/*
* NOTE: This copyright does *not* cover user programs that use HQ
* program services by normal system calls through the application
* program interfaces provided as part of the Hyperic Plug-in Development
* Kit or the Hyperic Client Development Kit - this is merely considered
* normal use of the program, and does *not* fall under the heading of
* "derived work".
*
* Copyright (C) [2004, 2005, 2006], Hyperic, Inc.
* This file is part of HQ.
*
* HQ is free software; you can redistribute it and/or modify
* it under the terms version 2 of the GNU General Public License as
* published by the Free Software Foundation. This program is distributed
* in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
* even the implied warranty of MERCHANTABILITY or FITNESS FOR A
* PARTICULAR PURPOSE. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
* USA.
*/
package org.hyperic.hq.agent.server;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InterruptedIOException;
import java.io.OutputStream;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicReference;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.hyperic.hq.agent.AgentCommand;
import org.hyperic.hq.agent.AgentCommandsAPI;
import org.hyperic.hq.agent.AgentConnectionException;
import org.hyperic.hq.agent.AgentRemoteException;
import org.hyperic.hq.agent.AgentRemoteValue;
import org.hyperic.hq.agent.server.monitor.AgentMonitorSimple;
/**
* The object used to read serialized object data from the network and
* send it to the CommandDispatcher.
*/
public class CommandListener extends AgentMonitorSimple {
private static final int POLL_FREQUENCY = 1000;
private static final String GENERIC_POOL = "generic";
private static final String[] THREAD_POOLS = new String[] {
AgentCommandsAPI.command_ping, AgentCommandsAPI.command_receive_file, GENERIC_POOL};
private final Map<String, ExecutorService> threadPools = new HashMap<String, ExecutorService>();
private final CommandDispatcher dispatcher; // Dispatcher which handles commands
private final Log log = LogFactory.getLog(CommandListener.class);
/** Shutdown the listenLoop thread and all thread pools */
private AtomicBoolean shutdown = new AtomicBoolean(true);
private AtomicReference<AgentConnectionListener> listener = new AtomicReference<AgentConnectionListener>();
/**
* Setup a listener on a specified port, with a dispatcher containing
* known methods which can be invoked.
*
* @param dispatcher Object to call when a command comes across the wire
*/
CommandListener(CommandDispatcher dispatcher) {
this.dispatcher = dispatcher;
setupThreadPools();
}
private void setupThreadPools() {
for (final String cmdName : THREAD_POOLS) {
final String poolName = cmdName.replace(AgentCommandsAPI.commandPrefix, "");
final ExecutorService pool = Executors.newFixedThreadPool(1, new ThreadFactory() {
private final AtomicLong num = new AtomicLong(0);
public Thread newThread(Runnable r) {
Thread rtn = new Thread(r, "commandlistener-" + poolName + "-" + num.getAndIncrement());
rtn.setDaemon(true);
return rtn;
}
});
threadPools.put(cmdName, pool);
}
}
void setConnectionListener(final AgentConnectionListener listener) throws AgentRunningException {
if (!shutdown.get()){
throw new AgentRunningException("Cannot replace listener while running");
}
this.listener.set(listener);
Runtime.getRuntime().addShutdownHook(new Thread() {
public void run() {
try {
if (listener != null) {
listener.cleanup();
}
} catch (Throwable e) {
log.error("could not close socket connection: " + e,e);
}
}
});
}
/**
* Shut down the command listener.
*
* @throws AgentRunningException indicating the listener was not listening
* when 'die' was requested.
*/
void die() throws AgentRunningException {
shutdown.set(true);
for (final Entry<String, ExecutorService> entry : threadPools.entrySet()) {
final ExecutorService pool = entry.getValue();
pool.shutdownNow();
log.info("Shut down executor service for CommandListener " + entry.getKey());
}
}
/**
* Cleanup any resources in use by the object. Notably, if the object
* is constructed, but the listenLoop is never called, this will need to
* be invoked.
*/
void cleanup() {
listener.get().cleanup();
}
void setup() throws AgentStartException {
listener.get().setup(CommandListener.POLL_FREQUENCY);
}
/**
* The main loop which blocks, waiting for connections. Connections are
* handled in a synchronous manner -- one connection is not processed
* until the previous one is finished.
*/
void listenLoop() {
boolean logDebug = log.isDebugEnabled();
shutdown.set(false);
while (!shutdown.get()) {
try {
try {
final AgentServerConnection conn = listener.get().getNewConnection();
if (logDebug) log.debug("Opened new connection");
final AgentCommand cmd = conn.readCommand();
final ExecutorService pool = getPool(cmd);
if (logDebug) log.debug("Dispatching command " + cmd.getCommand() + " to pool: " + pool);
pool.execute(new AgentDispatchTask(conn, cmd));
if (logDebug) log.debug("Done dispatching command " + cmd.getCommand() + " to pool " + pool);
} catch (EOFException e) {
log.debug(e, e);
} catch (InterruptedIOException e){
if (shutdown.get()) {
listener.get().cleanup();
return;
}
continue;
} catch (AgentConnectionException e){
if (!shutdown.get()) {
log.error("Failed handling new connection: " + e, e);
}
continue;
}
} catch (Throwable t) {
// only log to error if the agent isn't shutting down
if (!shutdown.get()) {
log.error(t,t);
} else {
log.debug(t,t);
}
}
}
}
private ExecutorService getPool(AgentCommand cmd) {
final ExecutorService pool = threadPools.get(cmd.getCommand());
return (pool == null) ? threadPools.get(GENERIC_POOL) : pool;
}
private class AgentDispatchTask implements Runnable {
private AgentServerConnection conn;
private AgentCommand cmd;
public AgentDispatchTask(AgentServerConnection conn, AgentCommand cmd) {
this.conn = conn;
this.cmd = cmd;
}
public void run() {
InputStream inputStream = null;
OutputStream outputStream = null;
try {
inputStream = conn.getInputStream();
outputStream = conn.getOutputStream();
handleConn(conn, cmd, inputStream, outputStream);
} catch (Throwable t) {
log.error(t,t);
} finally {
try {outputStream.flush();} catch(IOException ignExc) {}
try {outputStream.close();} catch(IOException ignExc) {}
try {inputStream.close();} catch(IOException ignExc) {}
conn.close();
}
}
}
private void handleConn(AgentServerConnection conn, AgentCommand cmd, InputStream inputStream, OutputStream outputStream) {
Object dispatchResult;
try {
log.debug("Dispatching request for '" + cmd.getCommand() + "'");
dispatchResult = dispatcher.processRequest(cmd, inputStream, outputStream);
} catch (AgentRemoteException e) {
// This is a fine result, raised via the AgentServerHandler interface
dispatchResult = e;
}
try {
if (dispatchResult instanceof AgentRemoteException){
log.warn("Error invoking method",
(Exception)dispatchResult);
String message = ((AgentRemoteException)dispatchResult).getMessage();
if (message == null){
message = "Problem occurred without an error message, see stacktrace for more information.";
}
conn.sendErrorResponse(message);
} else if(dispatchResult instanceof Exception){
log.warn("Error invoking method", (Exception)dispatchResult);
conn.sendErrorResponse(((Exception)dispatchResult).
toString());
} else if(dispatchResult == null){
log.debug("Method '" + cmd + "' returned null ");
conn.sendSuccessResponse(new AgentRemoteValue());
} else {
log.debug("Method '" + cmd + "' returned an object result");
conn.sendSuccessResponse((AgentRemoteValue)dispatchResult);
}
} catch(AgentConnectionException e) {
log.error("Error writing result to client: " + e, e);
}
}
}