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/*
* Copyright (c) 2020, 2020, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* The Universal Permissive License (UPL), Version 1.0
*
* Subject to the condition set forth below, permission is hereby granted to any
* person obtaining a copy of this software, associated documentation and/or
* data (collectively the "Software"), free of charge and under any and all
* copyright rights in the Software, and any and all patent rights owned or
* freely licensable by each licensor hereunder covering either (i) the
* unmodified Software as contributed to or provided by such licensor, or (ii)
* the Larger Works (as defined below), to deal in both
*
* (a) the Software, and
*
* (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
* one is included with the Software each a "Larger Work" to which the Software
* is contributed by such licensors),
*
* without restriction, including without limitation the rights to copy, create
* derivative works of, display, perform, and distribute the Software and make,
* use, sell, offer for sale, import, export, have made, and have sold the
* Software and the Larger Work(s), and to sublicense the foregoing rights on
* either these or other terms.
*
* This license is subject to the following condition:
*
* The above copyright notice and either this complete permission notice or at a
* minimum a reference to the UPL must be included in all copies or substantial
* portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* SOFTWARE.
*/
package com.oracle.truffle.api.instrumentation;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Deque;
import java.util.Map;
import java.util.WeakHashMap;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import java.util.function.BiConsumer;
import com.oracle.truffle.api.source.Source;
/*
* Lists of sources (executed or loaded, this description further mentions ony loaded sources,
* the same holds for executed) are initialized lazily, and, to prevent deadlocks, new sources
* can be loaded during this lazy initialization and also new bindings can be added at any time.
* In order to guarantee that each binding is notified about each source at most once without
* having to keep track of which binding was notified about which source, the notifications are
* added to a queue and resolving the sources is postponed to a time the notification is
* dequeued. The thread that adds the first notification to the queue is the one that will process them.
* Therefore, the notifications are serialized and the same order of sources for each binding is
* guaranteed. It is also guaranteed that each binding is notified about each source at most
* once and if the binding is added with notify=true, it is notified about each binding
* exactly once.
*/
final class SourceInstrumentationHandler {
/*
* Bindings can only be changed while holding the bindingsLock.writeLock() and read while
* holding the bindingsLock.readLock(); The only exceptions are the hasBindings and
* getBindingsArray methods which can be called without any locks.
*/
private final InstrumentationHandler.CopyOnWriteList> bindings = new InstrumentationHandler.CopyOnWriteList<>(new EventBinding.Source[0]);
/*
* sources, sourcesList, notifications can only be accessed while holding the
* bindingsLock.writeLock() or while holding the bindingsLock.readLock() and sources lock.
*/
private final WeakHashMap sources = new WeakHashMap<>();
private final InstrumentationHandler.WeakAsyncList sourcesList = new InstrumentationHandler.WeakAsyncList<>(16);
private final AtomicBoolean sourcesInitialized = new AtomicBoolean();
private final ReentrantReadWriteLock bindingsLock = new ReentrantReadWriteLock();
private final BiConsumer[], Source> notificationConsumer;
private SourcesNotificationQueue notifications = new SourcesNotificationQueue();
SourceInstrumentationHandler(BiConsumer[], Source> notificationConsumer) {
this.notificationConsumer = notificationConsumer;
}
private SourcesNotificationQueue addInitializeSourcesNotification() {
assert bindingsLock.getWriteHoldCount() > 0;
assert bindings.size() == 1;
notifications.enqueue(new InitializeSourcesNotification());
assert notifications.shouldProcess() : "Thread that added InitializeSourcesNotification is not the one to process the notification queue.";
assert notifications.isSourcesInitializationRequired();
return notifications;
}
private SourcesNotificationQueue addAllSourcesNotification(EventBinding.Source binding) {
assert bindingsLock.getWriteHoldCount() > 0;
notifications.enqueue(new AllSourcesNotification(new EventBinding.Source[]{binding}));
if (notifications.shouldProcess()) {
assert (!notifications.isSourcesInitializationRequired() && bindings.size() > 1) || (notifications.isSourcesInitializationRequired() && bindings.size() == 1);
return notifications;
} else {
return null;
}
}
private SourcesNotificationQueue addNotification(Map collectedSources, EventBinding.Source[] bindingsToNotify) {
assert bindingsLock.getReadHoldCount() > 0;
assert Thread.holdsLock(sources);
assert !bindings.isEmpty();
notifications.enqueue(new NewSourcesNotification(bindingsToNotify, collectedSources.keySet()));
if (notifications.shouldProcess()) {
assert !notifications.isSourcesInitializationRequired();
return notifications;
} else {
return null;
}
}
void setInitialized() {
sourcesInitialized.set(true);
}
boolean hasBindings() {
return !bindings.isEmpty();
}
EventBinding.Source[] getBindingsArray() {
return bindings.getArray();
}
void clearForDisposedBinding(EventBinding.Source disposedBinding) {
Lock lock = bindingsLock.writeLock();
lock.lock();
try {
bindings.remove(disposedBinding);
if (bindings.isEmpty()) {
clearAllInternal();
}
} finally {
lock.unlock();
}
}
void clearForDisposedInstrumenter(InstrumentationHandler.AbstractInstrumenter disposedInstrumenter) {
Lock lock = bindingsLock.writeLock();
lock.lock();
try {
Collection> disposedSourceLoadedBindings = InstrumentationHandler.filterBindingsForInstrumenter(bindings, disposedInstrumenter);
InstrumentationHandler.disposeBindingsBulk(disposedSourceLoadedBindings);
bindings.removeAll(disposedSourceLoadedBindings);
if (bindings.isEmpty()) {
clearAllInternal();
}
} finally {
lock.unlock();
}
}
void clearAll() {
Lock lock = bindingsLock.writeLock();
lock.lock();
try {
clearAllInternal();
} finally {
lock.unlock();
}
}
private void clearAllInternal() {
assert bindingsLock.getWriteHoldCount() > 0;
bindings.clear();
sources.clear();
sourcesList.clear();
sourcesInitialized.set(false);
notifications.clear();
notifications.invalidate();
notifications = new SourcesNotificationQueue();
}
SourcesNotificationQueue addBinding(EventBinding.Source binding, boolean notify) {
SourcesNotificationQueue notificationsToProcess = null;
Lock lock = bindingsLock.writeLock();
lock.lock();
try {
boolean initializeSources = false;
if (bindings.isEmpty()) {
initializeSources = true;
}
bindings.add(binding);
binding.attachedSemaphore.release();
if (notify) {
notificationsToProcess = addAllSourcesNotification(binding);
} else if (initializeSources) {
notificationsToProcess = addInitializeSourcesNotification();
}
} finally {
lock.unlock();
}
return notificationsToProcess;
}
SourcesNotificationQueue addNewSources(Map newSources, boolean notify) {
SourcesNotificationQueue notificationsToProcess = null;
Lock lock = bindingsLock.readLock();
lock.lock();
try {
if (!bindings.isEmpty()) {
synchronized (sources) {
if (notify) {
notificationsToProcess = addNotification(newSources, bindings.getArray());
} else {
for (Source src : newSources.keySet()) {
if (!sources.containsKey(src)) {
sources.put(src, null);
sourcesList.add(src);
}
}
}
}
}
} finally {
lock.unlock();
}
return notificationsToProcess;
}
final class SourcesNotificationQueue {
private boolean sourcesInitializationRequired;
private boolean valid = true;
private final Deque notificationQueue = new ArrayDeque<>();
SourcesNotificationQueue() {
this.sourcesInitializationRequired = true;
}
private boolean shouldProcess() {
assert bindingsLock.getWriteHoldCount() > 0 || (bindingsLock.getReadHoldCount() > 0 && Thread.holdsLock(sources));
return notificationQueue.size() == 1;
}
private void enqueue(SourcesNotification notification) {
assert bindingsLock.getWriteHoldCount() > 0 || (bindingsLock.getReadHoldCount() > 0 && Thread.holdsLock(sources));
notificationQueue.add(notification);
}
private SourcesNotification resolveFirst() {
SourcesNotification notification = null;
Lock lock = bindingsLock.readLock();
lock.lock();
try {
if (valid) {
synchronized (sources) {
notification = notificationQueue.peekFirst();
sourcesInitializationRequired = false;
if (notification != null) {
notification.resolveSources();
}
}
}
} finally {
lock.unlock();
}
return notification;
}
private boolean removeFirst() {
boolean queueNotEmpty = false;
Lock lock = bindingsLock.readLock();
lock.lock();
try {
if (valid) {
synchronized (sources) {
notificationQueue.removeFirst();
if (!notificationQueue.isEmpty()) {
queueNotEmpty = true;
}
}
}
} finally {
lock.unlock();
}
return queueNotEmpty;
}
private void clear() {
assert bindingsLock.getWriteHoldCount() > 0;
notificationQueue.clear();
}
private void invalidate() {
assert bindingsLock.getWriteHoldCount() > 0;
valid = false;
}
void process() {
do {
SourcesNotification notification = resolveFirst();
if (notification != null) {
try {
notification.runNotifications();
} catch (Throwable t) {
Lock writeLock = bindingsLock.writeLock();
writeLock.lock();
try {
clear();
} finally {
writeLock.unlock();
}
throw t;
}
}
/*
* The iteration has to be stopped as soon as the last element of the queue is
* removed and the element that is being processed has to be kept in the queue until
* its processing is complete, otherwise other threads could start processing the
* queue, because the thread that adds the first element to the queue processes the
* queue, and this thread could continue processing it too, if it tried to call
* resolveFirst after it removed the last element and other thread added another
* element.
*/
} while (removeFirst());
}
boolean isSourcesInitializationRequired() {
return sourcesInitializationRequired;
}
}
private abstract static class SourcesNotification {
protected final AtomicBoolean sourcesResolved = new AtomicBoolean();
protected final AtomicBoolean notificationsRun = new AtomicBoolean();
protected abstract void resolveSources();
protected abstract void runNotifications();
}
/*
* This notification does not notify about any sources, by being in the queue (it is always the
* first element in the queue) it makes sure the thread that added it is the one to process the
* notifications. If by that time there are more notifications in the queue, sources will be
* already initialized when these notifications are processed.
*/
private class InitializeSourcesNotification extends SourcesNotification {
@Override
protected void runNotifications() {
boolean firstCall = notificationsRun.compareAndSet(false, true);
assert firstCall : "runNotifications called more than once.";
}
@Override
protected void resolveSources() {
assert bindingsLock.getReadHoldCount() > 0;
assert Thread.holdsLock(sources);
assert sourcesInitialized.get();
boolean firstCall = sourcesResolved.compareAndSet(false, true);
assert firstCall : "resolveSources called more than once.";
}
}
/*
* This notification notifies about all sources in the sourcesList at the time the sources for
* this notification are resolved.
*/
private class AllSourcesNotification extends InitializeSourcesNotification {
protected final EventBinding.Source[] bindingsToNotify;
protected Collection sourcesForNotification;
AllSourcesNotification(EventBinding.Source[] bindingsToNotify) {
this.bindingsToNotify = bindingsToNotify;
}
@Override
protected void resolveSources() {
assert bindingsLock.getReadHoldCount() > 0;
assert Thread.holdsLock(sources);
assert sourcesInitialized.get();
boolean firstCall = sourcesResolved.compareAndSet(false, true);
assert firstCall : "resolveSources called more than once.";
sourcesForNotification = new ArrayList<>(sourcesList.getNextInsertionIndex());
for (Source source : sourcesList) {
sourcesForNotification.add(source);
}
}
@Override
protected final void runNotifications() {
assert bindingsLock.getReadHoldCount() + bindingsLock.getWriteHoldCount() == 0;
boolean firstCall = notificationsRun.compareAndSet(false, true);
assert firstCall : "runNotifications called more than once.";
if (sourcesForNotification != null) {
for (Source src : sourcesForNotification) {
notificationConsumer.accept(bindingsToNotify, src);
}
}
}
}
/*
* This notification notifies about all sources in the collectedSources that are not in the
* sourcesList already at the time sources for this notification are resolved.
*/
private class NewSourcesNotification extends AllSourcesNotification {
protected final Collection collectedSources;
NewSourcesNotification(EventBinding.Source[] bindingsToNotify, Collection collectedSources) {
super(bindingsToNotify);
this.collectedSources = collectedSources;
}
@Override
protected void resolveSources() {
assert bindingsLock.getReadHoldCount() > 0;
assert Thread.holdsLock(sources);
assert sourcesInitialized.get();
boolean firstCall = sourcesResolved.compareAndSet(false, true);
assert firstCall : "resolveSources called more than once.";
sourcesForNotification = new ArrayList<>();
for (Source src : collectedSources) {
if (!sources.containsKey(src)) {
sources.put(src, null);
sourcesList.add(src);
sourcesForNotification.add(src);
}
}
}
}
}
