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Add workaround for bug in older linux kernels handling epoll_wait(...)

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Motivation:

Older linux kernels have problems handling a large value for epoll_wait(...) and so wait for ever.

Modifications:

Adjust timeout on the fly if a too big value is passed in.

Result:

Correctly works also on older kernels.
This commit is contained in:
Norman Maurer 2015-02-06 07:34:54 +01:00
parent 4e6cec0e26
commit 0a452bef8e
1 changed files with 17 additions and 1 deletions
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18
transport-native-epoll/src/main/c/io_netty_channel_epoll_Native.c
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@ -33,6 +33,17 @@
#include <stddef.h>
#include "io_netty_channel_epoll_Native.h"
/**
* On older Linux kernels, epoll can't handle timeout
* values bigger than (LONG_MAX - 999ULL)/HZ.
*
* See:
* - https://github.com/libevent/libevent/blob/master/epoll.c#L138
* - http://cvs.schmorp.de/libev/ev_epoll.c?revision=1.68&view=markup
*/
#define MAX_EPOLL_TIMEOUT_MSEC (35*60*1000)
// optional
extern int accept4(int sockFd, struct sockaddr* addr, socklen_t* addrlen, int flags) __attribute__((weak));
extern int epoll_create1(int flags) __attribute__((weak));
@ -617,6 +628,11 @@ JNIEXPORT jint JNICALL Java_io_netty_channel_epoll_Native_epollWait0(JNIEnv* env
struct epoll_event *ev = (struct epoll_event*) address;
int ready;
int err;
if (timeout > MAX_EPOLL_TIMEOUT_MSEC) {
// Workaround for bug in older linux kernels that can not handle bigger timeout then MAX_EPOLL_TIMEOUT_MSEC.
timeout = MAX_EPOLL_TIMEOUT_MSEC;
}
do {
ready = epoll_wait(efd, ev, len, timeout);
// was interrupted try again.
@ -1500,4 +1516,4 @@ JNIEXPORT jint JNICALL Java_io_netty_channel_epoll_Native_sizeofEpollEvent(JNIEn
JNIEXPORT jint JNICALL Java_io_netty_channel_epoll_Native_offsetofEpollData(JNIEnv* env, jclass clazz) {
return offsetof(struct epoll_event, data);
}
}