public static void main(String[] args) {
// Sys.eval("J2ME.emitCheckArrayStore = false;");
// Sys.eval("J2ME.emitCheckArrayBounds = false;");
size = 32;
begin();
start = JVM.monotonicTimeMillis();
createObjectArrays();
createPrimitiveArrays();
writeByteArrayOutputStream();
concatStrings();
getBytes();
synch();
hashtable();
arrayTypeCheck();
finish("startup");
size = 32 * 64;
long start = JVM.monotonicTimeMillis();
begin();
createObjectArrays();
finish("createObjectArrays");
begin();
createPrimitiveArrays();
finish("createPrimitiveArrays");
begin();
writeByteArrayOutputStream();
finish("writeByteArrayOutputStream");
begin();
concatStrings();
finish("concatStrings");
begin();
getBytes();
finish("getBytes");
begin();
synch();
finish("synchronize");
begin();
hashtable();
finish("hashtable");
begin();
arrayTypeCheck();
finish("arrayTypeCheck");
System.out.println();
System.out.println("Total: " + (JVM.monotonicTimeMillis() - start));
}
/**
* Returns the value of the user clock skew in milliseconds. Returned is the deviation of the user
* clock from the monotonic clock accumulated since the previous invocation of this method in this
* task. Deviations below the <code>SKEW_THRESHOLD</code> are not reported. They are accumulated
* until they exceed the threshold.
*
* @return the user clock skew
*/
static long userClockSkew() {
long newDelta = System.currentTimeMillis() - JVM.monotonicTimeMillis();
long oldDelta = userClockOffset - monotonicClockOffset;
long skew = newDelta - oldDelta;
if (Math.abs(skew) < SKEW_THRESHOLD) {
skew = 0;
}
userClockOffset += skew;
return skew;
}
/**
* Schedule the specified timer task for execution at the specified time with the specified
* period, in milliseconds. If period is positive, the task is scheduled for repeated execution;
* if period is zero, the task is scheduled for one-time execution. Time is specified in
* Date.getTime() format. This method checks timer state, task state, and initial execution time,
* but not period.
*
* @param task task to be scheduled.
* @param userTime the user time at which task is to be executed or <tt>null</tt> if the delay is
* specified
* @param delay the delay in milliseconds before the task execution
* @param period time in milliseconds between successive task executions.
* @param isUserClock true if the time is bound to user clock
* @throws IllegalArgumentException if <tt>time()</tt> is negative.
* @throws IllegalStateException if task was already scheduled or cancelled, timer was cancelled,
* or timer thread terminated.
*/
private void sched(TimerTask task, Date userTime, long delay, long period) {
final boolean isUserClock = userTime != null;
long time;
if (isUserClock) {
long t = userTime.getTime();
if (t < 0) {
throw new IllegalArgumentException("Illegal execution time.");
}
time = Timer.userTimeFromStart(t);
} else {
time = Timer.monotonicTimeFromStart(JVM.monotonicTimeMillis() + delay);
}
synchronized (queue) {
if (!queue.newTasksMayBeScheduled) {
throw new IllegalStateException("Timer already cancelled.");
}
/*
* If the TimerThread has exited without an error
* it is restarted. See the commentary in TimerThread.run.
*/
if (thread == null || !thread.isAlive()) {
thread = new TimerThread(queue);
thread.start();
}
synchronized (task.lock) {
if (task.state != TimerTask.VIRGIN) {
throw new IllegalStateException("Task already scheduled or cancelled");
}
task.nextExecutionTime = time;
task.period = period;
task.state = TimerTask.SCHEDULED;
task.isUserClock = isUserClock;
}
queue.add(task);
if (queue.getMin() == task) queue.notify();
}
}
public static void finish(String name) {
System.out.println(name + ": " + (JVM.monotonicTimeMillis() - start));
}
public static void begin() {
System.gc();
start = JVM.monotonicTimeMillis();
}
/**
* A facility for threads to schedule tasks for future execution in a background thread. Tasks may
* be scheduled for one-time execution, or for repeated execution at regular intervals.
*
* <p>Corresponding to each <tt>Timer</tt> object is a single background thread that is used to
* execute all of the timer's tasks, sequentially. Timer tasks should complete quickly. If a timer
* task takes excessive time to complete, it "hogs" the timer's task execution thread. This can, in
* turn, delay the execution of subsequent tasks, which may "bunch up" and execute in rapid
* succession when (and if) the offending task finally completes.
*
* <p>After the last live reference to a <tt>Timer</tt> object goes away <i>and</i> all outstanding
* tasks have completed execution, the timer's task execution thread terminates gracefully (and
* becomes subject to garbage collection). However, this can take arbitrarily long to occur. By
* default, the task execution thread does not run as a <i>daemon thread</i>, so it is capable of
* keeping an application from terminating. If a caller wants to terminate a timer's task execution
* thread rapidly, the caller should invoke the timer's <tt>cancel</tt> method.
*
* <p>If the timer's task execution thread terminates unexpectedly, for example, because its
* <tt>stop</tt> method is invoked, any further attempt to schedule a task on the timer will result
* in an <tt>IllegalStateException</tt>, as if the timer's <tt>cancel</tt> method had been invoked.
*
* <p>This class is thread-safe: multiple threads can share a single <tt>Timer</tt> object without
* the need for external synchronization.
*
* <p>This class does <i>not</i> offer real-time guarantees: it schedules tasks using the
* <tt>Object.wait(long)</tt> method.
*
* <p>Timers function only within a single VM and are cancelled when the VM exits. When the VM is
* started no timers exist, they are created only by application request.
*
* @see TimerTask
* @see Object#wait(long)
* @since 1.3
*/
public class Timer {
/**
* The timer task queue. This data structure is shared with the timer thread. The timer produces
* tasks, via its various schedule calls, and the timer thread consumes, executing timer tasks as
* appropriate, and removing them from the queue when they're obsolete.
*/
private TaskQueue queue = new TaskQueue();
/** The timer thread. */
private TimerThread thread;
/** Time of this class initialization in the monotonic clock. */
private static final long monotonicClockOffset = JVM.monotonicTimeMillis();
/** Time of this class initialization in the user clock. Can change if the user clock changes. */
private static long userClockOffset = System.currentTimeMillis();
/**
* Creates a new timer. The associated thread does <i>not</i> run as a daemon thread, which may
* prevent an application from terminating.
*
* @see Thread
* @see #cancel()
*/
public Timer() {}
/**
* Schedules the specified task for execution after the specified delay.
*
* @param task task to be scheduled.
* @param delay delay in milliseconds before task is to be executed.
* @throws IllegalArgumentException if <tt>delay</tt> is negative, or <tt>delay +
* System.currentTimeMillis()</tt> is negative.
* @throws IllegalStateException if task was already scheduled or cancelled, or timer was
* cancelled.
*/
public void schedule(TimerTask task, long delay) {
if (delay < 0) throw new IllegalArgumentException("Negative delay.");
if (System.currentTimeMillis() + delay < 0) {
throw new IllegalArgumentException("Illegal execution time.");
}
sched(task, null, delay, 0);
}
/**
* Schedules the specified task for execution at the specified time. If the time is in the past,
* the task is scheduled for immediate execution.
*
* @param task task to be scheduled.
* @param time time at which task is to be executed.
* @throws IllegalArgumentException if <tt>time.getTime()</tt> is negative.
* @throws IllegalStateException if task was already scheduled or cancelled, timer was cancelled,
* or timer thread terminated.
*/
public void schedule(TimerTask task, Date time) {
if (time == null) {
throw new NullPointerException();
}
sched(task, time, 0, 0);
}
/**
* Schedules the specified task for repeated <i>fixed-delay execution</i>, beginning after the
* specified delay. Subsequent executions take place at approximately regular intervals separated
* by the specified period.
*
* <p>In fixed-delay execution, each execution is scheduled relative to the actual execution time
* of the previous execution. If an execution is delayed for any reason (such as garbage
* collection or other background activity), subsequent executions will be delayed as well. In the
* long run, the frequency of execution will generally be slightly lower than the reciprocal of
* the specified period (assuming the system clock underlying <tt>Object.wait(long)</tt> is
* accurate).
*
* <p>Fixed-delay execution is appropriate for recurring activities that require "smoothness." In
* other words, it is appropriate for activities where it is more important to keep the frequency
* accurate in the short run than in the long run. This includes most animation tasks, such as
* blinking a cursor at regular intervals. It also includes tasks wherein regular activity is
* performed in response to human input, such as automatically repeating a character as long as a
* key is held down.
*
* @param task task to be scheduled.
* @param delay delay in milliseconds before task is to be executed.
* @param period time in milliseconds between successive task executions.
* @throws IllegalArgumentException if <tt>delay</tt> is negative, or <tt>delay +
* System.currentTimeMillis()</tt> is negative.
* @throws IllegalStateException if task was already scheduled or cancelled, timer was cancelled,
* or timer thread terminated.
*/
public void schedule(TimerTask task, long delay, long period) {
if (delay < 0) throw new IllegalArgumentException("Negative delay.");
if (period <= 0) throw new IllegalArgumentException("Non-positive period.");
if (System.currentTimeMillis() + delay < 0) {
throw new IllegalArgumentException("Illegal execution time.");
}
sched(task, null, delay, -period);
}
/**
* Schedules the specified task for repeated <i>fixed-delay execution</i>, beginning at the
* specified time. Subsequent executions take place at approximately regular intervals, separated
* by the specified period.
*
* <p>In fixed-delay execution, each execution is scheduled relative to the actual execution time
* of the previous execution. If an execution is delayed for any reason (such as garbage
* collection or other background activity), subsequent executions will be delayed as well. In the
* long run, the frequency of execution will generally be slightly lower than the reciprocal of
* the specified period (assuming the system clock underlying <tt>Object.wait(long)</tt> is
* accurate).
*
* <p>Fixed-delay execution is appropriate for recurring activities that require "smoothness." In
* other words, it is appropriate for activities where it is more important to keep the frequency
* accurate in the short run than in the long run. This includes most animation tasks, such as
* blinking a cursor at regular intervals. It also includes tasks wherein regular activity is
* performed in response to human input, such as automatically repeating a character as long as a
* key is held down.
*
* @param task task to be scheduled.
* @param firstTime First time at which task is to be executed.
* @param period time in milliseconds between successive task executions.
* @throws IllegalArgumentException if <tt>time.getTime()</tt> is negative.
* @throws IllegalStateException if task was already scheduled or cancelled, timer was cancelled,
* or timer thread terminated.
*/
public void schedule(TimerTask task, Date firstTime, long period) {
if (period <= 0) throw new IllegalArgumentException("Non-positive period.");
if (firstTime == null) {
throw new NullPointerException();
}
sched(task, firstTime, 0, -period);
}
/**
* Schedules the specified task for repeated <i>fixed-rate execution</i>, beginning after the
* specified delay. Subsequent executions take place at approximately regular intervals, separated
* by the specified period.
*
* <p>In fixed-rate execution, each execution is scheduled relative to the scheduled execution
* time of the initial execution. If an execution is delayed for any reason (such as garbage
* collection or other background activity), two or more executions will occur in rapid succession
* to "catch up." In the long run, the frequency of execution will be exactly the reciprocal of
* the specified period (assuming the system clock underlying <tt>Object.wait(long)</tt> is
* accurate).
*
* <p>Fixed-rate execution is appropriate for recurring activities that are sensitive to
* <i>absolute</i> time, such as ringing a chime every hour on the hour, or running scheduled
* maintenance every day at a particular time. It is also appropriate for for recurring activities
* where the total time to perform a fixed number of executions is important, such as a countdown
* timer that ticks once every second for ten seconds. Finally, fixed-rate execution is
* appropriate for scheduling multiple repeating timer tasks that must remain synchronized with
* respect to one another.
*
* @param task task to be scheduled.
* @param delay delay in milliseconds before task is to be executed.
* @param period time in milliseconds between successive task executions.
* @throws IllegalArgumentException if <tt>delay</tt> is negative, or <tt>delay +
* System.currentTimeMillis()</tt> is negative.
* @throws IllegalStateException if task was already scheduled or cancelled, timer was cancelled,
* or timer thread terminated.
*/
public void scheduleAtFixedRate(TimerTask task, long delay, long period) {
if (delay < 0) throw new IllegalArgumentException("Negative delay.");
if (period <= 0) throw new IllegalArgumentException("Non-positive period.");
if (System.currentTimeMillis() + delay < 0) {
throw new IllegalArgumentException("Illegal execution time.");
}
sched(task, null, delay, period);
}
/**
* Schedules the specified task for repeated <i>fixed-rate execution</i>, beginning at the
* specified time. Subsequent executions take place at approximately regular intervals, separated
* by the specified period.
*
* <p>In fixed-rate execution, each execution is scheduled relative to the scheduled execution
* time of the initial execution. If an execution is delayed for any reason (such as garbage
* collection or other background activity), two or more executions will occur in rapid succession
* to "catch up." In the long run, the frequency of execution will be exactly the reciprocal of
* the specified period (assuming the system clock underlying <tt>Object.wait(long)</tt> is
* accurate).
*
* <p>Fixed-rate execution is appropriate for recurring activities that are sensitive to
* <i>absolute</i> time, such as ringing a chime every hour on the hour, or running scheduled
* maintenance every day at a particular time. It is also appropriate for for recurring activities
* where the total time to perform a fixed number of executions is important, such as a countdown
* timer that ticks once every second for ten seconds. Finally, fixed-rate execution is
* appropriate for scheduling multiple repeating timer tasks that must remain synchronized with
* respect to one another.
*
* @param task task to be scheduled.
* @param firstTime First time at which task is to be executed.
* @param period time in milliseconds between successive task executions.
* @throws IllegalArgumentException if <tt>time.getTime()</tt> is negative.
* @throws IllegalStateException if task was already scheduled or cancelled, timer was cancelled,
* or timer thread terminated.
*/
public void scheduleAtFixedRate(TimerTask task, Date firstTime, long period) {
if (period <= 0) throw new IllegalArgumentException("Non-positive period.");
if (firstTime == null) {
throw new NullPointerException();
}
sched(task, firstTime, 0, period);
}
/**
* Schedule the specified timer task for execution at the specified time with the specified
* period, in milliseconds. If period is positive, the task is scheduled for repeated execution;
* if period is zero, the task is scheduled for one-time execution. Time is specified in
* Date.getTime() format. This method checks timer state, task state, and initial execution time,
* but not period.
*
* @param task task to be scheduled.
* @param userTime the user time at which task is to be executed or <tt>null</tt> if the delay is
* specified
* @param delay the delay in milliseconds before the task execution
* @param period time in milliseconds between successive task executions.
* @param isUserClock true if the time is bound to user clock
* @throws IllegalArgumentException if <tt>time()</tt> is negative.
* @throws IllegalStateException if task was already scheduled or cancelled, timer was cancelled,
* or timer thread terminated.
*/
private void sched(TimerTask task, Date userTime, long delay, long period) {
final boolean isUserClock = userTime != null;
long time;
if (isUserClock) {
long t = userTime.getTime();
if (t < 0) {
throw new IllegalArgumentException("Illegal execution time.");
}
time = Timer.userTimeFromStart(t);
} else {
time = Timer.monotonicTimeFromStart(JVM.monotonicTimeMillis() + delay);
}
synchronized (queue) {
if (!queue.newTasksMayBeScheduled) {
throw new IllegalStateException("Timer already cancelled.");
}
/*
* If the TimerThread has exited without an error
* it is restarted. See the commentary in TimerThread.run.
*/
if (thread == null || !thread.isAlive()) {
thread = new TimerThread(queue);
thread.start();
}
synchronized (task.lock) {
if (task.state != TimerTask.VIRGIN) {
throw new IllegalStateException("Task already scheduled or cancelled");
}
task.nextExecutionTime = time;
task.period = period;
task.state = TimerTask.SCHEDULED;
task.isUserClock = isUserClock;
}
queue.add(task);
if (queue.getMin() == task) queue.notify();
}
}
/**
* Terminates this timer, discarding any currently scheduled tasks. Does not interfere with a
* currently executing task (if it exists). Once a timer has been terminated, its execution thread
* terminates gracefully, and no more tasks may be scheduled on it.
*
* <p>Note that calling this method from within the run method of a timer task that was invoked by
* this timer absolutely guarantees that the ongoing task execution is the last task execution
* that will ever be performed by this timer.
*
* <p>This method may be called repeatedly; the second and subsequent calls have no effect.
*/
public void cancel() {
synchronized (queue) {
queue.newTasksMayBeScheduled = false;
queue.clear();
queue.notify(); // In case queue was already empty.
}
}
private static long monotonicTimeFromStart(long monotonicTime) {
return monotonicTime - monotonicClockOffset;
}
private static long userTimeFromStart(long userTime) {
return userTime - userClockOffset;
}
static long relativeTimeToUserTime(long relativeTime) {
return relativeTime + userClockOffset;
}
static long monotonicTimeMillis() {
return monotonicTimeFromStart(JVM.monotonicTimeMillis());
}
/**
* The millisecond threshold to signal user clock skew. User clock deviations below the threshold
* are accumulated and reported only when they exceed the threshold.
*/
private static final int SKEW_THRESHOLD = 100;
/**
* The millisecond period to check for user clock skew. Since many platforms do not notify
* applications about the user clock change, we periodically check for the skew.
*/
static final int USER_CLOCK_CHECK_PERIOD = 1000;
/**
* Returns the value of the user clock skew in milliseconds. Returned is the deviation of the user
* clock from the monotonic clock accumulated since the previous invocation of this method in this
* task. Deviations below the <code>SKEW_THRESHOLD</code> are not reported. They are accumulated
* until they exceed the threshold.
*
* @return the user clock skew
*/
static long userClockSkew() {
long newDelta = System.currentTimeMillis() - JVM.monotonicTimeMillis();
long oldDelta = userClockOffset - monotonicClockOffset;
long skew = newDelta - oldDelta;
if (Math.abs(skew) < SKEW_THRESHOLD) {
skew = 0;
}
userClockOffset += skew;
return skew;
}
}
static long monotonicTimeMillis() {
return monotonicTimeFromStart(JVM.monotonicTimeMillis());
}
