X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=liblttng-ust%2Fclock.h;h=a7e8eb7b49e062b1e5ebe9f24cd7d60278a4c64e;hb=702d1b7d91bc75f4fc01415fc625af1b834ddec4;hp=ed191b0bf9b7ca4b75a55ddbb17682e052b0ad4c;hpb=35897f8b2d311b756b81657dad9c53ef1c0fad8a;p=lttng-ust.git

diff --git a/liblttng-ust/clock.h b/liblttng-ust/clock.h
index ed191b0b..a7e8eb7b 100644
--- a/liblttng-ust/clock.h
+++ b/liblttng-ust/clock.h
@@ -24,34 +24,148 @@
 #include <sys/time.h>
 #include <stdint.h>
 #include <stddef.h>
+#include <stdio.h>
+#include <urcu/system.h>
+#include <urcu/arch.h>
+#include <lttng/ust-clock.h>
 
-/* TRACE CLOCK */
+#include "lttng-ust-uuid.h"
 
-/*
- * Currently using the kernel MONOTONIC clock, waiting for kernel-side
- * LTTng to implement mmap'd trace clock.
- */
+struct lttng_trace_clock {
+	uint64_t (*read64)(void);
+	uint64_t (*freq)(void);
+	int (*uuid)(char *uuid);
+	const char *(*name)(void);
+	const char *(*description)(void);
+};
+
+extern struct lttng_trace_clock *lttng_trace_clock;
+
+void lttng_ust_clock_init(void);
 
-/* Choosing correct trace clock */
+/* Use the kernel MONOTONIC clock. */
 
-static __inline__ uint64_t trace_clock_read64(void)
+static __inline__
+uint64_t trace_clock_read64_monotonic(void)
 {
 	struct timespec ts;
 
-	clock_gettime(CLOCK_MONOTONIC, &ts);
-	return (ts.tv_sec * 1000000000) + ts.tv_nsec;
+	if (caa_unlikely(clock_gettime(CLOCK_MONOTONIC, &ts))) {
+		ts.tv_sec = 0;
+		ts.tv_nsec = 0;
+	}
+	return ((uint64_t) ts.tv_sec * 1000000000ULL) + ts.tv_nsec;
+}
+
+static __inline__
+uint64_t trace_clock_freq_monotonic(void)
+{
+	return 1000000000ULL;
+}
+
+static __inline__
+int trace_clock_uuid_monotonic(char *uuid)
+{
+	int ret = 0;
+	size_t len;
+	FILE *fp;
+
+	/*
+	 * boot_id needs to be read once before being used concurrently
+	 * to deal with a Linux kernel race. A fix is proposed for
+	 * upstream, but the work-around is needed for older kernels.
+	 */
+	fp = fopen("/proc/sys/kernel/random/boot_id", "r");
+	if (!fp) {
+		return -ENOENT;
+	}
+	len = fread(uuid, 1, LTTNG_UST_UUID_STR_LEN - 1, fp);
+	if (len < LTTNG_UST_UUID_STR_LEN - 1) {
+		ret = -EINVAL;
+		goto end;
+	}
+	uuid[LTTNG_UST_UUID_STR_LEN - 1] = '\0';
+end:
+	fclose(fp);
+	return ret;
+}
+
+static __inline__
+const char *trace_clock_name_monotonic(void)
+{
+	return "monotonic";
 }
 
-#if __i386__ || __x86_64__
-static __inline__ uint64_t trace_clock_frequency(void)
+static __inline__
+const char *trace_clock_description_monotonic(void)
 {
-	return 1000000000LL;
+	return "Monotonic Clock";
 }
-#endif /* #else #if __i386__ || __x86_64__ */
 
-static __inline__ uint32_t trace_clock_freq_scale(void)
+static __inline__
+uint64_t trace_clock_read64(void)
 {
-	return 1;
+	struct lttng_trace_clock *ltc = CMM_LOAD_SHARED(lttng_trace_clock);
+
+	if (caa_likely(!ltc)) {
+		return trace_clock_read64_monotonic();
+	} else {
+		cmm_read_barrier_depends();	/* load ltc before content */
+		return ltc->read64();
+	}
+}
+
+static __inline__
+uint64_t trace_clock_freq(void)
+{
+	struct lttng_trace_clock *ltc = CMM_LOAD_SHARED(lttng_trace_clock);
+
+	if (!ltc) {
+		return trace_clock_freq_monotonic();
+	} else {
+		cmm_read_barrier_depends();	/* load ltc before content */
+		return ltc->freq();
+	}
+}
+
+static __inline__
+int trace_clock_uuid(char *uuid)
+{
+	struct lttng_trace_clock *ltc = CMM_LOAD_SHARED(lttng_trace_clock);
+
+	cmm_read_barrier_depends();	/* load ltc before content */
+	/* Use default UUID cb when NULL */
+	if (!ltc || !ltc->uuid) {
+		return trace_clock_uuid_monotonic(uuid);
+	} else {
+		return ltc->uuid(uuid);
+	}
+}
+
+static __inline__
+const char *trace_clock_name(void)
+{
+	struct lttng_trace_clock *ltc = CMM_LOAD_SHARED(lttng_trace_clock);
+
+	if (!ltc) {
+		return trace_clock_name_monotonic();
+	} else {
+		cmm_read_barrier_depends();	/* load ltc before content */
+		return ltc->name();
+	}
+}
+
+static __inline__
+const char *trace_clock_description(void)
+{
+	struct lttng_trace_clock *ltc = CMM_LOAD_SHARED(lttng_trace_clock);
+
+	if (!ltc) {
+		return trace_clock_description_monotonic();
+	} else {
+		cmm_read_barrier_depends();	/* load ltc before content */
+		return ltc->description();
+	}
 }
 
 #endif /* _UST_CLOCK_H */