com.tangosol.util
Class AtomicCounter

java.lang.Object
  com.tangosol.util.Base
      com.tangosol.util.AtomicCounter

public abstract class AtomicCounter
extends Base

Abstract base class for AtomicCounters. The AtomicCounter allows for atomic updates to a "long" value where possible without requiring synchronization. The underlying AtomicCounter impelementation will be choosen based at runtime.

Since:

Coherence 3.2

Author:

mf 2006.05.09

Field Summary

protected static Class

s_clzImplementation The counter implementation which will be used.

Constructor Summary

AtomicCounter()

Method Summary

protected abstract long	adjust(long c) Adjust the value of the counter by the specified amount, and return the new value.
long	decrement() Decrement the value, and return the new value.
long	decrement(long c) Decrement the value by c, and return the new value.
abstract long	getCount() Return the current value of the counter.
long	increment() Incremenet the value, and return the new value.
long	increment(long c) Incremenet the value by c, and return the new value.
static AtomicCounter	newAtomicCounter() Instantiate and return a new AtomicCounter.
static AtomicCounter	newAtomicCounter(long l) Instantiate and return a new AtomicCounter initialized to a particular value.
protected abstract long	postAdjust(long c) Adjust the value of the counter by the specified amount, and return the old value.
long	postDecrement() Decrement the value, and return the original value.
long	postDecrement(long c) Decrement the value by c, and return the original value.
long	postIncrement() Incremenet the value, and return the original value.
long	postIncrement(long c) Incremenet the value by c, and return the original value.
abstract long	setCount(long cNew) Update the current value, and return the previous value.
abstract boolean	setCount(long cAssume, long cNew) Update the current value, only if it is equal to the assumed value.
String	toString() Return the count as a string.

Field Detail

s_clzImplementation

protected static Class s_clzImplementation

The counter implementation which will be used.

Constructor Detail

AtomicCounter

public AtomicCounter()

Method Detail

increment

public long increment()

Incremenet the value, and return the new value.

Returns:

the new value

increment

public long increment(long c)

Incremenet the value by c, and return the new value.

Parameters:

c - the amount to increment the counter by

Returns:

the new value

postIncrement

public long postIncrement()

Incremenet the value, and return the original value.

Returns:

the original value

postIncrement

public long postIncrement(long c)

Incremenet the value by c, and return the original value.

Parameters:

c - the amount to increment the counter by

Returns:

the original value

decrement

public long decrement()

Decrement the value, and return the new value.

Returns:

the new value

decrement

public long decrement(long c)

Decrement the value by c, and return the new value.

Parameters:

c - the amount to decrement the counter by

Returns:

the new value

postDecrement

public long postDecrement()

Decrement the value, and return the original value.

Returns:

the original value

postDecrement

public long postDecrement(long c)

Decrement the value by c, and return the original value.

Parameters:

c - the amount to decrement the counter by

Returns:

the original value

getCount

public abstract long getCount()

Return the current value of the counter.

Returns:

the current value

setCount

public abstract boolean setCount(long cAssume,
                                 long cNew)

Update the current value, only if it is equal to the assumed value.

Parameters:

cAssume - the assumed old value

cNew - the new value

Returns:

true if the value was updated, false otherwise

setCount

public abstract long setCount(long cNew)

Update the current value, and return the previous value.

Parameters:

cNew - the new value

Returns:

the previous value just before the update went through

toString

public String toString()

Return the count as a string.

Returns:

a string represenation of the count

adjust

protected abstract long adjust(long c)

Adjust the value of the counter by the specified amount, and return the new value.

Parameters:

c - the amount to adjust the counter by

Returns:

the new value, after the adjustment has been made

postAdjust

protected abstract long postAdjust(long c)

Adjust the value of the counter by the specified amount, and return the old value.

Parameters:

c - the amount to adjust the counter by

Returns:

the old value, prior to the adjustment having been made

newAtomicCounter

public static AtomicCounter newAtomicCounter()

Instantiate and return a new AtomicCounter. The underlying implementation be choosen based on the JVM.

Returns:

a new AtomicCounter with a count of zero

newAtomicCounter

public static AtomicCounter newAtomicCounter(long l)

Instantiate and return a new AtomicCounter initialized to a particular value.

Parameters:

l - the initial counter value

Returns:

a new AtomicCounter with the specified counter value