Commit eb90b3b1 authored by Gerald Squelart's avatar Gerald Squelart
Browse files

Bug 1784812 - JSONWriter may optionally not own its writer - r=canaltinova 

mWriter is now a reference, and the ownership is optional through a separate
member variable that could stay null.
User can now choose to keep the JSONWriteFunc on their stack, which saves a
heap allocation, and makes it easier to access the concrete JSONWriteFunc
implementation directly (instead of through WriteFunc()).

Differential Revision: https://phabricator.services.mozilla.com/D154617
parent 24798f28

browser/app/winlauncher/ErrorHandler.cpp

+2 −7
Original line number Diff line number Diff line
@@ -623,12 +623,8 @@ static bool PrepPing(const PingThreadContext& aContext, const std::wstring& aId, 
}



static bool DoSendPing(const PingThreadContext& aContext) {

  auto writeFunc = mozilla::MakeUnique<TempFileWriter>();

  if (!(*writeFunc)) {

    return false;

  }



  mozilla::JSONWriter json(std::move(writeFunc));

  TempFileWriter tempFile;

  mozilla::JSONWriter json(tempFile);



  UUID uuid;

  if (::UuidCreate(&uuid) != RPC_S_OK) {
@@ -650,7 +646,6 @@ static bool DoSendPing(const PingThreadContext& aContext) { 
  }



  // Obtain the name of the temp file that we have written

  TempFileWriter& tempFile = static_cast<TempFileWriter&>(json.WriteFunc());

  const std::wstring& fileName = tempFile.GetFileName();



  // Using the path to our executable binary, construct the path to

dom/reporting/ReportDeliver.cpp

+1 −1
Original line number Diff line number Diff line
@@ -111,7 +111,7 @@ class ReportJSONWriter final : public JSONWriter { 
                    const Span<const char>& aJSON) {

    Separator();

    PropertyNameAndColon(aProperty);

    mWriter->Write(aJSON);

    mWriter.Write(aJSON);

  }

};

mfbt/JSONWriter.h

+31 −20
Original line number Diff line number Diff line
@@ -250,14 +250,15 @@ class JSONWriter { 
  static constexpr Span<const char> scTopObjectEndString = MakeStringSpan("}");

  static constexpr Span<const char> scTrueString = MakeStringSpan("true");



  const UniquePtr<JSONWriteFunc> mWriter;

  JSONWriteFunc& mWriter;

  const UniquePtr<JSONWriteFunc> mMaybeOwnedWriter;

  Vector<bool, 8> mNeedComma;     // do we need a comma at depth N?

  Vector<bool, 8> mNeedNewlines;  // do we need newlines at depth N?

  size_t mDepth;                  // the current nesting depth



  void Indent() {

    for (size_t i = 0; i < mDepth; i++) {

      mWriter->Write(scSpaceString);

      mWriter.Write(scSpaceString);

    }

  }
@@ -266,22 +267,22 @@ class JSONWriter { 
  // before.

  void Separator() {

    if (mNeedComma[mDepth]) {

      mWriter->Write(scCommaString);

      mWriter.Write(scCommaString);

    }

    if (mDepth > 0 && mNeedNewlines[mDepth]) {

      mWriter->Write(scNewLineString);

      mWriter.Write(scNewLineString);

      Indent();

    } else if (mNeedComma[mDepth] && mNeedNewlines[0]) {

      mWriter->Write(scSpaceString);

      mWriter.Write(scSpaceString);

    }

  }



  void PropertyNameAndColon(const Span<const char>& aName) {

    mWriter->Write(scPropertyBeginString);

    mWriter->Write(EscapedString(aName).SpanRef());

    mWriter->Write(scPropertyEndString);

    mWriter.Write(scPropertyBeginString);

    mWriter.Write(EscapedString(aName).SpanRef());

    mWriter.Write(scPropertyEndString);

    if (mNeedNewlines[0]) {

      mWriter->Write(scSpaceString);

      mWriter.Write(scSpaceString);

    }

  }
@@ -291,7 +292,7 @@ class JSONWriter { 
    if (!aMaybePropertyName.empty()) {

      PropertyNameAndColon(aMaybePropertyName);

    }

    mWriter->Write(aStringValue);

    mWriter.Write(aStringValue);

    mNeedComma[mDepth] = true;

  }
@@ -301,9 +302,9 @@ class JSONWriter { 
    if (!aMaybePropertyName.empty()) {

      PropertyNameAndColon(aMaybePropertyName);

    }

    mWriter->Write(scQuoteString);

    mWriter->Write(aStringValue);

    mWriter->Write(scQuoteString);

    mWriter.Write(scQuoteString);

    mWriter.Write(aStringValue);

    mWriter.Write(scQuoteString);

    mNeedComma[mDepth] = true;

  }
@@ -323,7 +324,7 @@ class JSONWriter { 
    if (!aMaybePropertyName.empty()) {

      PropertyNameAndColon(aMaybePropertyName);

    }

    mWriter->Write(aStartChar);

    mWriter.Write(aStartChar);

    mNeedComma[mDepth] = true;

    mDepth++;

    NewVectorEntries(mNeedNewlines[mDepth - 1] && aStyle == MultiLineStyle);
@@ -333,28 +334,38 @@ class JSONWriter { 
  void EndCollection(const Span<const char>& aEndChar) {

    MOZ_ASSERT(mDepth > 0);

    if (mNeedNewlines[mDepth]) {

      mWriter->Write(scNewLineString);

      mWriter.Write(scNewLineString);

      mDepth--;

      Indent();

    } else {

      mDepth--;

    }

    mWriter->Write(aEndChar);

    mWriter.Write(aEndChar);

  }



 public:

  explicit JSONWriter(JSONWriteFunc& aWriter,

                      CollectionStyle aStyle = MultiLineStyle)

      : mWriter(aWriter), mNeedComma(), mNeedNewlines(), mDepth(0) {

    NewVectorEntries(aStyle == MultiLineStyle);

  }



  explicit JSONWriter(UniquePtr<JSONWriteFunc> aWriter,

                      CollectionStyle aStyle = MultiLineStyle)

      : mWriter(std::move(aWriter)), mNeedComma(), mNeedNewlines(), mDepth(0) {

      : mWriter(*aWriter),

        mMaybeOwnedWriter(std::move(aWriter)),

        mNeedComma(),

        mNeedNewlines(),

        mDepth(0) {

    MOZ_RELEASE_ASSERT(

        mWriter,

        mMaybeOwnedWriter,

        "JSONWriter must be given a non-null UniquePtr<JSONWriteFunc>");

    NewVectorEntries(aStyle == MultiLineStyle);

  }



  // Returns the JSONWriteFunc passed in at creation, for temporary use. The

  // JSONWriter object still owns the JSONWriteFunc.

  JSONWriteFunc& WriteFunc() const { return *mWriter.get(); }

  JSONWriteFunc& WriteFunc() const { return mWriter; }



  // For all the following functions, the "Prints:" comment indicates what the

  // basic output looks like. However, it doesn't indicate the whitespace and
@@ -371,7 +382,7 @@ class JSONWriter { 
  void End() {

    EndCollection(scTopObjectEndString);

    if (mNeedNewlines[mDepth]) {

      mWriter->Write(scNewLineString);

      mWriter.Write(scNewLineString);

    }

  }

mfbt/tests/TestJSONWriter.cpp

+2 −1
Original line number Diff line number Diff line
@@ -439,7 +439,8 @@ void TestOneLineJson() { 
{\"i\":1,\"array\":[null,[{}],{\"o\":{}},\"s\"],\"d\":3.33}\

";



  JSONWriter w(MakeUnique<StringWriteFunc>(), JSONWriter::SingleLineStyle);

  StringWriteFunc func;

  JSONWriter w(func, JSONWriter::SingleLineStyle);



  w.Start(w.MultiLineStyle);  // style overridden from above

mozglue/baseprofiler/core/platform.cpp

+2 −1
Original line number Diff line number Diff line
@@ -3028,7 +3028,8 @@ static void locked_profiler_save_profile_to_file(PSLockRef aLock, 
  std::ofstream stream;

  stream.open(aFilename);

  if (stream.is_open()) {

    SpliceableJSONWriter w(MakeUnique<OStreamJSONWriteFunc>(stream));

    OStreamJSONWriteFunc jw(stream);

    SpliceableJSONWriter w(jw);

    w.Start();

    {

      locked_profiler_stream_json_for_this_process(aLock, w, /* sinceTime */ 0,