stabilize build system: depends, installer, boost/bdb fixes, cross targets groundwork

depends/x86_64-pc-linux-gnu/include/boost/thread/user_scheduler.hpp

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+// Copyright (C) 2013 Vicente J. Botet Escriba
+//
+//  Distributed under the Boost Software License, Version 1.0. (See accompanying
+//  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+// 2013/11 Vicente J. Botet Escriba
+//    first implementation of a simple serial scheduler.
+
+#ifndef BOOST_THREAD_USER_SCHEDULER_HPP
+#define BOOST_THREAD_USER_SCHEDULER_HPP
+
+#include <boost/thread/detail/config.hpp>
+#include <boost/thread/detail/delete.hpp>
+#include <boost/thread/detail/move.hpp>
+#include <boost/thread/concurrent_queues/sync_queue.hpp>
+#include <boost/thread/executors/work.hpp>
+
+#include <boost/config/abi_prefix.hpp>
+
+namespace boost
+{
+
+  class user_scheduler
+  {
+    /// type-erasure to store the works to do
+    typedef  executors::work work;
+
+    /// the thread safe work queue
+    sync_queue<work > work_queue;
+
+  public:
+    /**
+     * Effects: try to execute one task.
+     * Returns: whether a task has been executed.
+     * Throws: whatever the current task constructor throws or the task() throws.
+     */
+    bool try_executing_one()
+    {
+      work task;
+      try
+      {
+        if (work_queue.try_pull(task) == queue_op_status::success)
+        {
+          task();
+          return true;
+        }
+        return false;
+      }
+      catch (std::exception& )
+      {
+        return false;
+      }
+      catch (...)
+      {
+        return false;
+      }
+    }
+  private:
+    /**
+     * Effects: schedule one task or yields
+     * Throws: whatever the current task constructor throws or the task() throws.
+     */
+    void schedule_one_or_yield()
+    {
+        if ( ! try_executing_one())
+        {
+          this_thread::yield();
+        }
+    }
+
+
+    /**
+     * The main loop of the worker thread
+     */
+    void worker_thread()
+    {
+      while (!closed())
+      {
+        schedule_one_or_yield();
+      }
+      while (try_executing_one())
+      {
+      }
+    }
+
+  public:
+    /// user_scheduler is not copyable.
+    BOOST_THREAD_NO_COPYABLE(user_scheduler)
+
+    /**
+     * \b Effects: creates a thread pool that runs closures using one of its closure-executing methods.
+     *
+     * \b Throws: Whatever exception is thrown while initializing the needed resources.
+     */
+    user_scheduler()
+    {
+    }
+    /**
+     * \b Effects: Destroys the thread pool.
+     *
+     * \b Synchronization: The completion of all the closures happen before the completion of the \c user_scheduler destructor.
+     */
+    ~user_scheduler()
+    {
+      // signal to all the worker thread that there will be no more submissions.
+      close();
+    }
+
+    /**
+     * loop
+     */
+    void loop() { worker_thread(); }
+    /**
+     * \b Effects: close the \c user_scheduler for submissions.
+     * The loop will work until there is no more closures to run.
+     */
+    void close()
+    {
+      work_queue.close();
+    }
+
+    /**
+     * \b Returns: whether the pool is closed for submissions.
+     */
+    bool closed()
+    {
+      return work_queue.closed();
+    }
+
+    /**
+     * \b Requires: \c Closure is a model of \c Callable(void()) and a model of \c CopyConstructible/MoveConstructible.
+     *
+     * \b Effects: The specified \c closure will be scheduled for execution at some point in the future.
+     * If invoked closure throws an exception the \c user_scheduler will call \c std::terminate, as is the case with threads.
+     *
+     * \b Synchronization: completion of \c closure on a particular thread happens before destruction of thread's thread local variables.
+     *
+     * \b Throws: \c sync_queue_is_closed if the thread pool is closed.
+     * Whatever exception that can be throw while storing the closure.
+     */
+
+#if defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+    template <typename Closure>
+    void submit(Closure & closure)
+    {
+      work w ((closure));
+      work_queue.push(boost::move(w));
+      //work_queue.push(work(closure)); // todo check why this doesn't work
+    }
+#endif
+    void submit(void (*closure)())
+    {
+      work w ((closure));
+      work_queue.push(boost::move(w));
+      //work_queue.push(work(closure)); // todo check why this doesn't work
+    }
+
+    template <typename Closure>
+    void submit(BOOST_THREAD_RV_REF(Closure) closure)
+    {
+      work w =boost::move(closure);
+      work_queue.push(boost::move(w));
+      //work_queue.push(work(boost::move(closure))); // todo check why this doesn't work
+    }
+
+    /**
+     * \b Requires: This must be called from an scheduled task.
+     *
+     * \b Effects: reschedule functions until pred()
+     */
+    template <typename Pred>
+    bool reschedule_until(Pred const& pred)
+    {
+      do {
+        if ( ! try_executing_one())
+        {
+          return false;
+        }
+      } while (! pred());
+      return true;
+    }
+    /**
+     * run queued closures
+     */
+    void run_queued_closures()
+    {
+      sync_queue<work>::underlying_queue_type q = work_queue.underlying_queue();
+      while (q.empty())
+      {
+        work task = q.front();
+        q.pop_front();
+        task();
+      }
+    }
+
+  };
+
+}
+
+#include <boost/config/abi_suffix.hpp>
+
+#endif