| java.lang.Object
 java.util.concurrent.Exchanger
| Exchanger | | public class Exchanger (Code) | | A synchronization point at which two threads can exchange objects.
Each thread presents some object on entry to the
Exchanger.exchangeexchange method, and receives the object presented by the other
thread on return.
Sample Usage:
Here are the highlights of a class that uses an Exchanger to
swap buffers between threads so that the thread filling the
buffer gets a freshly
emptied one when it needs it, handing off the filled one to
the thread emptying the buffer.
class FillAndEmpty {
Exchanger<DataBuffer> exchanger = new Exchanger();
DataBuffer initialEmptyBuffer = ... a made-up type
DataBuffer initialFullBuffer = ...
class FillingLoop implements Runnable {
public void run() {
DataBuffer currentBuffer = initialEmptyBuffer;
try {
while (currentBuffer != null) {
addToBuffer(currentBuffer);
if (currentBuffer.full())
currentBuffer = exchanger.exchange(currentBuffer);
}
} catch (InterruptedException ex) { ... handle ... }
}
}
class EmptyingLoop implements Runnable {
public void run() {
DataBuffer currentBuffer = initialFullBuffer;
try {
while (currentBuffer != null) {
takeFromBuffer(currentBuffer);
if (currentBuffer.empty())
currentBuffer = exchanger.exchange(currentBuffer);
}
} catch (InterruptedException ex) { ... handle ...}
}
}
void start() {
new Thread(new FillingLoop()).start();
new Thread(new EmptyingLoop()).start();
}
}
since:
1.5
author:
Doug Lea<
Parameters:
V - > The type of objects that may be exchanged |
| Constructor Summary | |
| public | Exchanger()
Create a new Exchanger. |
| Method Summary | |
| public V | exchange(V x)
Waits for another thread to arrive at this exchange point (unless
it is
Thread.interrupt interrupted ),
and then transfers the given object to it, receiving its object
in return.
If another thread is already waiting at the exchange point then
it is resumed for thread scheduling purposes and receives the object
passed in by the current thread. | | public V | exchange(V x, long timeout, TimeUnit unit)
Waits for another thread to arrive at this exchange point (unless
it is
Thread.interrupt interrupted , or the specified waiting
time elapses),
and then transfers the given object to it, receiving its object
in return.
If another thread is already waiting at the exchange point then
it is resumed for thread scheduling purposes and receives the object
passed in by the current thread. |
| Exchanger | | public Exchanger()(Code) | | Create a new Exchanger.
|
| exchange | | public V exchange(V x) throws InterruptedException(Code) | | Waits for another thread to arrive at this exchange point (unless
it is
Thread.interrupt interrupted ),
and then transfers the given object to it, receiving its object
in return.
If another thread is already waiting at the exchange point then
it is resumed for thread scheduling purposes and receives the object
passed in by the current thread. The current thread returns immediately,
receiving the object passed to the exchange by that other thread.
If no other thread is already waiting at the exchange then the
current thread is disabled for thread scheduling purposes and lies
dormant until one of two things happens:
- Some other thread enters the exchange; or
- Some other thread
Thread.interrupt interrupts the current
thread.
If the current thread:
- has its interrupted status set on entry to this method; or
- is
Thread.interrupt interrupted while waiting
for the exchange,
then
InterruptedException is thrown and the current thread's
interrupted status is cleared.
Parameters:
x - the object to exchange the object provided by the other thread.
throws:
InterruptedException - if current thread was interrupted while waiting |
| exchange | | public V exchange(V x, long timeout, TimeUnit unit) throws InterruptedException, TimeoutException(Code) | | Waits for another thread to arrive at this exchange point (unless
it is
Thread.interrupt interrupted , or the specified waiting
time elapses),
and then transfers the given object to it, receiving its object
in return.
If another thread is already waiting at the exchange point then
it is resumed for thread scheduling purposes and receives the object
passed in by the current thread. The current thread returns immediately,
receiving the object passed to the exchange by that other thread.
If no other thread is already waiting at the exchange then the
current thread is disabled for thread scheduling purposes and lies
dormant until one of three things happens:
- Some other thread enters the exchange; or
- Some other thread
Thread.interrupt interrupts the current
thread; or
- The specified waiting time elapses.
If the current thread:
- has its interrupted status set on entry to this method; or
- is
Thread.interrupt interrupted while waiting
for the exchange,
then
InterruptedException is thrown and the current thread's
interrupted status is cleared.
If the specified waiting time elapses then
TimeoutException is thrown.
If the time is
less than or equal to zero, the method will not wait at all.
Parameters:
x - the object to exchange
Parameters:
timeout - the maximum time to wait
Parameters:
unit - the time unit of the timeout argument. the object provided by the other thread.
throws:
InterruptedException - if current thread was interruptedwhile waiting
throws:
TimeoutException - if the specified waiting time elapses beforeanother thread enters the exchange. |
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