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Converted IteratingCallback to use SpinLock

This commit is contained in:
Greg Wilkins 2015-03-11 15:37:25 +11:00
parent 5456de2160
commit 870e0ab0b3
1 changed files with 119 additions and 153 deletions
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272
jetty-util/src/main/java/org/eclipse/jetty/util/IteratingCallback.java
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@ -21,6 +21,8 @@ package org.eclipse.jetty.util;
import java.nio.channels.ClosedChannelException;
import java.util.concurrent.atomic.AtomicReference;
import org.eclipse.jetty.util.thread.SpinLock;
/**
* This specialized callback implements a pattern that allows
* a large job to be broken into smaller tasks using iteration
@ -92,12 +94,7 @@ public abstract class IteratingCallback implements Callback
/**
* This callback has been closed and cannot be reset.
*/
CLOSED,
/**
* State is locked while leaving processing state to check the iterate boolean
*/
LOCKED
CLOSED
}
/**
@ -125,18 +122,19 @@ public abstract class IteratingCallback implements Callback
SUCCEEDED
}
private final AtomicReference<State> _state;
private SpinLock _lock = new SpinLock();
private State _state;
private boolean _iterate;
protected IteratingCallback()
{
_state = new AtomicReference<>(State.IDLE);
_state = State.IDLE;
}
protected IteratingCallback(boolean needReset)
{
_state = new AtomicReference<>(needReset ? State.SUCCEEDED : State.IDLE);
_state = needReset ? State.SUCCEEDED : State.IDLE;
}
/**
@ -183,43 +181,40 @@ public abstract class IteratingCallback implements Callback
*/
public void iterate()
{
boolean process=false;
loop: while (true)
{
State state=_state.get();
switch (state)
try (SpinLock.Lock lock = _lock.lock())
{
case PENDING:
case CALLED:
// process will be called when callback is handled
break loop;
case IDLE:
if (!_state.compareAndSet(state,State.PROCESSING))
continue;
processing();
break loop;
case PROCESSING:
if (!_state.compareAndSet(state,State.LOCKED))
continue;
// Tell the thread that is processing that it must iterate again
_iterate=true;
_state.set(State.PROCESSING);
break loop;
case LOCKED:
Thread.yield();
continue loop;
switch (_state)
{
case PENDING:
case CALLED:
// process will be called when callback is handled
break loop;
case FAILED:
case SUCCEEDED:
break loop;
case IDLE:
_state=State.PROCESSING;
process=true;
break loop;
case CLOSED:
default:
throw new IllegalStateException("state="+state);
case PROCESSING:
_iterate=true;
break loop;
case FAILED:
case SUCCEEDED:
break loop;
case CLOSED:
default:
throw new IllegalStateException("state="+_state);
}
}
}
if (process)
processing();
}
private void processing()
@ -227,6 +222,8 @@ public abstract class IteratingCallback implements Callback
// This should only ever be called when in processing state, however a failed or close call
// may happen concurrently, so state is not assumed.
boolean on_complete_success=false;
// While we are processing
processing: while (true)
{
@ -242,13 +239,10 @@ public abstract class IteratingCallback implements Callback
break processing;
}
// loop until we have successfully acted on the action we have just received
acting: while(true)
// acted on the action we have just received
try(SpinLock.Lock lock = _lock.lock())
{
// action handling needs to know the state
State state=_state.get();
switch (state)
switch (_state)
{
case PROCESSING:
{
@ -256,67 +250,56 @@ public abstract class IteratingCallback implements Callback
{
case IDLE:
{
// lock the state
if (!_state.compareAndSet(state,State.LOCKED))
continue acting;
// Has iterate been called while we were processing?
if (_iterate)
{
// yes, so skip idle and keep processing
_iterate=false;
_state.set(State.PROCESSING);
_state=State.PROCESSING;
continue processing;
}
// No, so we can go idle
_state.set(State.IDLE);
_state=State.IDLE;
break processing;
}
case SCHEDULED:
{
if (!_state.compareAndSet(state, State.PENDING))
continue acting;
{
// we won the race against the callback, so the callback has to process and we can break processing
_state=State.PENDING;
break processing;
}
case SUCCEEDED:
{
if (!_state.compareAndSet(state, State.LOCKED))
continue acting;
// we lost the race against the callback,
_iterate=false;
_state.set(State.SUCCEEDED);
onCompleteSuccess();
_state=State.SUCCEEDED;
on_complete_success=true;
break processing;
}
default:
throw new IllegalStateException("state="+state+" action="+action);
throw new IllegalStateException("state="+_state+" action="+action);
}
}
case CALLED:
{
switch (action)
{
case SCHEDULED:
{
if (!_state.compareAndSet(state, State.PROCESSING))
continue acting;
{
// we lost the race, so we have to keep processing
_state=State.PROCESSING;
continue processing;
}
default:
throw new IllegalStateException("state="+state+" action="+action);
throw new IllegalStateException("state="+_state+" action="+action);
}
}
case LOCKED:
Thread.yield();
continue acting;
case SUCCEEDED:
case FAILED:
@ -326,12 +309,15 @@ public abstract class IteratingCallback implements Callback
case IDLE:
case PENDING:
default:
throw new IllegalStateException("state="+state+" action="+action);
throw new IllegalStateException("state="+_state+" action="+action);
}
}
}
if (on_complete_success)
onCompleteSuccess();
}
/**
* Invoked when the sub task succeeds.
* Subclasses that override this method must always remember to call
@ -340,41 +326,36 @@ public abstract class IteratingCallback implements Callback
@Override
public void succeeded()
{
loop: while (true)
boolean process=false;
try(SpinLock.Lock lock = _lock.lock())
{
State state = _state.get();
switch (state)
switch (_state)
{
case PROCESSING:
{
if (!_state.compareAndSet(state, State.CALLED))
continue loop;
break loop;
_state=State.CALLED;
break;
}
case PENDING:
{
if (!_state.compareAndSet(state, State.PROCESSING))
continue loop;
processing();
break loop;
_state=State.PROCESSING;
process=true;
break;
}
case CLOSED:
case FAILED:
{
// Too late!
break loop;
}
case LOCKED:
{
Thread.yield();
continue loop;
}
break;
}
default:
{
throw new IllegalStateException("state="+state);
throw new IllegalStateException("state="+_state);
}
}
}
if (process)
processing();
}
/**
@ -385,73 +366,59 @@ public abstract class IteratingCallback implements Callback
@Override
public void failed(Throwable x)
{
loop: while (true)
boolean failure=false;
try(SpinLock.Lock lock = _lock.lock())
{
State state = _state.get();
switch (state)
switch (_state)
{
case SUCCEEDED:
case FAILED:
case IDLE:
case CLOSED:
case CALLED:
{
// too late!.
break loop;
}
case LOCKED:
{
Thread.yield();
continue loop;
}
break;
case PENDING:
case PROCESSING:
{
if (!_state.compareAndSet(state, State.FAILED))
continue loop;
onCompleteFailure(x);
break loop;
_state=State.FAILED;
failure=true;
break;
}
default:
throw new IllegalStateException("state="+state);
throw new IllegalStateException("state="+_state);
}
}
if (failure)
onCompleteFailure(x);
}
public void close()
{
loop: while (true)
boolean failure=false;
try(SpinLock.Lock lock = _lock.lock())
{
State state = _state.get();
switch (state)
switch (_state)
{
case IDLE:
case SUCCEEDED:
case FAILED:
{
if (!_state.compareAndSet(state, State.CLOSED))
continue loop;
break loop;
}
case PROCESSING:
_state=State.CLOSED;
break;
case CLOSED:
{
break loop;
}
case LOCKED:
{
Thread.yield();
continue loop;
}
break;
default:
{
if (!_state.compareAndSet(state, State.CLOSED))
continue loop;
onCompleteFailure(new ClosedChannelException());
break loop;
}
_state=State.CLOSED;
failure=true;
}
}
if(failure)
onCompleteFailure(new ClosedChannelException());
}
/*
@ -460,12 +427,18 @@ public abstract class IteratingCallback implements Callback
*/
boolean isIdle()
{
return _state.get() == State.IDLE;
try(SpinLock.Lock lock = _lock.lock())
{
return _state == State.IDLE;
}
}
public boolean isClosed()
{
return _state.get() == State.CLOSED;
try(SpinLock.Lock lock = _lock.lock())
{
return _state == State.CLOSED;
}
}
/**
@ -473,7 +446,10 @@ public abstract class IteratingCallback implements Callback
*/
public boolean isFailed()
{
return _state.get() == State.FAILED;
try(SpinLock.Lock lock = _lock.lock())
{
return _state == State.FAILED;
}
}
/**
@ -481,7 +457,10 @@ public abstract class IteratingCallback implements Callback
*/
public boolean isSucceeded()
{
return _state.get() == State.SUCCEEDED;
try(SpinLock.Lock lock = _lock.lock())
{
return _state == State.SUCCEEDED;
}
}
/**
@ -494,31 +473,18 @@ public abstract class IteratingCallback implements Callback
*/
public boolean reset()
{
while (true)
try(SpinLock.Lock lock = _lock.lock())
{
State state=_state.get();
switch(state)
switch(_state)
{
case IDLE:
return true;
case SUCCEEDED:
if (!_state.compareAndSet(state, State.LOCKED))
continue;
_iterate=false;
_state.set(State.IDLE);
return true;
case FAILED:
if (!_state.compareAndSet(state, State.LOCKED))
continue;
_iterate=false;
_state.set(State.IDLE);
return true;
case LOCKED:
Thread.yield();
continue;
case SUCCEEDED:
case FAILED:
_iterate=false;
_state=State.IDLE;
return true;
default:
return false;