/*
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package art;
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import java.lang.reflect.Method;
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import java.util.concurrent.atomic.*;
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import java.util.function.Function;
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import java.util.stream.Stream;
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import java.util.Arrays;
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import java.util.Objects;
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public class Monitors {
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public native static void setupMonitorEvents(
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Class<?> method_klass,
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Method monitor_contended_enter_event,
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Method monitor_contended_entered_event,
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Method monitor_wait_event,
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Method monitor_waited_event,
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Class<?> lock_klass,
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Thread thr);
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public native static void stopMonitorEvents();
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public static class NamedLock {
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public final String name;
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private volatile int calledNotify;
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public NamedLock(String name) {
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this.name = name;
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calledNotify = 0;
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}
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public String toString() {
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return String.format("NamedLock[%s]", name);
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}
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public final void DoWait() throws Exception {
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final int v = calledNotify;
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while (v == calledNotify) {
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wait();
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}
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}
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public final void DoWait(long t) throws Exception {
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final int v = calledNotify;
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final long target = System.currentTimeMillis() + (t / 2);
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while (v == calledNotify && (t < 0 || System.currentTimeMillis() < target)) {
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wait(t);
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}
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}
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public final void DoNotifyAll() throws Exception {
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calledNotify++;
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notifyAll();
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}
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public final void DoNotify() throws Exception {
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calledNotify++;
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notify();
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}
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}
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public static final class MonitorUsage {
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public final Object monitor;
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public final Thread owner;
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public final int entryCount;
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public final Thread[] waiters;
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public final Thread[] notifyWaiters;
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public MonitorUsage(
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Object monitor,
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Thread owner,
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int entryCount,
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Thread[] waiters,
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Thread[] notifyWaiters) {
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this.monitor = monitor;
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this.entryCount = entryCount;
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this.owner = owner;
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this.waiters = waiters;
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this.notifyWaiters = notifyWaiters;
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}
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private static String toNameList(Thread[] ts) {
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return Arrays.toString(Arrays.stream(ts).map((Thread t) -> t.getName()).toArray());
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}
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public String toString() {
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return String.format(
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"MonitorUsage{ monitor: %s, owner: %s, entryCount: %d, waiters: %s, notify_waiters: %s }",
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monitor,
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(owner != null) ? owner.getName() : "<NULL>",
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entryCount,
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toNameList(waiters),
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toNameList(notifyWaiters));
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}
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}
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public static native MonitorUsage getObjectMonitorUsage(Object monitor);
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public static native Object getCurrentContendedMonitor(Thread thr);
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public static class TestException extends Error {
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public TestException() { super(); }
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public TestException(String s) { super(s); }
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public TestException(String s, Throwable c) { super(s, c); }
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}
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public static class LockController {
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private static enum Action { HOLD, RELEASE, NOTIFY, NOTIFY_ALL, WAIT, TIMED_WAIT }
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public final NamedLock lock;
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public final long timeout;
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private final AtomicStampedReference<Action> action;
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private volatile Thread runner = null;
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private volatile boolean started = false;
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private volatile boolean held = false;
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private static final AtomicInteger cnt = new AtomicInteger(0);
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private volatile Throwable exe;
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public LockController(NamedLock lock) {
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this(lock, 10 * 1000);
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}
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public LockController(NamedLock lock, long timeout) {
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this.lock = lock;
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this.timeout = timeout;
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this.action = new AtomicStampedReference(Action.HOLD, 0);
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this.exe = null;
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}
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public boolean IsWorkerThread(Thread thd) {
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return Objects.equals(runner, thd);
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}
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public boolean IsLocked() {
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checkException();
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return held;
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}
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public void checkException() {
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if (exe != null) {
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throw new TestException("Exception thrown by other thread!", exe);
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}
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}
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private void setAction(Action a) {
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int stamp = action.getStamp();
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// Wait for it to be HOLD before updating.
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while (!action.compareAndSet(Action.HOLD, a, stamp, stamp + 1)) {
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stamp = action.getStamp();
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}
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}
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public synchronized void suspendWorker() throws Exception {
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checkException();
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if (runner == null) {
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throw new TestException("We don't have any runner holding " + lock);
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}
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Suspension.suspend(runner);
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}
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public Object getWorkerContendedMonitor() throws Exception {
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checkException();
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if (runner == null) {
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return null;
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}
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return getCurrentContendedMonitor(runner);
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}
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public synchronized void DoLock() {
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if (IsLocked()) {
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throw new Error("lock is already acquired or being acquired.");
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}
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if (runner != null) {
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throw new Error("Already have thread!");
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}
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runner = new Thread(() -> {
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started = true;
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try {
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synchronized (lock) {
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held = true;
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int[] stamp_h = new int[] { -1 };
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Action cur_action = Action.HOLD;
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try {
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while (true) {
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cur_action = action.get(stamp_h);
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int stamp = stamp_h[0];
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if (cur_action == Action.RELEASE) {
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// The other thread will deal with reseting action.
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break;
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}
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try {
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switch (cur_action) {
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case HOLD:
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Thread.yield();
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break;
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case NOTIFY:
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lock.DoNotify();
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break;
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case NOTIFY_ALL:
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lock.DoNotifyAll();
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break;
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case TIMED_WAIT:
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lock.DoWait(timeout);
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break;
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case WAIT:
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lock.DoWait();
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break;
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default:
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throw new Error("Unknown action " + action);
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}
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} finally {
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// reset action back to hold if it isn't something else.
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action.compareAndSet(cur_action, Action.HOLD, stamp, stamp+1);
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}
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}
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} catch (Exception e) {
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throw new TestException("Got an error while performing action " + cur_action, e);
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}
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}
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} finally {
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held = false;
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started = false;
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}
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}, "Locker thread " + cnt.getAndIncrement() + " for " + lock);
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// Make sure we can get any exceptions this throws.
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runner.setUncaughtExceptionHandler((t, e) -> { exe = e; });
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runner.start();
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}
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public void waitForLockToBeHeld() throws Exception {
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while (true) {
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if (IsLocked() && Objects.equals(runner, Monitors.getObjectMonitorUsage(lock).owner)) {
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return;
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}
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}
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}
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public synchronized void waitForNotifySleep() throws Exception {
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if (runner == null) {
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throw new Error("No thread trying to lock!");
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}
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do {
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checkException();
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} while (!started ||
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!Arrays.asList(Monitors.getObjectMonitorUsage(lock).notifyWaiters).contains(runner));
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}
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public synchronized void waitForContendedSleep() throws Exception {
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if (runner == null) {
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throw new Error("No thread trying to lock!");
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}
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do {
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checkException();
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} while (!started ||
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runner.getState() != Thread.State.BLOCKED ||
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!Arrays.asList(Monitors.getObjectMonitorUsage(lock).waiters).contains(runner));
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}
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public synchronized void DoNotify() {
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if (!IsLocked()) {
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throw new Error("Not locked");
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}
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setAction(Action.NOTIFY);
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}
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public synchronized void DoNotifyAll() {
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if (!IsLocked()) {
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throw new Error("Not locked");
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}
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setAction(Action.NOTIFY_ALL);
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}
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public synchronized void DoTimedWait() throws Exception {
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if (!IsLocked()) {
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throw new Error("Not locked");
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}
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setAction(Action.TIMED_WAIT);
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}
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public synchronized void DoWait() throws Exception {
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if (!IsLocked()) {
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throw new Error("Not locked");
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}
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setAction(Action.WAIT);
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}
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public synchronized void interruptWorker() throws Exception {
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if (!IsLocked()) {
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throw new Error("Not locked");
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}
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runner.interrupt();
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}
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public synchronized void waitForActionToFinish() throws Exception {
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checkException();
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while (action.getReference() != Action.HOLD) { checkException(); }
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}
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public synchronized void DoUnlock() throws Exception {
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Error throwing = null;
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if (!IsLocked()) {
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// We might just be racing some exception that was thrown by the worker thread. Cache the
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// exception, we will throw one from the worker before this one.
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throwing = new Error("Not locked!");
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}
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setAction(Action.RELEASE);
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Thread run = runner;
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runner = null;
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while (held) {}
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run.join();
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action.set(Action.HOLD, 0);
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// Make sure to throw any exception that occurred since it might not have unlocked due to our
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// request.
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checkException();
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DoCleanup();
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if (throwing != null) {
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throw throwing;
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}
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}
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public synchronized void DoCleanup() throws Exception {
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if (runner != null) {
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Thread run = runner;
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runner = null;
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while (held) {}
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run.join();
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}
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action.set(Action.HOLD, 0);
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exe = null;
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}
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}
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}
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