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