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/*
*
* 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 "src/core/lib/iomgr/port.h"
#include "src/core/lib/iomgr/is_epollexclusive_available.h"
#ifdef GRPC_LINUX_EPOLL
#include <grpc/support/log.h>
#include <errno.h>
#include <sys/eventfd.h>
#include <unistd.h>
#include "src/core/lib/iomgr/sys_epoll_wrapper.h"
/* 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) {
gpr_log(GPR_ERROR,
"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) {
gpr_log(GPR_ERROR,
"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 = nullptr;
if (epoll_ctl(fd, EPOLL_CTL_ADD, evfd, &ev) != 0) {
if (errno != EINVAL) {
if (!logged_why_not) {
gpr_log(
GPR_ERROR,
"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) {
gpr_log(GPR_ERROR,
"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;
}
#else
bool grpc_is_epollexclusive_available(void) { return false; }
#endif
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