/*
 * Copyright (c) 2008, The Android Open Source Project
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *  * Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  * Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the 
 *    distribution.
 *  * Neither the name of Google, Inc. nor the names of its contributors
 *    may be used to endorse or promote products derived from this
 *    software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/param.h>
#include <unistd.h>
#include <string.h>

struct state {
    long procs_r;
    long procs_b;

    long mem_free;
    long mem_mapped;
    long mem_anon;
    long mem_slab;

    long sys_in;
    long sys_cs;
    long sys_flt;

    long cpu_us;
    long cpu_ni;
    long cpu_sy;
    long cpu_id;
    long cpu_wa;
    long cpu_ir;
    long cpu_si;
};

#define MAX_LINE 256

char line[MAX_LINE];

static void read_state(struct state *s);
static int read_meminfo(struct state *s);
static int read_stat(struct state *s);
static int read_vmstat(struct state *s);
static void print_header(void);
static void print_line(struct state *old, struct state *new);
static void usage(char *cmd);

int vmstat_main(int argc, char *argv[]) {
    struct state s[2];
    int iterations, delay, header_interval;
    int toggle, count;
    int i;

    iterations = 0;
    delay = 1;
    header_interval = 20;

    for (i = 1; i < argc; i++) {
        if (!strcmp(argv[i], "-n")) { 
            if (i >= argc - 1) {
                fprintf(stderr, "Option -n requires an argument.\n");
                exit(EXIT_FAILURE);
            }
            iterations = atoi(argv[++i]);
            continue;
        }
        if (!strcmp(argv[i], "-d")) {
            if (i >= argc - 1) {
                fprintf(stderr, "Option -d requires an argument.\n");
                exit(EXIT_FAILURE);
            }
            delay = atoi(argv[++i]);
            continue;
        }
        if (!strcmp(argv[i], "-r")) {
            if (i >= argc - 1) {
                fprintf(stderr, "Option -r requires an argument.\n");
                exit(EXIT_FAILURE);
            }
            header_interval = atoi(argv[++i]);
            continue;
        }
        if (!strcmp(argv[i], "-h")) {
            usage(argv[0]);
            exit(EXIT_SUCCESS);
        }
        fprintf(stderr, "Invalid argument \"%s\".\n", argv[i]);
        usage(argv[0]);
	exit(EXIT_FAILURE);
    }

    toggle = 0;
    count = 0;

    if (!header_interval)
        print_header();
    read_state(&s[1 - toggle]);
    while ((iterations == 0) || (iterations-- > 0)) {
        sleep(delay);
        read_state(&s[toggle]);
        if (header_interval) {
            if (count == 0)
                print_header();
            count = (count + 1) % header_interval;
        }
        print_line(&s[1 - toggle], &s[toggle]);
        toggle = 1 - toggle;
    }

    return 0;
}

static void read_state(struct state *s) {
    int error;

    error = read_meminfo(s);
    if (error) {
        fprintf(stderr, "vmstat: could not read /proc/meminfo: %s\n", strerror(error));
        exit(EXIT_FAILURE);
    }

    error = read_stat(s);
    if (error) {
        fprintf(stderr, "vmstat: could not read /proc/stat: %s\n", strerror(error));
        exit(EXIT_FAILURE);
    }

    error = read_vmstat(s);
    if (error) {
        fprintf(stderr, "vmstat: could not read /proc/vmstat: %s\n", strerror(error));
        exit(EXIT_FAILURE);
    }
}

static int read_meminfo(struct state *s) {
    FILE *f;

    f = fopen("/proc/meminfo", "r");
    if (!f) return errno;

    while (fgets(line, MAX_LINE, f)) {
        sscanf(line, "MemFree: %ld kB", &s->mem_free);
        sscanf(line, "AnonPages: %ld kB", &s->mem_anon);
        sscanf(line, "Mapped: %ld kB", &s->mem_mapped);
        sscanf(line, "Slab: %ld kB", &s->mem_slab);
    }

    fclose(f);

    return 0;
}

static int read_stat(struct state *s) {
    FILE *f;

    f = fopen("/proc/stat", "r");
    if (!f) return errno;

    while (fgets(line, MAX_LINE, f)) {
        if (!strncmp(line, "cpu ", 4)) {
            sscanf(line, "cpu  %ld %ld %ld %ld %ld %ld %ld",
                &s->cpu_us, &s->cpu_ni, &s->cpu_sy, &s->cpu_id, &s->cpu_wa,
                &s->cpu_ir, &s->cpu_si);
        }
        sscanf(line, "intr %ld", &s->sys_in);
        sscanf(line, "ctxt %ld", &s->sys_cs);
        sscanf(line, "procs_running %ld", &s->procs_r);
        sscanf(line, "procs_blocked %ld", &s->procs_b);
    }

    fclose(f);

    return 0;
}

static int read_vmstat(struct state *s) {
    FILE *f;

    f = fopen("/proc/vmstat", "r");
    if (!f) return errno;

    while (fgets(line, MAX_LINE, f)) {
        sscanf(line, "pgmajfault %ld", &s->sys_flt);
    }

    fclose(f);

    return 0;
}

static void print_header(void) {
    printf("%-5s  %-27s  %-14s  %-17s\n", "procs", "memory", "system", "cpu");
    printf("%2s %2s  %6s %6s %6s %6s  %4s %4s %4s  %2s %2s %2s %2s %2s %2s\n", "r", "b", "free", "mapped", "anon", "slab", "in", "cs", "flt", "us", "ni", "sy", "id", "wa", "ir");
}

/* Jiffies to percent conversion */
#define JP(jif) ((jif) * 100 / (HZ))
#define NORM(var) ((var) = (((var) > 99) ? (99) : (var)))

static void print_line(struct state *old, struct state *new) {
    int us, ni, sy, id, wa, ir;
    us = JP(new->cpu_us - old->cpu_us); NORM(us);
    ni = JP(new->cpu_ni - old->cpu_ni); NORM(ni);
    sy = JP(new->cpu_sy - old->cpu_sy); NORM(sy);
    id = JP(new->cpu_id - old->cpu_id); NORM(id);
    wa = JP(new->cpu_wa - old->cpu_wa); NORM(wa);
    ir = JP(new->cpu_ir - old->cpu_ir); NORM(ir);
    printf("%2ld %2ld  %6ld %6ld %6ld %6ld  %4ld %4ld %4ld  %2d %2d %2d %2d %2d %2d\n",
        new->procs_r ? (new->procs_r - 1) : 0, new->procs_b,
        new->mem_free, new->mem_mapped, new->mem_anon, new->mem_slab,
        new->sys_in - old->sys_in, new->sys_cs - old->sys_cs, new->sys_flt - old->sys_flt,
        us, ni, sy, id, wa, ir);
}

static void usage(char *cmd) {
    fprintf(stderr, "Usage: %s [ -h ] [ -n iterations ] [ -d delay ] [ -r header_repeat ]\n"
                    "    -n iterations     How many rows of data to print.\n"
                    "    -d delay          How long to sleep between rows.\n"
                    "    -r header_repeat  How many rows to print before repeating\n"
                    "                      the header.  Zero means never repeat.\n"
                    "    -h                Displays this help screen.\n",
        cmd);
}