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クラス org.objectweb.cjdbc.controller.connection.RandomWaitPoolConnectionManager

org.objectweb.cjdbc.controller.connection.RandomWaitPoolConnectionManagerに対する継承グラフ

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説明

This connection manager waits when the pool is empty. Requests are stacked using the Java wait/notify mechanism. Therefore the FIFO order is not guaranteed and the first request to get the freed connection is the thread that gets elected by the scheduler.

作者:
Emmanuel Cecchet

Nicolas Modrzyk

バージョン:
1.0

RandomWaitPoolConnectionManager.java の 45 行で定義されています。

Public メソッド

 RandomWaitPoolConnectionManager (String backendUrl, String backendName, String login, String password, String driverPath, String driverClassName, int poolSize, int timeout)
int getTimeout ()
Connection getConnection () throws UnreachableBackendException
void releaseConnection (Connection c)
void deleteConnection (Connection c)
String getXmlImpl ()

Protected メソッド

Object clone () throws CloneNotSupportedException

Private 変数

int timeout

コンストラクタとデストラクタ

org.objectweb.cjdbc.controller.connection.RandomWaitPoolConnectionManager.RandomWaitPoolConnectionManager (  String  backendUrl,
String  backendName,
String  login,
String  password,
String  driverPath,
String  driverClassName,
int  poolSize,
int  timeout
) 
 

Creates a new RandomWaitPoolConnectionManager instance.

引数:
backendUrl URL of the DatabaseBackend owning this connection manager
backendName name of the DatabaseBackend owning this connection manager
login backend connection login to be used by this connection manager
password backend connection password to be used by this connection manager
driverPath path for driver
driverClassName class name for driver
poolSize size of the connection pool
timeout time to wait for a connection in seconds (0 means wait forever)
RandomWaitPoolConnectionManager.java の 68 行で定義されています。

参照元 org.objectweb.cjdbc.controller.connection.RandomWaitPoolConnectionManager.clone().

00071   {
00072     super(backendUrl, backendName, login, password, driverPath,
00073         driverClassName, poolSize);
00074     this.timeout = timeout * 1000;
00075   }

メソッド

Object org.objectweb.cjdbc.controller.connection.RandomWaitPoolConnectionManager.clone (   )  throws CloneNotSupportedException [protected, virtual]
 

参照:
java.lang.Object#clone()

org.objectweb.cjdbc.controller.connection.AbstractConnectionManagerを実装しています.

RandomWaitPoolConnectionManager.java の 80 行で定義されています。

参照先 org.objectweb.cjdbc.controller.connection.RandomWaitPoolConnectionManager.RandomWaitPoolConnectionManager(), と org.objectweb.cjdbc.controller.connection.RandomWaitPoolConnectionManager.timeout.

00081   {
00082     return new RandomWaitPoolConnectionManager(backendUrl, backendName, rLogin,
00083         rPassword, driverPath, driverClassName, poolSize,timeout);
00084   }

void org.objectweb.cjdbc.controller.connection.RandomWaitPoolConnectionManager.deleteConnection (  Connection  c  )  [virtual]
 

参照:
org.objectweb.cjdbc.controller.connection.AbstractPoolConnectionManager.deleteConnection(Connection)

org.objectweb.cjdbc.controller.connection.AbstractConnectionManagerを実装しています.

RandomWaitPoolConnectionManager.java の 242 行で定義されています。

参照先 org.objectweb.cjdbc.common.log.Trace.debug(), org.objectweb.cjdbc.common.log.Trace.error(), org.objectweb.cjdbc.controller.connection.AbstractConnectionManager.getConnectionFromDriver(), と org.objectweb.cjdbc.common.log.Trace.isDebugEnabled().

00243   {
00244     if (!initialized)
00245       return; // We probably have been disabled
00246 
00247     synchronized (freeConnections)
00248     {
00249       if (activeConnections.remove(c))
00250       {
00251         Connection newConnection = getConnectionFromDriver();
00252         if (newConnection == null)
00253         {
00254           if (logger.isDebugEnabled())
00255             logger.error("Bad connection " + c
00256                 + " has been removed but cannot be replaced.");
00257         }
00258         else
00259         {
00260           freeConnections.push(newConnection);
00261           freeConnections.notify();
00262           if (logger.isDebugEnabled())
00263             logger.debug("Bad connection " + c
00264                 + " has been replaced by a new connection.");
00265         }
00266       }
00267       else
00268         logger.error("Failed to release connection " + c
00269             + " (not found in active pool)");
00270     }
00271   }

Connection org.objectweb.cjdbc.controller.connection.RandomWaitPoolConnectionManager.getConnection (   )  throws UnreachableBackendException [virtual]
 

Gets a connection from the pool.

If the pool is empty, this methods blocks until a connection is freed or the timeout expires.

戻り値:
a connection from the pool or null if the timeout has expired.
例外:
UnreachableBackendException if the backend must be disabled
参照:
org.objectweb.cjdbc.controller.connection.AbstractConnectionManager.getConnection()

org.objectweb.cjdbc.controller.connection.AbstractConnectionManagerを実装しています.

RandomWaitPoolConnectionManager.java の 107 行で定義されています。

参照先 org.objectweb.cjdbc.common.log.Trace.error(), org.objectweb.cjdbc.controller.connection.AbstractConnectionManager.getConnectionFromDriver(), org.objectweb.cjdbc.common.log.Trace.info(), org.objectweb.cjdbc.common.log.Trace.isErrorEnabled(), org.objectweb.cjdbc.common.log.Trace.isWarnEnabled(), org.objectweb.cjdbc.controller.connection.RandomWaitPoolConnectionManager.timeout, と org.objectweb.cjdbc.common.log.Trace.warn().

00108   {
00109     if (!initialized)
00110     {
00111       logger
00112           .error("Requesting a connection from a non-initialized connection manager");
00113       return null;
00114     }
00115 
00116     long lTimeout = timeout;
00117     synchronized (freeConnections)
00118     {
00119       // We have to do a while loop() because there is a potential race here.
00120       // When freeConnections is notified in releaseConnection, a new thread
00121       // can
00122       // take the lock on freeConnections before we wake up/reacquire the lock
00123       // on freeConnections. Therefore, we could wake up and have no connection
00124       // to take! We ensure that everything is correct with a while statement
00125       // and recomputing the timeout between 2 wakeup.
00126       while (freeConnections.isEmpty())
00127       {
00128         // Wait
00129         try
00130         {
00131           if (lTimeout > 0)
00132           {
00133             long start = System.currentTimeMillis();
00134             // Convert seconds to milliseconds for wait call
00135             freeConnections.wait(timeout);
00136             long end = System.currentTimeMillis();
00137             lTimeout -= end - start;
00138             if (lTimeout <= 0)
00139             {
00140               if (activeConnections.size() == 0)
00141               { // No connection active and backend unreachable, the backend
00142                 // is probably dead
00143                 logger.error("Backend " + backendName
00144                     + " is no more accessible.");
00145                 throw new UnreachableBackendException();
00146               }
00147               if (logger.isWarnEnabled())
00148                 logger.warn("Timeout expired for connection on backend '"
00149                     + backendName
00150                     + "', consider increasing pool size (current size is "
00151                     + poolSize + ") or timeout (current timeout is "
00152                     + (timeout / 1000) + " seconds)");
00153               return null;
00154             }
00155           }
00156           else
00157             freeConnections.wait();
00158         }
00159         catch (InterruptedException e)
00160         {
00161           logger
00162               .error("Wait on freeConnections interrupted in RandomWaitPoolConnectionManager: "
00163                   + e);
00164           return null;
00165         }
00166       }
00167       // Get the connection
00168       try
00169       {
00170         Connection c = (Connection) freeConnections.pop();
00171         activeConnections.add(c);
00172         return c;
00173       }
00174       catch (EmptyStackException e)
00175       {
00176         int missing = poolSize
00177             - (activeConnections.size() + freeConnections.size());
00178         if (missing > 0)
00179         { // Re-allocate missing connections
00180           logger.info("Trying to reallocate " + missing
00181               + " missing connections.");
00182           Connection connectionToBeReturned = null;
00183           while (missing > 0)
00184           {
00185             Connection c = getConnectionFromDriver();
00186             if (c == null)
00187             {
00188               if (missing == poolSize)
00189               {
00190                 String msg = Translate.get("loadbalancer.backend.unreacheable",
00191                     backendName);
00192                 logger.error(msg);
00193                 throw new UnreachableBackendException(msg);
00194               }
00195               logger.warn("Unable to re-allocate " + missing
00196                   + " missing connections.");
00197               break;
00198             }
00199             else
00200             {
00201               if (connectionToBeReturned == null)
00202                 connectionToBeReturned = c;
00203               else
00204                 freeConnections.add(c);
00205             }
00206             missing--;
00207           }
00208           return connectionToBeReturned;
00209         }
00210         if (logger.isErrorEnabled())
00211           logger.error("Failed to get a connection on backend '" + backendName
00212               + "' whereas an idle connection was expected");
00213         return null;
00214       }
00215     }
00216   }

int org.objectweb.cjdbc.controller.connection.RandomWaitPoolConnectionManager.getTimeout (   ) 
 

Gets the timeout.

戻り値:
a int value.
RandomWaitPoolConnectionManager.java の 91 行で定義されています。

参照先 org.objectweb.cjdbc.controller.connection.RandomWaitPoolConnectionManager.timeout.

00092   {
00093     return timeout;
00094   }

String org.objectweb.cjdbc.controller.connection.RandomWaitPoolConnectionManager.getXmlImpl (   )  [virtual]
 

参照:
org.objectweb.cjdbc.controller.connection.AbstractConnectionManager.getXmlImpl()

org.objectweb.cjdbc.controller.connection.AbstractConnectionManagerを実装しています.

RandomWaitPoolConnectionManager.java の 276 行で定義されています。

参照先 org.objectweb.cjdbc.controller.connection.RandomWaitPoolConnectionManager.timeout.

00277   {
00278     StringBuffer info = new StringBuffer();
00279     info.append("<" + DatabasesXmlTags.ELT_RandomWaitPoolConnectionManager
00280         + " " + DatabasesXmlTags.ATT_poolSize + "=\"" + poolSize + "\" "
00281         + DatabasesXmlTags.ATT_timeout + "=\"" + timeout / 1000 + "\"/>");
00282     return info.toString();
00283   }

void org.objectweb.cjdbc.controller.connection.RandomWaitPoolConnectionManager.releaseConnection (  Connection  c  )  [virtual]
 

参照:
org.objectweb.cjdbc.controller.connection.AbstractPoolConnectionManager.releaseConnection(Connection)

org.objectweb.cjdbc.controller.connection.AbstractConnectionManagerを実装しています.

RandomWaitPoolConnectionManager.java の 221 行で定義されています。

参照先 org.objectweb.cjdbc.common.log.Trace.error().

00222   {
00223     if (!initialized)
00224       return; // We probably have been disabled
00225 
00226     synchronized (freeConnections)
00227     {
00228       if (activeConnections.remove(c))
00229       {
00230         freeConnections.push(c);
00231         freeConnections.notify();
00232       }
00233       else
00234         logger.error("Failed to release connection " + c
00235             + " (not found in active pool)");
00236     }
00237   }

変数

int org.objectweb.cjdbc.controller.connection.RandomWaitPoolConnectionManager.timeout [private]
 

Time to wait for a connection in milliseconds (0 means wait forever). RandomWaitPoolConnectionManager.java の 50 行で定義されています。

参照元 org.objectweb.cjdbc.controller.connection.RandomWaitPoolConnectionManager.clone(), org.objectweb.cjdbc.controller.connection.RandomWaitPoolConnectionManager.getConnection(), org.objectweb.cjdbc.controller.connection.RandomWaitPoolConnectionManager.getTimeout(), と org.objectweb.cjdbc.controller.connection.RandomWaitPoolConnectionManager.getXmlImpl().

このクラスの説明は次のファイルから生成されました:
CJDBCversion1.0.4に対してTue Oct 12 15:16:40 2004に生成されました。 doxygen 1.3.8