//
// 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.
//
// cpu.cfa -- checks that libcfa correctly counts the number of cpus.
//
// Author           : Thierry Delisle
// Created On       : Mon Jun 14 13:59:01 2021
// Last Modified By :
// Last Modified On :
// Update Count     :
//


#include <fstream.hfa>
#include <device/cpu.hfa>
#include <stdlib.hfa>

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

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

// go through a directory calling fn on each file
static int iterate_dir( const char * path, void (*fn)(struct dirent * ent) ) {
	// open the directory
	DIR *dir = opendir(path);
	if(dir == 0p) { return ENOTDIR; }

	// call fn for each
	struct dirent * ent;
	while ((ent = readdir(dir)) != 0p) {
		fn( ent );
	}

	// no longer need this
	closedir(dir);
	return 0;
}

// count the number of directories with the specified prefix
// the directories counted have the form '[prefix]N' where prefix is the parameter
// and N is an base 10 integer.
static int count_prefix_dirs(const char * path, const char * prefix) {
	// read the directory and find the cpu count
	// and make sure everything is as expected
	int max = -1;
	int count = 0;
	void lambda(struct dirent * ent) {
		// were are looking for prefixX, where X is a number
		// check that it starts with 'cpu
		char * s = strstr(ent->d_name, prefix);
		if(s == 0p) { return; }
		if(s != ent->d_name) { return; }

		// check that the next part is a number
		s += strlen(prefix);
		char * end;
		long int val = strtol(s, &end, 10);
		if(*end != '\0' || val < 0) { return; }

		// check that it's a directory
		if(ent->d_type != DT_DIR) { return; }

		// it's a match!
		max = max(val, max);
		count++;
	}
	iterate_dir(path, lambda);

	/* paranoid */ verifyf(count == max + 1, "Inconsistent %s count, counted %d, but max %s was %d", prefix, count, prefix, (int)max);

	return count;
}

// Count number of cache *indexes* in the system
// cache indexes are distinct from cache level as Data or Instruction cache
// can share a level but not an index
// PITFALL: assumes all cpus have the same indexes as cpu0
static int count_cache_indexes(void) {
	return count_prefix_dirs("/sys/devices/system/cpu/cpu0/cache", "index");
}

// read information about a spcficic cache index/cpu file into the output buffer
static size_t read_cpuidxinfo_into(unsigned cpu, unsigned idx, const char * file, char * out, size_t out_len) {
	// Pick the file we want and read it
	char buf[128];
	/* paranoid */ __attribute__((unused)) int len =
	snprintf(buf, 128, "/sys/devices/system/cpu/cpu%u/cache/index%u/%s", cpu, idx, file);
	/* paranoid */ verifyf(len > 0, "Could not generate '%s' filename for cpu %u, index %u", file, cpu, idx);

	int fd = open(buf, 0, O_RDONLY);
	/* paranoid */ verifyf(fd > 0, "Could not open file '%s'", buf);

	ssize_t r = read(fd, out, out_len);
	/* paranoid */ verifyf(r > 0, "Could not read file '%s'", buf);

	/* paranoid */ __attribute__((unused)) int ret =
	close(fd);
	/* paranoid */ verifyf(ret == 0, "Could not close file '%s'", buf);

	out[r-1] = '\0';
	return r-1;
}

unsigned find_idx() {
	int idxs = count_cache_indexes();

	unsigned found_level = 0;
	unsigned found = -1u;
	for(i; idxs) {
		unsigned idx = idxs - 1 - i;
		char buf[32];

		// Level is the cache level: higher means bigger and slower
		read_cpuidxinfo_into(0, idx, "level", buf, 32);
		char * end;
		unsigned long level = strtoul(buf, &end, 10);
		/* paranoid */ verifyf(level <= 250, "Cpu %u has more than 250 levels of cache, that doesn't sound right", 0);
		/* paranoid */ verify(*end == '\0');

		if(found_level < level) {
			found_level = level;
			found = idx;
		}
	}

	/* paranoid */ verify(found != -1u);
	return found;
}

int main() {
	//-----------------------------------------------------------------------
	int ret1 = get_nprocs();
	int ret2 = cpu_info.hthrd_count;
	if(ret1 != ret2) {
		sout | "No match! libcfa says" | ret2 | "hardware threads but linux counts" | ret1 | "processors";
	}
	else {
		sout | "Match!";
	}

	//-----------------------------------------------------------------------
	// Make sure no one has the same self
	for(ime; cpu_info.hthrd_count) {
		unsigned me = cpu_info.llc_map[ime].self;
		{
			unsigned s = cpu_info.llc_map[ime].start;
			unsigned e = s + cpu_info.llc_map[ime].count;
			if(me < s || me >= e) {
				sout | "CPU" | ime | "outside of it's own map: " | s | "<=" | me | "<" | e;
			}
		}


		for(ithem; cpu_info.hthrd_count) {
			if(ime == ithem) continue;

			unsigned them = cpu_info.llc_map[ithem].self;
			if(me == them) {
				sout | "CPU" | ime | "has conflicting self id with" | ithem | "(" | me | ")";
			}
		}
	}


	//-----------------------------------------------------------------------
	unsigned idx = find_idx();
	// For all procs check mapping is consistent
	for(cpu_me; cpu_info.hthrd_count) {
		char buf_me[32];
		size_t len_me = read_cpuidxinfo_into(cpu_me, idx, "shared_cpu_list", buf_me, 32);
		for(cpu_them; cpu_info.hthrd_count) {
			if(cpu_me == cpu_them) continue;
			char buf_them[32];
			size_t len_them = read_cpuidxinfo_into(cpu_them, idx, "shared_cpu_list", buf_them, 32);

			bool match_file = len_them == len_me && 0 == strncmp(buf_them, buf_me, len_me);
			bool match_info = cpu_info.llc_map[cpu_me].start == cpu_info.llc_map[cpu_them].start && cpu_info.llc_map[cpu_me].count == cpu_info.llc_map[cpu_them].count;

			if(match_file != match_info) {
				sout | "CPU" | cpu_me | "and" | cpu_them | "have inconsitent file and cpu_info";
				sout | cpu_me | ": <" | cpu_info.llc_map[cpu_me  ].start | "," | cpu_info.llc_map[cpu_me  ].count | "> '" | buf_me   | "'";
				sout | cpu_me | ": <" | cpu_info.llc_map[cpu_them].start | "," | cpu_info.llc_map[cpu_them].count | "> '" | buf_them | "'";
			}
		}
	}
}