Module com.aoapps.hodgepodge

Package com.aoapps.hodgepodge.io

Class AOPool<C extends AutoCloseable,Ex extends Throwable,I extends Throwable>

java.lang.Object

java.lang.Thread

com.aoapps.hodgepodge.io.AOPool<C,Ex,I>

Type Parameters:

Ex - An arbitrary exception type that may be thrown

All Implemented Interfaces:

Runnable

public abstract class AOPool<C extends AutoCloseable,Ex extends Throwable,I extends Throwable>
extends Thread

Reusable generic connection pooling with dynamic flaming tiger feature.

Two lists of connections are maintained. The first is the list of connections that are ready unused, and the second is the list of connections that are currently checked-out. By using this strategy, an available connection can be found without searching the entire list.

In addition to the global lists, a ThreadLocal list of connections checked-out by the current thread is maintained. When getting a new connection, this is used to check against maxConnections instead of checking the global lists.

Idea: Add some sort of thread-connection affinity, where the same connection slot will be used by the same thread when it is available. This should help cache locality.

Idea: Automatically connect ahead of time in the background. This could hide connection latency on first-use.

Author:

AO Industries, Inc.

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Thread

Thread.State, Thread.UncaughtExceptionHandler

Field Summary

Fields

Modifier and Type	Field	Description
static final int	DEFAULT_CONNECT_TIMEOUT
static final int	DEFAULT_DELAY_TIME
static final long	DEFAULT_MAX_CONNECTION_AGE
static final int	DEFAULT_MAX_IDLE_TIME
static final int	DEFAULT_SOCKET_SO_LINGER
protected final Logger	logger	All warnings are sent here if available, otherwise will be written to System.err.
static final long	UNLIMITED_MAX_CONNECTION_AGE

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	AOPool(int delayTime, int maxIdleTime, String name, int poolSize, long maxConnectionAge, Logger logger)
protected	AOPool(String name, int poolSize, long maxConnectionAge, Logger logger)

Method Summary

Modifier and Type	Method	Description
final void	close()	Shuts down the pool, exceptions during close will be logged as a warning and not thrown.
protected abstract void	close(C conn)	Closes the underlying connection.
final int	getConcurrency()	Gets the number of connections that are currently busy.
C	getConnection()	Gets either an available connection or creates a new connection, warning when a connection is already used by this thread.
C	getConnection(int maxConnections)	Gets either an available connection or creates a new connection.
final int	getConnectionCount()	Gets the number of connections currently connected.
protected abstract C	getConnectionObject()	Creates a new connection.
final long	getConnects()	Gets the total number of connects for the entire pool.
final Logger	getLogger()
final int	getMaxConcurrency()	Gets the maximum number of connections that have been busy at once.
final long	getMaxConnectionAge()	Gets the maximum age for connections.
final int	getPoolSize()	Gets the maximum number of connections the pool will create at once.
final long	getTotalTime()
final long	getTransactionCount()
protected abstract boolean	isClosed(C conn)	Determine if the underlying connection is closed.
protected void	logConnection(C conn)	Perform any connection logging before resetConnection(java.lang.AutoCloseable) and/or close(java.lang.AutoCloseable).
protected abstract Ex	newException(String message, Throwable cause)
protected abstract I	newInterruptedException(String message, Throwable cause)	Throws an exception when interrupted, must either throw InterruptedException or re-interrupt the current thread.
protected void	printConnectionStats(Appendable out, boolean isXhtml)	Prints additional connection pool details.
final void	printStatisticsHtml(Appendable out, boolean isXhtml)	Prints complete statistics about connection pool use.
final void	printStatisticsHTML(Appendable out)	Deprecated. Please specify if is HTML or XHTML
final void	printStatisticsHTML(Appendable out, boolean isXhtml)	Deprecated. Please use printStatisticsHtml(java.lang.Appendable, boolean) instead.
protected void	release(C connection)	Releases the database Connection to the Connection pool.
final void	releaseConnection(C connection)	Deprecated. Please release to the pool by closing the connection, preferably via try-with-resources.
protected abstract void	resetConnection(C conn)	Resets the given connection for release back to the pool.
final void	run()	The RefreshConnection thread polls every connection in the connection pool.

Methods inherited from class java.lang.Thread

activeCount, checkAccess, clone, countStackFrames, currentThread, dumpStack, enumerate, getAllStackTraces, getContextClassLoader, getDefaultUncaughtExceptionHandler, getId, getName, getPriority, getStackTrace, getState, getThreadGroup, getUncaughtExceptionHandler, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, onSpinWait, resume, setContextClassLoader, setDaemon, setDefaultUncaughtExceptionHandler, setName, setPriority, setUncaughtExceptionHandler, sleep, sleep, start, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Details

DEFAULT_DELAY_TIME

public static final int DEFAULT_DELAY_TIME

See Also:

• Constant Field Values

DEFAULT_MAX_IDLE_TIME

public static final int DEFAULT_MAX_IDLE_TIME

See Also:

• Constant Field Values

UNLIMITED_MAX_CONNECTION_AGE

public static final long UNLIMITED_MAX_CONNECTION_AGE

See Also:

• Constant Field Values

DEFAULT_MAX_CONNECTION_AGE

public static final long DEFAULT_MAX_CONNECTION_AGE

See Also:

• Constant Field Values

DEFAULT_CONNECT_TIMEOUT

public static final int DEFAULT_CONNECT_TIMEOUT

See Also:

• Constant Field Values

DEFAULT_SOCKET_SO_LINGER

public static final int DEFAULT_SOCKET_SO_LINGER

See Also:

• Constant Field Values

logger

protected final Logger logger

All warnings are sent here if available, otherwise will be written to System.err.

Constructor Details

AOPool

protected AOPool(String name,
 int poolSize,
 long maxConnectionAge,
 Logger logger)

AOPool

protected AOPool(int delayTime,
 int maxIdleTime,
 String name,
 int poolSize,
 long maxConnectionAge,
 Logger logger)

Method Details

close

protected abstract void close(C conn)
                       throws Ex

Closes the underlying connection. The connection may or may not already have been reset. The connection may or may not already be closed.

Please note, this is distinct from the implementation of AutoCloseable for use in try-with-resources.

Throws:

Ex

close

public final void close()

Shuts down the pool, exceptions during close will be logged as a warning and not thrown.

getConcurrency

public final int getConcurrency()

Gets the number of connections that are currently busy.

getConnectionCount

public final int getConnectionCount()

Gets the number of connections currently connected.

getConnection

public C getConnection()
                throws I,
Ex

Gets either an available connection or creates a new connection, warning when a connection is already used by this thread.

If all the connections in the pool are busy and the pool is at capacity, waits until a connection becomes available.

Returns:

Either a reused or new connection

Throws:

I - when interrupted

Ex - when an error occurs, or when a thread attempts to allocate more than half the pool

See Also:

• getConnection(int)
• AutoCloseable.close()

getConnection

public C getConnection(int maxConnections)
                throws I,
Ex

Gets either an available connection or creates a new connection.

If all the connections in the pool are busy and the pool is at capacity, waits until a connection becomes available.

Parameters:

maxConnections - The maximum number of connections expected to be used by the current thread. This should normally be one to avoid potential deadlock.

The connection will continue to be considered used by the allocating thread until released (via AutoCloseable.close(), even if the connection is shared by another thread.

Returns:

Either a reused or new connection

Throws:

I - when interrupted

Ex - when an error occurs, or when a thread attempts to allocate more than half the pool

See Also:

• getConnection()
• AutoCloseable.close()

getConnectionObject

protected abstract C getConnectionObject()
                                  throws I,
Ex

Creates a new connection.

The returned connection must call release(java.lang.AutoCloseable) on AutoCloseable.close(). This is to support use via try-with-resources, and is distinct from isClosed(java.lang.AutoCloseable) and close(java.lang.AutoCloseable), which must both work with the underlying connection.

Throws:

I - when interrupted

Ex - when error

getConnects

public final long getConnects()

Gets the total number of connects for the entire pool.

getMaxConnectionAge

public final long getMaxConnectionAge()

Gets the maximum age for connections.

getMaxConcurrency

public final int getMaxConcurrency()

Gets the maximum number of connections that have been busy at once.

getPoolSize

public final int getPoolSize()

Gets the maximum number of connections the pool will create at once.

getTotalTime

public final long getTotalTime()

getTransactionCount

public final long getTransactionCount()

isClosed

protected abstract boolean isClosed(C conn)
                             throws Ex

Determine if the underlying connection is closed.

Please note, this is distinct from the implementation of AutoCloseable for use in try-with-resources.

Throws:

Ex

printConnectionStats

protected void printConnectionStats(Appendable out,
 boolean isXhtml)
                             throws IOException

Prints additional connection pool details. Must have opened the <tbody>.

Throws:

IOException

printStatisticsHtml

public final void printStatisticsHtml(Appendable out,
 boolean isXhtml)
                               throws IOException,
Ex

Prints complete statistics about connection pool use.

Throws:

IOException

Ex

printStatisticsHTML

@Deprecated
public final void printStatisticsHTML(Appendable out,
 boolean isXhtml)
                               throws IOException,
Ex

Deprecated.

Please use printStatisticsHtml(java.lang.Appendable, boolean) instead.

Prints complete statistics about connection pool use.

Throws:

IOException

Ex

printStatisticsHTML

@Deprecated
public final void printStatisticsHTML(Appendable out)
                               throws IOException,
Ex

Deprecated.

Please specify if is HTML or XHTML

Prints complete statistics about connection pool use in XHTML.

Throws:

IOException

Ex

releaseConnection

@Deprecated
public final void releaseConnection(C connection)
                             throws Ex

Deprecated.

Please release to the pool by closing the connection, preferably via try-with-resources.

Throws:

Ex

See Also:

• AutoCloseable.close()

release

protected void release(C connection)
                throws Ex

Releases the database Connection to the Connection pool.

It is safe to call this method more than once, but only the first call will have any affect.

If the connection is not from this pool, no action is taken.

The connection will be reset and/or closed.

Throws:

Ex

See Also:

• isClosed(java.lang.AutoCloseable)
• logConnection(java.lang.AutoCloseable)
• resetConnection(java.lang.AutoCloseable)
• close(java.lang.AutoCloseable)
• release(com.aoapps.hodgepodge.io.AOPool.PooledConnection)

logConnection

protected void logConnection(C conn)
                      throws Ex

Perform any connection logging before resetConnection(java.lang.AutoCloseable) and/or close(java.lang.AutoCloseable). This is only called on connections that are not closed.

Throws:

Ex

resetConnection

protected abstract void resetConnection(C conn)
                                 throws I,
Ex

Resets the given connection for release back to the pool.

Throws:

I

Ex

run

public final void run()

The RefreshConnection thread polls every connection in the connection pool. If it detects a connection is idle for more than the pre-defined MAX_IDLE_TIME, it closes the connection. It will stop when the pool is flagged as closed.

Specified by:

run in interface Runnable

Overrides:

run in class Thread

newException

protected abstract Ex newException(String message,
 Throwable cause)

newInterruptedException

protected abstract I newInterruptedException(String message,
 Throwable cause)

Throws an exception when interrupted, must either throw InterruptedException or re-interrupt the current thread.

getLogger

public final Logger getLogger()