Changeset 243022 in webkit

Timestamp:

Mar 15, 2019, 4:12:12 PM (6 years ago)

Author:

rniwa@webkit.org

Message:

REGRESSION (r239814): Most classes that user Timer have 7 bytes of padding after the Timer
​https://bugs.webkit.org/show_bug.cgi?id=194196

Reviewed by Simon Fraser.

Use std::nan as the value of m_unalignedNextFireTime to indicate the timer had been deleted
instead of having a dedicated boolean, which consumes 7 extra bytes for padding.

Note that some code in WebKit uses +Infinity as a fire time so we can't use that.

• platform/Timer.cpp:

(WebCore::TimerBase::TimerBase):
(WebCore::TimerBase::~TimerBase):
(WebCore::TimerBase::setNextFireTime):
(WebCore::TimerBase::nextUnalignedFireInterval const):

• platform/Timer.h:

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• platform/Timer.cpp (modified) (4 diffs)
• platform/Timer.h (modified) (1 diff)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2019-03-15  Ryosuke Niwa  <rniwa@webkit.org>
+
+        REGRESSION (r239814): Most classes that user Timer have 7 bytes of padding after the Timer
+        https://bugs.webkit.org/show_bug.cgi?id=194196
+
+        Reviewed by Simon Fraser.
+
+        Use std::nan as the value of m_unalignedNextFireTime to indicate the timer had been deleted
+        instead of having a dedicated boolean, which consumes 7 extra bytes for padding.
+
+        Note that some code in WebKit uses +Infinity as a fire time so we can't use that.
+
+        * platform/Timer.cpp:
+        (WebCore::TimerBase::TimerBase):
+        (WebCore::TimerBase::~TimerBase):
+        (WebCore::TimerBase::setNextFireTime):
+        (WebCore::TimerBase::nextUnalignedFireInterval const):
+        * platform/Timer.h:
+
 2019-03-15  Sihui Liu  <sihui_liu@apple.com>
 

trunk/Source/WebCore/platform/Timer.cpp

@@ -255 +255 @@
 
 TimerBase::TimerBase()
-    : m_wasDeleted(false)
 {
 }
@@ -265 +264 @@
     stop();
     ASSERT(!inHeap());
-    if (m_heapItem) {
+    if (m_heapItem)
         m_heapItem->clearTimer();
-        m_heapItem = nullptr;
-    }
-    m_wasDeleted = true;
+    m_unalignedNextFireTime = MonotonicTime::nan();
 }
 
@@ -468 +465 @@
     ASSERT(canAccessThreadLocalDataForThread(m_thread.get()));
     RELEASE_ASSERT(canAccessThreadLocalDataForThread(m_thread.get()) || shouldSuppressThreadSafetyCheck());
-    RELEASE_ASSERT_WITH_SECURITY_IMPLICATION(!m_wasDeleted);
-
-    if (m_unalignedNextFireTime != newTime)
+    bool timerHasBeenDeleted = std::isnan(m_unalignedNextFireTime);
+    RELEASE_ASSERT_WITH_SECURITY_IMPLICATION(!timerHasBeenDeleted);
+
+    if (m_unalignedNextFireTime != newTime) {
+        RELEASE_ASSERT(!std::isnan(newTime));
         m_unalignedNextFireTime = newTime;
+    }
 
     // Keep heap valid while changing the next-fire time.
@@ -518 +518 @@
 {
     ASSERT(isActive());
-    return std::max(m_unalignedNextFireTime - MonotonicTime::now(), 0_s);
+    auto result = std::max(m_unalignedNextFireTime - MonotonicTime::now(), 0_s);
+    RELEASE_ASSERT(std::isfinite(result));
+    return result;
 }
 

trunk/Source/WebCore/platform/Timer.h

@@ -97 +97 @@
     MonotonicTime m_unalignedNextFireTime; // m_nextFireTime not considering alignment interval
     Seconds m_repeatInterval; // 0 if not repeating
-    bool m_wasDeleted { false };
 
     RefPtr<ThreadTimerHeapItem> m_heapItem;