// Copyright (C) 2002-2004 Andrew Tridgell
// Copyright (C) 2009-2018 Joel Rosdahl
//
// 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 3 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, write to the Free Software Foundation, Inc., 51
// Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

// Routines to handle the stats files. The stats file is stored one per cache
// subdirectory to make this more scalable.

#include "ccache.h"
#include "hashutil.h"

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

extern char *stats_file;
extern struct conf *conf;
extern unsigned lock_staleness_limit;
extern char *primary_config_path;
extern char *secondary_config_path;

static struct counters *counter_updates;

#define FLAG_NOZERO 1 // don't zero with the -z option
#define FLAG_ALWAYS 2 // always show, even if zero
#define FLAG_NEVER 4 // never show

static void display_size_times_1024(uint64_t size);

// Statistics fields in display order.
static struct {
	enum stats stat;
	char *message;
	void (*fn)(uint64_t);
	unsigned flags;
} stats_info[] = {
	{
		STATS_CACHEHIT_DIR,
		"cache hit (direct)",
		NULL,
		FLAG_ALWAYS
	},
	{
		STATS_CACHEHIT_CPP,
		"cache hit (preprocessed)",
		NULL,
		FLAG_ALWAYS
	},
	{
		STATS_TOCACHE,
		"cache miss",
		NULL,
		FLAG_ALWAYS
	},
	{
		STATS_LINK,
		"called for link",
		NULL,
		0
	},
	{
		STATS_PREPROCESSING,
		"called for preprocessing",
		NULL,
		0
	},
	{
		STATS_MULTIPLE,
		"multiple source files",
		NULL,
		0
	},
	{
		STATS_STDOUT,
		"compiler produced stdout",
		NULL,
		0
	},
	{
		STATS_NOOUTPUT,
		"compiler produced no output",
		NULL,
		0
	},
	{
		STATS_EMPTYOUTPUT,
		"compiler produced empty output",
		NULL,
		0
	},
	{
		STATS_STATUS,
		"compile failed",
		NULL,
		0
	},
	{
		STATS_ERROR,
		"ccache internal error",
		NULL,
		0
	},
	{
		STATS_PREPROCESSOR,
		"preprocessor error",
		NULL,
		0
	},
	{
		STATS_CANTUSEPCH,
		"can't use precompiled header",
		NULL,
		0
	},
	{
		STATS_COMPILER,
		"couldn't find the compiler",
		NULL,
		0
	},
	{
		STATS_MISSING,
		"cache file missing",
		NULL,
		0
	},
	{
		STATS_ARGS,
		"bad compiler arguments",
		NULL,
		0
	},
	{
		STATS_SOURCELANG,
		"unsupported source language",
		NULL,
		0
	},
	{
		STATS_COMPCHECK,
		"compiler check failed",
		NULL,
		0
	},
	{
		STATS_CONFTEST,
		"autoconf compile/link",
		NULL,
		0
	},
	{
		STATS_UNSUPPORTED_OPTION,
		"unsupported compiler option",
		NULL,
		0
	},
	{
		STATS_UNSUPPORTED_DIRECTIVE,
		"unsupported code directive",
		NULL,
		0
	},
	{
		STATS_OUTSTDOUT,
		"output to stdout",
		NULL,
		0
	},
	{
		STATS_DEVICE,
		"output to a non-regular file",
		NULL,
		0
	},
	{
		STATS_NOINPUT,
		"no input file",
		NULL,
		0
	},
	{
		STATS_BADEXTRAFILE,
		"error hashing extra file",
		NULL,
		0
	},
	{
		STATS_NUMCLEANUPS,
		"cleanups performed",
		NULL,
		FLAG_ALWAYS
	},
	{
		STATS_NUMFILES,
		"files in cache",
		NULL,
		FLAG_NOZERO|FLAG_ALWAYS
	},
	{
		STATS_TOTALSIZE,
		"cache size",
		display_size_times_1024,
		FLAG_NOZERO|FLAG_ALWAYS
	},
	{
		STATS_OBSOLETE_MAXFILES,
		"OBSOLETE",
		NULL,
		FLAG_NOZERO|FLAG_NEVER
	},
	{
		STATS_OBSOLETE_MAXSIZE,
		"OBSOLETE",
		NULL,
		FLAG_NOZERO|FLAG_NEVER
	},
	{
		STATS_ZEROTIMESTAMP,
		"stats last zeroed at",
		NULL,
		FLAG_NEVER
	},
	{
		STATS_NONE,
		NULL,
		NULL,
		0
	}
};

static void
display_size(uint64_t size)
{
	char *s = format_human_readable_size(size);
	printf("%11s", s);
	free(s);
}

static void
display_size_times_1024(uint64_t size)
{
	display_size(size * 1024);
}

// Parse a stats file from a buffer, adding to the counters.
static void
parse_stats(struct counters *counters, const char *buf)
{
	size_t i = 0;
	const char *p = buf;
	while (true) {
		char *p2;
		long val = strtol(p, &p2, 10);
		if (p2 == p) {
			break;
		}
		if (counters->size < i + 1) {
			counters_resize(counters, i + 1);
		}
		counters->data[i] += val;
		i++;
		p = p2;
	}
}

// Write out a stats file.
void
stats_write(const char *path, struct counters *counters)
{
	struct stat st;
	if (stat(path, &st) != 0 && errno == ENOENT) {
		// New stats, update zero timestamp.
		time_t now;
		time(&now);
		stats_timestamp(now, counters);
	}
	char *tmp_file = format("%s.tmp", path);
	FILE *f = create_tmp_file(&tmp_file, "wb");
	for (size_t i = 0; i < counters->size; i++) {
		if (fprintf(f, "%u\n", counters->data[i]) < 0) {
			fatal("Failed to write to %s", tmp_file);
		}
	}
	fclose(f);
	x_rename(tmp_file, path);
	free(tmp_file);
}

static void
init_counter_updates(void)
{
	if (!counter_updates) {
		counter_updates = counters_init(STATS_END);
	}
}

// Record that a number of bytes and files have been added to the cache. Size
// is in bytes.
void
stats_update_size(int64_t size, int files)
{
	init_counter_updates();
	counter_updates->data[STATS_NUMFILES] += files;
	counter_updates->data[STATS_TOTALSIZE] += size / 1024;
}

// Read in the stats from one directory and add to the counters.
void
stats_read(const char *sfile, struct counters *counters)
{
	char *data = read_text_file(sfile, 1024);
	if (data) {
		parse_stats(counters, data);
	}
	free(data);
}

// Set the timestamp when the counters were last zeroed out.
void
stats_timestamp(time_t time, struct counters *counters)
{
	counters->data[STATS_ZEROTIMESTAMP] = (unsigned) time;
}

// Write counter updates in counter_updates to disk.
void
stats_flush(void)
{
	assert(conf);

	if (!conf->stats) {
		return;
	}

	if (!counter_updates) {
		return;
	}

	bool should_flush = false;
	for (int i = 0; i < STATS_END; ++i) {
		if (counter_updates->data[i] > 0) {
			should_flush = true;
			break;
		}
	}
	if (!should_flush) {
		return;
	}

	if (!stats_file) {
		char *stats_dir;

		// A NULL stats_file means that we didn't get past calculate_object_hash(),
		// so we just choose one of stats files in the 16 subdirectories.
		stats_dir = format("%s/%x", conf->cache_dir, hash_from_int(getpid()) % 16);
		stats_file = format("%s/stats", stats_dir);
		free(stats_dir);
	}

	if (!lockfile_acquire(stats_file, lock_staleness_limit)) {
		return;
	}

	struct counters *counters = counters_init(STATS_END);
	stats_read(stats_file, counters);
	for (int i = 0; i < STATS_END; ++i) {
		counters->data[i] += counter_updates->data[i];
	}
	stats_write(stats_file, counters);
	lockfile_release(stats_file);

	if (!str_eq(conf->log_file, "")) {
		for (int i = 0; i < STATS_END; ++i) {
			if (counter_updates->data[stats_info[i].stat] != 0
			    && !(stats_info[i].flags & FLAG_NOZERO)) {
				cc_log("Result: %s", stats_info[i].message);
			}
		}
	}

	char *subdir = dirname(stats_file);
	bool need_cleanup = false;

	if (conf->max_files != 0
	    && counters->data[STATS_NUMFILES] > conf->max_files / 16) {
		cc_log("Need to clean up %s since it holds %u files (limit: %u files)",
		       subdir,
		       counters->data[STATS_NUMFILES],
		       conf->max_files / 16);
		need_cleanup = true;
	}
	if (conf->max_size != 0
	    && counters->data[STATS_TOTALSIZE] > conf->max_size / 1024 / 16) {
		cc_log("Need to clean up %s since it holds %u KiB (limit: %lu KiB)",
		       subdir,
		       counters->data[STATS_TOTALSIZE],
		       (unsigned long)conf->max_size / 1024 / 16);
		need_cleanup = true;
	}

	if (need_cleanup) {
		clean_up_dir(conf, subdir, conf->limit_multiple);
	}

	free(subdir);
	counters_free(counters);
}

// Update a normal stat.
void
stats_update(enum stats stat)
{
	assert(stat > STATS_NONE && stat < STATS_END);
	init_counter_updates();
	counter_updates->data[stat]++;
}

// Get the pending update of a counter value.
unsigned
stats_get_pending(enum stats stat)
{
	init_counter_updates();
	return counter_updates->data[stat];
}

// Sum and display the total stats for all cache dirs.
void
stats_summary(struct conf *conf)
{
	struct counters *counters = counters_init(STATS_END);
	time_t oldest = 0;

	assert(conf);

	// Add up the stats in each directory.
	for (int dir = -1; dir <= 0xF; dir++) {
		char *fname;

		if (dir == -1) {
			fname = format("%s/stats", conf->cache_dir);
		} else {
			fname = format("%s/%1x/stats", conf->cache_dir, dir);
		}

		counters->data[STATS_ZEROTIMESTAMP] = 0; // Don't add
		stats_read(fname, counters);
		time_t current = (time_t) counters->data[STATS_ZEROTIMESTAMP];
		if (current != 0 && (oldest == 0 || current < oldest)) {
			oldest = current;
		}
		free(fname);
	}

	printf("cache directory                     %s\n", conf->cache_dir);
	printf("primary config                      %s\n",
	       primary_config_path ? primary_config_path : "");
	printf("secondary config      (readonly)    %s\n",
	       secondary_config_path ? secondary_config_path : "");
	if (oldest) {
		struct tm *tm = localtime(&oldest);
		char timestamp[100];
		strftime(timestamp, sizeof(timestamp), "%c", tm);
		printf("stats zero time                     %s\n", timestamp);
	}

	// ...and display them.
	for (int i = 0; stats_info[i].message; i++) {
		enum stats stat = stats_info[i].stat;

		if (stats_info[i].flags & FLAG_NEVER) {
			continue;
		}
		if (counters->data[stat] == 0 && !(stats_info[i].flags & FLAG_ALWAYS)) {
			continue;
		}

		printf("%-31s ", stats_info[i].message);
		if (stats_info[i].fn) {
			stats_info[i].fn(counters->data[stat]);
			printf("\n");
		} else {
			printf("%8u\n", counters->data[stat]);
		}

		if (stat == STATS_TOCACHE) {
			unsigned direct = counters->data[STATS_CACHEHIT_DIR];
			unsigned preprocessed = counters->data[STATS_CACHEHIT_CPP];
			unsigned hit = direct + preprocessed;
			unsigned miss = counters->data[STATS_TOCACHE];
			unsigned total = hit + miss;
			double percent = total > 0 ? (100.0f * hit) / total : 0.0f;
			printf("cache hit rate                    %6.2f %%\n", percent);
		}
	}

	if (conf->max_files != 0) {
		printf("max files                       %8u\n", conf->max_files);
	}
	if (conf->max_size != 0) {
		printf("max cache size                  ");
		display_size(conf->max_size);
		printf("\n");
	}

	counters_free(counters);
}

// Zero all the stats structures.
void
stats_zero(void)
{
	assert(conf);

	char *fname = format("%s/stats", conf->cache_dir);
	x_unlink(fname);
	free(fname);

	for (int dir = 0; dir <= 0xF; dir++) {
		struct counters *counters = counters_init(STATS_END);
		struct stat st;
		fname = format("%s/%1x/stats", conf->cache_dir, dir);
		if (stat(fname, &st) != 0) {
			// No point in trying to reset the stats file if it doesn't exist.
			free(fname);
			continue;
		}
		if (lockfile_acquire(fname, lock_staleness_limit)) {
			stats_read(fname, counters);
			for (unsigned i = 0; stats_info[i].message; i++) {
				if (!(stats_info[i].flags & FLAG_NOZERO)) {
					counters->data[stats_info[i].stat] = 0;
				}
			}
			stats_timestamp(time(NULL), counters);
			stats_write(fname, counters);
			lockfile_release(fname);
		}
		counters_free(counters);
		free(fname);
	}
}

// Get the per-directory limits.
void
stats_get_obsolete_limits(const char *dir, unsigned *maxfiles,
                          uint64_t *maxsize)
{
	struct counters *counters = counters_init(STATS_END);
	char *sname = format("%s/stats", dir);
	stats_read(sname, counters);
	*maxfiles = counters->data[STATS_OBSOLETE_MAXFILES];
	*maxsize = (uint64_t)counters->data[STATS_OBSOLETE_MAXSIZE] * 1024;
	free(sname);
	counters_free(counters);
}

// Set the per-directory sizes.
void
stats_set_sizes(const char *dir, unsigned num_files, uint64_t total_size)
{
	struct counters *counters = counters_init(STATS_END);
	char *statsfile = format("%s/stats", dir);
	if (lockfile_acquire(statsfile, lock_staleness_limit)) {
		stats_read(statsfile, counters);
		counters->data[STATS_NUMFILES] = num_files;
		counters->data[STATS_TOTALSIZE] = total_size / 1024;
		stats_write(statsfile, counters);
		lockfile_release(statsfile);
	}
	free(statsfile);
	counters_free(counters);
}

// Count directory cleanup run.
void
stats_add_cleanup(const char *dir, unsigned count)
{
	struct counters *counters = counters_init(STATS_END);
	char *statsfile = format("%s/stats", dir);
	if (lockfile_acquire(statsfile, lock_staleness_limit)) {
		stats_read(statsfile, counters);
		counters->data[STATS_NUMCLEANUPS] += count;
		stats_write(statsfile, counters);
		lockfile_release(statsfile);
	}
	free(statsfile);
	counters_free(counters);
}
