)
{
return !IsConnected
? throw new InvalidOperationException("The underlying client is not connected to a cache node")
: Client!.GetObjectAsync(key, deserializer, cancellation);
}
///
public virtual Task AddOrUpdateAsync(string key, string? newKey, T value, ICacheObjectSerialzer serialzer, CancellationToken cancellation)
{
return !IsConnected
? throw new InvalidOperationException("The underlying client is not connected to a cache node")
: Client!.AddOrUpdateObjectAsync(key, newKey, value, serialzer, cancellation);
}
}
}