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/gprpp/crash.h"
32 #include "src/core/lib/gprpp/strerror.h"
33 #include "src/core/lib/iomgr/wakeup_fd_posix.h"
34
eventfd_create(grpc_wakeup_fd * fd_info)35 static grpc_error_handle eventfd_create(grpc_wakeup_fd* fd_info) {
36 fd_info->read_fd = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
37 fd_info->write_fd = -1;
38 if (fd_info->read_fd < 0) {
39 return GRPC_OS_ERROR(errno, "eventfd");
40 }
41 return absl::OkStatus();
42 }
43
eventfd_consume(grpc_wakeup_fd * fd_info)44 static grpc_error_handle eventfd_consume(grpc_wakeup_fd* fd_info) {
45 eventfd_t value;
46 int err;
47 do {
48 err = eventfd_read(fd_info->read_fd, &value);
49 } while (err < 0 && errno == EINTR);
50 if (err < 0 && errno != EAGAIN) {
51 return GRPC_OS_ERROR(errno, "eventfd_read");
52 }
53 return absl::OkStatus();
54 }
55
eventfd_wakeup(grpc_wakeup_fd * fd_info)56 static grpc_error_handle eventfd_wakeup(grpc_wakeup_fd* fd_info) {
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 absl::OkStatus();
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