Two-threaded parser

src/parser-thread.cc

+// Copyright 2014 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "parser-thread.h"
+
+#include "api.h"
+#include "platform/condition-variable.h"
+#include "preparse-data.h"
+#include "scanner-character-streams.h"
+#include "unbound-queue.h"
+
+namespace v8 {
+namespace internal {
+
+static const int kFastParserThreadStackSize = 64 * KB;
+
+class BackgroundParsingTask {
+ public:
+  BackgroundParsingTask(Utf16CharacterStream* stream,
+                        bool allow_harmony_scoping,
+                        bool allow_modules,
+                        bool allow_natives_syntax,
+                        bool allow_generators,
+                        bool allow_for_of,
+                        bool allow_harmony_numeric_literals)
+    : stream_(stream),
+      result_(PreParser::kPreParseSuccess),
+      allow_harmony_scoping_(allow_harmony_scoping),
+      allow_modules_(allow_modules),
+      allow_natives_syntax_(allow_natives_syntax),
+      allow_generators_(allow_generators),
+      allow_for_of_(allow_for_of),
+      allow_harmony_numeric_literals_(allow_harmony_numeric_literals) {}
+
+
+  void Produce(int start, int end, int literals,
+               int properties, StrictMode strict_mode) {
+    LockGuard<Mutex> lock_guard(&mutex_);
+    LazyFunction function(start, end, literals, properties, strict_mode);
+    data_.Enqueue(function);
+    have_data_.NotifyOne();
+  }
+
+
+  void Consume(int* start, int* end, int* literals,
+               int* properties, StrictMode* strict_mode) {
+    LockGuard<Mutex> lock_guard(&mutex_);
+    if (data_.IsEmpty())
+      have_data_.Wait(&mutex_);  // Implicitly unlocks and locks the mutex.
+    ASSERT(!data_.IsEmpty());
+    LazyFunction function;
+    data_.Dequeue(&function);
+    *start = function.start;
+    *end = function.end;
+    *literals = function.literals;
+    *properties = function.properties;
+    *strict_mode = function.strict_mode;
+  }
+
+
+  void Run(FastParserThread* thread) {
+    DisallowHeapAllocation no_allocation;
+    DisallowHandleAllocation no_handles;
+    DisallowHandleDereference no_deref;
+    UnicodeCache unicode_cache;
+    Scanner scanner(&unicode_cache);
+    uintptr_t limit =
+        reinterpret_cast<uintptr_t>(&limit) - kFastParserThreadStackSize;
+    PreParser preparser(&scanner, &recorder_, limit, thread);
+    preparser.set_allow_lazy(true);

[ulan, 2014/04/23 10:18:20]

Would it be worthwhile to put these flags into a separate struct that can be
copied? Then this code would look like
params_.allow_lazy = true;
preparser.set_params(params_);

In other places you would need to pass one struct instead of passing each flag
indiviually.

[Sven Panne, 2014/04/23 10:36:29]

+1 for this proposal, see
http://refactoring.com/catalog/introduceParameterObject.html

+    preparser.set_allow_harmony_scoping(allow_harmony_scoping_);
+    preparser.set_allow_modules(allow_modules_);
+    preparser.set_allow_natives_syntax(allow_natives_syntax_);
+    preparser.set_allow_generators(allow_generators_);
+    preparser.set_allow_for_of(allow_for_of_);
+    preparser.set_allow_harmony_numeric_literals(
+        allow_harmony_numeric_literals_);
+    scanner.Initialize(stream_);
+    result_ = preparser.PreParseProgram();
+
+    // Queue a dummy data element, so that the Parser doesn't wait forever if it
+    // expects the thread to produce more data than it will. (For example, when
+    // the thread parses a function and encounters an error.)
+    Produce(-1, -1, -1, -1, SLOPPY);
+  }
+
+ private:
+  friend class FastParserThread;
+  struct LazyFunction {
+    int start;
+    int end;
+    int literals;
+    int properties;
+    StrictMode strict_mode;
+    LazyFunction(int s, int e, int l, int p, StrictMode st)
+        : start(s), end(e), literals(l), properties(p), strict_mode(st) {}
+    LazyFunction()
+        : start(-1),
+          end(-1),
+          literals(-1),
+          properties(-1),
+          strict_mode(SLOPPY) {}
+  };
+
+  Utf16CharacterStream* stream_;
+  SingletonLogger recorder_;
+  Mutex mutex_;
+  ConditionVariable have_data_;
+  UnboundQueue<LazyFunction> data_;
+  PreParser::PreParseResult result_;
+  bool allow_harmony_scoping_;
+  bool allow_modules_;
+  bool allow_natives_syntax_;
+  bool allow_generators_;
+  bool allow_for_of_;
+  bool allow_harmony_numeric_literals_;
+};
+
+
+FastParserThread::FastParserThread()
+    : Thread(
+          Thread::Options("v8::FastParserThread", kFastParserThreadStackSize)),
+      current_task_(NULL),
+      have_work_(0),
+      work_done_(0),
+      should_stop_(false) {}
+
+
+void FastParserThread::StartBackgroundParsing(
+    Utf16CharacterStream* stream, bool allow_harmony_scoping,
+    bool allow_modules, bool allow_natives_syntax, bool allow_generators,
+    bool allow_for_of, bool allow_harmony_numeric_literals) {
+  ASSERT(current_task_ == NULL);
+  current_task_ = new BackgroundParsingTask(
+      stream, allow_harmony_scoping, allow_modules, allow_natives_syntax,
+      allow_generators, allow_for_of, allow_harmony_numeric_literals);
+  have_work_.Signal();
+}
+
+
+void FastParserThread::FinishBackgroundParsing() {
+  work_done_.Wait();
+  delete current_task_;

[Michael Starzinger, 2014/04/23 09:07:10]

This deletes the background parsing task, but I cannot find the place where the
external string stream is deleted. Is it missing?

+  current_task_ = NULL;
+}
+
+
+void FastParserThread::Run() {
+  while (true) {
+    have_work_.Wait();
+    if (should_stop_) {
+      break;
+    }
+    ASSERT(current_task_ != NULL);
+    current_task_->Run(this);
+    work_done_.Signal();
+  }
+}
+
+
+void FastParserThread::Stop() {
+  should_stop_ = true;
+  have_work_.Signal();
+  Join();
+}
+
+
+void FastParserThread::Produce(int start, int end, int literals, int properties,
+                               StrictMode strict_mode) {
+  ASSERT(current_task_);
+  current_task_->Produce(start, end, literals, properties, strict_mode);
+}
+
+
+void FastParserThread::Consume(int* start, int* end, int* literals,
+                               int* properties, StrictMode* strict_mode) {
+  ASSERT(current_task_);
+  current_task_->Consume(start, end, literals, properties, strict_mode);
+}
+
+
+PreParser::PreParseResult FastParserThread::result() const {
+  ASSERT(current_task_);
+  return current_task_->result_;
+}
+
+
+const SingletonLogger* FastParserThread::recorder() const {
+  ASSERT(current_task_);
+  return &(current_task_->recorder_);
+}
+
+
+} }  // namespace v8::internal