Add threading support.

gold/workqueue-internal.h

@@ -0,0 +1,129 @@
+// workqueue-internal.h -- internal work queue header for gold   -*- C++ -*-
+
+// Copyright 2006, 2007 Free Software Foundation, Inc.
+// Written by Ian Lance Taylor <iant@google.com>.
+
+// This file is part of gold.
+
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+// MA 02110-1301, USA.
+
+#ifndef GOLD_WORKQUEUE_INTERNAL_H
+#define GOLD_WORKQUEUE_INTERNAL_H
+
+#include <queue>
+
+#include "gold-threads.h"
+#include "workqueue.h"
+
+// This is an internal header file for different gold workqueue
+// implementations.
+
+namespace gold
+{
+
+class Workqueue_thread;
+
+// The Workqueue_runner abstract class.  This is the interface used by
+// the general workqueue code to actually run a task.
+
+class Workqueue_runner
+{
+ public:
+  Workqueue_runner(Workqueue* workqueue)
+    : workqueue_(workqueue)
+  { }
+  virtual ~Workqueue_runner()
+  { }
+
+  // Run a task.  This is always called in the main thread.
+  virtual void
+  run(Task*, Task_locker*) = 0;
+
+  // Set the number of threads to use.  This is ignored when not using
+  // threads.
+  virtual void
+  set_thread_count(int) = 0;
+
+ protected:
+  // This is called by an implementation when a task is completed.
+  void completed(Task* t, Task_locker* tl)
+  { this->workqueue_->completed(t, tl); }
+
+  Workqueue* get_workqueue() const
+  { return this->workqueue_; }
+
+ private:
+  Workqueue* workqueue_;
+};
+
+// The threaded instantiation of Workqueue_runner.
+
+class Workqueue_runner_threadpool : public Workqueue_runner
+{
+ public:
+  Workqueue_runner_threadpool(Workqueue* workqueue);
+
+  ~Workqueue_runner_threadpool();
+
+  void
+  run(Task*, Task_locker*);
+
+  void
+  set_thread_count(int);
+
+ private:
+  // This class can not be copied.
+  Workqueue_runner_threadpool(const Workqueue_runner_threadpool&);
+  Workqueue_runner_threadpool& operator=(const Workqueue_runner_threadpool&);
+
+  // Return the next Task and Task_locker to run.  This returns false
+  // if the calling thread should simply exit.
+  bool
+  get_next(Task**, Task_locker**);
+
+  // This is called when the thread completes a task.
+  void
+  thread_completed(Task*, Task_locker*);
+
+  // The Workqueue_thread class calls functions from this and from the
+  // parent Workqueue_runner.
+  friend class Workqueue_thread;
+
+  // An entry on the queue of tasks to run.
+  typedef std::pair<Task*, Task_locker*> Task_queue_entry;
+
+  // A queue of tasks to run.
+  typedef std::queue<Task_queue_entry> Task_queue;
+
+  // The number of threads we want to create.  This is only changed in
+  // the main thread or when only one thread is running.  This is set
+  // to zero when all threads should exit.
+  int desired_thread_count_;
+  // A lock controlling access to the remaining fields.
+  Lock lock_;
+  // The number of threads we have created.
+  int actual_thread_count_;
+  // The number of threads which are running a task.
+  int running_thread_count_;
+  // A queue of tasks to run.
+  Task_queue task_queue_;
+  // A condition variable which signals when the task_queue_ changed.
+  Condvar task_queue_condvar_;
+};
+
+} // End namespace gold.
+
+#endif // !defined(GOLD_WORKQUEUE_INTERNAL_H)