| 1 | /* |
| 2 | * Copyright (C) 2010 Pierre-Marc Fournier |
| 3 | * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 4 | * |
| 5 | * This library is free software; you can redistribute it and/or |
| 6 | * modify it under the terms of the GNU Lesser General Public |
| 7 | * License as published by the Free Software Foundation; version 2.1 of |
| 8 | * the License. |
| 9 | * |
| 10 | * This library is distributed in the hope that it will be useful, |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 13 | * Lesser General Public License for more details. |
| 14 | * |
| 15 | * You should have received a copy of the GNU Lesser General Public |
| 16 | * License along with this library; if not, write to the Free Software |
| 17 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 18 | */ |
| 19 | |
| 20 | #ifndef _UST_CLOCK_H |
| 21 | #define _UST_CLOCK_H |
| 22 | |
| 23 | #include <time.h> |
| 24 | #include <sys/time.h> |
| 25 | #include <stdint.h> |
| 26 | #include <stddef.h> |
| 27 | #include <stdio.h> |
| 28 | #include <urcu/system.h> |
| 29 | #include <urcu/arch.h> |
| 30 | #include <lttng/ust-clock.h> |
| 31 | |
| 32 | #include "lttng-ust-uuid.h" |
| 33 | |
| 34 | struct lttng_trace_clock { |
| 35 | uint64_t (*read64)(void); |
| 36 | uint64_t (*freq)(void); |
| 37 | int (*uuid)(char *uuid); |
| 38 | const char *(*name)(void); |
| 39 | const char *(*description)(void); |
| 40 | }; |
| 41 | |
| 42 | extern struct lttng_trace_clock *lttng_trace_clock; |
| 43 | |
| 44 | void lttng_ust_clock_init(void); |
| 45 | |
| 46 | /* Use the kernel MONOTONIC clock. */ |
| 47 | |
| 48 | static __inline__ |
| 49 | uint64_t trace_clock_read64_monotonic(void) |
| 50 | { |
| 51 | struct timespec ts; |
| 52 | |
| 53 | if (caa_unlikely(clock_gettime(CLOCK_MONOTONIC, &ts))) { |
| 54 | ts.tv_sec = 0; |
| 55 | ts.tv_nsec = 0; |
| 56 | } |
| 57 | return ((uint64_t) ts.tv_sec * 1000000000ULL) + ts.tv_nsec; |
| 58 | } |
| 59 | |
| 60 | static __inline__ |
| 61 | uint64_t trace_clock_freq_monotonic(void) |
| 62 | { |
| 63 | return 1000000000ULL; |
| 64 | } |
| 65 | |
| 66 | static __inline__ |
| 67 | int trace_clock_uuid_monotonic(char *uuid) |
| 68 | { |
| 69 | int ret = 0; |
| 70 | size_t len; |
| 71 | FILE *fp; |
| 72 | |
| 73 | /* |
| 74 | * boot_id needs to be read once before being used concurrently |
| 75 | * to deal with a Linux kernel race. A fix is proposed for |
| 76 | * upstream, but the work-around is needed for older kernels. |
| 77 | */ |
| 78 | fp = fopen("/proc/sys/kernel/random/boot_id", "r"); |
| 79 | if (!fp) { |
| 80 | return -ENOENT; |
| 81 | } |
| 82 | len = fread(uuid, 1, LTTNG_UST_UUID_STR_LEN - 1, fp); |
| 83 | if (len < LTTNG_UST_UUID_STR_LEN - 1) { |
| 84 | ret = -EINVAL; |
| 85 | goto end; |
| 86 | } |
| 87 | uuid[LTTNG_UST_UUID_STR_LEN - 1] = '\0'; |
| 88 | end: |
| 89 | fclose(fp); |
| 90 | return ret; |
| 91 | } |
| 92 | |
| 93 | static __inline__ |
| 94 | const char *trace_clock_name_monotonic(void) |
| 95 | { |
| 96 | return "monotonic"; |
| 97 | } |
| 98 | |
| 99 | static __inline__ |
| 100 | const char *trace_clock_description_monotonic(void) |
| 101 | { |
| 102 | return "Monotonic Clock"; |
| 103 | } |
| 104 | |
| 105 | static __inline__ |
| 106 | uint64_t trace_clock_read64(void) |
| 107 | { |
| 108 | struct lttng_trace_clock *ltc = CMM_LOAD_SHARED(lttng_trace_clock); |
| 109 | |
| 110 | if (caa_likely(!ltc)) { |
| 111 | return trace_clock_read64_monotonic(); |
| 112 | } else { |
| 113 | cmm_read_barrier_depends(); /* load ltc before content */ |
| 114 | return ltc->read64(); |
| 115 | } |
| 116 | } |
| 117 | |
| 118 | static __inline__ |
| 119 | uint64_t trace_clock_freq(void) |
| 120 | { |
| 121 | struct lttng_trace_clock *ltc = CMM_LOAD_SHARED(lttng_trace_clock); |
| 122 | |
| 123 | if (!ltc) { |
| 124 | return trace_clock_freq_monotonic(); |
| 125 | } else { |
| 126 | cmm_read_barrier_depends(); /* load ltc before content */ |
| 127 | return ltc->freq(); |
| 128 | } |
| 129 | } |
| 130 | |
| 131 | static __inline__ |
| 132 | int trace_clock_uuid(char *uuid) |
| 133 | { |
| 134 | struct lttng_trace_clock *ltc = CMM_LOAD_SHARED(lttng_trace_clock); |
| 135 | |
| 136 | cmm_read_barrier_depends(); /* load ltc before content */ |
| 137 | /* Use default UUID cb when NULL */ |
| 138 | if (!ltc || !ltc->uuid) { |
| 139 | return trace_clock_uuid_monotonic(uuid); |
| 140 | } else { |
| 141 | return ltc->uuid(uuid); |
| 142 | } |
| 143 | } |
| 144 | |
| 145 | static __inline__ |
| 146 | const char *trace_clock_name(void) |
| 147 | { |
| 148 | struct lttng_trace_clock *ltc = CMM_LOAD_SHARED(lttng_trace_clock); |
| 149 | |
| 150 | if (!ltc) { |
| 151 | return trace_clock_name_monotonic(); |
| 152 | } else { |
| 153 | cmm_read_barrier_depends(); /* load ltc before content */ |
| 154 | return ltc->name(); |
| 155 | } |
| 156 | } |
| 157 | |
| 158 | static __inline__ |
| 159 | const char *trace_clock_description(void) |
| 160 | { |
| 161 | struct lttng_trace_clock *ltc = CMM_LOAD_SHARED(lttng_trace_clock); |
| 162 | |
| 163 | if (!ltc) { |
| 164 | return trace_clock_description_monotonic(); |
| 165 | } else { |
| 166 | cmm_read_barrier_depends(); /* load ltc before content */ |
| 167 | return ltc->description(); |
| 168 | } |
| 169 | } |
| 170 | |
| 171 | #endif /* _UST_CLOCK_H */ |