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Subject: [Boost-commit] svn:boost r52942 - in sandbox/task: boost/task libs/task/doc libs/task/examples
From: oliver.kowalke_at_[hidden]
Date: 2009-05-12 14:33:34

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Author: olli
Date: 2009-05-12 14:33:31 EDT (Tue, 12 May 2009)
New Revision: 52942
URL: http://svn.boost.org/trac/boost/changeset/52942

Log:
* some updates to documentations
* corrections of handle.hpp and async.hpp related to as_sub_task
* examples modified

Added:
   sandbox/task/libs/task/doc/acknowledgements.qbk (contents, props changed)
   sandbox/task/libs/task/doc/appendices.qbk (contents, props changed)
   sandbox/task/libs/task/doc/boost_task.qbk (contents, props changed)
   sandbox/task/libs/task/doc/overview.qbk (contents, props changed)
   sandbox/task/libs/task/doc/rationale.qbk (contents, props changed)
   sandbox/task/libs/task/doc/todo.qbk (contents, props changed)
Removed:
   sandbox/task/libs/task/doc/acknowledgement.qbk
   sandbox/task/libs/task/doc/threadpool.qbk
   sandbox/task/libs/task/doc/threadpool.xml
Text files modified:
   sandbox/task/boost/task/async.hpp | 1
   sandbox/task/boost/task/handle.hpp | 3 +
   sandbox/task/libs/task/doc/Jamfile.v2 | 15 ++---
   sandbox/task/libs/task/doc/introduction.qbk | 100 ++++++++++++++++++++++++++++++++++-----
   sandbox/task/libs/task/examples/delay.cpp | 4
   sandbox/task/libs/task/examples/fork_join.cpp | 60 ++++++++---------------
   6 files changed, 121 insertions(+), 62 deletions(-)

Modified: sandbox/task/boost/task/async.hpp
==============================================================================
--- sandbox/task/boost/task/async.hpp (original)
+++ sandbox/task/boost/task/async.hpp 2009-05-12 14:33:31 EDT (Tue, 12 May 2009)
@@ -75,6 +75,7 @@
                 detail::worker * w( detail::worker::tss_get() );
                 if ( w)
                 {
+ detail::interrupter intr;
                         shared_future< R > fut( t.get_future() );
                         function< bool() > wcb(
                                 bind(

Modified: sandbox/task/boost/task/handle.hpp
==============================================================================
--- sandbox/task/boost/task/handle.hpp (original)
+++ sandbox/task/boost/task/handle.hpp 2009-05-12 14:33:31 EDT (Tue, 12 May 2009)
@@ -23,6 +23,7 @@

struct own_thread;
struct new_thread;
+struct as_sub_task;

template< typename R >
class handle
@@ -32,6 +33,7 @@
         friend class pool;
         friend struct own_thread;
         friend struct new_thread;
+ friend struct as_sub_task;
         template< typename Iterator >
         friend void waitfor_all( Iterator begin, Iterator end);
         template< typename T1, typename T2 >
@@ -136,6 +138,7 @@
         friend class pool;
         friend struct own_thread;
         friend struct new_thread;
+ friend struct as_sub_task;
         template< typename Iterator >
         friend void waitfor_all( Iterator begin, Iterator end);
         template< typename T1, typename T2 >

Modified: sandbox/task/libs/task/doc/Jamfile.v2
==============================================================================
--- sandbox/task/libs/task/doc/Jamfile.v2 (original)
+++ sandbox/task/libs/task/doc/Jamfile.v2 2009-05-12 14:33:31 EDT (Tue, 12 May 2009)
@@ -1,12 +1,11 @@
-# Boost.ThreadPool Library Documentation Jamfile
+# Boost.Task Library Documentation Jamfile

-# Copyright (C) 2008 Oliver Kowalke
-
-# Use, modification and distribution is subject to 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)
+# Copyright Oliver Kowalke 2009.
+# 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

using quickbook ;

-xml threadpool : threadpool.qbk ;
-boostbook standalone : threadpool ;
+xml task : boost_task.qbk ;
+boostbook standalone : task ;

Deleted: sandbox/task/libs/task/doc/acknowledgement.qbk
==============================================================================
--- sandbox/task/libs/task/doc/acknowledgement.qbk 2009-05-12 14:33:31 EDT (Tue, 12 May 2009)
+++ (empty file)
@@ -1,11 +0,0 @@
-[/
- (C) Copyright 2008 Oliver Kowalke.
- 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).
-]
-
-[section:acknowledgement Acknowledgements]
-I'd like to thank Vincente Botet Escriba for his comments on the implementation details of the code and
-Anthony Williams and Braddock Gaskill for their future libraries.
-[endsect]

Added: sandbox/task/libs/task/doc/acknowledgements.qbk
==============================================================================
--- (empty file)
+++ sandbox/task/libs/task/doc/acknowledgements.qbk 2009-05-12 14:33:31 EDT (Tue, 12 May 2009)
@@ -0,0 +1,12 @@
+[/
+ Copyright Oliver Kowalke 2009.
+ 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
+]
+
+
+[section:acknowledgements Appendix B: Acknowledgments]
+I'd like to thank Vicente J. Botet Escriba for his comments on the implementation and Anthony Williams and Braddock Gaskill for their future libraries.
+
+[endsect]

Added: sandbox/task/libs/task/doc/appendices.qbk
==============================================================================
--- (empty file)
+++ sandbox/task/libs/task/doc/appendices.qbk 2009-05-12 14:33:31 EDT (Tue, 12 May 2009)
@@ -0,0 +1,20 @@
+[/
+ Copyright Oliver Kowalke 2009.
+ 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
+]
+
+
+[section Appendices]
+
+[include rationale.qbk]
+
+[include acknowledgements.qbk]
+
+[include todo.qbk]
+
+[endsect]
+
+
+

Added: sandbox/task/libs/task/doc/boost_task.qbk
==============================================================================
--- (empty file)
+++ sandbox/task/libs/task/doc/boost_task.qbk 2009-05-12 14:33:31 EDT (Tue, 12 May 2009)
@@ -0,0 +1,80 @@
+[/
+ Copyright Oliver Kowalke 2009.
+ 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
+]
+
+
+[library Boost.Task
+ [quickbook 1.4]
+ [authors [Kowalke, Oliver]]
+ [copyright 2009 Oliver Kowalke]
+ [purpose C++ Library for asynchronous execution of tasks]
+ [category text]
+ [license
+ 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])
+ ]
+]
+
+[def __boost__ [*boost-1.39.0]]
+[def __boost_task__ [*Boost.Task]]
+[def __boost_thread__ [@http://www.boost.org/libs/thread [*Boost.Thread]]]
+[def __boost_future__ [@http://www.justsoftwaresolutions.co.uk/threading/updated-implementation-of-c++-futures-3.html [*Boost.Future]]]
+
+[template link_coop_task[link_text] [link boost_task.cooperative_task [link_text]]]
+[template link_channel[link_text] [link boost_task.channel [link_text]]]
+[template link_forkjoin[link_text] [link boost_task.forkjoin [link_text]]]
+[template link_task[link_text] [link boost_task.task [link_text]]]
+[template link_ws[link_text] [link boost_task.pool.work_stealing [link_text]]]
+
+[def __hardware_concurrency__ `boost::thread::hardware_concurrency()`]
+[def __thread__ `boost::thread`]
+
+[def __as_sub_task__ `as_sub_task`]
+[def __bounded_channel__ `bounded_channel`]
+[def __duration__ `Duration`]
+[def __handle__ `handle`]
+[def __new_thread__ `new_thread`]
+[def __own_thread__ `own_thread`]
+[def __task__ `task`]
+[def __system_time__ `system_time`]
+[def __unbounded_channel__ `unbounded_channel`]
+
+[def __async__ `async()`]
+[def __default_pool__ `default_pool()`]
+[def __delay__ `delay()`]
+[def __get__ `get()`]
+[def __get_id__ `get_id()`]
+[def __get_pool__ `get_pool()`]
+[def __has_value__ `has_value()`]
+[def __has_exception__ `has_exception()`]
+[def __interrupt__ `interrupt()`]
+[def __interrupt_and_wait__ `interrupt_and_wait()`]
+[def __interruption_requested__ `interruption_requested()`]
+[def __is_ready__ `is_ready()`]
+[def __make_task__ `make_task()`]
+[def __reschedule_until__ `reschedule_until()`]
+[def __runs_in_pool__ `runs_in_pool()`]
+[def __wait__ `wait()`]
+[def __worker_id__ `worker_id()`]
+[def __yield__ `yield()`]
+
+[def __act__ `asynchronous-completion-token`]
+[def __ae__ `asynchronous-executor`]
+[def __aes__ `asynchronous-executors`]
+[def __blocked__ ['blocked]]
+[def __fork_join__ ['fork/join]]
+[def __interruption_point__ ['interruption point]]
+[def __task_id__ ['task id]]
+[def __thread_pool__ ['thread pool]]
+[def __work_stealing__ ['work stealing]]
+[def __worker_queue__ ['worker queue]]
+[def __worker_thread__ ['worker thread]]
+
+
+[include overview.qbk]
+[include reference.qbk]
+[include appendices.qbk]

Modified: sandbox/task/libs/task/doc/introduction.qbk
==============================================================================
--- sandbox/task/libs/task/doc/introduction.qbk (original)
+++ sandbox/task/libs/task/doc/introduction.qbk 2009-05-12 14:33:31 EDT (Tue, 12 May 2009)
@@ -8,27 +8,99 @@

[section:motivation Motivation]

-In order to take advantage of the technological evolution from single-core to many-core architectures multi-core machines requires to partition the compute bound work into smaller chunks that can run in parallel.
+In order to take advantage of the technological evolution from single-core to many-core architectures multi-core machines,
+partitioning the compute bound work into smaller chunks that can run in parallel is required.
+The code can scale as the hardware gets better without changing the code (achieving desired load balancing).

-The goal of parallel programming is to write once and have our code scale well as the hardware underneath it gets better, i.e. see incremental benefits when running our app on machines with more cores without changing the code.
-
-Had we partitioned the work into much smaller chunks, when a core is finished with the item it executes, it would be able to start working on another chunk hence achieving the desired load balancing.
+[note Equating multithreading to parallelism is not accurate. You can have multithreading on a single-core machine,
+but you can only have parallelism on a multi-core machine (portions of your code that can truly run at the same time).]

__boost_task__ provides a framework to utilize the available hardware and provide a way for efficient asynchronous processing of time consuming operations in the same process.

-[note Equating multithreading to parallelism is not accurate. You can have multithreading on a single-core machine, but you can only have parallelism on a multi-core machine. the portions of your code that can truly run at the same time.]
-
-[heading Executing a task]
+The framework provides some __aes__, like __new_thread__, in order to launch __task__ in a new thread:

std::string echo( std::string const& msg)
{ return msg; }

- boost::task::handle< std::string > h(
- boost::task::async(
- boost::task::new_thread(),
- boost::task::make_task(
- echo,
- "Hello World!") ) );
- std::cout << h.get() << std::endl;
+ void main()
+ {
+ boost::task::handle< std::string > h(
+ boost::task::async(
+ boost::task::new_thread(),
+ boost::task::make_task(
+ echo,
+ "Hello World!") ) );
+ std::cout << h.get() << std::endl;
+ }
+
+__handle__ manages the __task__ and allows to transfer the result to the caller thread.
+
+With __runs_in_pool__ the task can detect if it is running inside a __thread_pool__ (executed by a __worker_thread__) at runtime.
+
+ long serial_fib( long n)
+ {
+ if( n < 2) return n;
+ else return serial_fib( n - 1) + serial_fib( n - 2);
+ }
+
+ long parallel_fib( long n, long cutof)
+ {
+ if ( n < cutof) return serial_fib( n);
+ else
+ {
+ boost::task::handle< long > h1, h2;
+ if ( boost::this_task::runs_in_pool() )
+ {
+ // task is executed inside a thread-pool
+ // the sub-tasks are submitted to the thread-local
+ // worker-queue for speed improvments
+ h1 = boost::task::async(
+ boost::this_task::as_sub_task(),
+ boost::task::make_task(
+ parallel_fib,
+ n - 1,
+ cutof) );
+ h2 = boost::task::async(
+ boost::this_task::as_sub_task(),
+ boost::task::make_task(
+ parallel_fib,
+ n - 2,
+ cutof) );
+ }
+ else
+ {
+ // task is not running inside a thread-pool
+ // the sub-tasks are executed in new threads
+ h1 = boost::task::async(
+ boost::this_task::new_thread(),
+ tsk::make_task(
+ parallel_fib,
+ n - 1,
+ cutof) );
+ h2 = boost::task::async(
+ boost::this_task::new_thread(),
+ boost::task::make_task(
+ parallel_fib,
+ n - 2,
+ cutof) );
+ }
+ return h1.get() + h2.get();
+ }
+ }
+
+ void main()
+ {
+ boost::task::handle< long > h(
+ boost::task::async(
+ // boost::task::new_thread(),
+ boost::task::default_pool(),
+ boost::task::make_task(
+ parallel_fib,
+ 10,
+ 5) ) );
+ std::cout << h.get() << std::endl;
+ }
+};
+

[endsect]

Added: sandbox/task/libs/task/doc/overview.qbk
==============================================================================
--- (empty file)
+++ sandbox/task/libs/task/doc/overview.qbk 2009-05-12 14:33:31 EDT (Tue, 12 May 2009)
@@ -0,0 +1,76 @@
+[/
+ Copyright Oliver Kowalke 2009.
+ 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
+]
+
+
+[section:overview Overview]
+
+[heading Description]
+
+__boost_task__ provides an abstraction for parallel execution of tasks - a task is a small unit of code that can be executed independently.
+
+* __task__, representing fine-grained work-item:
+ * get_id() returning an identifier
+ * operator() to execute the fine-grained work-item
+ * get_future() providing an __act__ in order to pass the result (values, exceptions) back to initiator
+
+* __handle__, __act__ of the asynchronously executed task:
+ * get_id() for identifying associated __task__
+ * interrupt(), interrupt_and_wait() allow to cancel an coop_task_link[cooperative task]
+ * interface of __act__:
+ * get() retrieve value or exception of task execution
+ * is_ready() test if task was executed
+ * wait(), wait_for() and wait_until() block until task is executed and the result is set
+
+* __async__, execute a task on behalf of __aes__
+
+* __ae__ models:
+ * __own_thread__: executes task in current thread.
+ * __new_thread__: executes task in a newly created thread (thread will be destroyed after)
+ * __default_pool__: task gets executed by a __worker_thread__ of the default __thread_pool__
+ * __as_sub_task__: executes task in newly created thread or in a pool depending on whether current task is already executed in a pool
+ * custom pool: task gets executed by a __worker_thread__ of a custom __thread_pool__
+
+
+References
+
+* N2185: Proposed Text for Parallel Task Execution [@http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2185.html] written by Peter Dimov.
+
+* N2276: Thread Pools and Futures [@http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2276.html] written by Anthony Williams.
+
+* N2802: A plea to reconsider detach-on-destruction for thread objects [http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2802.html] written by Hans-J. Boehm.
+
+* C++task-force mailing list
+
+[note __boost_task__ uses __boost_future__ from Anthony Williams (will be integrated in some of the next releases of __boost__thread__).]
+
+In order to use the classes and functions described here, you can either include the specific headers specified by the descriptions of each class or function,
+or include the master library header:
+
+ #include <boost/task.hpp>
+
+which includes all the other headers in turn.
+
+
+[heading Tested Platforms]
+__boost_task__ has been tested on the following platforms and compilers:
+
+* Linux 2.6.29.2 (amd64), GCC 4.3.2
+* Linux 2.6.23.9 (i386), GCC 4.2.4
+* FreeBSD 7.2 (amd64), GCC 4.2.1
+* OpenSolaris 0811 (amd64), GCC 4.2.1
+* Windows XP Professional (i386), MSVC 9.0
+
+
+[heading How to build]
+* define environment variable BOOST_SOURCE_ROOT pointing to the source directory of __boost__
+* extract archive of __boost_task__
+* call bjam in the directory of __boost_task__
+
+
+[include introduction.qbk]
+
+[endsect]

Added: sandbox/task/libs/task/doc/rationale.qbk
==============================================================================
--- (empty file)
+++ sandbox/task/libs/task/doc/rationale.qbk 2009-05-12 14:33:31 EDT (Tue, 12 May 2009)
@@ -0,0 +1,23 @@
+[/
+ Copyright Oliver Kowalke 2009.
+ 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
+]
+
+
+[section:rationale Appendix A: Rationale]
+
+* task : because future does not catch std::exceptions, boost::thread_interrupted, boost::exception
+ support of task-id
+
+* pool : work-stealing and pre-forking of threads, inline execution of local tasks; scheduling
+ default pool with worker-threads as cores
+
+* this-task : functions useable inside tasks
+
+* handle : async completion token, task interruption, association with task via task-id
+
+* async : from mailing-list, execution of task in current thread, new thread in pool
+
+[endsect]

Deleted: sandbox/task/libs/task/doc/threadpool.qbk
==============================================================================
--- sandbox/task/libs/task/doc/threadpool.qbk 2009-05-12 14:33:31 EDT (Tue, 12 May 2009)
+++ (empty file)
@@ -1,59 +0,0 @@
-[/
- (C) Copyright 2008 Oliver Kowalke.
- 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).
-]
-
-[library Boost.Threadpool
- [quickbook 1.4]
- [copyright 2008 Oliver Kowalke]
- [purpose C++ Library for executing actions in a pool of worker threads]
- [license
- 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])
- ]
- [authors [Kowalke, Oliver]]
- [category text]
-]
-
-
-[def __action__ action]
-[def __actions__ actions]
-[def __Actions__ Actions]
-[def __boost__ [*boost-1.37.0]]
-[def __boost_future__ [*Boost.Future]]
-[def __boost_threadpool__ [*Boost.Threadpool]]
-[def __bounded_channel__ [link boost_threadpool.channel.bounded_channel ['bounded channel]]]
-[def __unbounded_channel__ [link boost_threadpool.channel.unbounded_channel ['unbounded channel]]]
-[def __channel__ [link boost_threadpool.channel ['channel]]]
-[def __channels__ [link boost_threadpool.channel ['channels]]]
-[def __fork_join__ [link boost_threadpool.forkjoin ['fork/join]]]
-[def __global_queue__ [link boost_threadpool.pool.work_stealing ['global queue]]]
-[def __hardware_concurrency__ boost::thread::hardware_concurrency]
-[def __hwm__ high watermark]
-[def __interruption_point__ [link boost_threadpool.task.interruption ['interruption point]]]
-[def __lwm__ low watermark]
-[def __scheduler_type__ [link boost_threadpool.scheduling ['scheduler type]]]
-[def __sub_action__ sub_action]
-[def __sub_actions__ sub_actions]
-[def __task__ [link boost_threadpool.task ['task]]]
-[def __tasks__ [link boost_threadpool.task ['tasks]]]
-[def __threadpool__ thread pool]
-[def __work_stealing__ [link boost_threadpool.pool.work_stealing ['work stealing]]]
-[def __worker_queue__ [link boost_threadpool.pool.work_stealing ['worker queue]]]
-[def __worker_queues__ [link boost_threadpool.pool.work_stealing ['worker queues]]]
-[def __worker_thread__ worker thread]
-[def __worker_threads__ worker threads]
-
-
-[include introduction.qbk]
-[include pool.qbk]
-[include task.qbk]
-[include this_task.qbk]
-[include channel.qbk]
-[include scheduling.qbk]
-[include forkjoin.qbk]
-[include acknowledgement.qbk]
-[include reference.qbk]

Added: sandbox/task/libs/task/doc/todo.qbk
==============================================================================
--- (empty file)
+++ sandbox/task/libs/task/doc/todo.qbk 2009-05-12 14:33:31 EDT (Tue, 12 May 2009)
@@ -0,0 +1,30 @@
+[/
+ Copyright Oliver Kowalke 2009.
+ 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
+]
+
+
+[section:todo Appendix C: Future development]
+
+[heading Event variable]
+A event variable is a bivalued variable (up/down) on which a task can wait for an event to be set or reset. The calling task will be suspended until the state of the event variable is that required by the caller.
+
+[heading Buffer]
+A bounded/unbounded buffer is shared between several tasks. The data must be placed in, and retrieved from, the buffer under mutual exclusion.
+Condition synchronisation is required because a calling task attempting to place data into the buffer. Whne the buffer is full, must be suspended until there is space int the buffer. Also a retrieving task must be suspended when the buffer is empty. The data, once read, is destroyed.
+
+[heading Multicast]
+The data is sent to a specific group of tasks and all tasks in the group should receive the data. Only when all tasks have received one item of data then another item is allowed to be transmitted.
+
+[heading Rendezvous]
+A rendezvous uses direct naming and synchronous communication between tasks. One task that executes its command first will be delayed until the other tasks is ready to rendezvous.
+
+[heading Protected resource]
+A protected resource is a passive entity that controls access to the internal states (to the controled real resources).
+
+[heading Task groups]
+A task group defines a graph of inter-dependent tasks that can mostly be run in parallel. THe tasks in the group have dependencies or communicate with each other.
+
+[endsect]

Modified: sandbox/task/libs/task/examples/delay.cpp
==============================================================================
--- sandbox/task/libs/task/examples/delay.cpp (original)
+++ sandbox/task/libs/task/examples/delay.cpp 2009-05-12 14:33:31 EDT (Tue, 12 May 2009)
@@ -47,14 +47,14 @@
                 {
                         tsk::handle< long > h1(
                                 tsk::async(
- tsk::default_pool(),
+ tsk::as_sub_task(),
                                         tsk::make_task(
                                                 & fib_task::execute,
                                                 boost::ref( * this),
                                                 n - 1) ) );
                         tsk::handle< long > h2(
                                 tsk::async(
- tsk::default_pool(),
+ tsk::as_sub_task(),
                                         tsk::make_task(
                                                 & fib_task::execute,
                                                 boost::ref( * this),

Modified: sandbox/task/libs/task/examples/fork_join.cpp
==============================================================================
--- sandbox/task/libs/task/examples/fork_join.cpp (original)
+++ sandbox/task/libs/task/examples/fork_join.cpp 2009-05-12 14:33:31 EDT (Tue, 12 May 2009)
@@ -27,45 +27,28 @@
                 return serial_fib( n - 1) + serial_fib( n - 2);
}

-class fib_task
+long parallel_fib( long n, long cutof)
{
-private:
- long cutof_;
-
-public:
- fib_task( long cutof)
- : cutof_( cutof)
- {}
-
- long execute( long n)
+ if ( n < cutof) return serial_fib( n);
+ else
         {
- if ( n < cutof_) return serial_fib( n);
- else
- {
- BOOST_ASSERT( boost::this_task::runs_in_pool() );
- tsk::handle< long > h1(
- tsk::async(
- boost::this_task::get_pool< pool_type >(),
- tsk::make_task(
- & fib_task::execute,
- boost::ref( * this),
- n - 1) ) ) ;
- tsk::handle< long > h2(
- tsk::async(
- boost::this_task::get_pool< pool_type >(),
- tsk::make_task(
- & fib_task::execute,
- boost::ref( * this),
- n - 2) ) );
- return h1.get() + h2.get();
- }
+ BOOST_ASSERT( boost::this_task::runs_in_pool() );
+ tsk::handle< long > h1(
+ tsk::async(
+ tsk::as_sub_task(),
+ tsk::make_task(
+ parallel_fib,
+ n - 1,
+ cutof) ) ) ;
+ tsk::handle< long > h2(
+ tsk::async(
+ tsk::as_sub_task(),
+ tsk::make_task(
+ parallel_fib,
+ n - 2,
+ cutof) ) );
+ return h1.get() + h2.get();
         }
-};
-
-long parallel_fib( long n)
-{
- fib_task a( 5);
- return a.execute( n);
}

int main( int argc, char *argv[])
@@ -79,13 +62,14 @@

                 pt::ptime start( pt::microsec_clock::universal_time() );

- for ( int i = 0; i < 15; ++i)
+ for ( int i = 0; i < 10; ++i)
                         results.push_back(
                                 tsk::async(
                                         pool,
                                         tsk::make_task(
                                                 & parallel_fib,
- i) ) );
+ i,
+ 5) ) );

                 tsk::waitfor_all( results.begin(), results.end() );

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