com.peterphi.std.system.exec.AbstractProcessTracker Maven / Gradle / Ivy
package com.peterphi.std.system.exec;
import com.peterphi.std.io.StreamUtil;
import com.peterphi.std.threading.Deadline;
import com.peterphi.std.threading.Timeout;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Writer;
import java.util.List;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
abstract class AbstractProcessTracker
{
protected final List cmd;
protected final Process process;
protected final boolean combinedOutput;
protected boolean finished = false;
protected int exitCode = Integer.MIN_VALUE;
protected AbstractProcessTracker(final List cmd, final Process p, final boolean combinedOutput)
{
this.cmd = cmd;
this.process = p;
this.combinedOutput = combinedOutput;
}
public Process getProcess()
{
return process;
}
public final void kill()
{
kill(false);
}
public void kill(boolean force)
{
if (force)
process.destroyForcibly();
else
process.destroy();
}
/**
* Determines if the application has completed yet
*
* @return true if the process has terminated, otherwise false
*/
public boolean isFinished()
{
if (finished)
return true;
try
{
final int code = exitCode();
finished(code);
return true;
}
catch (IllegalThreadStateException e)
{
return false;
}
}
/**
* Returns the exit code of the application, assuming it has already terminated. If the process has not yet terminated then
* an
* IllegalStateException will be thrown
*
* @return the exit code of the process
*
* @throws IllegalStateException
* if the process has not yet terminated
*/
public int exitCode() throws IllegalThreadStateException
{
if (finished)
return exitCode;
return process.exitValue();
}
/**
* Wait an indefinite amount of time for the process to exit, expecting the return code to be expected. If the
* output is not expected then a RuntimeException is thrown
*
* @param expected
* the expected return code
*
* @return the exit code of the process
*
* @throws RuntimeException
* if the return code was not what was expected
*/
public int waitForExit(final int expected)
{
return waitForExit(Deadline.MAX_VALUE, expected);
}
/**
* Wait until deadline for the process to exit, expecting the return code to be expected. If the
* output is not expected (or if the operation times out) then a RuntimeException is thrown
* In the event of a timeout the process is not terminated
*
* @param deadline
* @param expected
*
* @return the exit code of the process
*
* @throws RuntimeException
* if a timeout occurrs or if the return code was not what was expected
*/
public int waitForExit(final Deadline deadline, final int expected)
{
final int code = waitForExit(deadline);
if (code == Integer.MIN_VALUE)
throw new RuntimeException("Unexpected timeout while waiting for exit and expecting code " + expected,
new TimeoutException("waitForExit timed out"));
else if (code != expected)
throw new RuntimeException("Unexpected code: wanted " + expected + " but got " + code);
else
return code;
}
/**
* Wait an indefinite amount of time for the process to exit
*
* @return the exit code of the process
*/
public int waitForExit()
{
return waitForExit(Deadline.MAX_VALUE);
}
/**
* Waits for the process to exit; this method blocks until the process has completed (at which point it returns the process
* exit code) or until deadline has elapsed, at which point it returns Integer.MIN_VALUE
*
* @param deadline
*
* @return the exit code of the process
*/
public int waitForExit(final Deadline deadline)
{
final int intervalMax = 4500; // the maximum time between polls is 4.5 seconds
int interval = 5; // initial sleep will be 3* this, so 15ms
while (!isFinished() && deadline.isValid())
{
try
{
// Check very frequently initially, tripling the wait each time
// this allows us to return very quickly for short-running processes, but not hammer the CPU for long-running processes
if (interval != intervalMax)
{
interval = Math.min(interval * 3, intervalMax);
}
final boolean hasExited = this.process.waitFor(Math.min(deadline.getTimeLeft(), interval), TimeUnit.MILLISECONDS);
if (hasExited)
{
// Wait for the deadline to expire or for any output reading to complete
while (deadline.isValid() && isStillReadingOutput())
new Timeout(10, TimeUnit.MILLISECONDS).sleep();
return exitCode();
}
}
catch (InterruptedException e)
{
}
}
if (deadline.isExpired())
return Integer.MIN_VALUE;
else
return exitCode();
}
/**
* Returns true if the output of this process is still being read
*
* @return false if this instance is copying the stdout/stderr and they have been closed, otherwise true if we are still
* copying stdout/stderr. Always returns false if some external agent is handling the stdout/stderr streams.
*/
protected abstract boolean isStillReadingOutput();
public InputStream getStandardOutputStream()
{
return process.getInputStream();
}
public InputStream getStandardErrorStream()
{
return process.getErrorStream();
}
public OutputStream getStandardInputStream()
{
return process.getOutputStream();
}
/**
* Indicates that the output of this process should be discarded
*/
public abstract void discardOutput();
protected void finished(int exitCode)
{
this.exitCode = exitCode;
this.finished = true;
}
protected void unexpectedFailure(IOException e)
{
if (finished)
return;
if (!isFinished())
finished(Integer.MIN_VALUE);
}
// Commence a background copy
protected Thread copy(final InputStream in, final Writer out)
{
Runnable r = () -> {
try
{
StreamUtil.streamCopy(in, out);
}
catch (IOException e)
{
try
{
out.flush();
}
catch (Throwable t)
{
}
unexpectedFailure(e);
}
};
Thread t = new Thread(r);
t.setName(this + " - IOCopy " + in + " to " + out);
t.setDaemon(true);
t.start();
return t;
}
protected Thread discard(final InputStream in)
{
if (in == null)
return null;
Runnable r = () -> StreamUtil.eatInputStream(in);
Thread t = new Thread(r);
t.setDaemon(true);
t.setName(this + " - IODiscard " + in);
t.start();
return t;
}
}