//                              -*- Mode: CFA -*-
//
// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// threads --
//
// Author           : Thierry Delisle
// Created On       : Mon Nov 28 12:27:26 2016
// Last Modified By : Thierry Delisle
// Last Modified On : Mon Nov 28 12:27:26 2016
// Update Count     : 0
//

#ifndef __THREADS_H__
#define __THREADS_H__

#include "assert"       //
#include "invoke.h"

//-----------------------------------------------------------------------------
// Coroutine trait
// Anything that implements this trait can be resumed.
// Anything that is resumed is a coroutine.
trait is_coroutine(dtype T) {
      void co_main(T* this);
      coroutine* get_coroutine(T* this);
};

//-----------------------------------------------------------------------------
// Ctors and dtors
void ?{}(coStack_t* this);
void ?{}(coroutine* this);
void ^?{}(coStack_t* this);
void ^?{}(coroutine* this);

//-----------------------------------------------------------------------------
// Public coroutine API
static inline void suspend();

forall(dtype T | is_coroutine(T))
static inline void resume(T* cor);

forall(dtype T | is_coroutine(T))
void prime(T* cor);

//-----------------------------------------------------------------------------
// PRIVATE exposed because of inline

// Start coroutine routines
extern "C" {
      forall(dtype T | is_coroutine(T))
      void CtxInvokeCoroutine(T* this);

      forall(dtype T | is_coroutine(T))
      void CtxStart(T* this, void (*invoke)(T*));
}

// Get current coroutine
extern coroutine* current_coroutine; //PRIVATE, never use directly
static inline coroutine* this_coroutine(void) {
	return current_coroutine;
}

// Private wrappers for context switch and stack creation
extern void corCxtSw(coroutine* src, coroutine* dst);
extern void create_stack( coStack_t* this, unsigned int storageSize );

// Suspend implementation inlined for performance
static inline void suspend() {
      coroutine* src = this_coroutine();		// optimization

	assertf( src->last != 0, 
		"Attempt to suspend coroutine %.256s (%p) that has never been resumed.\n"
		"Possible cause is a suspend executed in a member called by a coroutine user rather than by the coroutine main.",
		src->name, src );
	assertf( src->last->notHalted, 
		"Attempt by coroutine %.256s (%p) to suspend back to terminated coroutine %.256s (%p).\n"
		"Possible cause is terminated coroutine's main routine has already returned.",
		src->name, src, src->last->name, src->last );

	corCxtSw( src, src->last );
}

// Resume implementation inlined for performance
forall(dtype T | is_coroutine(T))
static inline void resume(T* cor) {
	coroutine* src = this_coroutine();		// optimization
	coroutine* dst = get_coroutine(cor);

      if( unlikely(!dst->stack.base) ) {
		create_stack(&dst->stack, dst->stack.size);
		CtxStart(cor, CtxInvokeCoroutine);
	}

      // not resuming self ?
	if ( src != dst ) {
		assertf( dst->notHalted , 
			"Attempt by coroutine %.256s (%p) to resume terminated coroutine %.256s (%p).\n"
			"Possible cause is terminated coroutine's main routine has already returned.",
			src->name, src, dst->name, dst );

            // set last resumer
		dst->last = src;
	} // if

      // always done for performance testing
	corCxtSw( src, dst );
}

#endif //__THREADS_H__

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