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 "src/core/lib/iomgr/wakeup_fd_posix.h"
30 #include "src/core/util/crash.h"
31 #include "src/core/util/strerror.h"
32
eventfd_create(grpc_wakeup_fd * fd_info)33 static grpc_error_handle eventfd_create(grpc_wakeup_fd* fd_info) {
34 fd_info->read_fd = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
35 fd_info->write_fd = -1;
36 if (fd_info->read_fd < 0) {
37 return GRPC_OS_ERROR(errno, "eventfd");
38 }
39 return absl::OkStatus();
40 }
41
eventfd_consume(grpc_wakeup_fd * fd_info)42 static grpc_error_handle eventfd_consume(grpc_wakeup_fd* fd_info) {
43 eventfd_t value;
44 int err;
45 do {
46 err = eventfd_read(fd_info->read_fd, &value);
47 } while (err < 0 && errno == EINTR);
48 if (err < 0 && errno != EAGAIN) {
49 return GRPC_OS_ERROR(errno, "eventfd_read");
50 }
51 return absl::OkStatus();
52 }
53
eventfd_wakeup(grpc_wakeup_fd * fd_info)54 static grpc_error_handle eventfd_wakeup(grpc_wakeup_fd* fd_info) {
55 int err;
56 do {
57 err = eventfd_write(fd_info->read_fd, 1);
58 } while (err < 0 && errno == EINTR);
59 if (err < 0) {
60 return GRPC_OS_ERROR(errno, "eventfd_write");
61 }
62 return absl::OkStatus();
63 }
64
eventfd_destroy(grpc_wakeup_fd * fd_info)65 static void eventfd_destroy(grpc_wakeup_fd* fd_info) {
66 if (fd_info->read_fd != 0) close(fd_info->read_fd);
67 }
68
eventfd_check_availability(void)69 static int eventfd_check_availability(void) {
70 const int efd = eventfd(0, 0);
71 const int is_available = efd >= 0;
72 if (is_available) close(efd);
73 return is_available;
74 }
75
76 const grpc_wakeup_fd_vtable grpc_specialized_wakeup_fd_vtable = {
77 eventfd_create, eventfd_consume, eventfd_wakeup, eventfd_destroy,
78 eventfd_check_availability};
79
80 #endif // GRPC_LINUX_EVENTFD
81