mcs/class/Mono.Data.Tds/Mono.Data.Tds.Protocol/TdsConnectionPool.cs

   1 //
   2 // Mono.Data.TdsClient.TdsConnectionPool.cs
   3 //
   4 // Author:
   5 //   Lluis Sanchez Gual (lluis@ximian.com)
   6 //   Christian Hergert (christian.hergert@gmail.com)
   7 //   Gonzalo Paniagua Javier (gonzalo@novell.com)
   8 //
   9 // Copyright (C) 2004 Novell, Inc.
  10 // Copyright (C) 2009 Novell, Inc.
  11
  12 //
  13 // Permission is hereby granted, free of charge, to any person obtaining
  14 // a copy of this software and associated documentation files (the
  15 // "Software"), to deal in the Software without restriction, including
  16 // without limitation the rights to use, copy, modify, merge, publish,
  17 // distribute, sublicense, and/or sell copies of the Software, and to
  18 // permit persons to whom the Software is furnished to do so, subject to
  19 // the following conditions:
  20 //
  21 // The above copyright notice and this permission notice shall be
  22 // included in all copies or substantial portions of the Software.
  23 //
  24 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  25 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  26 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  27 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  28 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  29 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  30 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  31 //
  32
  33 using System;
  34 using System.Collections;
  35 using System.Text;
  36 using System.Threading;
  37
  38 namespace Mono.Data.Tds.Protocol
  39 {
  40         public class TdsConnectionPoolManager
  41         {
  42                 Hashtable pools = Hashtable.Synchronized (new Hashtable ());
  43                 TdsVersion version;
  44
  45                 public TdsConnectionPoolManager (TdsVersion version)
  46                 {
  47                         this.version = version;
  48                 }
  49
  50                 public TdsConnectionPool GetConnectionPool (string connectionString, TdsConnectionInfo info)
  51                 {
  52                         TdsConnectionPool pool = (TdsConnectionPool) pools [connectionString];
  53                         if (pool == null) {
  54                                 pools [connectionString] = new TdsConnectionPool (this, info);
  55                                 pool = (TdsConnectionPool) pools [connectionString];
  56                         }
  57                         return pool;
  58                 }
  59
  60                 public TdsConnectionPool GetConnectionPool (string connectionString)
  61                 {
  62                         return (TdsConnectionPool) pools [connectionString];
  63                 }
  64
  65                 public virtual Tds CreateConnection (TdsConnectionInfo info)
  66                 {
  67                         //Console.WriteLine ("CreateConnection: TdsVersion:{0}", version);
  68                         switch (version)
  69                         {
  70                                 case TdsVersion.tds42:
  71                                         return new Tds42 (info.DataSource, info.Port, info.PacketSize, info.Timeout);
  72                                 case TdsVersion.tds50:
  73                                         return new Tds50 (info.DataSource, info.Port, info.PacketSize, info.Timeout);
  74                                 case TdsVersion.tds70:
  75                                         return new Tds70 (info.DataSource, info.Port, info.PacketSize, info.Timeout);
  76                                 case TdsVersion.tds80:
  77                                         return new Tds80 (info.DataSource, info.Port, info.PacketSize, info.Timeout);
  78                         }
  79                         throw new NotSupportedException ();
  80                 }
  81
  82                 public IDictionary GetConnectionPool ()
  83                 {
  84                         return pools;
  85                 }
  86         }
  87
  88         public class TdsConnectionInfo
  89         {
  90                 public TdsConnectionInfo (string dataSource, int port, int packetSize, int timeout, int minSize, int maxSize)
  91                 {
  92                         DataSource = dataSource;
  93                         Port = port;
  94                         PacketSize = packetSize;
  95                         Timeout = timeout;
  96                         PoolMinSize = minSize;
  97                         PoolMaxSize = maxSize;
  98                 }
  99
 100                 public string DataSource;
 101                 public int Port;
 102                 public int PacketSize;
 103                 public int Timeout;
 104                 public int PoolMinSize;
 105                 public int PoolMaxSize;
 106
 107                 public override string ToString ()
 108                 {
 109                         StringBuilder sb = new StringBuilder ();
 110                         sb.AppendFormat ("DataSouce: {0}\n", DataSource);
 111                         sb.AppendFormat ("Port: {0}\n", Port);
 112                         sb.AppendFormat ("PacketSize: {0}\n", PacketSize);
 113                         sb.AppendFormat ("Timeout: {0}\n", Timeout);
 114                         sb.AppendFormat ("PoolMinSize: {0}\n", PoolMinSize);
 115                         sb.AppendFormat ("PoolMaxSize: {0}", PoolMaxSize);
 116                         return sb.ToString ();
 117                 }
 118         }
 119
 120         public class TdsConnectionPool
 121         {
 122                 TdsConnectionInfo info;
 123                 bool no_pooling;
 124                 TdsConnectionPoolManager manager;
 125                 Queue available;
 126                 ArrayList conns;
 127
 128                 public TdsConnectionPool (TdsConnectionPoolManager manager, TdsConnectionInfo info)
 129                 {
 130                         this.info = info;
 131                         this.manager = manager;
 132                         conns = new ArrayList (info.PoolMaxSize);
 133                         available = new Queue (info.PoolMaxSize);
 134                         InitializePool ();
 135                 }
 136
 137                 void InitializePool ()
 138                 {
 139                         /* conns.Count might not be 0 when we are resetting the connection pool */
 140                         for (int i = conns.Count; i < info.PoolMinSize; i++) {
 141                                 try {
 142                                         Tds t = manager.CreateConnection (info);
 143                                         conns.Add (t);
 144                                         available.Enqueue (t);
 145                                 } catch {
 146                                         // Ignore. GetConnection will throw again.
 147                                 }
 148                         }
 149                 }
 150
 151                 public bool Pooling {
 152                         get { return !no_pooling; }
 153                         set { no_pooling = !value; }
 154                 }
 155
 156                 #region Methods
 157
 158                 int in_progress;
 159                 public Tds GetConnection ()
 160                 {
 161                         if (no_pooling)
 162                                 return manager.CreateConnection (info);
 163
 164                         Tds result = null;
 165                         bool create_new;
 166                         int retries = info.PoolMaxSize * 2;
 167 retry:
 168                         while (result == null) {
 169                                 create_new = false;
 170                                 lock (available) {
 171                                         if (available.Count > 0) {
 172                                                 result = (Tds) available.Dequeue ();
 173                                                 break; // .. and do the reset out of the loop
 174                                         }
 175                                         Monitor.Enter (conns);
 176                                         try {
 177                                                 if (conns.Count >= info.PoolMaxSize - in_progress) {
 178                                                         Monitor.Exit (conns);
 179                                                         bool got_lock = Monitor.Wait (available, info.Timeout * 1000);
 180                                                         if (!got_lock) {
 181                                                                 throw new InvalidOperationException (
 182                                                                         "Timeout expired. The timeout period elapsed before a " +
 183                                                                         "connection could be obtained. A possible explanation " +
 184                                                                         "is that all the connections in the pool are in use, " +
 185                                                                         "and the maximum pool size is reached.");
 186                                                         } else if (available.Count > 0) {
 187                                                                 result = (Tds) available.Dequeue ();
 188                                                                 break; // .. and do the reset out of the loop
 189                                                         }
 190                                                         continue;
 191                                                 } else {
 192                                                         create_new = true;
 193                                                         in_progress++;
 194                                                 }
 195                                         } finally {
 196                                                 Monitor.Exit (conns); // Exiting if not owned is ok < 2.x
 197                                         }
 198                                 }
 199                                 if (create_new) {
 200                                         try {
 201                                                 result = manager.CreateConnection (info);
 202                                                 lock (conns)
 203                                                         conns.Add (result);
 204                                                 return result;
 205                                         } finally {
 206                                                 lock (available)
 207                                                         in_progress--;
 208                                         }
 209                                 }
 210                         }
 211
 212                         bool remove_cnc = true;
 213                         Exception exc = null;
 214                         try {
 215                                 remove_cnc = (!result.IsConnected || !result.Reset ());
 216                         } catch (Exception e) {
 217                                 remove_cnc = true;
 218                                 exc = e;
 219                         }
 220                         if (remove_cnc) {
 221                                 lock (conns)
 222                                         conns.Remove (result);
 223                                 result.Disconnect ();
 224                                 retries--;
 225                                 if (retries == 0)
 226                                         throw exc;
 227                                 goto retry;
 228                         }
 229                         return result;
 230                 }
 231
 232                 public void ReleaseConnection (Tds connection)
 233                 {
 234                         if (connection == null)
 235                                 return;
 236                         if (no_pooling) {
 237                                 connection.Disconnect ();
 238                                 return;
 239                         }
 240
 241                         if (connection.poolStatus == 2) {
 242                                 lock (conns)
 243                                         conns.Remove (connection);
 244                                 connection.Disconnect ();
 245                                 connection = null;
 246                         }
 247                         lock (available) {
 248                                 if (connection != null) // connection is still open
 249                                         available.Enqueue (connection);
 250                                 // We pulse even if we don't queue, because null means that there's a slot
 251                                 // available in 'conns'
 252                                 Monitor.Pulse (available);
 253                         }
 254                 }
 255
 256 #if NET_2_0
 257                 public void ResetConnectionPool ()
 258                 {
 259                         lock (available) {
 260                                 lock (conns) {
 261                                         Tds tds;
 262                                         int i;
 263                                         for (i = conns.Count - 1; i >= 0; i--) {
 264                                                 tds = (Tds) conns [i];
 265                                                 tds.poolStatus = 2; // 2 -> disconnect me upon release
 266                                         }
 267                                         for (i = available.Count - 1; i >= 0; i--) {
 268                                                 tds = (Tds) available.Dequeue ();
 269                                                 tds.Disconnect ();
 270                                                 conns.Remove (tds);
 271                                         }
 272                                         available.Clear ();
 273                                         InitializePool ();
 274                                 }
 275                                 Monitor.PulseAll (available);
 276                         }
 277                 }
 278 #endif
 279                 #endregion // Methods
 280         }
 281 }
 282