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374 lines
13 KiB
374 lines
13 KiB
// Copyright (c) 2004, 2019, Oracle and/or its affiliates. All rights reserved.
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//
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License, version 2.0, as
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// published by the Free Software Foundation.
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//
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// This program is also distributed with certain software (including
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// but not limited to OpenSSL) that is licensed under separate terms,
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// as designated in a particular file or component or in included license
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// documentation. The authors of MySQL hereby grant you an
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// additional permission to link the program and your derivative works
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// with the separately licensed software that they have included with
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// MySQL.
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//
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// Without limiting anything contained in the foregoing, this file,
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// which is part of MySQL Connector/NET, is also subject to the
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// Universal FOSS Exception, version 1.0, a copy of which can be found at
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// http://oss.oracle.com/licenses/universal-foss-exception.
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//
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// This program is distributed in the hope that it will be useful, but
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// WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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// See the GNU General Public License, version 2.0, for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software Foundation, Inc.,
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// 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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using MySql.Data.Common;
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using MySql.Data.Failover;
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using System;
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using System.Collections;
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using System.Collections.Generic;
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using System.Diagnostics;
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using System.Threading;
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using Sog.Properties;
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namespace MySql.Data.MySqlClient
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{
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/// <summary>
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/// Summary description for MySqlPool.
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/// </summary>
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internal sealed class MySqlPool
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{
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private readonly List<Driver> _inUsePool;
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private readonly Queue<Driver> _idlePool;
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private readonly uint _minSize;
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private readonly uint _maxSize;
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private readonly AutoResetEvent _autoEvent;
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private int _available;
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// Object used to lock the list of host obtained from DNS SRV lookup.
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private readonly object _dnsSrvLock = new object();
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private void EnqueueIdle(Driver driver)
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{
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driver.IdleSince = DateTime.Now;
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this._idlePool.Enqueue(driver);
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}
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public MySqlPool(MySqlConnectionStringBuilder settings)
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{
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this._minSize = settings.MinimumPoolSize;
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this._maxSize = settings.MaximumPoolSize;
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this._available = (int)this._maxSize;
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this._autoEvent = new AutoResetEvent(false);
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if (this._minSize > this._maxSize)
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{
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this._minSize = this._maxSize;
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}
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this.Settings = settings;
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this._inUsePool = new List<Driver>((int)this._maxSize);
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this._idlePool = new Queue<Driver>((int)this._maxSize);
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// prepopulate the idle pool to minSize
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for (int i = 0; i < this._minSize; i++)
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{
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this.EnqueueIdle(this.CreateNewPooledConnection());
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}
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this.ProcedureCache = new ProcedureCache((int)settings.ProcedureCacheSize);
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}
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#region Properties
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public MySqlConnectionStringBuilder Settings { get; set; }
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public ProcedureCache ProcedureCache { get; }
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/// <summary>
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/// It is assumed that this property will only be used from inside an active
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/// lock.
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/// </summary>
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private bool HasIdleConnections => this._idlePool.Count > 0;
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private int NumConnections => this._idlePool.Count + this._inUsePool.Count;
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/// <summary>
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/// Indicates whether this pool is being cleared.
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/// </summary>
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public bool BeingCleared { get; private set; }
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internal Dictionary<string, string> ServerProperties { get; set; }
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#endregion
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/// <summary>
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/// It is assumed that this method is only called from inside an active lock.
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/// </summary>
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private Driver GetPooledConnection()
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{
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Driver driver = null;
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// if we don't have an idle connection but we have room for a new
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// one, then create it here.
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lock ((this._idlePool as ICollection).SyncRoot)
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{
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if (this.HasIdleConnections)
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{
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driver = this._idlePool.Dequeue();
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}
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}
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// Obey the connection timeout
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if (driver != null)
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{
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try
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{
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driver.ResetTimeout((int)this.Settings.ConnectionTimeout * 1000);
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}
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catch (Exception)
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{
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driver.Close();
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driver = null;
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}
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}
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if (driver != null)
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{
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// first check to see that the server is still alive
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if (!driver.Ping())
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{
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driver.Close();
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driver = null;
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}
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else if (this.Settings.ConnectionReset)
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{
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// if the user asks us to ping/reset pooled connections
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// do so now
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try { driver.Reset(); }
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catch (Exception) { this.Clear(); }
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}
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}
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if (driver == null)
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{
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driver = this.CreateNewPooledConnection();
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}
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Debug.Assert(driver != null);
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lock ((this._inUsePool as ICollection).SyncRoot)
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{
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this._inUsePool.Add(driver);
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}
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return driver;
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}
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/// <summary>
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/// It is assumed that this method is only called from inside an active lock.
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/// </summary>
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private Driver CreateNewPooledConnection()
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{
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Debug.Assert((this._maxSize - this.NumConnections) > 0, "Pool out of sync.");
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Driver driver = Driver.Create(this.Settings);
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driver.Pool = this;
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return driver;
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}
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public void ReleaseConnection(Driver driver)
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{
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lock ((this._inUsePool as ICollection).SyncRoot)
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{
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if (this._inUsePool.Contains(driver))
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{
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this._inUsePool.Remove(driver);
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}
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}
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if (driver.ConnectionLifetimeExpired() || this.BeingCleared)
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{
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driver.Close();
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Debug.Assert(!this._idlePool.Contains(driver));
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}
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else
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{
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lock ((this._idlePool as ICollection).SyncRoot)
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{
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this.EnqueueIdle(driver);
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}
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}
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lock (this._dnsSrvLock)
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{
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if (driver.Settings.DnsSrv)
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{
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var dnsSrvRecords = DnsResolver.GetDnsSrvRecords(DnsResolver.ServiceName);
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FailoverManager.SetHostList(
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dnsSrvRecords.ConvertAll(r => new FailoverServer(r.Target, r.Port, null)),
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FailoverMethod.Sequential);
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foreach (var idleConnection in this._idlePool)
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{
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string idleServer = idleConnection.Settings.Server;
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if (!FailoverManager.FailoverGroup.Hosts.Exists(h => h.Host == idleServer) && !idleConnection.IsInActiveUse)
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{
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idleConnection.Close();
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}
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}
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}
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}
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Interlocked.Increment(ref this._available);
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this._autoEvent.Set();
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}
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/// <summary>
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/// Removes a connection from the in use pool. The only situations where this method
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/// would be called are when a connection that is in use gets some type of fatal exception
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/// or when the connection is being returned to the pool and it's too old to be
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/// returned.
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/// </summary>
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/// <param name="driver"></param>
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public void RemoveConnection(Driver driver)
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{
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lock ((this._inUsePool as ICollection).SyncRoot)
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{
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if (this._inUsePool.Contains(driver))
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{
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this._inUsePool.Remove(driver);
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Interlocked.Increment(ref this._available);
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this._autoEvent.Set();
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}
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}
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// if we are being cleared and we are out of connections then have
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// the manager destroy us.
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if (this.BeingCleared && this.NumConnections == 0)
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{
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MySqlPoolManager.RemoveClearedPool(this);
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}
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}
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private Driver TryToGetDriver()
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{
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int count = Interlocked.Decrement(ref this._available);
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if (count < 0)
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{
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Interlocked.Increment(ref this._available);
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return null;
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}
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try
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{
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Driver driver = this.GetPooledConnection();
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return driver;
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}
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catch (Exception ex)
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{
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MySqlTrace.LogError(-1, ex.Message);
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Interlocked.Increment(ref this._available);
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throw;
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}
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}
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public Driver GetConnection()
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{
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int fullTimeOut = (int)this.Settings.ConnectionTimeout * 1000;
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int timeOut = fullTimeOut;
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DateTime start = DateTime.Now;
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while (timeOut > 0)
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{
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Driver driver = this.TryToGetDriver();
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if (driver != null)
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{
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return driver;
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}
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// We have no tickets right now, lets wait for one.
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if (!this._autoEvent.WaitOne(timeOut, false))
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{
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break;
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}
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timeOut = fullTimeOut - (int)DateTime.Now.Subtract(start).TotalMilliseconds;
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}
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throw new MySqlException(Resources.TimeoutGettingConnection);
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}
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/// <summary>
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/// Clears this pool of all idle connections and marks this pool and being cleared
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/// so all other connections are closed when they are returned.
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/// </summary>
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internal void Clear()
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{
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lock ((this._idlePool as ICollection).SyncRoot)
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{
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// first, mark ourselves as being cleared
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this.BeingCleared = true;
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// then we remove all connections sitting in the idle pool
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while (this._idlePool.Count > 0)
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{
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Driver d = this._idlePool.Dequeue();
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d.Close();
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}
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// there is nothing left to do here. Now we just wait for all
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// in use connections to be returned to the pool. When they are
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// they will be closed. When the last one is closed, the pool will
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// be destroyed.
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}
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}
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/// <summary>
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/// Remove expired drivers from the idle pool
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/// </summary>
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/// <returns></returns>
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/// <remarks>
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/// Closing driver is a potentially lengthy operation involving network
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/// IO. Therefore we do not close expired drivers while holding
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/// idlePool.SyncRoot lock. We just remove the old drivers from the idle
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/// queue and return them to the caller. The caller will need to close
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/// them (or let GC close them)
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/// </remarks>
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internal List<Driver> RemoveOldIdleConnections()
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{
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List<Driver> oldDrivers = new List<Driver>();
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DateTime now = DateTime.Now;
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lock ((this._idlePool as ICollection).SyncRoot)
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{
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// The drivers appear to be ordered by their age, i.e it is
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// sufficient to remove them until the first element is not
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// too old.
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while (this._idlePool.Count > this._minSize)
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{
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Driver d = this._idlePool.Peek();
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DateTime expirationTime = d.IdleSince.Add(
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new TimeSpan(0, 0, MySqlPoolManager.maxConnectionIdleTime));
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if (expirationTime.CompareTo(now) < 0)
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{
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oldDrivers.Add(d);
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this._idlePool.Dequeue();
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}
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else
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{
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break;
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}
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}
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}
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return oldDrivers;
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}
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}
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}
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