1/* 2 * Copyright (C) 2012 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 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 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#ifndef StackStats_h 27#define StackStats_h 28 29#include "ExportMacros.h" 30#include <mutex> 31 32 33// Define this flag to enable Stack stats collection. This feature is useful 34// for getting a sample of native stack usage sizes. 35// 36// Enabling this will cause stats to be collected and written to a log file at 37// various instrumented points in the code. It will result in noticeable 38// performance loss. Hence, this should only be enable when you want to do 39// some stats location in your local build. This code is provided here as a 40// convenience for collecting that data. It is not meant to be enabled by 41// default on release or debug builds. 42 43#define ENABLE_STACK_STATS 0 44 45 46namespace WTF { 47 48#if !ENABLE(STACK_STATS) 49 50class StackStats { 51public: 52 // The CheckPoint class is for marking check points corresponding 53 // each location in code where a stack recursion check is being done. 54 55 class CheckPoint { 56 public: 57 CheckPoint() { } 58 }; 59 60 class PerThreadStats { 61 public: 62 PerThreadStats() { } 63 }; 64 65 class LayoutCheckPoint { 66 public: 67 LayoutCheckPoint() { } 68 }; 69 70 static void initialize() { } 71 static void probe() { } 72}; 73 74#else // ENABLE(STACK_STATS) 75 76class StackStats { 77public: 78 // The CheckPoint class is for marking check points corresponding 79 // each location in code where a stack recursion check is being done. 80 81 class CheckPoint { 82 public: 83 CheckPoint(); 84 ~CheckPoint(); 85 private: 86 CheckPoint* m_prev; 87 }; 88 89 class PerThreadStats { 90 public: 91 PerThreadStats(); 92 93 private: 94 int m_reentryDepth; 95 char* m_stackStart; 96 CheckPoint* m_currentCheckPoint; 97 98 friend class CheckPoint; 99 friend class StackStats; 100 }; 101 102 class LayoutCheckPoint { 103 public: 104 WTF_EXPORT_PRIVATE LayoutCheckPoint(); 105 WTF_EXPORT_PRIVATE ~LayoutCheckPoint(); 106 107 private: 108 LayoutCheckPoint* m_prev; 109 int m_depth; 110 }; 111 112 // Initializes locks and the log file. Should only be called once. 113 static void initialize(); 114 115 // Used for probing the stack at places where we suspect to be high 116 // points of stack usage but are NOT check points where stack recursion 117 // is checked. 118 // 119 // The more places where we add this probe, the more accurate our 120 // stats data will be. However, adding too many probes will also 121 // result in unnecessary performance loss. So, only add these probes 122 // judiciously where appropriate. 123 static void probe(); 124 125private: 126 // CheckPoint management: 127 static std::mutex* s_sharedMutex; 128 static CheckPoint* s_topCheckPoint; 129 static LayoutCheckPoint* s_firstLayoutCheckPoint; 130 static LayoutCheckPoint* s_topLayoutCheckPoint; 131 132 // High watermark stats: 133 static int s_maxCheckPointDiff; 134 static int s_maxStackHeight; 135 static int s_maxReentryDepth; 136 137 static int s_maxLayoutCheckPointDiff; 138 static int s_maxTotalLayoutCheckPointDiff; 139 static int s_maxLayoutReentryDepth; 140 141 friend class CheckPoint; 142 friend class LayoutCheckPoint; 143}; 144 145#endif // ENABLE(STACK_STATS) 146 147} // namespace WTF 148 149using WTF::StackStats; 150 151#endif // StackStats_h 152