gecko-dev/tools/profiler/core/ProfileBuffer.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 "ProfileBuffer.h"

#include "ProfilerMarker.h"
#include "jsfriendapi.h"
#include "nsScriptSecurityManager.h"
#include "nsJSPrincipals.h"

using namespace mozilla;

ProfileBuffer::ProfileBuffer(int aEntrySize)
  : mEntries(mozilla::MakeUnique<ProfileBufferEntry[]>(aEntrySize))
  , mWritePos(0)
  , mReadPos(0)
  , mEntrySize(aEntrySize)
  , mGeneration(0)
{
}

ProfileBuffer::~ProfileBuffer()
{
  while (mStoredMarkers.peek()) {
    delete mStoredMarkers.popHead();
  }
}

// Called from signal, call only reentrant functions
void
ProfileBuffer::AddEntry(const ProfileBufferEntry& aEntry)
{
  mEntries[mWritePos++] = aEntry;
  if (mWritePos == mEntrySize) {
    // Wrapping around may result in things referenced in the buffer (e.g.,
    // JIT code addresses and markers) being incorrectly collected.
    MOZ_ASSERT(mGeneration != UINT32_MAX);
    mGeneration++;
    mWritePos = 0;
  }

  if (mWritePos == mReadPos) {
    // Keep one slot open.
    mEntries[mReadPos] = ProfileBufferEntry();
    mReadPos = (mReadPos + 1) % mEntrySize;
  }
}

void
ProfileBuffer::AddThreadIdEntry(int aThreadId, LastSample* aLS)
{
  if (aLS) {
    // This is the start of a sample, so make a note of its location in |aLS|.
    aLS->mGeneration = mGeneration;
    aLS->mPos = mWritePos;
  }
  AddEntry(ProfileBufferEntry::ThreadId(aThreadId));
}

void
ProfileBuffer::AddStoredMarker(ProfilerMarker *aStoredMarker)
{
  aStoredMarker->SetGeneration(mGeneration);
  mStoredMarkers.insert(aStoredMarker);
}

void
ProfileBuffer::CollectCodeLocation(
  const char* aLabel, const char* aStr, int aLineNumber,
  const Maybe<js::ProfileEntry::Category>& aCategory)
{
  AddEntry(ProfileBufferEntry::Label(aLabel));

  if (aStr) {
    // Store the string using one or more DynamicStringFragment entries.
    size_t strLen = strlen(aStr) + 1;   // +1 for the null terminator
    for (size_t j = 0; j < strLen; ) {
      // Store up to kNumChars characters in the entry.
      char chars[ProfileBufferEntry::kNumChars];
      size_t len = ProfileBufferEntry::kNumChars;
      if (j + len >= strLen) {
        len = strLen - j;
      }
      memcpy(chars, &aStr[j], len);
      j += ProfileBufferEntry::kNumChars;

      AddEntry(ProfileBufferEntry::DynamicStringFragment(chars));
    }
  }

  if (aLineNumber != -1) {
    AddEntry(ProfileBufferEntry::LineNumber(aLineNumber));
  }

  if (aCategory.isSome()) {
    AddEntry(ProfileBufferEntry::Category(int(*aCategory)));
  }
}

void
ProfileBuffer::DeleteExpiredStoredMarkers()
{
  // Delete markers of samples that have been overwritten due to circular
  // buffer wraparound.
  uint32_t generation = mGeneration;
  while (mStoredMarkers.peek() &&
         mStoredMarkers.peek()->HasExpired(generation)) {
    delete mStoredMarkers.popHead();
  }
}

void
ProfileBuffer::Reset()
{
  mGeneration += 2;
  mReadPos = mWritePos = 0;
}

size_t
ProfileBuffer::SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
{
  size_t n = aMallocSizeOf(this);
  n += aMallocSizeOf(mEntries.get());

  // Measurement of the following members may be added later if DMD finds it
  // is worthwhile:
  // - memory pointed to by the elements within mEntries
  // - mStoredMarkers

  return n;
}

/* ProfileBufferCollector */

static bool
IsChromeJSScript(JSScript* aScript)
{
  // WARNING: this function runs within the profiler's "critical section".

  nsIScriptSecurityManager* const secman =
    nsScriptSecurityManager::GetScriptSecurityManager();
  NS_ENSURE_TRUE(secman, false);

  JSPrincipals* const principals = JS_GetScriptPrincipals(aScript);
  return secman->IsSystemPrincipal(nsJSPrincipals::get(principals));
}

Maybe<uint32_t>
ProfileBufferCollector::Generation()
{
  return Some(mBuf.mGeneration);
}

void
ProfileBufferCollector::CollectNativeLeafAddr(void* aAddr)
{
  mBuf.AddEntry(ProfileBufferEntry::NativeLeafAddr(aAddr));
}

void
ProfileBufferCollector::CollectJitReturnAddr(void* aAddr)
{
  mBuf.AddEntry(ProfileBufferEntry::JitReturnAddr(aAddr));
}

void
ProfileBufferCollector::CollectWasmFrame(const char* aLabel)
{
  mBuf.CollectCodeLocation("", aLabel, -1, Nothing());
}

void
ProfileBufferCollector::CollectPseudoEntry(const js::ProfileEntry& aEntry)
{
  // WARNING: this function runs within the profiler's "critical section".

  MOZ_ASSERT(aEntry.kind() == js::ProfileEntry::Kind::CPP_NORMAL ||
             aEntry.kind() == js::ProfileEntry::Kind::JS_NORMAL);

  const char* label = aEntry.label();
  const char* dynamicString = aEntry.dynamicString();
  bool isChromeJSEntry = false;
  int lineno = -1;

  if (aEntry.isJs()) {
    // There are two kinds of JS frames that get pushed onto the PseudoStack.
    //
    // - label = "", dynamic string = <something>
    // - label = "js::RunScript", dynamic string = nullptr
    //
    // The line number is only interesting in the first case.

    if (label[0] == '\0') {
      MOZ_ASSERT(dynamicString);

      // We call aEntry.script() repeatedly -- rather than storing the result in
      // a local variable in order -- to avoid rooting hazards.
      if (aEntry.script()) {
        isChromeJSEntry = IsChromeJSScript(aEntry.script());
        if (aEntry.pc()) {
          lineno = JS_PCToLineNumber(aEntry.script(), aEntry.pc());
        }
      }

    } else {
      MOZ_ASSERT(strcmp(label, "js::RunScript") == 0 && !dynamicString);
    }
  } else {
    MOZ_ASSERT(aEntry.isCpp());
    lineno = aEntry.line();
  }

  if (dynamicString) {
    // Adjust the dynamic string as necessary.
    if (ProfilerFeature::HasPrivacy(mFeatures) && !isChromeJSEntry) {
      dynamicString = "(private)";
    } else if (strlen(dynamicString) >= ProfileBuffer::kMaxFrameKeyLength) {
      dynamicString = "(too long)";
    }
  }

  mBuf.CollectCodeLocation(label, dynamicString, lineno,
                           Some(aEntry.category()));
}