Add coreupdownd

Signed-off-by: Mattias Andrée <maandree@kth.se>

1 files changed, 280 insertions, 33 deletions

diff --git a/coreupdown.c b/coreupdown.c
index 1de5007..403bdf6 100644
--- a/coreupdown.c
+++ b/coreupdown.c
@@ -3,37 +3,46 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <limits.h>
+#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <time.h>
 #include <unistd.h>
 
-int
-main(int argc, char *argv[])
+static const char *argv0;
+
+#define coreup() coreupdown(ULONG_MAX)
+#define coredown() coreupdown(1)
+
+static int
+coreupdown(unsigned long int count)
 {
-	unsigned long i, count;
-	const char *command, *argv0;
-	char path[sizeof("/sys/devices/system/cpu/cpu/online") + 3 * sizeof(i)];
+	char path[sizeof("/sys/devices/system/cpu/cpu/online") + 3 * sizeof(count)];
+	unsigned long int i;
 	int fd, ret = 0;
 
-	if (argc == 0) {
-	wrong_command:
-		fprintf(stderr, "usage: coreup [count]\nusage: coredown [count]\n");
-		return 1;
+	for (i = 1; i; i++) {
+		sprintf(path, "/sys/devices/system/cpu/cpu%zu/online", i);
+		fd = open(path, O_WRONLY);
+		if (fd < 0) {
+			if (errno == ENOENT)
+				break;
+			fprintf(stderr, "%s: open %s O_WRONLY\n", argv0, path);
+			return -1;
+		}
+		if (write(fd, i < count ? "1\n" : "0\n", 2) < 0) {
+			fprintf(stderr, "%s: write %s\n", argv0, path);
+			ret = -1;
+		}
+		close(fd);
 	}
+	return ret;
+}
 
-	argv0 = *argv++;
-	argc--;
-	command = strrchr(argv0, '/');
-	command = command ? &command[1] : argv0;
-
-	if (!strcmp(command, "coreup"))
-		count = ULONG_MAX;
-	else if (!strcmp(command, "coredown"))
-		count = 1;
-	else
-		goto wrong_command;
-
+static int
+oneshot_main(int argc, char **argv, unsigned long int count)
+{
 	if (argc && !strcmp(argv[0], "--")) {
 		argv++;
 		argc--;
@@ -45,7 +54,7 @@ main(int argc, char *argv[])
 		return 1;
 	}
 
-	if (argc >= 1) {
+	if (argc) {
 		char *end;
 		errno = 0;
 		if (!isdigit(**argv))
@@ -57,21 +66,259 @@ main(int argc, char *argv[])
 		argc--;
 	}
 
-	for (i = 1; i; i++) {
-		sprintf(path, "/sys/devices/system/cpu/cpu%zu/online", i);
-		fd = open(path, O_WRONLY);
-		if (fd < 0) {
-			if (errno == ENOENT)
+	return -coreupdown(count);
+}
+
+static int
+getusage(uintmax_t *total_out, uintmax_t *idle_out, size_t *cpus_out)
+{
+#define IDLE_FIELD 3
+
+	static uintmax_t last_total = 0, last_idle = 0;
+	uintmax_t cur_total, cur_idle;
+	char buf[512];
+	int fd;
+	size_t off, len, field;
+	ssize_t r;
+	int line_incomplete = 0, beginning_of_line = 1;
+	uintmax_t amount[] = {0, 0}, value;
+
+	*cpus_out = 0;
+
+	fd = open("/proc/stat", O_RDONLY);
+	if (fd < 0) {
+		fprintf(stderr, "%s: open /proc/stat O_RDONLY\n", argv0);
+		return -1;
+	}
+
+	len = 0;
+	for (;;) {
+		r = read(fd, &buf[len], sizeof(buf) - len);
+		if (!r) {
+			fprintf(stderr, "%s: /proc/stat did not contain \"cpu\" line\n", argv0);
+			close(fd);
+			return -1;
+		} else if (r < 0) {
+			if (errno == EINTR)
+				continue;
+			fprintf(stderr, "%s: read /proc/stat: %s\n", argv0, strerror(errno));
+			close(fd);
+			return -1;
+		}
+		len += (size_t)r;
+
+		if (line_incomplete)
+			goto skip_line;
+
+		for (off = 0; off < len;) {
+			if (len - off < 4) {
+				memmove(&buf[0], &buf[off], len -= off);
 				break;
-			fprintf(stderr, "%s: open %s O_WRONLY\n", argv0, path);
-			return 1;
+			} else if (!strncmp(&buf[off], "cpu", 3)) {
+				if (isspace(buf[off + 3]))
+					goto cpu_line_found;
+				else if (isdigit(buf[off + 3]))
+					*cpus_out += 1;
+			}
+
+		skip_line:
+			while (off < len && buf[off] != '\n')
+				off++;
+			if (off == len) {
+				line_incomplete = 0;
+				break;
+			} else {
+				off++;
+				line_incomplete = 1;
+			}
 		}
-		if (write(fd, i < count ? "1\n" : "0\n", 2) < 0) {
-			fprintf(stderr, "%s: write %s\n", argv0, path);
-			ret = 1;
+	}
+cpu_line_found:
+
+	off += 4;
+	field = 0;
+	value = 0;
+	for (;;) {
+		if (off == len) {
+			off = len = 0;
+			r = read(fd, buf, sizeof(buf));
+			if (!r) {
+				goto line_done;
+			} else if (r < 0) {
+				if (errno == EINTR)
+					continue;
+				fprintf(stderr, "%s: read /proc/stat: %s\n", argv0, strerror(errno));
+				close(fd);
+				return -1;
+			}
+			len = (size_t)r;
 		}
+		while (off < len && isspace(buf[off]))
+			off++;
+		if (off == len)
+			continue;
+		while (off < len) {
+			if (buf[off] == '\n') {
+				amount[field++ == IDLE_FIELD] += value;
+				off++;
+				goto line_done;
+			} else if (isspace(buf[off])) {
+				amount[field++ == IDLE_FIELD] += value;
+				value = 0;
+				off++;
+				break;
+			} else {
+				value *= 10;
+				value += buf[off] & 15;
+				off++;
+			}
+		}
+	}
+line_done:
+
+	for (;;) {
+		if (off == len) {
+			off = len = 0;
+		read_more:
+			r = read(fd, &buf[len], sizeof(buf) - len);
+			if (!r) {
+				break;
+			} else if (r < 0) {
+				if (errno == EINTR)
+					continue;
+				fprintf(stderr, "%s: read /proc/stat: %s\n", argv0, strerror(errno));
+				close(fd);
+				return -1;
+			}
+			len = (size_t)r;
+		}
+		for (; off < len; off++) {
+			if (beginning_of_line) {
+				if (len - off < 5) {
+					memmove(&buf[0], &buf[off], len -= off);
+					goto read_more;
+				}
+				if (!strncmp(&buf[off], "cpu", 3) && isdigit(buf[off + 3]))
+					*cpus_out += 1;
+				beginning_of_line = 0;
+			}
+			if (buf[off] == '\n')
+				beginning_of_line = 1;
+		}
+	}
+
+	close(fd);
+
+	if (field < IDLE_FIELD) {
+		fprintf(stderr, "%s: /proc/stat did not contain CPU idle time\n", argv0);
 		close(fd);
+		return -1;
 	}
 
-	return ret;
+	cur_total = amount[0] + amount[1];
+	cur_idle = amount[1];
+	*total_out = cur_total - last_total;
+	*idle_out = cur_idle - last_idle;
+	last_total = cur_total;
+	last_idle = cur_idle;
+	return 0;
+
+#undef IDLE_FIELD
+}
+
+static int
+daemon_main(int argc, char **argv)
+{
+	uintmax_t total, idle;
+	size_t cpus;
+	int up_time = 0, down_time = 0, cooldown = 0;
+	struct timespec interval, rem;
+
+	if (argc && !strcmp(argv[0], "--")) {
+		argv++;
+		argc--;
+	}
+
+	if (argc > 0) {
+		fprintf(stderr, "usage: %s\n", argv0);
+		return 1;
+	}
+
+	/* TODO configurations should be configurable */
+
+	/* TODO add SIGHUP support */
+
+	/* TODO add proper daemonisation */
+
+	interval.tv_sec = DAEMON_INTERVAL_SEC;
+	interval.tv_nsec = DAEMON_INTERVAL_NSEC;
+
+	if (getusage(&total, &idle, &cpus))
+		return 1;
+
+	close(STDIN_FILENO);
+	close(STDOUT_FILENO);
+
+	for (;;) {
+		if (clock_nanosleep(CLOCK_REALTIME /* = monotonic */, 0, &interval, &rem)) {
+			do {
+				if (errno != EINTR) {
+					fprintf(stderr, "%s: clock_nanosleep CLOCK_REALTIME: %s\n",
+					        argv0, strerror(errno));
+					return 1;
+				}
+			} while (clock_nanosleep(CLOCK_REALTIME, 0, &rem, &rem));
+		}
+		sleep(1);
+		if (getusage(&total, &idle, &cpus))
+			return 1;
+		if (cooldown) {
+			cooldown--;
+			continue;
+		}
+
+		if (cpus == 1 && 100 * (total - idle) > COREUP_THRESHOLD_CPU * total) {
+			down_time = 0;
+			if (up_time++ >= COREUP_THRESHOLD_TIME) {
+				cooldown = COREUP_COOLDOWN;
+				coreup();
+				up_time = 0;
+			}
+		} else if (cpus > 1 && 100 * (total - idle) < COREDOWN_THRESHOLD_CPU * total * cpus) {
+			up_time = 0;
+			if (down_time++ >= COREDOWN_THRESHOLD_TIME) {
+				cooldown = COREDOWN_COOLDOWN;
+				coredown();
+				down_time = 0;
+			}
+		} else {
+			up_time = 0;
+			down_time = 0;
+		}
+	}
+
+	return 0;
+}
+
+int
+main(int argc, char **argv)
+{
+	const char *command;
+
+	if (argc--) {
+		command = strrchr(argv0 = *argv++, '/');
+		command = command ? &command[1] : argv0;
+		if (!strcmp(command, "coreup"))
+			return oneshot_main(argc, argv, ULONG_MAX);
+		if (!strcmp(command, "coredown"))
+			return oneshot_main(argc, argv, 1);
+		if (!strcmp(command, "coreupdownd"))
+			return daemon_main(argc, argv);
+	}
+
+	fprintf(stderr, "usage: coreup [count]\n"
+	                "usage: coredown [count]\n"
+	                "usage: coreupdownd\n");
+
+	return 1;
 }