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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/iomgr/exec_ctx.h"
22 
23 #include <grpc/support/log.h>
24 #include <grpc/support/sync.h>
25 
26 #include "src/core/lib/gprpp/thd.h"
27 #include "src/core/lib/iomgr/combiner.h"
28 #include "src/core/lib/profiling/timers.h"
29 
exec_ctx_run(grpc_closure * closure,grpc_error_handle error)30 static void exec_ctx_run(grpc_closure* closure, grpc_error_handle error) {
31 #ifndef NDEBUG
32   closure->scheduled = false;
33   if (grpc_trace_closure.enabled()) {
34     gpr_log(GPR_DEBUG, "running closure %p: created [%s:%d]: %s [%s:%d]",
35             closure, closure->file_created, closure->line_created,
36             closure->run ? "run" : "scheduled", closure->file_initiated,
37             closure->line_initiated);
38   }
39 #endif
40   closure->cb(closure->cb_arg, error);
41 #ifndef NDEBUG
42   if (grpc_trace_closure.enabled()) {
43     gpr_log(GPR_DEBUG, "closure %p finished", closure);
44   }
45 #endif
46   GRPC_ERROR_UNREF(error);
47 }
48 
exec_ctx_sched(grpc_closure * closure,grpc_error_handle error)49 static void exec_ctx_sched(grpc_closure* closure, grpc_error_handle error) {
50   grpc_closure_list_append(grpc_core::ExecCtx::Get()->closure_list(), closure,
51                            error);
52 }
53 
54 static gpr_timespec g_start_time;
55 static gpr_cycle_counter g_start_cycle;
56 
timespan_to_millis_round_down(gpr_timespec ts)57 static grpc_millis timespan_to_millis_round_down(gpr_timespec ts) {
58   double x = GPR_MS_PER_SEC * static_cast<double>(ts.tv_sec) +
59              static_cast<double>(ts.tv_nsec) / GPR_NS_PER_MS;
60   if (x < 0) return 0;
61   if (x > static_cast<double>(GRPC_MILLIS_INF_FUTURE)) {
62     return GRPC_MILLIS_INF_FUTURE;
63   }
64   return static_cast<grpc_millis>(x);
65 }
66 
timespec_to_millis_round_down(gpr_timespec ts)67 static grpc_millis timespec_to_millis_round_down(gpr_timespec ts) {
68   return timespan_to_millis_round_down(gpr_time_sub(ts, g_start_time));
69 }
70 
timespan_to_millis_round_up(gpr_timespec ts)71 static grpc_millis timespan_to_millis_round_up(gpr_timespec ts) {
72   double x = GPR_MS_PER_SEC * static_cast<double>(ts.tv_sec) +
73              static_cast<double>(ts.tv_nsec) / GPR_NS_PER_MS +
74              static_cast<double>(GPR_NS_PER_SEC - 1) /
75                  static_cast<double>(GPR_NS_PER_SEC);
76   if (x < 0) return 0;
77   if (x > static_cast<double>(GRPC_MILLIS_INF_FUTURE)) {
78     return GRPC_MILLIS_INF_FUTURE;
79   }
80   return static_cast<grpc_millis>(x);
81 }
82 
timespec_to_millis_round_up(gpr_timespec ts)83 static grpc_millis timespec_to_millis_round_up(gpr_timespec ts) {
84   return timespan_to_millis_round_up(gpr_time_sub(ts, g_start_time));
85 }
86 
grpc_millis_to_timespec(grpc_millis millis,gpr_clock_type clock_type)87 gpr_timespec grpc_millis_to_timespec(grpc_millis millis,
88                                      gpr_clock_type clock_type) {
89   // special-case infinities as grpc_millis can be 32bit on some platforms
90   // while gpr_time_from_millis always takes an int64_t.
91   if (millis == GRPC_MILLIS_INF_FUTURE) {
92     return gpr_inf_future(clock_type);
93   }
94   if (millis == GRPC_MILLIS_INF_PAST) {
95     return gpr_inf_past(clock_type);
96   }
97 
98   if (clock_type == GPR_TIMESPAN) {
99     return gpr_time_from_millis(millis, GPR_TIMESPAN);
100   }
101   return gpr_time_add(gpr_convert_clock_type(g_start_time, clock_type),
102                       gpr_time_from_millis(millis, GPR_TIMESPAN));
103 }
104 
grpc_timespec_to_millis_round_down(gpr_timespec ts)105 grpc_millis grpc_timespec_to_millis_round_down(gpr_timespec ts) {
106   return timespec_to_millis_round_down(
107       gpr_convert_clock_type(ts, g_start_time.clock_type));
108 }
109 
grpc_timespec_to_millis_round_up(gpr_timespec ts)110 grpc_millis grpc_timespec_to_millis_round_up(gpr_timespec ts) {
111   return timespec_to_millis_round_up(
112       gpr_convert_clock_type(ts, g_start_time.clock_type));
113 }
114 
grpc_cycle_counter_to_millis_round_down(gpr_cycle_counter cycles)115 grpc_millis grpc_cycle_counter_to_millis_round_down(gpr_cycle_counter cycles) {
116   return timespan_to_millis_round_down(
117       gpr_cycle_counter_sub(cycles, g_start_cycle));
118 }
119 
grpc_cycle_counter_to_millis_round_up(gpr_cycle_counter cycles)120 grpc_millis grpc_cycle_counter_to_millis_round_up(gpr_cycle_counter cycles) {
121   return timespan_to_millis_round_up(
122       gpr_cycle_counter_sub(cycles, g_start_cycle));
123 }
124 
125 namespace grpc_core {
126 GPR_TLS_CLASS_DEF(ExecCtx::exec_ctx_);
127 GPR_TLS_CLASS_DEF(ApplicationCallbackExecCtx::callback_exec_ctx_);
128 
129 // WARNING: for testing purposes only!
TestOnlyGlobalInit(gpr_timespec new_val)130 void ExecCtx::TestOnlyGlobalInit(gpr_timespec new_val) {
131   g_start_time = new_val;
132   gpr_tls_init(&exec_ctx_);
133 }
134 
GlobalInit(void)135 void ExecCtx::GlobalInit(void) {
136   // gpr_now(GPR_CLOCK_MONOTONIC) incurs a syscall. We don't actually know the
137   // exact cycle the time was captured, so we use the average of cycles before
138   // and after the syscall as the starting cycle.
139   const gpr_cycle_counter cycle_before = gpr_get_cycle_counter();
140   g_start_time = gpr_now(GPR_CLOCK_MONOTONIC);
141   const gpr_cycle_counter cycle_after = gpr_get_cycle_counter();
142   g_start_cycle = (cycle_before + cycle_after) / 2;
143   gpr_tls_init(&exec_ctx_);
144 }
145 
Flush()146 bool ExecCtx::Flush() {
147   bool did_something = false;
148   GPR_TIMER_SCOPE("grpc_exec_ctx_flush", 0);
149   for (;;) {
150     if (!grpc_closure_list_empty(closure_list_)) {
151       grpc_closure* c = closure_list_.head;
152       closure_list_.head = closure_list_.tail = nullptr;
153       while (c != nullptr) {
154         grpc_closure* next = c->next_data.next;
155         grpc_error_handle error = c->error_data.error;
156         did_something = true;
157         exec_ctx_run(c, error);
158         c = next;
159       }
160     } else if (!grpc_combiner_continue_exec_ctx()) {
161       break;
162     }
163   }
164   GPR_ASSERT(combiner_data_.active_combiner == nullptr);
165   return did_something;
166 }
167 
Now()168 grpc_millis ExecCtx::Now() {
169   if (!now_is_valid_) {
170     now_ = timespec_to_millis_round_down(gpr_now(GPR_CLOCK_MONOTONIC));
171     now_is_valid_ = true;
172   }
173   return now_;
174 }
175 
Run(const DebugLocation & location,grpc_closure * closure,grpc_error_handle error)176 void ExecCtx::Run(const DebugLocation& location, grpc_closure* closure,
177                   grpc_error_handle error) {
178   (void)location;
179   if (closure == nullptr) {
180     GRPC_ERROR_UNREF(error);
181     return;
182   }
183 #ifndef NDEBUG
184   if (closure->scheduled) {
185     gpr_log(GPR_ERROR,
186             "Closure already scheduled. (closure: %p, created: [%s:%d], "
187             "previously scheduled at: [%s: %d], newly scheduled at [%s: %d]",
188             closure, closure->file_created, closure->line_created,
189             closure->file_initiated, closure->line_initiated, location.file(),
190             location.line());
191     abort();
192   }
193   closure->scheduled = true;
194   closure->file_initiated = location.file();
195   closure->line_initiated = location.line();
196   closure->run = false;
197   GPR_ASSERT(closure->cb != nullptr);
198 #endif
199   exec_ctx_sched(closure, error);
200 }
201 
RunList(const DebugLocation & location,grpc_closure_list * list)202 void ExecCtx::RunList(const DebugLocation& location, grpc_closure_list* list) {
203   (void)location;
204   grpc_closure* c = list->head;
205   while (c != nullptr) {
206     grpc_closure* next = c->next_data.next;
207 #ifndef NDEBUG
208     if (c->scheduled) {
209       gpr_log(GPR_ERROR,
210               "Closure already scheduled. (closure: %p, created: [%s:%d], "
211               "previously scheduled at: [%s: %d], newly scheduled at [%s:%d]",
212               c, c->file_created, c->line_created, c->file_initiated,
213               c->line_initiated, location.file(), location.line());
214       abort();
215     }
216     c->scheduled = true;
217     c->file_initiated = location.file();
218     c->line_initiated = location.line();
219     c->run = false;
220     GPR_ASSERT(c->cb != nullptr);
221 #endif
222     exec_ctx_sched(c, c->error_data.error);
223     c = next;
224   }
225   list->head = list->tail = nullptr;
226 }
227 
228 }  // namespace grpc_core
229