org.glassfish.osgi.cli.remote.RemoteCommandSession Maven / Gradle / Ivy
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// Portions Copyright [2018] [Payara Foundation and/or its affiliates]
package org.glassfish.osgi.cli.remote;
import java.io.InputStream;
import java.io.PrintStream;
import java.lang.reflect.Field;
import java.nio.channels.Channel;
import java.nio.channels.Channels;
import java.nio.channels.ReadableByteChannel;
import java.nio.channels.WritableByteChannel;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.UUID;
import org.apache.felix.service.command.CommandSession;
/**
* This delegating class is used to overcome some limitations of the
* {@link CommandSession} interface when it comes to session management.
*
*
* Once implementations are mature enough to not assume environmental behavior
* this class will become obsolete.
*
*
* @author ancoron
*/
public class RemoteCommandSession {
private final CommandSession delegate;
private final String id;
public RemoteCommandSession(CommandSession delegate)
{
this.delegate = delegate;
this.id = UUID.randomUUID().toString();
}
/**
* Get the identifier for this session, which is a UUID of type 4.
*
* @return
*/
public String getId() {
return id;
}
/**
* Attached the specified streams to the delegate of this instance and
* returns the modified delegate.
*
* @param in The "stdin" stream for the session
* @param out The "stdout" stream for the session
* @param err The "stderr" stream for the session
*
* @return The modified {@link CommandSession} delegate
*
* @see #detach()
*/
public CommandSession attach(InputStream in, PrintStream out, PrintStream err) {
set(this.delegate, "in", in);
set(this.delegate, "out", out);
set(this.delegate, "err", err);
ReadableByteChannel inCh = Channels.newChannel(in);
WritableByteChannel outCh = Channels.newChannel(out);
WritableByteChannel errCh = out == err ? outCh : Channels.newChannel(err);
set(this.delegate, "channels", new Channel[] {inCh, outCh, errCh});
return this.delegate;
}
/**
* Detaches all previously attached streams and hence, ensures that there
* are no stale references left.
*
* @see #attach(java.io.InputStream, java.io.PrintStream, java.io.PrintStream)
*/
public void detach() {
set(this.delegate, "in", null);
set(this.delegate, "out", null);
set(this.delegate, "err", null);
}
private void set(final Object obj, final String field, final Object value) {
try {
final Field f = obj.getClass().getDeclaredField(field);
final boolean accessible = f.isAccessible();
if(!accessible) {
AccessController.doPrivileged(new PrivilegedAction() {
@Override
public Void run() {
f.setAccessible(true);
try {
f.set(obj, value);
} catch(Exception x) {
throw new RuntimeException(x);
}
// reset to previous state...
f.setAccessible(accessible);
return null;
}
});
} else {
f.set(obj, value);
}
} catch(Exception x) {
throw new RuntimeException(x);
}
}
}