Made SuspendableTimer smaller (removed redudant m_active field)

Source/core/frame/SuspendableTimer.cpp

 /*
  * Copyright (C) 2008 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. 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.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``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 APPLE COMPUTER, INC. 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/frame/SuspendableTimer.h"
 
+#include <cfloat>
+
 namespace blink {
 
+namespace {
+const double kNextFireIntervalInvalid = -DBL_MAX;

[João Eiras, 2014/10/17 16:04:10]

m_nextFireInterval could be zero for the case of setTimeout(...,0) (I thought
that was rounded up). So, now I'm using this as invalid value. Still lgtm ?

[Mike West, 2014/10/18 09:06:42]

Hrm. This kills some of the elegance of the previous solution. Ah well.

1. This value can't ever be negative, can it? If not, then -1 would be fine.
There's no reason to allow all sorts of negative values which are greated than
-DBL_MAX.

2. If we run with -MAX, let's spell it `std::numeric_limits<double>::min()`.

+}
+
 SuspendableTimer::SuspendableTimer(ExecutionContext* context)
     : ActiveDOMObject(context)
-    , m_nextFireInterval(0)
+    , m_nextFireInterval(kNextFireIntervalInvalid)
     , m_repeatInterval(0)
-    , m_active(false)
 #if ENABLE(ASSERT)
     , m_suspended(false)
 #endif
 {
 }
 
 SuspendableTimer::~SuspendableTimer()
 {
 }
 
 bool SuspendableTimer::hasPendingActivity() const
 {
     return isActive();
 }
 
 void SuspendableTimer::stop()
 {
+    m_nextFireInterval = kNextFireIntervalInvalid;
     TimerBase::stop();
 }
 
 void SuspendableTimer::suspend()
 {
 #if ENABLE(ASSERT)
     ASSERT(!m_suspended);
     m_suspended = true;
 #endif
-    m_active = isActive();
-    if (m_active) {
+    if (isActive()) {
         m_nextFireInterval = nextUnalignedFireInterval();
         m_repeatInterval = repeatInterval();
         TimerBase::stop();
     }
 }
 
 void SuspendableTimer::resume()
 {
 #if ENABLE(ASSERT)
     ASSERT(m_suspended);
     m_suspended = false;
 #endif
-    // FIXME: FROM_HERE is wrong here.
-    if (m_active)
-        start(m_nextFireInterval, m_repeatInterval, FROM_HERE);
+    if (m_nextFireInterval > kNextFireIntervalInvalid) {
+        // start() was called before, therefore location() is already set.
+        // m_nextFireInterval is only set in suspend() if the Timer was active.
+        start(m_nextFireInterval, m_repeatInterval, location());
+        m_nextFireInterval = kNextFireIntervalInvalid;
+    }
 }
 
 } // namespace blink