The Tor Browser: tools/profiler/ProfileEntry.cpp@97036ab72558 (annotated)

tools/profiler/ProfileEntry.cpp@97036ab72558 (annotated)

tools/profiler/ProfileEntry.cpp

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #include <ostream>
 #include <sstream>
 #include "platform.h"
 #include "nsThreadUtils.h"
 #include "nsXULAppAPI.h"
 #include "jsapi.h"
 // JSON
 #include "JSStreamWriter.h"
 // Self
 #include "ProfileEntry.h"
 #if _MSC_VER
  #define snprintf _snprintf
 #endif
 ////////////////////////////////////////////////////////////////////////
 // BEGIN ProfileEntry
 ProfileEntry::ProfileEntry()
   : mTagData(nullptr)
   , mTagName(0)
 { }
 // aTagData must not need release (i.e. be a string from the text segment)
 ProfileEntry::ProfileEntry(char aTagName, const char *aTagData)
   : mTagData(aTagData)
   , mTagName(aTagName)
 { }
 ProfileEntry::ProfileEntry(char aTagName, ProfilerMarker *aTagMarker)
   : mTagMarker(aTagMarker)
   , mTagName(aTagName)
 { }
 ProfileEntry::ProfileEntry(char aTagName, void *aTagPtr)
   : mTagPtr(aTagPtr)
   , mTagName(aTagName)
 { }
 ProfileEntry::ProfileEntry(char aTagName, float aTagFloat)
   : mTagFloat(aTagFloat)
   , mTagName(aTagName)
 { }
 ProfileEntry::ProfileEntry(char aTagName, uintptr_t aTagOffset)
   : mTagOffset(aTagOffset)
   , mTagName(aTagName)
 { }
 ProfileEntry::ProfileEntry(char aTagName, Address aTagAddress)
   : mTagAddress(aTagAddress)
   , mTagName(aTagName)
 { }
 ProfileEntry::ProfileEntry(char aTagName, int aTagLine)
   : mTagLine(aTagLine)
   , mTagName(aTagName)
 { }
 ProfileEntry::ProfileEntry(char aTagName, char aTagChar)
   : mTagChar(aTagChar)
   , mTagName(aTagName)
 { }
 bool ProfileEntry::is_ent_hint(char hintChar) {
   return mTagName == 'h' && mTagChar == hintChar;
 }
 bool ProfileEntry::is_ent_hint() {
   return mTagName == 'h';
 }
 bool ProfileEntry::is_ent(char tagChar) {
   return mTagName == tagChar;
 }
 void* ProfileEntry::get_tagPtr() {
   // No consistency checking.  Oh well.
   return mTagPtr;
 }
 void ProfileEntry::log()
 {
   // There is no compiler enforced mapping between tag chars
   // and union variant fields, so the following was derived
   // by looking through all the use points of TableTicker.cpp.
   //   mTagMarker (ProfilerMarker*) m
   //   mTagData   (const char*)  c,s
   //   mTagPtr    (void*)        d,l,L,B (immediate backtrace), S(start-of-stack)
   //   mTagLine   (int)          n,f
   //   mTagChar   (char)         h
   //   mTagFloat  (double)       r,t,p
   switch (mTagName) {
     case 'm':
       LOGF("%c \"%s\"", mTagName, mTagMarker->GetMarkerName()); break;
     case 'c': case 's':
       LOGF("%c \"%s\"", mTagName, mTagData); break;
     case 'd': case 'l': case 'L': case 'B': case 'S':
       LOGF("%c %p", mTagName, mTagPtr); break;
     case 'n': case 'f':
       LOGF("%c %d", mTagName, mTagLine); break;
     case 'h':
       LOGF("%c \'%c\'", mTagName, mTagChar); break;
     case 'r': case 't': case 'p':
       LOGF("%c %f", mTagName, mTagFloat); break;
     default:
       LOGF("'%c' unknown_tag", mTagName); break;
   }
 }
 std::ostream& operator<<(std::ostream& stream, const ProfileEntry& entry)
 {
   if (entry.mTagName == 'r' || entry.mTagName == 't') {
     stream << entry.mTagName << "-" << std::fixed << entry.mTagFloat << "\n";
   } else if (entry.mTagName == 'l' || entry.mTagName == 'L') {
     // Bug 739800 - Force l-tag addresses to have a "0x" prefix on all platforms
     // Additionally, stringstream seemed to be ignoring formatter flags.
     char tagBuff[1024];
     unsigned long long pc = (unsigned long long)(uintptr_t)entry.mTagPtr;
     snprintf(tagBuff, 1024, "%c-%#llx\n", entry.mTagName, pc);
     stream << tagBuff;
   } else if (entry.mTagName == 'd') {
     // TODO implement 'd' tag for text profile
   } else {
     stream << entry.mTagName << "-" << entry.mTagData << "\n";
   }
   return stream;
 }
 // END ProfileEntry
 ////////////////////////////////////////////////////////////////////////
 ////////////////////////////////////////////////////////////////////////
 // BEGIN ThreadProfile
 #define DYNAMIC_MAX_STRING 512
 ThreadProfile::ThreadProfile(const char* aName, int aEntrySize,
                              PseudoStack *aStack, Thread::tid_t aThreadId,
                              PlatformData* aPlatform,
                              bool aIsMainThread, void *aStackTop)
   : mWritePos(0)
   , mLastFlushPos(0)
   , mReadPos(0)
   , mEntrySize(aEntrySize)
   , mPseudoStack(aStack)
   , mMutex("ThreadProfile::mMutex")
   , mName(strdup(aName))
   , mThreadId(aThreadId)
   , mIsMainThread(aIsMainThread)
   , mPlatformData(aPlatform)
   , mGeneration(0)
   , mPendingGenerationFlush(0)
   , mStackTop(aStackTop)
 {
   mEntries = new ProfileEntry[mEntrySize];
 }
 ThreadProfile::~ThreadProfile()
 {
   free(mName);
   delete[] mEntries;
 }
 void ThreadProfile::addTag(ProfileEntry aTag)
 {
   // Called from signal, call only reentrant functions
   mEntries[mWritePos] = aTag;
   mWritePos = mWritePos + 1;
   if (mWritePos >= mEntrySize) {
     mPendingGenerationFlush++;
     mWritePos = mWritePos % mEntrySize;
   }
   if (mWritePos == mReadPos) {
     // Keep one slot open
     mEntries[mReadPos] = ProfileEntry();
     mReadPos = (mReadPos + 1) % mEntrySize;
   }
   // we also need to move the flush pos to ensure we
   // do not pass it
   if (mWritePos == mLastFlushPos) {
     mLastFlushPos = (mLastFlushPos + 1) % mEntrySize;
   }
 }
 // flush the new entries
 void ThreadProfile::flush()
 {
   mLastFlushPos = mWritePos;
   mGeneration += mPendingGenerationFlush;
   mPendingGenerationFlush = 0;
 }
 // discards all of the entries since the last flush()
 // NOTE: that if mWritePos happens to wrap around past
 // mLastFlushPos we actually only discard mWritePos - mLastFlushPos entries
 //
 // r = mReadPos
 // w = mWritePos
 // f = mLastFlushPos
 //
 //     r          f    w
 // |-----------------------------|
 // |   abcdefghijklmnopq         | -> 'abcdefghijklmnopq'
 // |-----------------------------|
 //
 //
 // mWritePos and mReadPos have passed mLastFlushPos
 //                      f
 //                    w r
 // |-----------------------------|
 // |ABCDEFGHIJKLMNOPQRSqrstuvwxyz|
 // |-----------------------------|
 //                       w
 //                       r
 // |-----------------------------|
 // |ABCDEFGHIJKLMNOPQRSqrstuvwxyz| -> ''
 // |-----------------------------|
 //
 //
 // mWritePos will end up the same as mReadPos
 //                r
 //              w f
 // |-----------------------------|
 // |ABCDEFGHIJKLMklmnopqrstuvwxyz|
 // |-----------------------------|
 //                r
 //                w
 // |-----------------------------|
 // |ABCDEFGHIJKLMklmnopqrstuvwxyz| -> ''
 // |-----------------------------|
 //
 //
 // mWritePos has moved past mReadPos
 //      w r       f
 // |-----------------------------|
 // |ABCDEFdefghijklmnopqrstuvwxyz|
 // |-----------------------------|
 //        r       w
 // |-----------------------------|
 // |ABCDEFdefghijklmnopqrstuvwxyz| -> 'defghijkl'
 // |-----------------------------|
 void ThreadProfile::erase()
 {
   mWritePos = mLastFlushPos;
   mPendingGenerationFlush = 0;
 }
 char* ThreadProfile::processDynamicTag(int readPos,
                                        int* tagsConsumed, char* tagBuff)
 {
   int readAheadPos = (readPos + 1) % mEntrySize;
   int tagBuffPos = 0;
   // Read the string stored in mTagData until the null character is seen
   bool seenNullByte = false;
   while (readAheadPos != mLastFlushPos && !seenNullByte) {
     (*tagsConsumed)++;
     ProfileEntry readAheadEntry = mEntries[readAheadPos];
     for (size_t pos = 0; pos < sizeof(void*); pos++) {
       tagBuff[tagBuffPos] = readAheadEntry.mTagChars[pos];
       if (tagBuff[tagBuffPos] == '\0' || tagBuffPos == DYNAMIC_MAX_STRING-2) {
         seenNullByte = true;
         break;
       }
       tagBuffPos++;
     }
     if (!seenNullByte)
       readAheadPos = (readAheadPos + 1) % mEntrySize;
   }
   return tagBuff;
 }
 void ThreadProfile::IterateTags(IterateTagsCallback aCallback)
 {
   MOZ_ASSERT(aCallback);
   int readPos = mReadPos;
   while (readPos != mLastFlushPos) {
     // Number of tag consumed
     int incBy = 1;
     const ProfileEntry& entry = mEntries[readPos];
     // Read ahead to the next tag, if it's a 'd' tag process it now
     const char* tagStringData = entry.mTagData;
     int readAheadPos = (readPos + 1) % mEntrySize;
     char tagBuff[DYNAMIC_MAX_STRING];
     // Make sure the string is always null terminated if it fills up DYNAMIC_MAX_STRING-2
     tagBuff[DYNAMIC_MAX_STRING-1] = '\0';
     if (readAheadPos != mLastFlushPos && mEntries[readAheadPos].mTagName == 'd') {
       tagStringData = processDynamicTag(readPos, &incBy, tagBuff);
     }
     aCallback(entry, tagStringData);
     readPos = (readPos + incBy) % mEntrySize;
   }
 }
 void ThreadProfile::ToStreamAsJSON(std::ostream& stream)
 {
   JSStreamWriter b(stream);
   StreamJSObject(b);
 }
 void ThreadProfile::StreamJSObject(JSStreamWriter& b)
 {
   b.BeginObject();
     // Thread meta data
     if (XRE_GetProcessType() == GeckoProcessType_Plugin) {
       // TODO Add the proper plugin name
       b.NameValue("name", "Plugin");
     } else {
       b.NameValue("name", mName);
     }
     b.NameValue("tid", static_cast<int>(mThreadId));
     b.Name("samples");
     b.BeginArray();
       bool sample = false;
       int readPos = mReadPos;
       while (readPos != mLastFlushPos) {
         // Number of tag consumed
         ProfileEntry entry = mEntries[readPos];
         switch (entry.mTagName) {
           case 'r':
             {
               if (sample) {
                 b.NameValue("responsiveness", entry.mTagFloat);
               }
             }
             break;
           case 'p':
             {
               if (sample) {
                 b.NameValue("power", entry.mTagFloat);
               }
             }
             break;
           case 'f':
             {
               if (sample) {
                 b.NameValue("frameNumber", entry.mTagLine);
               }
             }
             break;
           case 't':
             {
               if (sample) {
                 b.NameValue("time", entry.mTagFloat);
               }
             }
             break;
           case 's':
             {
               // end the previous sample if there was one
               if (sample) {
                 b.EndObject();
               }
               // begin the next sample
               b.BeginObject();
               sample = true;
               // Seek forward through the entire sample, looking for frames
               // this is an easier approach to reason about than adding more
               // control variables and cases to the loop that goes through the buffer once
               b.Name("frames");
               b.BeginArray();
                 b.BeginObject();
                   b.NameValue("location", "(root)");
                 b.EndObject();
                 int framePos = (readPos + 1) % mEntrySize;
                 ProfileEntry frame = mEntries[framePos];
                 while (framePos != mLastFlushPos && frame.mTagName != 's') {
                   int incBy = 1;
                   frame = mEntries[framePos];
                   // Read ahead to the next tag, if it's a 'd' tag process it now
                   const char* tagStringData = frame.mTagData;
                   int readAheadPos = (framePos + 1) % mEntrySize;
                   char tagBuff[DYNAMIC_MAX_STRING];
                   // Make sure the string is always null terminated if it fills up
                   // DYNAMIC_MAX_STRING-2
                   tagBuff[DYNAMIC_MAX_STRING-1] = '\0';
                   if (readAheadPos != mLastFlushPos && mEntries[readAheadPos].mTagName == 'd') {
                     tagStringData = processDynamicTag(framePos, &incBy, tagBuff);
                   }
                   // Write one frame. It can have either
                   // 1. only location - 'l' containing a memory address
                   // 2. location and line number - 'c' followed by 'd's and an optional 'n'
                   if (frame.mTagName == 'l') {
                     b.BeginObject();
                       // Bug 753041
                       // We need a double cast here to tell GCC that we don't want to sign
                       // extend 32-bit addresses starting with 0xFXXXXXX.
                       unsigned long long pc = (unsigned long long)(uintptr_t)frame.mTagPtr;
                       snprintf(tagBuff, DYNAMIC_MAX_STRING, "%#llx", pc);
                       b.NameValue("location", tagBuff);
                     b.EndObject();
                   } else if (frame.mTagName == 'c') {
                     b.BeginObject();
                       b.NameValue("location", tagStringData);
                       readAheadPos = (framePos + incBy) % mEntrySize;
                       if (readAheadPos != mLastFlushPos &&
                           mEntries[readAheadPos].mTagName == 'n') {
                         b.NameValue("line", mEntries[readAheadPos].mTagLine);
                         incBy++;
                       }
                     b.EndObject();
                   }
                   framePos = (framePos + incBy) % mEntrySize;
                 }
               b.EndArray();
             }
             break;
         }
         readPos = (readPos + 1) % mEntrySize;
       }
       if (sample) {
         b.EndObject();
       }
     b.EndArray();
     b.Name("markers");
     b.BeginArray();
       readPos = mReadPos;
       while (readPos != mLastFlushPos) {
         ProfileEntry entry = mEntries[readPos];
         if (entry.mTagName == 'm') {
            entry.getMarker()->StreamJSObject(b);
         }
         readPos = (readPos + 1) % mEntrySize;
       }
     b.EndArray();
   b.EndObject();
 }
 JSObject* ThreadProfile::ToJSObject(JSContext *aCx)
 {
   JS::RootedValue val(aCx);
   std::stringstream ss;
   {
     // Define a scope to prevent a moving GC during ~JSStreamWriter from
     // trashing the return value.
     JSStreamWriter b(ss);
     StreamJSObject(b);
     NS_ConvertUTF8toUTF16 js_string(nsDependentCString(ss.str().c_str()));
     JS_ParseJSON(aCx, static_cast<const jschar*>(js_string.get()), js_string.Length(), &val);
   }
   return &val.toObject();
 }
 PseudoStack* ThreadProfile::GetPseudoStack()
 {
   return mPseudoStack;
 }
 void ThreadProfile::BeginUnwind()
 {
   mMutex.Lock();
 }
 void ThreadProfile::EndUnwind()
 {
   mMutex.Unlock();
 }
 mozilla::Mutex* ThreadProfile::GetMutex()
 {
   return &mMutex;
 }
 void ThreadProfile::DuplicateLastSample() {
   // Scan the whole buffer (even unflushed parts)
   // Adding mEntrySize makes the result of the modulus positive
   // We search backwards from mWritePos-1 to mReadPos
   for (int readPos  = (mWritePos + mEntrySize - 1) % mEntrySize;
            readPos !=  (mReadPos + mEntrySize - 1) % mEntrySize;
            readPos  =   (readPos + mEntrySize - 1) % mEntrySize) {
     if (mEntries[readPos].mTagName == 's') {
       // Found the start of the last entry at position readPos
       int copyEndIdx = mWritePos;
       // Go through the whole entry and duplicate it
       for (;readPos != copyEndIdx; readPos = (readPos + 1) % mEntrySize) {
         switch (mEntries[readPos].mTagName) {
           // Copy with new time
           case 't':
             addTag(ProfileEntry('t', static_cast<float>((mozilla::TimeStamp::Now() - sStartTime).ToMilliseconds())));
             break;
           // Don't copy markers
           case 'm':
             break;
           // Copy anything else we don't know about
           // L, B, S, c, s, d, l, f, h, r, t, p
           default:
             addTag(mEntries[readPos]);
             break;
         }
       }
       break;
     }
   }
 }
 std::ostream& operator<<(std::ostream& stream, const ThreadProfile& profile)
 {
   int readPos = profile.mReadPos;
   while (readPos != profile.mLastFlushPos) {
     stream << profile.mEntries[readPos];
     readPos = (readPos + 1) % profile.mEntrySize;
   }
   return stream;
 }
 // END ThreadProfile
 ////////////////////////////////////////////////////////////////////////

The Tor Browser / annotate

tools/profiler/ProfileEntry.cpp@97036ab72558 (annotated)

tools/profiler/ProfileEntry.cpp