1 /* 2 * Copyright (C) 2008 Apple Inc. All Rights Reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY 14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE COMPUTER, INC. OR 17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY 21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24 * 25 */ 26 27 #include "config.h" 28 #include "core/frame/DOMTimer.h" 29 30 #include "core/dom/ExecutionContext.h" 31 #include "core/inspector/InspectorInstrumentation.h" 32 #include "core/inspector/InspectorTraceEvents.h" 33 #include "platform/TraceEvent.h" 34 #include "wtf/CurrentTime.h" 35 36 namespace WebCore { 37 38 static const int maxIntervalForUserGestureForwarding = 1000; // One second matches Gecko. 39 static const int maxTimerNestingLevel = 5; 40 static const double oneMillisecond = 0.001; 41 // Chromium uses a minimum timer interval of 4ms. We'd like to go 42 // lower; however, there are poorly coded websites out there which do 43 // create CPU-spinning loops. Using 4ms prevents the CPU from 44 // spinning too busily and provides a balance between CPU spinning and 45 // the smallest possible interval timer. 46 static const double minimumInterval = 0.004; 47 48 static int timerNestingLevel = 0; 49 50 static inline bool shouldForwardUserGesture(int interval, int nestingLevel) 51 { 52 return UserGestureIndicator::processingUserGesture() 53 && interval <= maxIntervalForUserGestureForwarding 54 && nestingLevel == 1; // Gestures should not be forwarded to nested timers. 55 } 56 57 double DOMTimer::hiddenPageAlignmentInterval() 58 { 59 // Timers on hidden pages are aligned so that they fire once per 60 // second at most. 61 return 1.0; 62 } 63 64 double DOMTimer::visiblePageAlignmentInterval() 65 { 66 // Alignment does not apply to timers on visible pages. 67 return 0; 68 } 69 70 int DOMTimer::install(ExecutionContext* context, PassOwnPtr<ScheduledAction> action, int timeout, bool singleShot) 71 { 72 int timeoutID = context->installNewTimeout(action, timeout, singleShot); 73 TRACE_EVENT_INSTANT1(TRACE_DISABLED_BY_DEFAULT("devtools.timeline"), "TimerInstall", "data", InspectorTimerInstallEvent::data(context, timeoutID, timeout, singleShot)); 74 TRACE_EVENT_INSTANT1(TRACE_DISABLED_BY_DEFAULT("devtools.timeline.stack"), "CallStack", "stack", InspectorCallStackEvent::currentCallStack()); 75 // FIXME(361045): remove InspectorInstrumentation calls once DevTools Timeline migrates to tracing. 76 InspectorInstrumentation::didInstallTimer(context, timeoutID, timeout, singleShot); 77 return timeoutID; 78 } 79 80 void DOMTimer::removeByID(ExecutionContext* context, int timeoutID) 81 { 82 context->removeTimeoutByID(timeoutID); 83 TRACE_EVENT_INSTANT1(TRACE_DISABLED_BY_DEFAULT("devtools.timeline"), "TimerRemove", "data", InspectorTimerRemoveEvent::data(context, timeoutID)); 84 TRACE_EVENT_INSTANT1(TRACE_DISABLED_BY_DEFAULT("devtools.timeline.stack"), "CallStack", "stack", InspectorCallStackEvent::currentCallStack()); 85 // FIXME(361045): remove InspectorInstrumentation calls once DevTools Timeline migrates to tracing. 86 InspectorInstrumentation::didRemoveTimer(context, timeoutID); 87 } 88 89 DOMTimer::DOMTimer(ExecutionContext* context, PassOwnPtr<ScheduledAction> action, int interval, bool singleShot, int timeoutID) 90 : SuspendableTimer(context) 91 , m_timeoutID(timeoutID) 92 , m_nestingLevel(timerNestingLevel + 1) 93 , m_action(action) 94 { 95 ASSERT(timeoutID > 0); 96 if (shouldForwardUserGesture(interval, m_nestingLevel)) 97 m_userGestureToken = UserGestureIndicator::currentToken(); 98 99 double intervalMilliseconds = std::max(oneMillisecond, interval * oneMillisecond); 100 if (intervalMilliseconds < minimumInterval && m_nestingLevel >= maxTimerNestingLevel) 101 intervalMilliseconds = minimumInterval; 102 if (singleShot) 103 startOneShot(intervalMilliseconds, FROM_HERE); 104 else 105 startRepeating(intervalMilliseconds, FROM_HERE); 106 } 107 108 DOMTimer::~DOMTimer() 109 { 110 } 111 112 int DOMTimer::timeoutID() const 113 { 114 return m_timeoutID; 115 } 116 117 void DOMTimer::fired() 118 { 119 ExecutionContext* context = executionContext(); 120 timerNestingLevel = m_nestingLevel; 121 ASSERT(!context->activeDOMObjectsAreSuspended()); 122 // Only the first execution of a multi-shot timer should get an affirmative user gesture indicator. 123 UserGestureIndicator gestureIndicator(m_userGestureToken.release()); 124 125 TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("devtools.timeline"), "TimerFire", "data", InspectorTimerFireEvent::data(context, m_timeoutID)); 126 // FIXME(361045): remove InspectorInstrumentation calls once DevTools Timeline migrates to tracing. 127 InspectorInstrumentationCookie cookie = InspectorInstrumentation::willFireTimer(context, m_timeoutID); 128 129 // Simple case for non-one-shot timers. 130 if (isActive()) { 131 if (repeatInterval() && repeatInterval() < minimumInterval) { 132 m_nestingLevel++; 133 if (m_nestingLevel >= maxTimerNestingLevel) 134 augmentRepeatInterval(minimumInterval - repeatInterval()); 135 } 136 137 // No access to member variables after this point, it can delete the timer. 138 m_action->execute(context); 139 140 InspectorInstrumentation::didFireTimer(cookie); 141 142 return; 143 } 144 145 // Delete timer before executing the action for one-shot timers. 146 OwnPtr<ScheduledAction> action = m_action.release(); 147 148 // This timer is being deleted; no access to member variables allowed after this point. 149 context->removeTimeoutByID(m_timeoutID); 150 151 action->execute(context); 152 153 InspectorInstrumentation::didFireTimer(cookie); 154 TRACE_EVENT_INSTANT1(TRACE_DISABLED_BY_DEFAULT("devtools.timeline"), "UpdateCounters", "data", InspectorUpdateCountersEvent::data()); 155 156 timerNestingLevel = 0; 157 } 158 159 void DOMTimer::contextDestroyed() 160 { 161 SuspendableTimer::contextDestroyed(); 162 } 163 164 void DOMTimer::stop() 165 { 166 SuspendableTimer::stop(); 167 // Need to release JS objects potentially protected by ScheduledAction 168 // because they can form circular references back to the ExecutionContext 169 // which will cause a memory leak. 170 m_action.clear(); 171 } 172 173 double DOMTimer::alignedFireTime(double fireTime) const 174 { 175 double alignmentInterval = executionContext()->timerAlignmentInterval(); 176 if (alignmentInterval) { 177 double currentTime = monotonicallyIncreasingTime(); 178 if (fireTime <= currentTime) 179 return fireTime; 180 181 // When a repeating timer is scheduled for exactly the 182 // background page alignment interval, because it's impossible 183 // for the timer to be rescheduled instantaneously, it misses 184 // every other fire time. Avoid this by looking at the next 185 // fire time rounded both down and up. 186 187 double alignedTimeRoundedDown = floor(fireTime / alignmentInterval) * alignmentInterval; 188 double alignedTimeRoundedUp = ceil(fireTime / alignmentInterval) * alignmentInterval; 189 190 // If the version rounded down is in the past, discard it 191 // immediately. 192 193 if (alignedTimeRoundedDown <= currentTime) 194 return alignedTimeRoundedUp; 195 196 // Only use the rounded-down time if it's within a certain 197 // tolerance of the fire time. This avoids speeding up timers 198 // on background pages in the common case. 199 200 if (fireTime - alignedTimeRoundedDown < minimumInterval) 201 return alignedTimeRoundedDown; 202 203 return alignedTimeRoundedUp; 204 } 205 206 return fireTime; 207 } 208 209 } // namespace WebCore 210