1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
|
/*
* Copyright (C) 2013, 2015 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 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 "Watchdog.h"
#include "CallFrame.h"
#include <wtf/CurrentTime.h>
#include <wtf/MathExtras.h>
namespace JSC {
const std::chrono::microseconds Watchdog::noTimeLimit = std::chrono::microseconds::max();
static std::chrono::microseconds currentWallClockTime()
{
auto steadyTimeSinceEpoch = std::chrono::steady_clock::now().time_since_epoch();
return std::chrono::duration_cast<std::chrono::microseconds>(steadyTimeSinceEpoch);
}
Watchdog::Watchdog()
: m_timerDidFire(false)
, m_timeLimit(noTimeLimit)
, m_cpuDeadline(noTimeLimit)
, m_wallClockDeadline(noTimeLimit)
, m_callback(0)
, m_callbackData1(0)
, m_callbackData2(0)
, m_timerQueue(WorkQueue::create("jsc.watchdog.queue", WorkQueue::Type::Serial, WorkQueue::QOS::Utility))
{
}
void Watchdog::setTimeLimit(std::chrono::microseconds limit,
ShouldTerminateCallback callback, void* data1, void* data2)
{
LockHolder locker(m_lock);
m_timeLimit = limit;
m_callback = callback;
m_callbackData1 = data1;
m_callbackData2 = data2;
if (m_hasEnteredVM && hasTimeLimit())
startTimer(locker, m_timeLimit);
}
JS_EXPORT_PRIVATE void Watchdog::terminateSoon()
{
LockHolder locker(m_lock);
m_timeLimit = std::chrono::microseconds(0);
m_cpuDeadline = std::chrono::microseconds(0);
m_wallClockDeadline = std::chrono::microseconds(0);
m_timerDidFire = true;
}
bool Watchdog::shouldTerminateSlow(ExecState* exec)
{
{
LockHolder locker(m_lock);
ASSERT(m_timerDidFire);
m_timerDidFire = false;
if (currentWallClockTime() < m_wallClockDeadline)
return false; // Just a stale timer firing. Nothing to do.
// Set m_wallClockDeadline to noTimeLimit here so that we can reject all future
// spurious wakes.
m_wallClockDeadline = noTimeLimit;
auto cpuTime = currentCPUTime();
if (cpuTime < m_cpuDeadline) {
auto remainingCPUTime = m_cpuDeadline - cpuTime;
startTimer(locker, remainingCPUTime);
return false;
}
}
// Note: we should not be holding the lock while calling the callbacks. The callbacks may
// call setTimeLimit() which will try to lock as well.
// If m_callback is not set, then we terminate by default.
// Else, we let m_callback decide if we should terminate or not.
bool needsTermination = !m_callback
|| m_callback(exec, m_callbackData1, m_callbackData2);
if (needsTermination)
return true;
{
LockHolder locker(m_lock);
// If we get here, then the callback above did not want to terminate execution. As a
// result, the callback may have done one of the following:
// 1. cleared the time limit (i.e. watchdog is disabled),
// 2. set a new time limit via Watchdog::setTimeLimit(), or
// 3. did nothing (i.e. allow another cycle of the current time limit).
//
// In the case of 1, we don't have to do anything.
// In the case of 2, Watchdog::setTimeLimit() would already have started the timer.
// In the case of 3, we need to re-start the timer here.
ASSERT(m_hasEnteredVM);
bool callbackAlreadyStartedTimer = (m_cpuDeadline != noTimeLimit);
if (hasTimeLimit() && !callbackAlreadyStartedTimer)
startTimer(locker, m_timeLimit);
}
return false;
}
bool Watchdog::hasTimeLimit()
{
return (m_timeLimit != noTimeLimit);
}
void Watchdog::enteredVM()
{
m_hasEnteredVM = true;
if (hasTimeLimit()) {
LockHolder locker(m_lock);
startTimer(locker, m_timeLimit);
}
}
void Watchdog::exitedVM()
{
ASSERT(m_hasEnteredVM);
LockHolder locker(m_lock);
stopTimer(locker);
m_hasEnteredVM = false;
}
void Watchdog::startTimer(LockHolder&, std::chrono::microseconds timeLimit)
{
ASSERT(m_hasEnteredVM);
ASSERT(hasTimeLimit());
ASSERT(timeLimit <= m_timeLimit);
m_cpuDeadline = currentCPUTime() + timeLimit;
auto wallClockTime = currentWallClockTime();
auto wallClockDeadline = wallClockTime + timeLimit;
if ((wallClockTime < m_wallClockDeadline)
&& (m_wallClockDeadline <= wallClockDeadline))
return; // Wait for the current active timer to expire before starting a new one.
// Else, the current active timer won't fire soon enough. So, start a new timer.
this->ref(); // m_timerHandler will deref to match later.
m_wallClockDeadline = wallClockDeadline;
m_timerQueue->dispatchAfter(std::chrono::nanoseconds(timeLimit), [this] {
{
LockHolder locker(m_lock);
m_timerDidFire = true;
}
deref();
});
}
void Watchdog::stopTimer(LockHolder&)
{
m_cpuDeadline = noTimeLimit;
}
} // namespace JSC
|
