/* THREADWRAPPER.hpp - thin convenience wrapper for starting lumiera threads Copyright (C) Lumiera.org 2008, Hermann Vosseler 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 2 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., 675 Mass Ave, Cambridge, MA 02139, USA. */ #ifndef LIB_THREADWRAPPER_H #define LIB_THREADWRAPPER_H #include "include/logging.h" #include "lib/sync.hpp" extern "C" { #include "backend/threads.h" } #include #include namespace backend { using std::tr1::bind; using std::tr1::function; using lib::Literal; using lib::Sync; using lib::RecursiveLock_Waitable; using lib::NonrecursiveLock_Waitable; typedef struct nobug_flag* NoBugFlag; class Thread; /** * Brainstorming-in-code: how I would like to shape the API for joining threads. * Intended use: This non-copyable handle has to be created within the thread which * wants to wait-blocking on the termination of another thread. You then pass it * into the ctor of the Thread starting wrapper class (see below), which causes * the embedded lock/condition var to be used to sync on the end of the newly * created thread. Note, after ending the execution, the newly created thread * will be on hold until either the #join() function is called or this handle * goes out of scope altogether. Explanation: this is implemented by locking * the embedded monitor immediately in the ctor. Thus, unless entering the * wait state, the contained mutex remains locked and prevents the thread * manager from invoking the broadcast() on the condition var. * * @see thread-wrapper-join-test.cpp */ class JoinHandle : public Sync , Sync::Lock // noncopyable, immediately acquire the lock { typedef Sync SyncBase; bool isWaiting_; volatile bool armed_; friend class Thread; LumieraReccondition accessLockedCondition() { ASSERT (!armed_, "Lifecycle error, JoinHandle used for several threads."); armed_ = true; return accessMonitor().accessCond(); } bool wakeupCheck() { if (!armed_) throw lumiera::error::Logic ("no thread created blocking on this JoinHandle"); if (!isWaiting_) { isWaiting_ = true; return false; // causes entering the blocking wait } return true; // causes end of blocking wait } public: /** Create a promise, that the current thread will or may * wait-blocking on another not-yet existing thread to terminate. * When passed in on creation of the other thread, as long as this * handle lives, the other thread will be on hold after termination. */ JoinHandle() : SyncBase::Lock(this) , isWaiting_(false) , armed_(false) { } /** put the current thread into a blocking wait until another thread * has terminated. This other thread needs to be created by the Thread * wrapper, passing this JoinHandle as ctor parameter. * @throws error::Logic if no thread has been registered to block on this */ void join() { accessMonitor().wait (*this, &JoinHandle::wakeupCheck); } }; /**************************************************************************** * A thin convenience wrapper for dealing with threads, * as implemented by the backend (on top of pthread). * Using this wrapper... * - helps with passing data to the function executed in the new thread * - allows to bind to various kinds of functions including member functions * - supports integrating with an existing object monitor based lock (planned) * The new thread starts immediately within the ctor; after returning, the new * thread has already copied the arguments and indeed actively started to run. * * @note this class is \em not a thread handle. Within Lumiera, we do all of * our thread management such as to avoid using global thread handles. * If some cooperation between threads is needed, this should be done * in a implementation private way, e.g. by sharing a condition var. * * @todo Ichthyo started this wrapper 12/08 while our own thread handling * was just being shaped. It may well be possible that such a wrapper * is superfluous in the final application. Re-evaluate this! */ class Thread : public Sync , boost::noncopyable { volatile bool started_; typedef function Operation; Operation const& operation_; static void run (void* arg) { REQUIRE (arg); Thread* startingWrapper = reinterpret_cast(arg); Operation _doIt_(startingWrapper->operation_); { Lock sync(startingWrapper); startingWrapper->started_ = true; sync.notify(); // handshake signalling we've gotten the parameter } _doIt_(); // execute the actual operation in the new thread } void start_thread (lumiera_thread_class kind, Literal& purpose, NoBugFlag logging_flag, LumieraReccondition joinCond=0) { Lock sync(this); LumieraThread res = lumiera_thread_run ( kind , &run // invoking the run helper and.. , this // passing this start context as parameter , joinCond // maybe wait-blocking for the thread to terminate , purpose.c() , logging_flag ); if (!res) throw lumiera::error::State("failed to create new thread."); // make sure the new thread had the opportunity to take the Operation // prior to leaving and thereby possibly destroying this local context sync.wait (started_); } public: /** Create a new thread to execute the given operation. * The new thread starts up synchronously, i.e. when the ctor returns, the new thread * has started running and taken over (copied) the operation functor passed in. The * thread will be created by lumiera_thread_run (declared in threads.h), it can't * be cancelled and it can't be joined. * @param purpose fixed char string used to denote the thread for diagnostics * @param logging_flag NoBug flag to receive diagnostics regarding the new thread * @param operation defining what to execute within the new thread. Any functor * which can be bound to function. Note this functor will be * copied onto the stack of the new thread, thus it can be transient. * */ Thread (Literal purpose, Operation const& operation, NoBugFlag logging_flag = &NOBUG_FLAG(thread)) : started_(false), operation_(operation) { start_thread (LUMIERA_THREAD_INTERACTIVE, purpose, logging_flag); } /** Variant of the standard case, used to register a JoinHandle in addition to starting a thread. * @param join ref to a JoinHandle, which needs to be created in the thread which plans * to wait-blocking on the termination of this newly created thread * */ Thread (Literal purpose, Operation const& operation, JoinHandle& join, NoBugFlag logging_flag = &NOBUG_FLAG(thread)) : started_(false), operation_(operation) { start_thread (LUMIERA_THREAD_INTERACTIVE, purpose, logging_flag, join.accessLockedCondition()); } }; } // namespace backend #endif