[Boost-commit] svn:boost r48031 - trunk/boost/asio/detail

From: chris_at_[hidden]
Date: 2008-08-08 10:47:58

Author: chris_kohlhoff
Date: 2008-08-08 10:47:58 EDT (Fri, 08 Aug 2008)
New Revision: 48031
URL: http://svn.boost.org/trac/boost/changeset/48031

Log:
Fix a tight spin on epoll (or /dev/poll) that occurs when the EPOLLERR and
EPOLLHUP events are reported for a descriptor and there are no pending
operations.

Text files modified: 
   trunk/boost/asio/detail/dev_poll_reactor.hpp |    15 ++++++++-------                         
   trunk/boost/asio/detail/epoll_reactor.hpp    |    15 ++++++++-------                         
   2 files changed, 16 insertions(+), 14 deletions(-)

Modified: trunk/boost/asio/detail/dev_poll_reactor.hpp
==============================================================================
--- trunk/boost/asio/detail/dev_poll_reactor.hpp	(original)
+++ trunk/boost/asio/detail/dev_poll_reactor.hpp	2008-08-08 10:47:58 EDT (Fri, 08 Aug 2008)
@@ -423,14 +423,15 @@
         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;

Modified: trunk/boost/asio/detail/epoll_reactor.hpp
==============================================================================
--- trunk/boost/asio/detail/epoll_reactor.hpp	(original)
+++ trunk/boost/asio/detail/epoll_reactor.hpp	2008-08-08 10:47:58 EDT (Fri, 08 Aug 2008)
@@ -497,14 +497,15 @@
         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);