com.ericsson.research.trap.utils.impl.SingleCallback Maven / Gradle / Ivy
package com.ericsson.research.trap.utils.impl;
/*
* ##_BEGIN_LICENSE_##
* Transport Abstraction Package (trap)
* ----------
* Copyright (C) 2014 Ericsson AB
* ----------
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* 3. Neither the name of the Ericsson AB nor the names of its contributors
* may be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
* ##_END_LICENSE_##
*/
import com.ericsson.research.trap.utils.Callback;
public class SingleCallback implements Callback
{
private com.ericsson.research.trap.utils.Callback.SingleArgumentCallback callback;
private T value = null;
private boolean called = false;
public SingleCallback callback(T value)
{
SingleArgumentCallback cb;
synchronized (this)
{
if (called)
return this; // Do nothing if we already were called
this.value = value;
called = true;
if (this.callback == null)
{
this.notifyAll();
return this;
}
cb = this.callback;
}
cb.receiveSingleArgumentCallback(value);
return this;
}
public T get() throws InterruptedException
{
// By doing this subtraction, we guard against overflow errors caused by the clock changing (since System.currentTimeMillis() reports absolute time).
return this.get(Long.MAX_VALUE - Integer.MAX_VALUE);
}
public T get(long timeout) throws InterruptedException
{
long start = System.currentTimeMillis();
long elapsed;
synchronized (this)
{
while (!called)
{
elapsed = System.currentTimeMillis() - start;
long remaining = timeout - elapsed;
if (remaining <= 0)
break;
this.wait(remaining);
}
return this.value;
}
}
public void setCallback(com.ericsson.research.trap.utils.Callback.SingleArgumentCallback callback)
{
T val;
SingleArgumentCallback cb;
synchronized (this)
{
this.callback = callback;
if (!called)
return;
// Retrieve the results outside of synchronized to prevent deadlocks.
val = this.value;
cb = callback;
}
cb.receiveSingleArgumentCallback(val);
}
public boolean isDone()
{
return called;
}
}