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/*
* Copyright (C) 2016 "IoT.bzh"
* Author José Bollo <jose.bollo@iot.bzh>
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <netdb.h>
#include <fcntl.h>
#include <math.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/timerfd.h>
#include <json-c/json.h>
#include <systemd/sd-event.h>
#include <afb/afb-binding.h>
#include <afb/afb-service-itf.h>
/*
* the interface to afb-daemon
*/
const struct afb_binding_interface *afbitf;
#define DEFAULT_PERIOD 1 /* 1 second */
struct event;
const char *cpu_fields[]= {
"user",
"nice",
"system",
"idle",
"iowait",
"irq",
"softirq",
"steal",
"guest",
"guest_nice"
};
#define CPU_FIELD_COUNT (sizeof cpu_fields / sizeof *cpu_fields)
struct status {
uint64_t cpu[CPU_FIELD_COUNT];
};
static int fd_proc;
static int fd_timer;
static struct sd_event_source *source = NULL;
static struct status older;
static struct status newer;
static struct status diff;
static struct afb_event event;
/***************************************************************************************/
/***************************************************************************************/
/** **/
/** **/
/** SECTION: BINDING VERBS IMPLEMENTATION **/
/** **/
/** **/
/***************************************************************************************/
/***************************************************************************************/
static int read_status(int fd, struct status *s)
{
int n;
ssize_t sz;
off_t off;
char buffer[8192];
long long unsigned x[CPU_FIELD_COUNT];
off = lseek(fd, 0, SEEK_SET);
if (off == (off_t)-1)
return -1;
sz = read(fd, buffer, sizeof buffer);
if (sz == -1)
return -1;
n = sscanf(buffer, "cpu %Lu %Lu %Lu %Lu %Lu %Lu %Lu %Lu %Lu %Lu", &x[0], &x[1], &x[2], &x[3], &x[4], &x[5], &x[6], &x[7], &x[8], &x[9]);
if (n != CPU_FIELD_COUNT)
return -1;
while(n) {
n--;
s->cpu[n] = x[n];
}
return 0;
}
static void stop()
{
sd_event_source_unref(source);
afb_event_drop(event);
close(fd_timer);
close(fd_proc);
fd_timer = -1;
fd_proc = -1;
event.itf = NULL;
source = NULL;
}
static int emit(sd_event_source *src, int fd, uint32_t revents, void *userdata)
{
int f, rc, p;
struct json_object *obj;
uint64_t u, s, i;
read(fd, &i, sizeof i);
memcpy(&older, &newer, sizeof older);
rc = read_status(fd_proc, &newer);
for(f = 0; f < (int)CPU_FIELD_COUNT ; f++)
diff.cpu[f] = newer.cpu[f] - older.cpu[f];
u = 0;
s = 0;
i = 0;
u += diff.cpu[0]; // "user",
u += diff.cpu[1]; // "nice",
s += diff.cpu[2]; // "system",
i += diff.cpu[3]; // "idle",
i += diff.cpu[4]; // "iowait",
s += diff.cpu[5]; // "irq",
s += diff.cpu[6]; // "softirq",
i += diff.cpu[7]; // "steal",
u += diff.cpu[8]; // "guest",
u += diff.cpu[9]; // "guest_nice"
p = (int)(unsigned)((100 * (u + s)) / (u + s + i));
obj = json_object_new_int(p);
if (afb_event_push(event, obj) == 0)
stop();
return 0;
}
static int start()
{
int fdp, fdt, rc;
struct itimerspec ts;
struct sd_event_source *src;
fdp = open("/proc/stat", O_RDONLY|O_CLOEXEC);
if (fdp >= 0) {
rc = read_status(fdp, &newer);
if (rc >= 0) {
fdt = timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK|TFD_CLOEXEC);
if (fdt >= 0) {
ts.it_interval.tv_sec = 1;
ts.it_value.tv_sec = 1;
ts.it_interval.tv_nsec = 0;
ts.it_value.tv_nsec = 0;
rc = timerfd_settime(fdt, 0, &ts, NULL);
if (rc >= 0) {
event = afb_daemon_make_event(afbitf->daemon, "stat");
if (afb_event_is_valid(event)) {
rc = sd_event_add_io(afb_daemon_get_event_loop(afbitf->daemon), &src, fdt, EPOLLIN, emit, NULL);
if (rc >= 0) {
fd_proc = fdp;
fd_timer = fdt;
source = src;
return 0;
}
afb_event_drop(event);
}
}
close(fdt);
}
}
close(fdp);
}
return -1;
}
static int ensure_started()
{
return source == NULL ? start() : 0;
}
/***************************************************************************************/
/***************************************************************************************/
/** **/
/** **/
/** SECTION: BINDING VERBS IMPLEMENTATION **/
/** **/
/** **/
/***************************************************************************************/
/***************************************************************************************/
/*
* subscribe to notification of stat
*/
static void subscribe(struct afb_req req)
{
int rc;
rc = ensure_started();
if (rc < 0) {
afb_req_fail(req, "failed", "Can't start");
} else if (afb_req_subscribe(req, event) != 0) {
afb_req_fail_f(req, "failed", "afb_req_subscribe returned an error: %m");
} else {
afb_req_success(req, NULL, NULL);
}
}
/*
* unsubscribe a previous subscription
*
* parameters of the unsubscription are:
*
* id: integer: the numeric identifier of the event as returned when subscribing
*/
static void unsubscribe(struct afb_req req)
{
if (afb_event_is_valid(event))
afb_req_unsubscribe(req, event);
afb_req_success(req, NULL, NULL);
}
/*
* array of the verbs exported to afb-daemon
*/
static const struct afb_verb_desc_v1 binding_verbs[] = {
/* VERB'S NAME SESSION MANAGEMENT FUNCTION TO CALL SHORT DESCRIPTION */
{ .name= "subscribe", .session= AFB_SESSION_NONE, .callback= subscribe, .info= "subscribe to notification of statistics" },
{ .name= "unsubscribe", .session= AFB_SESSION_NONE, .callback= unsubscribe, .info= "unsubscribe a previous subscription" },
{ .name= NULL } /* marker for end of the array */
};
/*
* description of the binding for afb-daemon
*/
static const struct afb_binding binding_description =
{
/* description conforms to VERSION 1 */
.type= AFB_BINDING_VERSION_1,
.v1= { /* fills the v1 field of the union when AFB_BINDING_VERSION_1 */
.prefix= "stat", /* the API name (or binding name or prefix) */
.info= "Get system statistics", /* short description of of the binding */
.verbs = binding_verbs /* the array describing the verbs of the API */
}
};
/*
* activation function for registering the binding called by afb-daemon
*/
const struct afb_binding *afbBindingV1Register(const struct afb_binding_interface *itf)
{
afbitf = itf; /* records the interface for accessing afb-daemon */
return &binding_description; /* returns the description of the binding */
}
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