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Fix a tight spin on epoll (or /dev/poll) that occurs when the EPOLLERR and

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EPOLLHUP events are reported for a descriptor and there are no pending
operations.


[SVN r48031]
This commit is contained in:
Christopher Kohlhoff
2008-08-08 14:47:58 +00:00
parent 2d79a40ae6
commit 71d47ca98c
2 changed files with 16 additions and 14 deletions
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15
include/boost/asio/detail/dev_poll_reactor.hpp
View File

@@ -423,14 +423,15 @@ private:
else
more_writes = write_op_queue_.has_operation(descriptor);
if ((events[i].events == POLLHUP)
&& !more_except && !more_reads && !more_writes)
if ((events[i].events & (POLLERR | POLLHUP)) != 0
&& (events[i].events & ~(POLLERR | POLLHUP)) == 0
&& !more_except && !more_reads && !more_writes)
{
// If we have only an POLLHUP event and no operations associated
// with the descriptor then we need to delete the descriptor from
// /dev/poll. The poll operation might produce POLLHUP events even
// if they are not specifically requested, so if we do not remove the
// descriptor we can end up in a tight polling loop.
// If we have an event and no operations associated with the
// descriptor then we need to delete the descriptor from /dev/poll.
// The poll operation can produce POLLHUP or POLLERR events when there
// is no operation pending, so if we do not remove the descriptor we
// can end up in a tight polling loop.
::pollfd ev = { 0 };
ev.fd = descriptor;
ev.events = POLLREMOVE;

15
include/boost/asio/detail/epoll_reactor.hpp
View File

@@ -497,14 +497,15 @@ private:
else
more_writes = write_op_queue_.has_operation(descriptor);
if ((events[i].events == EPOLLHUP)
&& !more_except && !more_reads && !more_writes)
if ((events[i].events & (EPOLLERR | EPOLLHUP)) != 0
&& (events[i].events & ~(EPOLLERR | EPOLLHUP)) == 0
&& !more_except && !more_reads && !more_writes)
{
// If we have only an EPOLLHUP event and no operations associated
// with the descriptor then we need to delete the descriptor from
// epoll. The epoll_wait system call will produce EPOLLHUP events
// even if they are not specifically requested, so if we do not
// remove the descriptor we can end up in a tight loop of repeated
// If we have an event and no operations associated with the
// descriptor then we need to delete the descriptor from epoll. The
// epoll_wait system call can produce EPOLLHUP or EPOLLERR events
// when there is no operation pending, so if we do not remove the
// descriptor we can end up in a tight loop of repeated
// calls to epoll_wait.
epoll_event ev = { 0, { 0 } };
epoll_ctl(epoll_fd_, EPOLL_CTL_DEL, descriptor, &ev);