//
// Cforall Version 1.0.0 Copyright (C) 2021 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// many_read.cfa -- Make sure that multiple concurrent reads to mess up.
//
// Author           : Thierry Delisle
// Created On       : Thu Feb 18 15:26:05 2021
// Last Modified By :
// Last Modified On :
// Update Count     :
//

extern "C" {
	#include <sys/types.h>
	#include <sys/stat.h>
	#include <fcntl.h>
	#include <unistd.h>
}

#include <string.h>

#include <fstream.hfa>
#include <iofwd.hfa>

#include <thread.hfa>
#include <kernel.hfa>

#define xstr(s) str(s)
#define str(s) #s

const char * file = xstr(IN_DIR) "many_read.data";
int fd;
off_t size;

const char * content;

thread reader {};
void ?{}(reader & this) {}
void ^?{}(reader & mutex this) {}
void main(reader & this);

int main() {
	fd = open(file, 0);
	if(fd < 0) {
		serr | "Failed to open file: " | file;
		exit(1);
	}

	struct stat sb;
	int ret = fstat(fd, &sb);
	if(ret < 0) {
		serr | "Failed to stat file: " | file;
		exit(1);
	}

	size = sb.st_size;
	sout | "File has size: " | size | "bytes";

	char data[size+1];
	{
		size_t left = size;
		char * it = data;

		while(left) {
			ret = read(fd, it, left);
			if(ret < 0) {
				serr | "Failed to read file: " | file | " (the first time)";
				exit(1);
			}
			it += ret;
			left -= ret;
		}
	}
	data[size] = 0;
	content = data;
	sout | content;

	{
		processor proc[2];
		{
			reader readers[17];
		}
	}

	sout | "Yup, it all matches.";
}

#ifdef CFA_HAVE_PREADV2
	extern "C" {
		#include <sys/uio.h>
	}
#endif

void main(reader & this) {
	for(50) {
		char data[size];
		char * it = data;
		size_t left = size;
		off_t offset = 0;

		#ifdef CFA_HAVE_PREADV2
			while(left) {
				struct iovec vec;
				vec.iov_base = (void*)it;
				vec.iov_len = left;
				int ret = cfa_preadv2(fd, &vec, 1, offset, 0, 0);
				if(ret < 0) {
					serr | "Failed to read file: " | file | " (NOT the first time)";
					exit(1);
				}
				it += ret;
				left -= ret;
				offset += ret;
			}

			if(strncmp(content, data, size) != 0) {
				serr | "Subsequent read of file '" | file | "' return different content";
				exit(1);
			}
		#endif
	}
}