Torne (Richard Coles) | 1e20218 | 2013-10-18 15:46:42 +0100 | [diff] [blame] | 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 | |
Torne (Richard Coles) | 1e20218 | 2013-10-18 15:46:42 +0100 | [diff] [blame] | 30 | #include "core/dom/ExecutionContext.h" |
| 31 | #include "core/inspector/InspectorInstrumentation.h" |
| 32 | #include "wtf/CurrentTime.h" |
| 33 | |
| 34 | using namespace std; |
| 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 | InspectorInstrumentation::didInstallTimer(context, timeoutID, timeout, singleShot); |
| 74 | return timeoutID; |
| 75 | } |
| 76 | |
| 77 | void DOMTimer::removeByID(ExecutionContext* context, int timeoutID) |
| 78 | { |
| 79 | context->removeTimeoutByID(timeoutID); |
| 80 | InspectorInstrumentation::didRemoveTimer(context, timeoutID); |
| 81 | } |
| 82 | |
| 83 | DOMTimer::DOMTimer(ExecutionContext* context, PassOwnPtr<ScheduledAction> action, int interval, bool singleShot, int timeoutID) |
| 84 | : SuspendableTimer(context) |
| 85 | , m_timeoutID(timeoutID) |
| 86 | , m_nestingLevel(timerNestingLevel + 1) |
| 87 | , m_action(action) |
| 88 | { |
| 89 | ASSERT(timeoutID > 0); |
| 90 | if (shouldForwardUserGesture(interval, m_nestingLevel)) |
| 91 | m_userGestureToken = UserGestureIndicator::currentToken(); |
| 92 | |
| 93 | double intervalMilliseconds = max(oneMillisecond, interval * oneMillisecond); |
| 94 | if (intervalMilliseconds < minimumInterval && m_nestingLevel >= maxTimerNestingLevel) |
| 95 | intervalMilliseconds = minimumInterval; |
| 96 | if (singleShot) |
| 97 | startOneShot(intervalMilliseconds); |
| 98 | else |
| 99 | startRepeating(intervalMilliseconds); |
| 100 | } |
| 101 | |
| 102 | DOMTimer::~DOMTimer() |
| 103 | { |
| 104 | } |
| 105 | |
| 106 | int DOMTimer::timeoutID() const |
| 107 | { |
| 108 | return m_timeoutID; |
| 109 | } |
| 110 | |
| 111 | void DOMTimer::fired() |
| 112 | { |
| 113 | ExecutionContext* context = executionContext(); |
| 114 | timerNestingLevel = m_nestingLevel; |
| 115 | ASSERT(!context->activeDOMObjectsAreSuspended()); |
| 116 | // Only the first execution of a multi-shot timer should get an affirmative user gesture indicator. |
| 117 | UserGestureIndicator gestureIndicator(m_userGestureToken.release()); |
| 118 | |
| 119 | InspectorInstrumentationCookie cookie = InspectorInstrumentation::willFireTimer(context, m_timeoutID); |
| 120 | |
| 121 | // Simple case for non-one-shot timers. |
| 122 | if (isActive()) { |
| 123 | if (repeatInterval() && repeatInterval() < minimumInterval) { |
| 124 | m_nestingLevel++; |
| 125 | if (m_nestingLevel >= maxTimerNestingLevel) |
| 126 | augmentRepeatInterval(minimumInterval - repeatInterval()); |
| 127 | } |
| 128 | |
| 129 | // No access to member variables after this point, it can delete the timer. |
| 130 | m_action->execute(context); |
| 131 | |
| 132 | InspectorInstrumentation::didFireTimer(cookie); |
| 133 | |
| 134 | return; |
| 135 | } |
| 136 | |
| 137 | // Delete timer before executing the action for one-shot timers. |
| 138 | OwnPtr<ScheduledAction> action = m_action.release(); |
| 139 | |
| 140 | // This timer is being deleted; no access to member variables allowed after this point. |
| 141 | context->removeTimeoutByID(m_timeoutID); |
| 142 | |
| 143 | action->execute(context); |
| 144 | |
| 145 | InspectorInstrumentation::didFireTimer(cookie); |
| 146 | |
| 147 | timerNestingLevel = 0; |
| 148 | } |
| 149 | |
| 150 | void DOMTimer::contextDestroyed() |
| 151 | { |
| 152 | SuspendableTimer::contextDestroyed(); |
| 153 | } |
| 154 | |
| 155 | void DOMTimer::stop() |
| 156 | { |
| 157 | SuspendableTimer::stop(); |
| 158 | // Need to release JS objects potentially protected by ScheduledAction |
| 159 | // because they can form circular references back to the ExecutionContext |
| 160 | // which will cause a memory leak. |
| 161 | m_action.clear(); |
| 162 | } |
| 163 | |
| 164 | double DOMTimer::alignedFireTime(double fireTime) const |
| 165 | { |
| 166 | double alignmentInterval = executionContext()->timerAlignmentInterval(); |
| 167 | if (alignmentInterval) { |
| 168 | double currentTime = monotonicallyIncreasingTime(); |
| 169 | if (fireTime <= currentTime) |
| 170 | return fireTime; |
| 171 | |
| 172 | // When a repeating timer is scheduled for exactly the |
| 173 | // background page alignment interval, because it's impossible |
| 174 | // for the timer to be rescheduled instantaneously, it misses |
| 175 | // every other fire time. Avoid this by looking at the next |
| 176 | // fire time rounded both down and up. |
| 177 | |
| 178 | double alignedTimeRoundedDown = floor(fireTime / alignmentInterval) * alignmentInterval; |
| 179 | double alignedTimeRoundedUp = ceil(fireTime / alignmentInterval) * alignmentInterval; |
| 180 | |
| 181 | // If the version rounded down is in the past, discard it |
| 182 | // immediately. |
| 183 | |
| 184 | if (alignedTimeRoundedDown <= currentTime) |
| 185 | return alignedTimeRoundedUp; |
| 186 | |
| 187 | // Only use the rounded-down time if it's within a certain |
| 188 | // tolerance of the fire time. This avoids speeding up timers |
| 189 | // on background pages in the common case. |
| 190 | |
| 191 | if (fireTime - alignedTimeRoundedDown < minimumInterval) |
| 192 | return alignedTimeRoundedDown; |
| 193 | |
| 194 | return alignedTimeRoundedUp; |
| 195 | } |
| 196 | |
| 197 | return fireTime; |
| 198 | } |
| 199 | |
| 200 | } // namespace WebCore |