kicad/include/tool/coroutine.h

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