Move to kernel style SPDX license identifiers

[lttng-ust.git] / liblttng-ust / clock.h

diff --git a/liblttng-ust/clock.h b/liblttng-ust/clock.h
index 88eca432a5733f7e4bc35f1878b911617a5119d5..b68e563f6206b1eb6394011dfd96522d3587f9c7 100644 (file)
--- 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 <urcu/system.h>
+#include <urcu/arch.h>
+#include <lttng/ust-clock.h>
+
 #include "lttng-ust-uuid.h"
 
-/* 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);
+};
 
-/*
- * Currently using the kernel MONOTONIC clock, waiting for kernel-side
- * LTTng to implement mmap'd trace clock.
- */
+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)
+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__
-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 */