//
// Cforall Version 1.0.0 Copyright (C) 2022 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// comp_basic.cfa -- Test that simple completions work correctly
//                   even when mixing io_uring and regular calls
//
// Author           : Thierry Delisle
// Created On       : Thu Sep 01 11:27:08 2022
// Last Modified By :
// Last Modified On :
// Update Count     :
//


#include <concurrency/barrier.hfa>
#include <fstream.hfa>
#include <iofwd.hfa>
#include <kernel.hfa>
#include <thread.hfa>

#include <errno.h>
#include <string.h>
#include <unistd.h>

static struct {
	barrier & bar;
	int pipe[2];
} globals;

Duration default_preemption() {
	return 0;
}

enum { TIMES = 1000 };

volatile unsigned counter = 0;


// ----- Reader -----
// Reader from the pipe to test completion doesn't starve
thread Reader {};
void main(Reader & this) {
	char thrash[1];
	bool do_read = has_user_level_blocking( (fptr_t)async_read );

	for(TIMES) {
		io_future_t f;
		if ( do_read ) {
			async_read(f, globals.pipe[0], thrash, 1, 0);
		} else {
			fulfil(f, 0); // If we don't have user-level blocking just play along
		}

		block( globals.bar );

		yield( prng( this, 15 ) );

		unsigned i = __atomic_add_fetch( &counter, 1, __ATOMIC_SEQ_CST );
		if(0 == (i % 100)) sout | i;

		wait( f );

		if(f.result < 0)
			abort | "Read error" | -f.result | ":" | strerror(-f.result);

		block( globals.bar );
	}
}

// ----- Writer -----
// Writes to the pipe so the Reader can unblock
// takes its sweet time so the Reader has to block
thread Writer {};
void main(Writer & this) {
	for(TIMES) {
		block( globals.bar );

		sleep( 1`us );

		char buf[1] = { '+' };
		int ret = write( globals.pipe[1], buf, 1 );
		if(ret < 0)
			abort | "Write error" | errno | ":" | strerror(errno);

		block( globals.bar );
	}
}

int main() {
	barrier bar = { 2 };
	&globals.bar = &bar;
	int ret = pipe(globals.pipe);
	if(ret != 0)
		abort | "Pipe error" | errno | ":" | strerror(errno);

     	sout | "starting";
	{
		Reader ior;
		Writer iow;
	}
	sout | "done";
}