Created
January 6, 2018 09:16
-
-
Save overvenus/2b8eb4c8d86e112593f90a9a31bba60a to your computer and use it in GitHub Desktop.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| /* | |
| * | |
| * Copyright 2017 gRPC authors. | |
| * | |
| * Licensed under the Apache License, Version 2.0 (the "License"); | |
| * you may not use this file except in compliance with the License. | |
| * You may obtain a copy of the License at | |
| * | |
| * http://www.apache.org/licenses/LICENSE-2.0 | |
| * | |
| * Unless required by applicable law or agreed to in writing, software | |
| * distributed under the License is distributed on an "AS IS" BASIS, | |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
| * See the License for the specific language governing permissions and | |
| * limitations under the License. | |
| * | |
| */ | |
| #include <errno.h> | |
| #include <sys/eventfd.h> | |
| #include <sys/epoll.h> | |
| #include <unistd.h> | |
| #include <stdio.h> | |
| #ifndef EPOLLEXCLUSIVE | |
| #define EPOLLEXCLUSIVE (1 << 28) | |
| #endif | |
| /* This polling engine is only relevant on linux kernels supporting epoll() */ | |
| bool grpc_is_epollexclusive_available(void) { | |
| static bool logged_why_not = false; | |
| int fd = epoll_create1(EPOLL_CLOEXEC); | |
| if (fd < 0) { | |
| if (!logged_why_not) { | |
| printf( | |
| "epoll_create1 failed with error: %d. Not using epollex polling " | |
| "engine.", | |
| fd); | |
| logged_why_not = true; | |
| } | |
| return false; | |
| } | |
| int evfd = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC); | |
| if (evfd < 0) { | |
| if (!logged_why_not) { | |
| printf( | |
| "eventfd failed with error: %d. Not using epollex polling " | |
| "engine.", | |
| fd); | |
| logged_why_not = true; | |
| } | |
| close(fd); | |
| return false; | |
| } | |
| struct epoll_event ev; | |
| /* choose events that should cause an error on | |
| EPOLLEXCLUSIVE enabled kernels - specifically the combination of | |
| EPOLLONESHOT and EPOLLEXCLUSIVE */ | |
| ev.events = (uint32_t)(EPOLLET | EPOLLIN | EPOLLEXCLUSIVE | EPOLLONESHOT); | |
| ev.data.ptr = NULL; | |
| if (epoll_ctl(fd, EPOLL_CTL_ADD, evfd, &ev) != 0) { | |
| if (errno != EINVAL) { | |
| if (!logged_why_not) { | |
| printf( | |
| "epoll_ctl with EPOLLEXCLUSIVE | EPOLLONESHOT failed with error: " | |
| "%d. Not using epollex polling engine.", | |
| errno); | |
| logged_why_not = true; | |
| } | |
| close(fd); | |
| close(evfd); | |
| return false; | |
| } | |
| } else { | |
| if (!logged_why_not) { | |
| printf( | |
| "epoll_ctl with EPOLLEXCLUSIVE | EPOLLONESHOT succeeded. This is " | |
| "evidence of no EPOLLEXCLUSIVE support. Not using " | |
| "epollex polling engine."); | |
| logged_why_not = true; | |
| } | |
| close(fd); | |
| close(evfd); | |
| return false; | |
| } | |
| close(evfd); | |
| close(fd); | |
| return true; | |
| } | |
| int main() { | |
| if (grpc_is_epollexclusive_available()) { | |
| printf("\nepollexclusive IS available\n"); | |
| } else { | |
| printf("\nepollexclusive is NOT available\n"); | |
| } | |
| } |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment