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/port.h"
22
23 #ifdef GRPC_LINUX_EVENTFD
24
25 #include <errno.h>
26 #include <sys/eventfd.h>
27 #include <unistd.h>
28
29 #include <grpc/support/log.h>
30
31 #include "src/core/lib/iomgr/wakeup_fd_posix.h"
32 #include "src/core/lib/profiling/timers.h"
33
eventfd_create(grpc_wakeup_fd * fd_info)34 static grpc_error* eventfd_create(grpc_wakeup_fd* fd_info) {
35 fd_info->read_fd = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
36 fd_info->write_fd = -1;
37 if (fd_info->read_fd < 0) {
38 return GRPC_OS_ERROR(errno, "eventfd");
39 }
40 return GRPC_ERROR_NONE;
41 }
42
eventfd_consume(grpc_wakeup_fd * fd_info)43 static grpc_error* eventfd_consume(grpc_wakeup_fd* fd_info) {
44 eventfd_t value;
45 int err;
46 do {
47 err = eventfd_read(fd_info->read_fd, &value);
48 } while (err < 0 && errno == EINTR);
49 if (err < 0 && errno != EAGAIN) {
50 return GRPC_OS_ERROR(errno, "eventfd_read");
51 }
52 return GRPC_ERROR_NONE;
53 }
54
eventfd_wakeup(grpc_wakeup_fd * fd_info)55 static grpc_error* eventfd_wakeup(grpc_wakeup_fd* fd_info) {
56 GPR_TIMER_SCOPE("eventfd_wakeup", 0);
57 int err;
58 do {
59 err = eventfd_write(fd_info->read_fd, 1);
60 } while (err < 0 && errno == EINTR);
61 if (err < 0) {
62 return GRPC_OS_ERROR(errno, "eventfd_write");
63 }
64 return GRPC_ERROR_NONE;
65 }
66
eventfd_destroy(grpc_wakeup_fd * fd_info)67 static void eventfd_destroy(grpc_wakeup_fd* fd_info) {
68 if (fd_info->read_fd != 0) close(fd_info->read_fd);
69 }
70
eventfd_check_availability(void)71 static int eventfd_check_availability(void) {
72 const int efd = eventfd(0, 0);
73 const int is_available = efd >= 0;
74 if (is_available) close(efd);
75 return is_available;
76 }
77
78 const grpc_wakeup_fd_vtable grpc_specialized_wakeup_fd_vtable = {
79 eventfd_create, eventfd_consume, eventfd_wakeup, eventfd_destroy,
80 eventfd_check_availability};
81
82 #endif /* GRPC_LINUX_EVENTFD */
83