DevTools: Support asynchronous call stacks on backend.

Source/core/inspector/AsyncCallStackTracker.cpp

+/*
+ * Copyright (C) 2013 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "config.h"
+#include "core/inspector/AsyncCallStackTracker.h"
+
+namespace WebCore {
+
+AsyncCallStackTracker::AsyncCallStack::AsyncCallStack(AsyncCallStack* next)
+    : m_callFrames(ScriptValue())
+    , m_next(next)
+    , m_pathCount(0)
+{
+}
+
+AsyncCallStackTracker::AsyncCallStackIterator::AsyncCallStackIterator(AsyncCallStack* head, AsyncCallStack* tail)
+    : m_head(head)
+    , m_tail(tail)
+{
+}
+
+bool AsyncCallStackTracker::AsyncCallStackIterator::hasNext() const
+{
+    return m_head && m_head != m_tail && !m_head->m_callFrames.hasNoValue();
+}
+
+ScriptValue AsyncCallStackTracker::AsyncCallStackIterator::next()
+{
+    ASSERT(hasNext());
+    ScriptValue result = m_head->m_callFrames;
+    m_head = m_head->m_next;
+    if (m_head == m_tail)
+        m_head = m_tail = 0;
+    return result;
+}
+
+AsyncCallStackTracker::AsyncCallStackTracker()
+    : m_maxAsyncCallStackDepth(0)
+    , m_currentAsyncCallStackDelta(0)
+{
+}
+
+void AsyncCallStackTracker::setAsyncCallStackDepth(int depth)
+{
+    if (depth <= 0) {
+        m_maxAsyncCallStackDepth = 0;
+        clear();
+    } else {
+        m_maxAsyncCallStackDepth = depth;
+    }
+}
+
+AsyncCallStackTracker::AsyncCallStackIterator AsyncCallStackTracker::currentAsyncCallStack()
+{
+    RefPtr<AsyncCallStack> head = m_currentAsyncCallStack;
+    RefPtr<AsyncCallStack> tail = m_currentAsyncCallStack;
+    for (int i = 0; tail && i < m_maxAsyncCallStackDepth; ++i)
+        tail = tail->m_next;
+    return AsyncCallStackTracker::AsyncCallStackIterator(head.get(), tail.get());
+}
+
+void AsyncCallStackTracker::didInstallTimer(int timerId, bool singleShot)
+{
+    if (!isEnabled())
+        return;
+    ASSERT(timerId > 0);
+    m_timerCallStacks.add(timerId, requestAsyncCallStack());
+    if (!singleShot)
+        m_intervalTimerIds.add(timerId);
+}
+
+void AsyncCallStackTracker::didRemoveTimer(int timerId)
+{
+    if (!isEnabled() || timerId <= 0)
+        return;
+    m_intervalTimerIds.remove(timerId);
+    modifyPathCount(m_timerCallStacks.take(timerId), -1);
+}
+
+void AsyncCallStackTracker::willFireTimer(int timerId)
+{
+    if (!isEnabled())
+        return;
+    ASSERT(timerId > 0);
+    ASSERT(!m_currentAsyncCallStack);
+    if (m_intervalTimerIds.contains(timerId))
+        setCurrentAsyncCallStack(m_timerCallStacks.get(timerId), 0);
+    else
+        setCurrentAsyncCallStack(m_timerCallStacks.take(timerId), -1);
+}
+
+void AsyncCallStackTracker::didRequestAnimationFrame(int callbackId)
+{
+    if (!isEnabled())
+        return;
+    ASSERT(callbackId > 0);
+    m_animationFrameCallStacks.add(callbackId, requestAsyncCallStack());
+}
+
+void AsyncCallStackTracker::didCancelAnimationFrame(int callbackId)
+{
+    if (!isEnabled() || callbackId <= 0)
+        return;
+    modifyPathCount(m_animationFrameCallStacks.take(callbackId), -1);
+}
+
+void AsyncCallStackTracker::willFireAnimationFrame(int callbackId)
+{
+    if (!isEnabled())
+        return;
+    ASSERT(callbackId > 0);
+    ASSERT(!m_currentAsyncCallStack);
+    setCurrentAsyncCallStack(m_animationFrameCallStacks.take(callbackId), -1);
+}
+
+void AsyncCallStackTracker::didAsyncCall()
+{
+    if (!isEnabled())
+        return;
+    setCurrentAsyncCallStack(0, 0);
+}
+
+void AsyncCallStackTracker::didRequestAsyncCallFrames(ScriptValue callFrames)
+{
+    if (!isEnabled())
+        return;
+    ASSERT(m_requestedAsyncCallStack);
+    if (!m_requestedAsyncCallStack)
+        return;
+    m_requestedAsyncCallStack->m_callFrames = callFrames;
+    m_requestedAsyncCallStack = 0;
+}
+
+AsyncCallStackTracker::AsyncCallStack* AsyncCallStackTracker::requestAsyncCallStack()
+{
+    ASSERT(isEnabled());
+    ASSERT(!m_requestedAsyncCallStack);
+    m_requestedAsyncCallStack = adoptRef(new AsyncCallStackTracker::AsyncCallStack(m_currentAsyncCallStack.get()));
+    modifyPathCount(m_requestedAsyncCallStack, 1);
+    return m_requestedAsyncCallStack.get();
+}
+
+void AsyncCallStackTracker::setCurrentAsyncCallStack(PassRefPtr<AsyncCallStack> callStack, int delta)
+{
+    if (m_currentAsyncCallStack)
+        modifyPathCount(m_currentAsyncCallStack.release(), m_currentAsyncCallStackDelta);
+    m_currentAsyncCallStack = callStack;
+    m_currentAsyncCallStackDelta = delta;
+}
+
+void AsyncCallStackTracker::modifyPathCount(PassRefPtr<AsyncCallStack> head, int delta)
+{
+    if (!head || !delta)
+        return;
+    if (head == m_currentAsyncCallStack) {
+        // Defer modifying the path count.

[yurys, 2013/11/28 09:18:16]

Why do you need to defer here, can't we simply check that
m_currentAsyncCallStack.m_pathCount == 0 and delete m_currentAsyncCallStack (in
fact we won't need to do this check explicitly as m_currentAsyncCallStack should
have only on refCount == 1 if its m_pathCount == 0).

+        m_currentAsyncCallStackDelta += delta;
+        return;
+    }
+    int depth = 0;
+    RefPtr<AsyncCallStack> current = head;
+    while (current && depth < m_maxAsyncCallStackDepth) {
+        ++depth;
+        current->m_pathCount += delta;
+        if (current->m_pathCount <= 0) {

[yurys, 2013/11/28 09:18:16]

If m_pathCount == 0 we should dispose of current, shouldn't we?

+            ASSERT(!current->m_pathCount);
+            current = current->m_next.release();
+        } else {
+            current = current->m_next;
+        }
+    }
+}
+
+void AsyncCallStackTracker::clear()
+{
+    m_currentAsyncCallStackDelta = 0;
+    m_currentAsyncCallStack = 0;
+    m_requestedAsyncCallStack = 0;
+    m_intervalTimerIds.clear();
+    m_timerCallStacks.clear();
+    m_animationFrameCallStacks.clear();
+}
+
+} // namespace WebCore