416 lines
12 KiB
C++
416 lines
12 KiB
C++
/*
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* This program source code file is part of KiCad, a free EDA CAD application.
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*
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* Copyright (C) 2013 CERN
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* Copyright (C) 2016-2020 KiCad Developers, see AUTHORS.txt for contributors.
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*
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* @author Tomasz Wlostowski <tomasz.wlostowski@cern.ch>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, you may find one here:
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* http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
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* or you may search the http://www.gnu.org website for the version 2 license,
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* or you may write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
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*/
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#ifndef __COROUTINE_H
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#define __COROUTINE_H
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#include <cassert>
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#include <cstdlib>
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#include <type_traits>
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#ifdef KICAD_USE_VALGRIND
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#include <valgrind/valgrind.h>
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#endif
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#include <libcontext.h>
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#include <memory>
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#include <advanced_config.h>
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/**
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* Implement a coroutine.
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*
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* Wikipedia has a good explanation:
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*
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* "Coroutines are computer program components that generalize subroutines to
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* allow multiple entry points for suspending and resuming execution at certain locations.
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* Coroutines are well-suited for implementing more familiar program components such as cooperative
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* tasks, exceptions, event loop, iterators, infinite lists and pipes."
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*
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* In other words, a coroutine can be considered a lightweight thread - which can be
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* preempted only when it deliberately yields the control to the caller. This way,
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* we avoid concurrency problems such as locking / race conditions.
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*
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* Uses libcontext library to do the actual context switching.
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*
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* This particular version takes a DELEGATE as an entry point, so it can invoke
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* methods within a given object as separate coroutines.
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*
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* See coroutine_example.cpp for sample code.
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*/
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template <typename ReturnType, typename ArgType>
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class COROUTINE
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{
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private:
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class CALL_CONTEXT;
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struct INVOCATION_ARGS
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{
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enum
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{
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FROM_ROOT, // a stub was called/a coroutine was resumed from the main-stack context
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FROM_ROUTINE, // a stub was called/a coroutine was resumed from a coroutine context
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CONTINUE_AFTER_ROOT // a function sent a request to invoke a function on the main
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// stack context
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} type; // invocation type
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COROUTINE* destination; // stores the coroutine pointer for the stub OR the coroutine
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// ptr for the coroutine to be resumed if a
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// root(main-stack)-call-was initiated.
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CALL_CONTEXT* context; // pointer to the call context of the current callgraph this
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// call context holds a reference to the main stack context
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};
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using CONTEXT_T = libcontext::fcontext_t;
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using CALLEE_STORAGE = CONTEXT_T;
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class CALL_CONTEXT
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{
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public:
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CALL_CONTEXT() :
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m_mainStackContext( nullptr )
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{
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}
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~CALL_CONTEXT()
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{
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if ( m_mainStackContext )
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libcontext::release_fcontext( *m_mainStackContext );
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}
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void SetMainStack( CONTEXT_T* aStack )
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{
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m_mainStackContext = aStack;
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}
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void RunMainStack( COROUTINE* aCor, std::function<void()> aFunc )
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{
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m_mainStackFunction = std::move( aFunc );
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INVOCATION_ARGS args{ INVOCATION_ARGS::CONTINUE_AFTER_ROOT, aCor, this };
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libcontext::jump_fcontext( &aCor->m_callee, *m_mainStackContext,
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reinterpret_cast<intptr_t>( &args ) );
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}
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void Continue( INVOCATION_ARGS* args )
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{
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while( args->type == INVOCATION_ARGS::CONTINUE_AFTER_ROOT )
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{
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m_mainStackFunction();
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args->type = INVOCATION_ARGS::FROM_ROOT;
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args = args->destination->doResume( args );
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}
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}
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private:
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CONTEXT_T* m_mainStackContext;
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std::function<void()> m_mainStackFunction;
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};
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public:
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COROUTINE() :
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COROUTINE( nullptr )
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{
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}
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/**
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* Create a coroutine from a member method of an object.
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*/
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template <class T>
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COROUTINE( T* object, ReturnType(T::*ptr)( ArgType ) ) :
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COROUTINE( std::bind( ptr, object, std::placeholders::_1 ) )
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{
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}
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/**
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* Create a coroutine from a delegate object.
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*/
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COROUTINE( std::function<ReturnType(ArgType)> aEntry ) :
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m_func( std::move( aEntry ) ),
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m_running( false ),
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m_args( 0 ),
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m_caller( nullptr ),
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m_callContext( nullptr ),
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m_callee( nullptr ),
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m_retVal( 0 )
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#ifdef KICAD_USE_VALGRIND
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,valgrind_stack( 0 )
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#endif
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{
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m_stacksize = ADVANCED_CFG::GetCfg().m_CoroutineStackSize;
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}
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~COROUTINE()
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{
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#ifdef KICAD_USE_VALGRIND
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VALGRIND_STACK_DEREGISTER( valgrind_stack );
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#endif
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if(m_caller)
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libcontext::release_fcontext( m_caller );
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if(m_callee)
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libcontext::release_fcontext( m_callee );
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}
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public:
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/**
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* Stop execution of the coroutine and returns control to the caller.
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*
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* After a yield, Call() or Resume() methods invoked by the caller will
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* immediately return true, indicating that we are not done yet, just asleep.
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*/
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void KiYield()
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{
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jumpOut();
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}
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/**
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* KiYield with a value.
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*
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* Passe a value of given type to the caller. Useful for implementing generator objects.
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*/
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void KiYield( ReturnType& aRetVal )
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{
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m_retVal = aRetVal;
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jumpOut();
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}
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/**
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* Run a functor inside the application main stack context.
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*
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* Call this function for example if the operation will spawn a webkit browser instance which
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* will walk the stack to the upper border of the address space on mac osx systems because
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* its javascript needs garbage collection (for example if you paste text into an edit box).
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*/
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void RunMainStack( std::function<void()> func )
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{
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assert( m_callContext );
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m_callContext->RunMainStack( this, std::move( func ) );
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}
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/**
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* Start execution of a coroutine, passing args as its arguments.
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*
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* Call this method from the application main stack only.
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*
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* @return true if the coroutine has yielded and false if it has finished its
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* execution (returned).
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*/
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bool Call( ArgType aArg )
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{
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CALL_CONTEXT ctx;
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INVOCATION_ARGS args{ INVOCATION_ARGS::FROM_ROOT, this, &ctx };
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ctx.Continue( doCall( &args, aArg ) );
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return Running();
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}
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/**
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* Start execution of a coroutine, passing args as its arguments.
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*
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* Call this method for a nested coroutine invocation.
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*
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* @return true if the coroutine has yielded and false if it has finished its
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* execution (returned).
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*/
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bool Call( const COROUTINE& aCor, ArgType aArg )
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{
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INVOCATION_ARGS args{ INVOCATION_ARGS::FROM_ROUTINE, this, aCor.m_callContext };
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doCall( &args, aArg );
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// we will not be asked to continue
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return Running();
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}
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/**
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* Resume execution of a previously yielded coroutine.
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*
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* Call this method only from the main application stack.
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*
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* @return true if the coroutine has yielded again and false if it has finished its
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* execution (returned).
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*/
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bool Resume()
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{
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CALL_CONTEXT ctx;
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INVOCATION_ARGS args{ INVOCATION_ARGS::FROM_ROOT, this, &ctx };
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ctx.Continue( doResume( &args ) );
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return Running();
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}
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/**
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* Resume execution of a previously yielded coroutine.
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*
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* Call this method for a nested coroutine invocation.
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*
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* @return true if the coroutine has yielded again and false if it has finished its
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* execution (returned).
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*/
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bool Resume( const COROUTINE& aCor )
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{
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INVOCATION_ARGS args{ INVOCATION_ARGS::FROM_ROUTINE, this, aCor.m_callContext };
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doResume( &args );
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// we will not be asked to continue
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return Running();
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}
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/**
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* Return the yielded value (the argument KiYield() was called with).
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*/
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const ReturnType& ReturnValue() const
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{
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return m_retVal;
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}
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/**
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* @return true if the coroutine is active.
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*/
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bool Running() const
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{
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return m_running;
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}
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private:
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INVOCATION_ARGS* doCall( INVOCATION_ARGS* aInvArgs, ArgType aArgs )
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{
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assert( m_func );
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assert( !m_callee );
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m_args = &aArgs;
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assert( m_stack == nullptr );
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size_t stackSize = m_stacksize;
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void* sp = nullptr;
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#ifndef LIBCONTEXT_HAS_OWN_STACK
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// fixme: Clean up stack stuff. Add a guard
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m_stack.reset( new char[stackSize] );
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// align to 16 bytes
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sp = (void*)((((ptrdiff_t) m_stack.get()) + stackSize - 0xf) & (~0x0f));
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// correct the stack size
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stackSize -= size_t( ( (ptrdiff_t) m_stack.get() + stackSize ) - (ptrdiff_t) sp );
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#ifdef KICAD_USE_VALGRIND
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valgrind_stack = VALGRIND_STACK_REGISTER( sp, m_stack.get() );
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#endif
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#endif
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m_callee = libcontext::make_fcontext( sp, stackSize, callerStub );
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m_running = true;
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// off we go!
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return jumpIn( aInvArgs );
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}
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INVOCATION_ARGS* doResume( INVOCATION_ARGS* args )
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{
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return jumpIn( args );
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}
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/* real entry point of the coroutine */
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static void callerStub( intptr_t aData )
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{
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INVOCATION_ARGS& args = *reinterpret_cast<INVOCATION_ARGS*>( aData );
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// get pointer to self
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COROUTINE* cor = args.destination;
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cor->m_callContext = args.context;
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if( args.type == INVOCATION_ARGS::FROM_ROOT )
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cor->m_callContext->SetMainStack( &cor->m_caller );
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// call the coroutine method
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cor->m_retVal = cor->m_func( *(cor->m_args) );
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cor->m_running = false;
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// go back to wherever we came from.
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cor->jumpOut();
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}
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INVOCATION_ARGS* jumpIn( INVOCATION_ARGS* args )
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{
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args = reinterpret_cast<INVOCATION_ARGS*>(
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libcontext::jump_fcontext( &m_caller, m_callee,
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reinterpret_cast<intptr_t>( args ) )
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);
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return args;
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}
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void jumpOut()
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{
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INVOCATION_ARGS args{ INVOCATION_ARGS::FROM_ROUTINE, nullptr, nullptr };
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INVOCATION_ARGS* ret;
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ret = reinterpret_cast<INVOCATION_ARGS*>(
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libcontext::jump_fcontext( &m_callee, m_caller,
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reinterpret_cast<intptr_t>( &args ) )
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);
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m_callContext = ret->context;
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if( ret->type == INVOCATION_ARGS::FROM_ROOT )
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{
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m_callContext->SetMainStack( &m_caller );
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}
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}
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///< coroutine stack
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std::unique_ptr<char[]> m_stack;
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int m_stacksize;
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std::function<ReturnType( ArgType )> m_func;
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bool m_running;
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///< pointer to coroutine entry arguments. Stripped of references
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///< to avoid compiler errors.
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typename std::remove_reference<ArgType>::type* m_args;
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///< saved caller context
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CONTEXT_T m_caller;
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///< main stack information
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CALL_CONTEXT* m_callContext;
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///< saved coroutine context
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CALLEE_STORAGE m_callee;
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ReturnType m_retVal;
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#ifdef KICAD_USE_VALGRIND
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uint32_t valgrind_stack;
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#endif
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};
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#endif
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