X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=liblttng-ust%2Fclock.h;h=b68e563f6206b1eb6394011dfd96522d3587f9c7;hb=c0c0989ab70574e09b2f7e8b48c2da6af664a849;hp=b4d17e785e164e3ae9a59c89fd7a897853754bc8;hpb=ff0545c9666d3f76db2ab1da1cf5073cf1ecfc45;p=lttng-ust.git

diff --git a/liblttng-ust/clock.h b/liblttng-ust/clock.h
index b4d17e78..b68e563f 100644
--- a/liblttng-ust/clock.h
+++ b/liblttng-ust/clock.h
@@ -1,20 +1,8 @@
 /*
- * Copyright (C) 2010  Pierre-Marc Fournier
- * Copyright (C) 2011  Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * SPDX-License-Identifier: LGPL-2.1-only
  *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; version 2.1 of
- * the License.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
+ * Copyright (C) 2010 Pierre-Marc Fournier
+ * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  */
 
 #ifndef _UST_CLOCK_H
@@ -25,57 +13,49 @@
 #include <stdint.h>
 #include <stddef.h>
 #include <stdio.h>
-#include "uuid.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);
+};
 
-/* Choosing correct trace clock */
+extern struct lttng_trace_clock *lttng_trace_clock;
+
+void lttng_ust_clock_init(void);
+
+/* Use the kernel MONOTONIC clock. */
 
 static __inline__
-uint64_t trace_clock_read64(void)
+uint64_t trace_clock_read64_monotonic(void)
 {
 	struct timespec ts;
 
-	clock_gettime(CLOCK_MONOTONIC, &ts);
+	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(void)
-{
-	return 1000000000ULL;
-}
-
-static __inline__
-const int trace_clock_uuid(char *uuid)
+uint64_t trace_clock_read64(void)
 {
-	int ret = 0;
-	size_t len;
-	FILE *fp;
+	struct lttng_trace_clock *ltc = CMM_LOAD_SHARED(lttng_trace_clock);
 
-	/*
-	 * 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;
+	if (caa_likely(!ltc)) {
+		return trace_clock_read64_monotonic();
+	} else {
+		cmm_read_barrier_depends();	/* load ltc before content */
+		return ltc->read64();
 	}
-	uuid[LTTNG_UST_UUID_STR_LEN - 1] = '\0';
-end:
-	fclose(fp);
-	return ret;
 }
 
 #endif /* _UST_CLOCK_H */