org.glassfish.api.admin.AdminCommandLock Maven / Gradle / Ivy
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package org.glassfish.api.admin;
import org.jvnet.hk2.annotations.Service;
import javax.inject.Inject;
import javax.inject.Singleton;
import java.util.Date;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* The implementation of the admin command lock.
*
* @author Bill Shannon
* @author Chris Kasso
*/
@Service
@Singleton
public class AdminCommandLock {
@Inject
Logger logger;
/**
* The read/write lock. We depend on this class being a singleton
* and thus there being exactly one such lock object, shared by all
* users of this class.
*/
private static final ReentrantReadWriteLock rwlock = new ReentrantReadWriteLock();
private String lockOwner = null;
private Date lockTimeOfAcquisition = null;
/**
* Return the appropriate Lock object for the specified LockType.
* The returned lock has not been locked. If the LockType is
* not SHARED or EXCLUSIVE null is returned.
*
* @param type the LockType
* @return the Lock object to use, or null
*/
public Lock getLock(CommandLock.LockType type) {
if (type == CommandLock.LockType.SHARED)
return rwlock.readLock();
if (type == CommandLock.LockType.EXCLUSIVE)
return rwlock.writeLock();
return null; // no lock
}
public void dumpState(Logger logger, Level level) {
if (logger.isLoggable(level)) {
logger.log(level, "Current locking conditions are " + rwlock.getReadLockCount()
+ "/"+ rwlock.getReadHoldCount() + " shared locks"
+ "and " + rwlock.getWriteHoldCount() + " write lock");
}
}
/**
* Return the appropriate Lock object for the specified command.
* The returned lock has not been locked. If this command needs
* no lock, null is returned.
*
* @param command the AdminCommand object
* @return the Lock object to use, or null if no lock needed
*/
public Lock getLock(AdminCommand command) {
CommandLock alock = command.getClass().getAnnotation(CommandLock.class);
if (alock == null || alock.value() == CommandLock.LockType.SHARED)
return rwlock.readLock();
if (alock.value() == CommandLock.LockType.EXCLUSIVE)
return rwlock.writeLock();
return null; // no lock
}
/**
* Return the appropriate Lock object for the specified command.
* The returned lock has been locked. If this command needs
* no lock, null is returned.
*
* @param command the AdminCommand object
* @param owner the authority who requested the lock
* @return the Lock object to use, or null if no lock needed
*/
public Lock getLock(AdminCommand command, String owner) throws
AdminCommandLockTimeoutException,
AdminCommandLockException {
Lock lock = null;
boolean exclusive = false;
int timeout = 30;
CommandLock alock = command.getClass().getAnnotation(CommandLock.class);
if (alock == null || alock.value() == CommandLock.LockType.SHARED)
lock = rwlock.readLock();
else if (alock.value() == CommandLock.LockType.EXCLUSIVE) {
lock = rwlock.writeLock();
exclusive = true;
}
if (lock == null)
return null; // no lock
boolean badTimeOutValue = false;
String timeout_s = System.getProperty(
"com.sun.aas.commandLockTimeOut", "30");
try {
timeout = Integer.parseInt(timeout_s);
if (timeout < 0)
badTimeOutValue = true;
} catch (NumberFormatException e) {
badTimeOutValue = true;
}
if (badTimeOutValue) {
//XXX: Deal with logger injection attack.
logger.log(Level.INFO,
"Bad value com.sun.aas.commandLockTimeOut: "
+ timeout_s + ". Using 30 seconds.");
timeout = 30;
}
boolean lockAcquired = false;
while (!lockAcquired) {
try {
if (lock.tryLock(timeout, TimeUnit.SECONDS)) {
lockAcquired = true;
} else {
throw new AdminCommandLockTimeoutException(
"timeout acquiring lock",
getLockTimeOfAcquisition(),
getLockOwner());
}
} catch (java.lang.InterruptedException e) {
logger.log(Level.FINE, "Interrupted acquiring command lock. ",
e);
}
}
if (lockAcquired && exclusive) {
setLockOwner(owner);
setLockTimeOfAcquisition(new Date());
}
return lock;
}
/**
* Sets the admin user id for the user who acquired the exclusive lock.
*
* @param owner the admin user who acquired the lock.
*/
private void setLockOwner(String owner) {
lockOwner = owner;
}
/**
* Get the admin user id for the user who acquired the exclusive lock.
* This does not imply the lock is still held.
*
* @return the admin user who acquired the lock
*/
public synchronized String getLockOwner() {
return lockOwner;
}
/**
* Sets the time the exclusive lock was acquired.
*
* @param time the time the lock was acquired
*/
private void setLockTimeOfAcquisition(Date time) {
lockTimeOfAcquisition = time;
}
/**
* Get the time the exclusive lock was acquired. This does not
* imply the lock is still held.
*
* @return the time the lock was acquired
*/
public synchronized Date getLockTimeOfAcquisition() {
return lockTimeOfAcquisition;
}
}