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1 /*
2  *
3  * Copyright 2015 gRPC authors.
4  *
5  * Licensed under the Apache License, Version 2.0 (the "License");
6  * you may not use this file except in compliance with the License.
7  * You may obtain a copy of the License at
8  *
9  *     http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  *
17  */
18 
19 #include <grpc/support/port_platform.h>
20 
21 #include "src/core/lib/gpr/time_precise.h"
22 
23 #ifdef GPR_POSIX_TIME
24 
25 #include <stdlib.h>
26 #include <time.h>
27 #include <unistd.h>
28 #ifdef __linux__
29 #include <sys/syscall.h>
30 #endif
31 #include <grpc/support/atm.h>
32 #include <grpc/support/log.h>
33 #include <grpc/support/time.h>
34 
timespec_from_gpr(gpr_timespec gts)35 static struct timespec timespec_from_gpr(gpr_timespec gts) {
36   struct timespec rv;
37   if (sizeof(time_t) < sizeof(int64_t)) {
38     /* fine to assert, as this is only used in gpr_sleep_until */
39     GPR_ASSERT(gts.tv_sec <= INT32_MAX && gts.tv_sec >= INT32_MIN);
40   }
41   rv.tv_sec = static_cast<time_t>(gts.tv_sec);
42   rv.tv_nsec = gts.tv_nsec;
43   return rv;
44 }
45 
46 #if _POSIX_TIMERS > 0 || defined(__OpenBSD__)
gpr_from_timespec(struct timespec ts,gpr_clock_type clock_type)47 static gpr_timespec gpr_from_timespec(struct timespec ts,
48                                       gpr_clock_type clock_type) {
49   /*
50    * timespec.tv_sec can have smaller size than gpr_timespec.tv_sec,
51    * but we are only using this function to implement gpr_now
52    * so there's no need to handle "infinity" values.
53    */
54   gpr_timespec rv;
55   rv.tv_sec = ts.tv_sec;
56   rv.tv_nsec = static_cast<int32_t>(ts.tv_nsec);
57   rv.clock_type = clock_type;
58   return rv;
59 }
60 
61 /** maps gpr_clock_type --> clockid_t for clock_gettime */
62 static const clockid_t clockid_for_gpr_clock[] = {CLOCK_MONOTONIC,
63                                                   CLOCK_REALTIME};
64 
gpr_time_init(void)65 void gpr_time_init(void) { gpr_precise_clock_init(); }
66 
now_impl(gpr_clock_type clock_type)67 static gpr_timespec now_impl(gpr_clock_type clock_type) {
68   struct timespec now;
69   GPR_ASSERT(clock_type != GPR_TIMESPAN);
70   if (clock_type == GPR_CLOCK_PRECISE) {
71     gpr_timespec ret;
72     gpr_precise_clock_now(&ret);
73     return ret;
74   } else {
75 #if defined(GPR_BACKWARDS_COMPATIBILITY_MODE) && defined(__linux__)
76     /* avoid ABI problems by invoking syscalls directly */
77     syscall(SYS_clock_gettime, clockid_for_gpr_clock[clock_type], &now);
78 #else
79     clock_gettime(clockid_for_gpr_clock[clock_type], &now);
80 #endif
81     return gpr_from_timespec(now, clock_type);
82   }
83 }
84 #else
85 /* For some reason Apple's OSes haven't implemented clock_gettime. */
86 
87 #include <mach/mach.h>
88 #include <mach/mach_time.h>
89 #include <sys/time.h>
90 
91 static double g_time_scale;
92 static uint64_t g_time_start;
93 
gpr_time_init(void)94 void gpr_time_init(void) {
95   mach_timebase_info_data_t tb = {0, 1};
96   gpr_precise_clock_init();
97   mach_timebase_info(&tb);
98   g_time_scale = tb.numer;
99   g_time_scale /= tb.denom;
100   g_time_start = mach_absolute_time();
101 }
102 
now_impl(gpr_clock_type clock)103 static gpr_timespec now_impl(gpr_clock_type clock) {
104   gpr_timespec now;
105   struct timeval now_tv;
106   double now_dbl;
107 
108   now.clock_type = clock;
109   switch (clock) {
110     case GPR_CLOCK_REALTIME:
111       // gettimeofday(...) function may return with a value whose tv_usec is
112       // greater than 1e6 on iOS The case is resolved with the guard at end of
113       // this function.
114       gettimeofday(&now_tv, nullptr);
115       now.tv_sec = now_tv.tv_sec;
116       now.tv_nsec = now_tv.tv_usec * 1000;
117       break;
118     case GPR_CLOCK_MONOTONIC:
119       now_dbl = ((double)(mach_absolute_time() - g_time_start)) * g_time_scale;
120       now.tv_sec = (int64_t)(now_dbl * 1e-9);
121       now.tv_nsec = (int32_t)(now_dbl - ((double)now.tv_sec) * 1e9);
122       break;
123     case GPR_CLOCK_PRECISE:
124       gpr_precise_clock_now(&now);
125       break;
126     case GPR_TIMESPAN:
127       abort();
128   }
129 
130   // Guard the tv_nsec field in valid range for all clock types
131   while (GPR_UNLIKELY(now.tv_nsec >= 1e9)) {
132     now.tv_sec++;
133     now.tv_nsec -= 1e9;
134   }
135   while (GPR_UNLIKELY(now.tv_nsec < 0)) {
136     now.tv_sec--;
137     now.tv_nsec += 1e9;
138   }
139 
140   return now;
141 }
142 #endif
143 
144 gpr_timespec (*gpr_now_impl)(gpr_clock_type clock_type) = now_impl;
145 
146 #ifdef GPR_LOW_LEVEL_COUNTERS
147 gpr_atm gpr_now_call_count;
148 #endif
gpr_now(gpr_clock_type clock_type)149 gpr_timespec gpr_now(gpr_clock_type clock_type) {
150 #ifdef GPR_LOW_LEVEL_COUNTERS
151   __atomic_fetch_add(&gpr_now_call_count, 1, __ATOMIC_RELAXED);
152 #endif
153   // validate clock type
154   GPR_ASSERT(clock_type == GPR_CLOCK_MONOTONIC ||
155              clock_type == GPR_CLOCK_REALTIME ||
156              clock_type == GPR_CLOCK_PRECISE);
157   gpr_timespec ts = gpr_now_impl(clock_type);
158   // tv_nsecs must be in the range [0, 1e9).
159   GPR_ASSERT(ts.tv_nsec >= 0 && ts.tv_nsec < 1e9);
160   return ts;
161 }
162 
gpr_sleep_until(gpr_timespec until)163 void gpr_sleep_until(gpr_timespec until) {
164   gpr_timespec now;
165   gpr_timespec delta;
166   struct timespec delta_ts;
167   int ns_result;
168 
169   for (;;) {
170     /* We could simplify by using clock_nanosleep instead, but it might be
171      * slightly less portable. */
172     now = gpr_now(until.clock_type);
173     if (gpr_time_cmp(until, now) <= 0) {
174       return;
175     }
176 
177     delta = gpr_time_sub(until, now);
178     delta_ts = timespec_from_gpr(delta);
179     ns_result = nanosleep(&delta_ts, nullptr);
180     if (ns_result == 0) {
181       break;
182     }
183   }
184 }
185 
186 #endif /* GPR_POSIX_TIME */
187