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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
* @author Tomasz Wlostowski <tomasz.wlostowski@cern.ch>
* Copyright (C) 2016 KiCad Developers, see AUTHORS.txt for contributors.
*
* 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 <cstdlib>
#include <boost/version.hpp>
#include <type_traits>
#if BOOST_VERSION < 106100
#include <boost/context/fcontext.hpp>
#else
#include <boost/context/execution_context.hpp>
#include <boost/context/protected_fixedsize_stack.hpp>
#endif
/**
* Note: in the history of boost, two changes to the context interface happened.
* [1.54, 1.56)
* http://www.boost.org/doc/libs/1_55_0/libs/context/doc/html/context/context/boost_fcontext.html
* intptr_t jump_fcontext(
* fcontext_t* ofc,
* fcontext_t const* nfc,
* intptr_t vp,
* bool preserve_fpu = true
* );
*
* fcontext_t* make_fcontext(
* void* sp,
* std::size_t size,
* void (*fn)(intptr_t)
* );
*
* [1.56, 1.61)
* http://www.boost.org/doc/libs/1_56_0/libs/context/doc/html/context/context/boost_fcontext.html
* intptr_t jump_fcontext(
* fcontext_t* ofc,
* fcontext_t nfc, <-----
* intptr_t vp,
* bool preserve_fpu = true
* );
*
* fcontext_t make_fcontext( <-----
* void* sp,
* std::size_t size,
* void(*fn)(intptr_t)
* );
*
* [1.61, oo)
* http://www.boost.org/doc/libs/1_61_0/libs/context/doc/html/context/ecv2.html
* fcontext_t is hidden away behind the boost::execution_context(_v2) and the stack is created on behalf of
* the user.
*/
/**
* Class COROUNTINE.
* Implements 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 boost::context 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>
class COROUTINE
{
private:
class CALL_CONTEXT;
struct INVOCATION_ARGS
{
enum
{
FROM_ROOT, // a stub was called/a corutine was resumed from the main-stack context
FROM_ROUTINE, // a stub was called/a coroutine was resumed fron 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
};
#if BOOST_VERSION < 106100
using CONTEXT_T = boost::context::fcontext_t;
#else
using CONTEXT_T = boost::context::execution_context<INVOCATION_ARGS*>;
#endif
#if BOOST_VERSION < 105600
using CALLEE_STORAGE = CONTEXT_T*;
#else
using CALLEE_STORAGE = CONTEXT_T;
#endif
class CALL_CONTEXT
{
public:
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 };
#if BOOST_VERSION < 105600
boost::context::jump_fcontext( aCor->m_callee, m_mainStackContext,
reinterpret_cast<intptr_t>( &args ) );
#elif BOOST_VERSION < 106100
boost::context::jump_fcontext( &aCor->m_callee, *m_mainStackContext,
reinterpret_cast<intptr_t>( &args ) );
#else
*m_mainStackContext = std::get<0>( ( *m_mainStackContext )( &args ) );
#endif
}
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:
COROUTINE() :
COROUTINE( nullptr )
{
}
/**
* Constructor
* Creates 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 ) )
{
}
/**
* Constructor
* Creates a coroutine from a delegate object
*/
COROUTINE( std::function<ReturnType(ArgType)> aEntry ) :
m_func( std::move( aEntry ) ),
m_running( false ),
m_args( 0 ),
#if BOOST_VERSION < 106100 // -> m_callee = void* or void**
m_callee( nullptr ),
#endif
m_retVal( 0 )
{
}
~COROUTINE()
{
}
public:
/**
* Function Yield()
*
* Stops 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 Yield()
{
jumpOut();
}
/**
* Function Yield()
*
* Yield with a value - passes a value of given type to the caller.
* Useful for implementing generator objects.
*/
void Yield( ReturnType& aRetVal )
{
m_retVal = aRetVal;
jumpOut();
}
/**
* Function SetEntry()
*
* Defines the entry point for the coroutine, if not set in the constructor.
*/
void SetEntry( std::function<ReturnType(ArgType)> aEntry )
{
m_func = std::move( aEntry );
}
/**
* Function RunMainStack()
*
* 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 ) );
}
/**
* Function Call()
*
* Starts execution of a coroutine, passing args as its arguments. Call this method
* from the application main stack only.
* @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();
}
/**
* Function Call()
*
* Starts execution of a coroutine, passing args as its arguments. 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();
}
/**
* Function Resume()
*
* Resumes 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();
}
/**
* Function Resume()
*
* Resumes 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();
}
/**
* Function ReturnValue()
*
* Returns the yielded value (the argument Yield() was called with)
*/
const ReturnType& ReturnValue() const
{
return m_retVal;
}
/**
* Function Running()
*
* @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;
#if BOOST_VERSION < 106100
assert( m_stack == nullptr );
// fixme: Clean up stack stuff. Add a guard
size_t stackSize = c_defaultStackSize;
m_stack.reset( new char[stackSize] );
// align to 16 bytes
void* sp = (void*)((((ptrdiff_t) m_stack.get()) + stackSize - 0xf) & (~0x0f));
// correct the stack size
stackSize -= size_t( ( (ptrdiff_t) m_stack.get() + stackSize ) - (ptrdiff_t) sp );
m_callee = boost::context::make_fcontext( sp, stackSize, callerStub );
#else
m_callee = CONTEXT_T(
std::allocator_arg_t(),
boost::context::protected_fixedsize_stack( c_defaultStackSize ),
&COROUTINE::callerStub
);
#endif
m_running = true;
// off we go!
return jumpIn( aInvArgs );
}
INVOCATION_ARGS* doResume( INVOCATION_ARGS* args )
{
return jumpIn( args );
}
/* real entry point of the coroutine */
#if BOOST_VERSION < 106100
static void callerStub( intptr_t aData )
{
INVOCATION_ARGS& args = *reinterpret_cast<INVOCATION_ARGS*>( aData );
// 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();
}
#else
/* real entry point of the coroutine */
static CONTEXT_T callerStub( CONTEXT_T caller, INVOCATION_ARGS* aArgsPtr )
{
const auto& args = *aArgsPtr;
auto* cor = args.destination;
cor->m_caller = std::move( caller );
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.
return std::move( cor->m_caller );
}
#endif
INVOCATION_ARGS* jumpIn( INVOCATION_ARGS* args )
{
#if BOOST_VERSION < 105600
args = reinterpret_cast<INVOCATION_ARGS*>(
boost::context::jump_fcontext( &m_caller, m_callee,
reinterpret_cast<intptr_t>( args ) )
);
#elif BOOST_VERSION < 106100
args = reinterpret_cast<INVOCATION_ARGS*>(
boost::context::jump_fcontext( &m_caller, m_callee,
reinterpret_cast<intptr_t>( args ) )
);
#else
std::tie( m_callee, args ) = m_callee( args );
#endif
return args;
}
void jumpOut()
{
INVOCATION_ARGS args{ INVOCATION_ARGS::FROM_ROUTINE, nullptr, nullptr };
INVOCATION_ARGS* ret;
#if BOOST_VERSION < 105600
ret = reinterpret_cast<INVOCATION_ARGS*>(
boost::context::jump_fcontext( m_callee, &m_caller,
reinterpret_cast<intptr_t>( &args ) )
);
#elif BOOST_VERSION < 106100
ret = reinterpret_cast<INVOCATION_ARGS*>(
boost::context::jump_fcontext( &m_callee, m_caller,
reinterpret_cast<intptr_t>( &args ) )
);
#else
std::tie( m_caller, ret ) = m_caller( &args );
#endif
m_callContext = ret->context;
if( ret->type == INVOCATION_ARGS::FROM_ROOT )
{
m_callContext->SetMainStack( &m_caller );
}
}
static constexpr int c_defaultStackSize = 2000000; // fixme: make configurable
#if BOOST_VERSION < 106100
///< coroutine stack
std::unique_ptr<char[]> m_stack;
#endif
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;
};
#endif
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