OffThreadScriptCompilation.cpp

/* -*- Mode: C++; tab-width: 8; 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 "js/OffThreadScriptCompilation.h"

#include "mozilla/Assertions.h"  // MOZ_ASSERT
#include "mozilla/Range.h"       // mozilla::Range
#include "mozilla/Utf8.h"        // mozilla::Utf8Unit
#include "mozilla/Vector.h"      // mozilla::Vector

#include <stddef.h>  // size_t

#include "jspubtd.h"  // js::CurrentThreadCanAccessRuntime
#include "jstypes.h"  // JS_PUBLIC_API

#include "js/CompileOptions.h"  // JS::ReadOnlyCompileOptions
#include "vm/HelperThreads.h"  // js::OffThreadParsingMustWaitForGC, js::StartOffThreadParseScript
#include "vm/JSContext.h"  // JSContext
#include "vm/Runtime.h"    // js::CanUseExtraThreads

using namespace js;

using mozilla::Utf8Unit;

using JS::ReadOnlyCompileOptions;

enum class OffThread { Compile, Decode, DecodeBinAST };

static bool CanDoOffThread(JSContext* cx, const ReadOnlyCompileOptions& options,
                           size_t length, OffThread what) {
  static const size_t TINY_LENGTH = 5 * 1000;
  static const size_t HUGE_SRC_LENGTH = 100 * 1000;
  static const size_t HUGE_BC_LENGTH = 367 * 1000;
  static const size_t HUGE_BINAST_LENGTH = 70 * 1000;

  // These are heuristics which the caller may choose to ignore (e.g., for
  // testing purposes).
  if (!options.forceAsync) {
    // Compiling off the main thread inolves creating a new Zone and other
    // significant overheads.  Don't bother if the script is tiny.
    if (length < TINY_LENGTH) {
      return false;
    }

    // If the parsing task would have to wait for GC to complete, it'll probably
    // be faster to just start it synchronously on the main thread unless the
    // script is huge.
    if (OffThreadParsingMustWaitForGC(cx->runtime())) {
      if (what == OffThread::Compile && length < HUGE_SRC_LENGTH) {
        return false;
      }
      if (what == OffThread::Decode && length < HUGE_BC_LENGTH) {
        return false;
      }
      if (what == OffThread::DecodeBinAST && length < HUGE_BINAST_LENGTH) {
        return false;
      }
    }
  }

  return cx->runtime()->canUseParallelParsing() && CanUseExtraThreads() &&
         !mozilla::recordreplay::IsRecordingOrReplaying();
}

JS_PUBLIC_API bool JS::CanCompileOffThread(
    JSContext* cx, const ReadOnlyCompileOptions& options, size_t length) {
  return CanDoOffThread(cx, options, length, OffThread::Compile);
}

JS_PUBLIC_API bool JS::CanDecodeOffThread(JSContext* cx,
                                          const ReadOnlyCompileOptions& options,
                                          size_t length) {
  return CanDoOffThread(cx, options, length, OffThread::Decode);
}

#ifdef JS_BUILD_BINAST
JS_PUBLIC_API bool JS::CanDecodeBinASTOffThread(
    JSContext* cx, const ReadOnlyCompileOptions& options, size_t length) {
  return CanDoOffThread(cx, options, length, OffThread::DecodeBinAST);
}
#endif

JS_PUBLIC_API bool JS::CompileOffThread(JSContext* cx,
                                        const ReadOnlyCompileOptions& options,
                                        JS::SourceText<char16_t>& srcBuf,
                                        OffThreadCompileCallback callback,
                                        void* callbackData) {
  MOZ_ASSERT(CanCompileOffThread(cx, options, srcBuf.length()));
  return StartOffThreadParseScript(cx, options, srcBuf, callback, callbackData);
}

JS_PUBLIC_API bool JS::CompileOffThread(JSContext* cx,
                                        const ReadOnlyCompileOptions& options,
                                        JS::SourceText<Utf8Unit>& srcBuf,
                                        OffThreadCompileCallback callback,
                                        void* callbackData) {
  MOZ_ASSERT(CanCompileOffThread(cx, options, srcBuf.length()));
  return StartOffThreadParseScript(cx, options, srcBuf, callback, callbackData);
}

JS_PUBLIC_API JSScript* JS::FinishOffThreadScript(JSContext* cx,
                                                  JS::OffThreadToken* token) {
  MOZ_ASSERT(cx);
  MOZ_ASSERT(CurrentThreadCanAccessRuntime(cx->runtime()));
  return HelperThreadState().finishScriptParseTask(cx, token);
}

JS_PUBLIC_API void JS::CancelOffThreadScript(JSContext* cx,
                                             JS::OffThreadToken* token) {
  MOZ_ASSERT(cx);
  MOZ_ASSERT(CurrentThreadCanAccessRuntime(cx->runtime()));
  HelperThreadState().cancelParseTask(cx->runtime(), ParseTaskKind::Script,
                                      token);
}

JS_PUBLIC_API bool JS::CompileOffThreadModule(
    JSContext* cx, const ReadOnlyCompileOptions& options,
    JS::SourceText<char16_t>& srcBuf, OffThreadCompileCallback callback,
    void* callbackData) {
  MOZ_ASSERT(CanCompileOffThread(cx, options, srcBuf.length()));
  return StartOffThreadParseModule(cx, options, srcBuf, callback, callbackData);
}

JS_PUBLIC_API bool JS::CompileOffThreadModule(
    JSContext* cx, const ReadOnlyCompileOptions& options,
    JS::SourceText<Utf8Unit>& srcBuf, OffThreadCompileCallback callback,
    void* callbackData) {
  MOZ_ASSERT(CanCompileOffThread(cx, options, srcBuf.length()));
  return StartOffThreadParseModule(cx, options, srcBuf, callback, callbackData);
}

JS_PUBLIC_API JSObject* JS::FinishOffThreadModule(JSContext* cx,
                                                  JS::OffThreadToken* token) {
  MOZ_ASSERT(cx);
  MOZ_ASSERT(CurrentThreadCanAccessRuntime(cx->runtime()));
  return HelperThreadState().finishModuleParseTask(cx, token);
}

JS_PUBLIC_API void JS::CancelOffThreadModule(JSContext* cx,
                                             JS::OffThreadToken* token) {
  MOZ_ASSERT(cx);
  MOZ_ASSERT(CurrentThreadCanAccessRuntime(cx->runtime()));
  HelperThreadState().cancelParseTask(cx->runtime(), ParseTaskKind::Module,
                                      token);
}

JS_PUBLIC_API bool JS::DecodeOffThreadScript(
    JSContext* cx, const ReadOnlyCompileOptions& options,
    mozilla::Vector<uint8_t>& buffer /* TranscodeBuffer& */, size_t cursor,
    OffThreadCompileCallback callback, void* callbackData) {
  JS::TranscodeRange range(buffer.begin() + cursor, buffer.length() - cursor);
  MOZ_ASSERT(CanDecodeOffThread(cx, options, range.length()));
  return StartOffThreadDecodeScript(cx, options, range, callback, callbackData);
}

JS_PUBLIC_API bool JS::DecodeOffThreadScript(
    JSContext* cx, const ReadOnlyCompileOptions& options,
    const mozilla::Range<uint8_t>& range /* TranscodeRange& */,
    OffThreadCompileCallback callback, void* callbackData) {
  MOZ_ASSERT(CanDecodeOffThread(cx, options, range.length()));
  return StartOffThreadDecodeScript(cx, options, range, callback, callbackData);
}

JS_PUBLIC_API bool JS::DecodeMultiOffThreadScripts(
    JSContext* cx, const ReadOnlyCompileOptions& options,
    TranscodeSources& sources, OffThreadCompileCallback callback,
    void* callbackData) {
#ifdef DEBUG
  size_t length = 0;
  for (auto& source : sources) {
    length += source.range.length();
  }
  MOZ_ASSERT(CanCompileOffThread(cx, options, length));
#endif
  return StartOffThreadDecodeMultiScripts(cx, options, sources, callback,
                                          callbackData);
}

JS_PUBLIC_API JSScript* JS::FinishOffThreadScriptDecoder(
    JSContext* cx, JS::OffThreadToken* token) {
  MOZ_ASSERT(cx);
  MOZ_ASSERT(CurrentThreadCanAccessRuntime(cx->runtime()));
  return HelperThreadState().finishScriptDecodeTask(cx, token);
}

JS_PUBLIC_API void JS::CancelOffThreadScriptDecoder(JSContext* cx,
                                                    JS::OffThreadToken* token) {
  MOZ_ASSERT(cx);
  MOZ_ASSERT(CurrentThreadCanAccessRuntime(cx->runtime()));
  HelperThreadState().cancelParseTask(cx->runtime(),
                                      ParseTaskKind::ScriptDecode, token);
}

JS_PUBLIC_API bool JS::FinishMultiOffThreadScriptsDecoder(
    JSContext* cx, JS::OffThreadToken* token,
    MutableHandle<ScriptVector> scripts) {
  MOZ_ASSERT(cx);
  MOZ_ASSERT(CurrentThreadCanAccessRuntime(cx->runtime()));
  return HelperThreadState().finishMultiScriptsDecodeTask(cx, token, scripts);
}

JS_PUBLIC_API void JS::CancelMultiOffThreadScriptsDecoder(
    JSContext* cx, JS::OffThreadToken* token) {
  MOZ_ASSERT(cx);
  MOZ_ASSERT(CurrentThreadCanAccessRuntime(cx->runtime()));
  HelperThreadState().cancelParseTask(cx->runtime(),
                                      ParseTaskKind::MultiScriptsDecode, token);
}