1 /*
2 *
3 * Copyright 2017 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/port.h"
22
23 #ifdef GRPC_POSIX_FORK
24
25 #include <string.h>
26
27 #include <grpc/fork.h>
28 #include <grpc/grpc.h>
29 #include <grpc/support/log.h>
30
31 #include "src/core/lib/gpr/env.h"
32 #include "src/core/lib/gprpp/fork.h"
33 #include "src/core/lib/gprpp/thd.h"
34 #include "src/core/lib/iomgr/ev_posix.h"
35 #include "src/core/lib/iomgr/executor.h"
36 #include "src/core/lib/iomgr/timer_manager.h"
37 #include "src/core/lib/iomgr/wakeup_fd_posix.h"
38
39 /*
40 * NOTE: FORKING IS NOT GENERALLY SUPPORTED, THIS IS ONLY INTENDED TO WORK
41 * AROUND VERY SPECIFIC USE CASES.
42 */
43
44 namespace {
45 bool skipped_handler = true;
46 bool registered_handlers = false;
47 } // namespace
48
grpc_prefork()49 void grpc_prefork() {
50 grpc_core::ExecCtx exec_ctx;
51 skipped_handler = true;
52 if (!grpc_is_initialized()) {
53 return;
54 }
55 if (!grpc_core::Fork::Enabled()) {
56 gpr_log(GPR_ERROR,
57 "Fork support not enabled; try running with the "
58 "environment variable GRPC_ENABLE_FORK_SUPPORT=1");
59 return;
60 }
61 if (strcmp(grpc_get_poll_strategy_name(), "epoll1") != 0 &&
62 strcmp(grpc_get_poll_strategy_name(), "poll") != 0) {
63 gpr_log(GPR_ERROR,
64 "Fork support is only compatible with the epoll1 and poll polling "
65 "strategies");
66 }
67 if (!grpc_core::Fork::BlockExecCtx()) {
68 gpr_log(GPR_INFO,
69 "Other threads are currently calling into gRPC, skipping fork() "
70 "handlers");
71 return;
72 }
73 grpc_timer_manager_set_threading(false);
74 grpc_executor_set_threading(false);
75 grpc_core::ExecCtx::Get()->Flush();
76 grpc_core::Fork::AwaitThreads();
77 skipped_handler = false;
78 }
79
grpc_postfork_parent()80 void grpc_postfork_parent() {
81 if (!skipped_handler) {
82 grpc_core::Fork::AllowExecCtx();
83 grpc_core::ExecCtx exec_ctx;
84 grpc_timer_manager_set_threading(true);
85 grpc_executor_set_threading(true);
86 }
87 }
88
grpc_postfork_child()89 void grpc_postfork_child() {
90 if (!skipped_handler) {
91 grpc_core::Fork::AllowExecCtx();
92 grpc_core::ExecCtx exec_ctx;
93 grpc_core::Fork::child_postfork_func reset_polling_engine =
94 grpc_core::Fork::GetResetChildPollingEngineFunc();
95 if (reset_polling_engine != nullptr) {
96 reset_polling_engine();
97 }
98 grpc_timer_manager_set_threading(true);
99 grpc_executor_set_threading(true);
100 }
101 }
102
grpc_fork_handlers_auto_register()103 void grpc_fork_handlers_auto_register() {
104 if (grpc_core::Fork::Enabled() & !registered_handlers) {
105 #ifdef GRPC_POSIX_FORK_ALLOW_PTHREAD_ATFORK
106 pthread_atfork(grpc_prefork, grpc_postfork_parent, grpc_postfork_child);
107 registered_handlers = true;
108 #endif // GRPC_POSIX_FORK_ALLOW_PTHREAD_ATFORK
109 }
110 }
111
112 #endif // GRPC_POSIX_FORK
113