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-rw-r--r--src/clock.c405
1 files changed, 405 insertions, 0 deletions
diff --git a/src/clock.c b/src/clock.c
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+/*
+ * General time-keeping code and variables
+ *
+ * Copyright 2000-2021 Willy Tarreau <w@1wt.eu>
+ *
+ * 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
+ * 2 of the License, or (at your option) any later version.
+ *
+ */
+
+#include <sys/time.h>
+#include <signal.h>
+#include <time.h>
+
+#ifdef USE_THREAD
+#include <pthread.h>
+#endif
+
+#include <haproxy/api.h>
+#include <haproxy/activity.h>
+#include <haproxy/clock.h>
+#include <haproxy/signal-t.h>
+#include <haproxy/time.h>
+#include <haproxy/tinfo-t.h>
+#include <haproxy/tools.h>
+
+struct timeval start_date; /* the process's start date in wall-clock time */
+volatile ullong global_now; /* common monotonic date between all threads (32:32) */
+volatile uint global_now_ms; /* common monotonic date in milliseconds (may wrap) */
+
+THREAD_ALIGNED(64) static ullong now_offset; /* global offset between system time and global time */
+
+THREAD_LOCAL uint now_ms; /* internal monotonic date in milliseconds (may wrap) */
+THREAD_LOCAL struct timeval now; /* internal monotonic date derived from real clock */
+THREAD_LOCAL struct timeval date; /* the real current date (wall-clock time) */
+
+static THREAD_LOCAL struct timeval before_poll; /* system date before calling poll() */
+static THREAD_LOCAL struct timeval after_poll; /* system date after leaving poll() */
+static THREAD_LOCAL unsigned int samp_time; /* total elapsed time over current sample */
+static THREAD_LOCAL unsigned int idle_time; /* total idle time over current sample */
+static THREAD_LOCAL unsigned int iso_time_sec; /* last iso time value for this thread */
+static THREAD_LOCAL char iso_time_str[34]; /* ISO time representation of gettimeofday() */
+
+#if defined(_POSIX_TIMERS) && (_POSIX_TIMERS > 0) && defined(_POSIX_THREAD_CPUTIME)
+static clockid_t per_thread_clock_id[MAX_THREADS];
+#endif
+
+/* returns the system's monotonic time in nanoseconds if supported, otherwise zero */
+uint64_t now_mono_time(void)
+{
+ uint64_t ret = 0;
+#if defined(_POSIX_TIMERS) && defined(_POSIX_TIMERS) && (_POSIX_TIMERS > 0) && defined(_POSIX_MONOTONIC_CLOCK)
+ struct timespec ts;
+ clock_gettime(CLOCK_MONOTONIC, &ts);
+ ret = ts.tv_sec * 1000000000ULL + ts.tv_nsec;
+#endif
+ return ret;
+}
+
+/* returns the current thread's cumulated CPU time in nanoseconds if supported, otherwise zero */
+uint64_t now_cpu_time(void)
+{
+ uint64_t ret = 0;
+#if defined(_POSIX_TIMERS) && (_POSIX_TIMERS > 0) && defined(_POSIX_THREAD_CPUTIME)
+ struct timespec ts;
+ clock_gettime(CLOCK_THREAD_CPUTIME_ID, &ts);
+ ret = ts.tv_sec * 1000000000ULL + ts.tv_nsec;
+#endif
+ return ret;
+}
+
+/* returns another thread's cumulated CPU time in nanoseconds if supported, otherwise zero */
+uint64_t now_cpu_time_thread(int thr)
+{
+ uint64_t ret = 0;
+#if defined(_POSIX_TIMERS) && (_POSIX_TIMERS > 0) && defined(_POSIX_THREAD_CPUTIME)
+ struct timespec ts;
+ clock_gettime(per_thread_clock_id[thr], &ts);
+ ret = ts.tv_sec * 1000000000ULL + ts.tv_nsec;
+#endif
+ return ret;
+}
+
+/* set the clock source for the local thread */
+void clock_set_local_source(void)
+{
+#if defined(_POSIX_TIMERS) && (_POSIX_TIMERS > 0) && defined(_POSIX_THREAD_CPUTIME)
+#ifdef USE_THREAD
+ pthread_getcpuclockid(pthread_self(), &per_thread_clock_id[tid]);
+#else
+ per_thread_clock_id[tid] = CLOCK_THREAD_CPUTIME_ID;
+#endif
+#endif
+}
+
+/* registers a timer <tmr> of type timer_t delivering signal <sig> with value
+ * <val>. It tries on the current thread's clock ID first and falls back to
+ * CLOCK_REALTIME. Returns non-zero on success, 1 on failure.
+ */
+int clock_setup_signal_timer(void *tmr, int sig, int val)
+{
+ int ret = 0;
+
+#if defined(USE_RT) && (_POSIX_TIMERS > 0) && defined(_POSIX_THREAD_CPUTIME)
+ struct sigevent sev = { };
+ timer_t *timer = tmr;
+ sigset_t set;
+
+ /* unblock the WDTSIG signal we intend to use */
+ sigemptyset(&set);
+ sigaddset(&set, WDTSIG);
+ ha_sigmask(SIG_UNBLOCK, &set, NULL);
+
+ /* this timer will signal WDTSIG when it fires, with tid in the si_int
+ * field (important since any thread will receive the signal).
+ */
+ sev.sigev_notify = SIGEV_SIGNAL;
+ sev.sigev_signo = sig;
+ sev.sigev_value.sival_int = val;
+ if (timer_create(per_thread_clock_id[tid], &sev, timer) != -1 ||
+ timer_create(CLOCK_REALTIME, &sev, timer) != -1)
+ ret = 1;
+#endif
+ return ret;
+}
+
+/* clock_update_date: sets <date> to system time, and sets <now> to something as
+ * close as possible to real time, following a monotonic function. The main
+ * principle consists in detecting backwards and forwards time jumps and adjust
+ * an offset to correct them. This function should be called once after each
+ * poll, and never farther apart than MAX_DELAY_MS*2. The poll's timeout should
+ * be passed in <max_wait>, and the return value in <interrupted> (a non-zero
+ * value means that we have not expired the timeout).
+ *
+ * clock_init_process_date() must have been called once first, and
+ * clock_init_thread_date() must also have been called once for each thread.
+ *
+ * An offset is used to adjust the current time (date), to figure a monotonic
+ * local time (now). The offset is not critical, as it is only updated after a
+ * clock jump is detected. From this point all threads will apply it to their
+ * locally measured time, and will then agree around a common monotonic
+ * global_now value that serves to further refine their local time. As it is
+ * not possible to atomically update a timeval, both global_now and the
+ * now_offset values are instead stored as 64-bit integers made of two 32 bit
+ * values for the tv_sec and tv_usec parts. The offset is made of two signed
+ * ints so that the clock can be adjusted in the two directions.
+ */
+void clock_update_date(int max_wait, int interrupted)
+{
+ struct timeval min_deadline, max_deadline, tmp_now;
+ uint old_now_ms;
+ ullong old_now;
+ ullong new_now;
+ ullong ofs, ofs_new;
+ uint sec_ofs, usec_ofs;
+
+ gettimeofday(&date, NULL);
+
+ /* compute the minimum and maximum local date we may have reached based
+ * on our past date and the associated timeout. There are three possible
+ * extremities:
+ * - the new date cannot be older than before_poll
+ * - if not interrupted, the new date cannot be older than
+ * before_poll+max_wait
+ * - in any case the new date cannot be newer than
+ * before_poll+max_wait+some margin (100ms used here).
+ * In case of violation, we'll ignore the current date and instead
+ * restart from the last date we knew.
+ */
+ _tv_ms_add(&min_deadline, &before_poll, max_wait);
+ _tv_ms_add(&max_deadline, &before_poll, max_wait + 100);
+
+ ofs = HA_ATOMIC_LOAD(&now_offset);
+
+ if (unlikely(__tv_islt(&date, &before_poll) || // big jump backwards
+ (!interrupted && __tv_islt(&date, &min_deadline)) || // small jump backwards
+ __tv_islt(&max_deadline, &date))) { // big jump forwards
+ if (!interrupted)
+ _tv_ms_add(&now, &now, max_wait);
+ } else {
+ /* The date is still within expectations. Let's apply the
+ * now_offset to the system date. Note: ofs if made of two
+ * independent signed ints.
+ */
+ now.tv_sec = date.tv_sec + (int)(ofs >> 32); // note: may be positive or negative
+ now.tv_usec = date.tv_usec + (int)ofs; // note: may be positive or negative
+ if ((int)now.tv_usec < 0) {
+ now.tv_usec += 1000000;
+ now.tv_sec -= 1;
+ } else if (now.tv_usec >= 1000000) {
+ now.tv_usec -= 1000000;
+ now.tv_sec += 1;
+ }
+ }
+
+ /* now that we have bounded the local time, let's check if it's
+ * realistic regarding the global date, which only moves forward,
+ * otherwise catch up.
+ */
+ old_now = global_now;
+ old_now_ms = global_now_ms;
+
+ do {
+ tmp_now.tv_sec = (unsigned int)(old_now >> 32);
+ tmp_now.tv_usec = old_now & 0xFFFFFFFFU;
+
+ if (__tv_islt(&now, &tmp_now))
+ now = tmp_now;
+
+ /* now <now> is expected to be the most accurate date,
+ * equal to <global_now> or newer.
+ */
+ new_now = ((ullong)now.tv_sec << 32) + (uint)now.tv_usec;
+ now_ms = __tv_to_ms(&now);
+
+ /* let's try to update the global <now> (both in timeval
+ * and ms forms) or loop again.
+ */
+ } while (((new_now != old_now && !_HA_ATOMIC_CAS(&global_now, &old_now, new_now)) ||
+ (now_ms != old_now_ms && !_HA_ATOMIC_CAS(&global_now_ms, &old_now_ms, now_ms))) &&
+ __ha_cpu_relax());
+
+ /* <now> and <now_ms> are now updated to the last value of global_now
+ * and global_now_ms, which were also monotonically updated. We can
+ * compute the latest offset, we don't care who writes it last, the
+ * variations will not break the monotonic property.
+ */
+
+ sec_ofs = now.tv_sec - date.tv_sec;
+ usec_ofs = now.tv_usec - date.tv_usec;
+ if ((int)usec_ofs < 0) {
+ usec_ofs += 1000000;
+ sec_ofs -= 1;
+ }
+ ofs_new = ((ullong)sec_ofs << 32) + usec_ofs;
+ if (ofs_new != ofs)
+ HA_ATOMIC_STORE(&now_offset, ofs_new);
+}
+
+/* must be called once at boot to initialize some global variables */
+void clock_init_process_date(void)
+{
+ now_offset = 0;
+ gettimeofday(&date, NULL);
+ now = after_poll = before_poll = date;
+ global_now = ((ullong)date.tv_sec << 32) + (uint)date.tv_usec;
+ global_now_ms = now.tv_sec * 1000 + now.tv_usec / 1000;
+ th_ctx->idle_pct = 100;
+ clock_update_date(0, 1);
+}
+
+/* must be called once per thread to initialize their thread-local variables.
+ * Note that other threads might also be initializing and running in parallel.
+ */
+void clock_init_thread_date(void)
+{
+ ullong old_now;
+
+ gettimeofday(&date, NULL);
+ after_poll = before_poll = date;
+
+ old_now = _HA_ATOMIC_LOAD(&global_now);
+ now.tv_sec = old_now >> 32;
+ now.tv_usec = (uint)old_now;
+ th_ctx->idle_pct = 100;
+ th_ctx->prev_cpu_time = now_cpu_time();
+ clock_update_date(0, 1);
+}
+
+/* report the average CPU idle percentage over all running threads, between 0 and 100 */
+uint clock_report_idle(void)
+{
+ uint total = 0;
+ uint rthr = 0;
+ uint thr;
+
+ for (thr = 0; thr < MAX_THREADS; thr++) {
+ if (!(all_threads_mask & (1UL << thr)))
+ continue;
+ total += HA_ATOMIC_LOAD(&ha_thread_ctx[thr].idle_pct);
+ rthr++;
+ }
+ return rthr ? total / rthr : 0;
+}
+
+/* Update the idle time value twice a second, to be called after
+ * clock_update_date() when called after poll(), and currently called only by
+ * clock_leaving_poll() below. It relies on <before_poll> to be updated to
+ * the system time before calling poll().
+ */
+static inline void clock_measure_idle(void)
+{
+ /* Let's compute the idle to work ratio. We worked between after_poll
+ * and before_poll, and slept between before_poll and date. The idle_pct
+ * is updated at most twice every second. Note that the current second
+ * rarely changes so we avoid a multiply when not needed.
+ */
+ int delta;
+
+ if ((delta = date.tv_sec - before_poll.tv_sec))
+ delta *= 1000000;
+ idle_time += delta + (date.tv_usec - before_poll.tv_usec);
+
+ if ((delta = date.tv_sec - after_poll.tv_sec))
+ delta *= 1000000;
+ samp_time += delta + (date.tv_usec - after_poll.tv_usec);
+
+ after_poll.tv_sec = date.tv_sec; after_poll.tv_usec = date.tv_usec;
+ if (samp_time < 500000)
+ return;
+
+ HA_ATOMIC_STORE(&th_ctx->idle_pct, (100ULL * idle_time + samp_time / 2) / samp_time);
+ idle_time = samp_time = 0;
+}
+
+/* Collect date and time information after leaving poll(). <timeout> must be
+ * set to the maximum sleep time passed to poll (in milliseconds), and
+ * <interrupted> must be zero if the poller reached the timeout or non-zero
+ * otherwise, which generally is provided by the poller's return value.
+ */
+void clock_leaving_poll(int timeout, int interrupted)
+{
+ clock_measure_idle();
+ th_ctx->prev_cpu_time = now_cpu_time();
+ th_ctx->prev_mono_time = now_mono_time();
+}
+
+/* Collect date and time information before calling poll(). This will be used
+ * to count the run time of the past loop and the sleep time of the next poll.
+ * It also compares the elasped and cpu times during the activity period to
+ * estimate the amount of stolen time, which is reported if higher than half
+ * a millisecond.
+ */
+void clock_entering_poll(void)
+{
+ uint64_t new_mono_time;
+ uint64_t new_cpu_time;
+ uint32_t run_time;
+ int64_t stolen;
+
+ gettimeofday(&before_poll, NULL);
+
+ run_time = (before_poll.tv_sec - after_poll.tv_sec) * 1000000U + (before_poll.tv_usec - after_poll.tv_usec);
+
+ new_cpu_time = now_cpu_time();
+ new_mono_time = now_mono_time();
+
+ if (th_ctx->prev_cpu_time && th_ctx->prev_mono_time) {
+ new_cpu_time -= th_ctx->prev_cpu_time;
+ new_mono_time -= th_ctx->prev_mono_time;
+ stolen = new_mono_time - new_cpu_time;
+ if (unlikely(stolen >= 500000)) {
+ stolen /= 500000;
+ /* more than half a millisecond difference might
+ * indicate an undesired preemption.
+ */
+ report_stolen_time(stolen);
+ }
+ }
+
+ /* update the average runtime */
+ activity_count_runtime(run_time);
+}
+
+/* returns the current date as returned by gettimeofday() in ISO+microsecond
+ * format. It uses a thread-local static variable that the reader can consume
+ * for as long as it wants until next call. Thus, do not call it from a signal
+ * handler. If <pad> is non-0, a trailing space will be added. It will always
+ * return exactly 32 or 33 characters (depending on padding) and will always be
+ * zero-terminated, thus it will always fit into a 34 bytes buffer.
+ * This also always include the local timezone (in +/-HH:mm format) .
+ */
+char *timeofday_as_iso_us(int pad)
+{
+ struct timeval new_date;
+ struct tm tm;
+ const char *offset;
+ char c;
+
+ gettimeofday(&new_date, NULL);
+ if (new_date.tv_sec != iso_time_sec || !new_date.tv_sec) {
+ get_localtime(new_date.tv_sec, &tm);
+ offset = get_gmt_offset(new_date.tv_sec, &tm);
+ if (unlikely(strftime(iso_time_str, sizeof(iso_time_str), "%Y-%m-%dT%H:%M:%S.000000+00:00", &tm) != 32))
+ strcpy(iso_time_str, "YYYY-mm-ddTHH:MM:SS.000000-00:00"); // make the failure visible but respect format.
+ iso_time_str[26] = offset[0];
+ iso_time_str[27] = offset[1];
+ iso_time_str[28] = offset[2];
+ iso_time_str[30] = offset[3];
+ iso_time_str[31] = offset[4];
+ iso_time_sec = new_date.tv_sec;
+ }
+
+ /* utoa_pad adds a trailing 0 so we save the char for restore */
+ c = iso_time_str[26];
+ utoa_pad(new_date.tv_usec, iso_time_str + 20, 7);
+ iso_time_str[26] = c;
+ if (pad) {
+ iso_time_str[32] = ' ';
+ iso_time_str[33] = 0;
+ }
+ return iso_time_str;
+}
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