2009-07-08 13:19:16 -07:00
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/*
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2017-02-06 04:41:41 +00:00
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* Copyright (c) 2008, 2009, 2010, 2011, 2013, 2017 Nicira, Inc.
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2009-07-08 13:19:16 -07:00
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*
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2009-06-15 15:11:30 -07:00
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at:
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2009-07-08 13:19:16 -07:00
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*
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2009-06-15 15:11:30 -07:00
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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2009-07-08 13:19:16 -07:00
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*/
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/* High-level wrapper around the "poll" system call.
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*
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2013-07-10 10:54:41 -07:00
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* The intended usage is for each thread's main loop to go about its business
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2009-07-08 13:19:16 -07:00
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* servicing whatever events it needs to. Then, when it runs out of immediate
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* tasks, it calls each subordinate module's "wait" function, which in turn
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* calls one (or more) of the functions poll_fd_wait(), poll_immediate_wake(),
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* and poll_timer_wait() to register to be awakened when the appropriate event
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* occurs. Then the main loop calls poll_block(), which blocks until one of
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2013-07-10 10:54:41 -07:00
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* the registered events happens.
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*
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*
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* Thread-safety
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* =============
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*
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* The poll set is per-thread, so all functions in this module are thread-safe.
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*/
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2009-07-08 13:19:16 -07:00
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#ifndef POLL_LOOP_H
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#define POLL_LOOP_H 1
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2017-11-03 13:53:53 +08:00
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#ifndef _WIN32
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2009-07-08 13:19:16 -07:00
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#include <poll.h>
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2017-11-03 13:53:53 +08:00
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#endif
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#ifdef _WIN32
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#include <windows.h>
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#endif
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2009-07-08 13:19:16 -07:00
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2010-02-17 10:36:57 -05:00
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#ifdef __cplusplus
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extern "C" {
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#endif
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2009-07-08 13:19:16 -07:00
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poll-loop: Make wakeup logging more portable and easier to understand.
Until now, when the poll_loop module's log level was turned up to "debug",
it would log a backtrace of the call stack for the event that caused poll()
to wake up in poll_block(). This was pretty useful from time to time to
find out why ovs-vswitchd was using more CPU than expected, because we
could find out what was causing it to wake up.
But there were some issues. One is simply that the backtrace was printed
as a series of hexadecimal numbers, so GDB or another debugger was needed
to translate it into human-readable format. Compiler optimizations meant
that even the human-readable backtrace wasn't, in my experience, as helpful
as it could have been. And, of course, one needed to have the binary to
interpret the backtrace. When the backtrace couldn't be interpreted or
wasn't meaningful, there was essentially nothing to fall back on.
This commit changes the way that "debug" logging for poll_block() wakeups
works. Instead of logging a backtrace, it logs the source code file name
and line number of the call to a poll_loop function, using __FILE__ and
__LINE__. This is by itself much more meaningful than a sequence of
hexadecimal numbers, since no additional interpretation is necessary. It
can be useful even if the Open vSwitch version is only approximately known.
In addition to the file and line, this commit adds, for wakeups caused by
file descriptors, information about the file descriptor itself: what kind
of file it is (regular file, directory, socket, etc.), the name of the file
(on Linux only), and the local and remote endpoints for socket file
descriptors.
Here are a few examples of the new output format:
932-ms timeout at ../ofproto/in-band.c:507
[POLLIN] on fd 20 (192.168.0.20:35388<->192.168.0.3:6633) at ../lib/stream-fd.c:149
[POLLIN] on fd 7 (FIFO pipe:[48049]) at ../lib/fatal-signal.c:168
2011-05-13 13:06:49 -07:00
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/* Schedule events to wake up the following poll_block().
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*
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* The poll_loop logs the 'where' argument to each function at "debug" level
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2013-07-29 15:24:45 -07:00
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* when an event causes a wakeup. Each of these ways to schedule an event has
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* a function and a macro wrapper. The macro version automatically supplies
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* the source code location of the caller. The function version allows the
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* caller to supply a location explicitly, which is useful if the caller's own
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* caller would be more useful in log output. See timer_wait_at() for an
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* example. */
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poll-loop: Create Windows event handles for sockets automatically.
We currently have a poll_fd_wait_event(fd, wevent, events) function that
is used at places common to Windows and Linux where we have to wait on
sockets. On Linux, 'wevent' is always set as zero. On Windows, for sockets,
when we send both 'fd' and 'wevent', we associate them with each other for
'events' and then wait on 'wevent'. Also on Windows, when we only send 'wevent'
to this function, we would simply wait for all events for that 'wevent'.
There is a disadvantage with this approach.
* Windows clients need to create a 'wevent' and then pass it along. This
means that at a lot of places where we create sockets, we also are forced
to create a 'wevent'.
With this commit, we pass the responsibility of creating a 'wevent' to
poll_fd_wait() in case of sockets. That way, a client using poll_fd_wait()
is only concerned about sockets and not about 'wevents'. There is a potential
disadvantage with this change in that we create events more often and that
may have a performance penalty. If that turns out to be the case, we will
eventually need to create a pool of wevents that can be re-used.
In Windows, there are cases where we want to wait on a event (not
associated with any sockets) and then control it using functions
like SetEvent() etc. For that purpose, introduce a new function
poll_wevent_wait(). For this function, the client needs to create a event
and then pass it along as an argument.
Signed-off-by: Gurucharan Shetty <gshetty@nicira.com>
Acked-By: Ben Pfaff <blp@nicira.com>
2014-06-27 13:30:49 -07:00
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void poll_fd_wait_at(int fd, short int events, const char *where);
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2014-12-15 14:10:38 +01:00
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#define poll_fd_wait(fd, events) poll_fd_wait_at(fd, events, OVS_SOURCE_LOCATOR)
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poll-loop: Create Windows event handles for sockets automatically.
We currently have a poll_fd_wait_event(fd, wevent, events) function that
is used at places common to Windows and Linux where we have to wait on
sockets. On Linux, 'wevent' is always set as zero. On Windows, for sockets,
when we send both 'fd' and 'wevent', we associate them with each other for
'events' and then wait on 'wevent'. Also on Windows, when we only send 'wevent'
to this function, we would simply wait for all events for that 'wevent'.
There is a disadvantage with this approach.
* Windows clients need to create a 'wevent' and then pass it along. This
means that at a lot of places where we create sockets, we also are forced
to create a 'wevent'.
With this commit, we pass the responsibility of creating a 'wevent' to
poll_fd_wait() in case of sockets. That way, a client using poll_fd_wait()
is only concerned about sockets and not about 'wevents'. There is a potential
disadvantage with this change in that we create events more often and that
may have a performance penalty. If that turns out to be the case, we will
eventually need to create a pool of wevents that can be re-used.
In Windows, there are cases where we want to wait on a event (not
associated with any sockets) and then control it using functions
like SetEvent() etc. For that purpose, introduce a new function
poll_wevent_wait(). For this function, the client needs to create a event
and then pass it along as an argument.
Signed-off-by: Gurucharan Shetty <gshetty@nicira.com>
Acked-By: Ben Pfaff <blp@nicira.com>
2014-06-27 13:30:49 -07:00
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#ifdef _WIN32
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2017-02-06 04:41:41 +00:00
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void poll_wevent_wait_at(HANDLE wevent, const char *where);
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2014-12-15 14:10:38 +01:00
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#define poll_wevent_wait(wevent) poll_wevent_wait_at(wevent, OVS_SOURCE_LOCATOR)
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poll-loop: Create Windows event handles for sockets automatically.
We currently have a poll_fd_wait_event(fd, wevent, events) function that
is used at places common to Windows and Linux where we have to wait on
sockets. On Linux, 'wevent' is always set as zero. On Windows, for sockets,
when we send both 'fd' and 'wevent', we associate them with each other for
'events' and then wait on 'wevent'. Also on Windows, when we only send 'wevent'
to this function, we would simply wait for all events for that 'wevent'.
There is a disadvantage with this approach.
* Windows clients need to create a 'wevent' and then pass it along. This
means that at a lot of places where we create sockets, we also are forced
to create a 'wevent'.
With this commit, we pass the responsibility of creating a 'wevent' to
poll_fd_wait() in case of sockets. That way, a client using poll_fd_wait()
is only concerned about sockets and not about 'wevents'. There is a potential
disadvantage with this change in that we create events more often and that
may have a performance penalty. If that turns out to be the case, we will
eventually need to create a pool of wevents that can be re-used.
In Windows, there are cases where we want to wait on a event (not
associated with any sockets) and then control it using functions
like SetEvent() etc. For that purpose, introduce a new function
poll_wevent_wait(). For this function, the client needs to create a event
and then pass it along as an argument.
Signed-off-by: Gurucharan Shetty <gshetty@nicira.com>
Acked-By: Ben Pfaff <blp@nicira.com>
2014-06-27 13:30:49 -07:00
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#endif /* _WIN32 */
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poll-loop: Make wakeup logging more portable and easier to understand.
Until now, when the poll_loop module's log level was turned up to "debug",
it would log a backtrace of the call stack for the event that caused poll()
to wake up in poll_block(). This was pretty useful from time to time to
find out why ovs-vswitchd was using more CPU than expected, because we
could find out what was causing it to wake up.
But there were some issues. One is simply that the backtrace was printed
as a series of hexadecimal numbers, so GDB or another debugger was needed
to translate it into human-readable format. Compiler optimizations meant
that even the human-readable backtrace wasn't, in my experience, as helpful
as it could have been. And, of course, one needed to have the binary to
interpret the backtrace. When the backtrace couldn't be interpreted or
wasn't meaningful, there was essentially nothing to fall back on.
This commit changes the way that "debug" logging for poll_block() wakeups
works. Instead of logging a backtrace, it logs the source code file name
and line number of the call to a poll_loop function, using __FILE__ and
__LINE__. This is by itself much more meaningful than a sequence of
hexadecimal numbers, since no additional interpretation is necessary. It
can be useful even if the Open vSwitch version is only approximately known.
In addition to the file and line, this commit adds, for wakeups caused by
file descriptors, information about the file descriptor itself: what kind
of file it is (regular file, directory, socket, etc.), the name of the file
(on Linux only), and the local and remote endpoints for socket file
descriptors.
Here are a few examples of the new output format:
932-ms timeout at ../ofproto/in-band.c:507
[POLLIN] on fd 20 (192.168.0.20:35388<->192.168.0.3:6633) at ../lib/stream-fd.c:149
[POLLIN] on fd 7 (FIFO pipe:[48049]) at ../lib/fatal-signal.c:168
2011-05-13 13:06:49 -07:00
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2013-07-29 15:24:45 -07:00
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void poll_timer_wait_at(long long int msec, const char *where);
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2014-12-15 14:10:38 +01:00
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#define poll_timer_wait(msec) poll_timer_wait_at(msec, OVS_SOURCE_LOCATOR)
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poll-loop: Make wakeup logging more portable and easier to understand.
Until now, when the poll_loop module's log level was turned up to "debug",
it would log a backtrace of the call stack for the event that caused poll()
to wake up in poll_block(). This was pretty useful from time to time to
find out why ovs-vswitchd was using more CPU than expected, because we
could find out what was causing it to wake up.
But there were some issues. One is simply that the backtrace was printed
as a series of hexadecimal numbers, so GDB or another debugger was needed
to translate it into human-readable format. Compiler optimizations meant
that even the human-readable backtrace wasn't, in my experience, as helpful
as it could have been. And, of course, one needed to have the binary to
interpret the backtrace. When the backtrace couldn't be interpreted or
wasn't meaningful, there was essentially nothing to fall back on.
This commit changes the way that "debug" logging for poll_block() wakeups
works. Instead of logging a backtrace, it logs the source code file name
and line number of the call to a poll_loop function, using __FILE__ and
__LINE__. This is by itself much more meaningful than a sequence of
hexadecimal numbers, since no additional interpretation is necessary. It
can be useful even if the Open vSwitch version is only approximately known.
In addition to the file and line, this commit adds, for wakeups caused by
file descriptors, information about the file descriptor itself: what kind
of file it is (regular file, directory, socket, etc.), the name of the file
(on Linux only), and the local and remote endpoints for socket file
descriptors.
Here are a few examples of the new output format:
932-ms timeout at ../ofproto/in-band.c:507
[POLLIN] on fd 20 (192.168.0.20:35388<->192.168.0.3:6633) at ../lib/stream-fd.c:149
[POLLIN] on fd 7 (FIFO pipe:[48049]) at ../lib/fatal-signal.c:168
2011-05-13 13:06:49 -07:00
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2013-07-29 15:24:45 -07:00
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void poll_timer_wait_until_at(long long int msec, const char *where);
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#define poll_timer_wait_until(msec) \
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2014-12-15 14:10:38 +01:00
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poll_timer_wait_until_at(msec, OVS_SOURCE_LOCATOR)
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poll-loop: Make wakeup logging more portable and easier to understand.
Until now, when the poll_loop module's log level was turned up to "debug",
it would log a backtrace of the call stack for the event that caused poll()
to wake up in poll_block(). This was pretty useful from time to time to
find out why ovs-vswitchd was using more CPU than expected, because we
could find out what was causing it to wake up.
But there were some issues. One is simply that the backtrace was printed
as a series of hexadecimal numbers, so GDB or another debugger was needed
to translate it into human-readable format. Compiler optimizations meant
that even the human-readable backtrace wasn't, in my experience, as helpful
as it could have been. And, of course, one needed to have the binary to
interpret the backtrace. When the backtrace couldn't be interpreted or
wasn't meaningful, there was essentially nothing to fall back on.
This commit changes the way that "debug" logging for poll_block() wakeups
works. Instead of logging a backtrace, it logs the source code file name
and line number of the call to a poll_loop function, using __FILE__ and
__LINE__. This is by itself much more meaningful than a sequence of
hexadecimal numbers, since no additional interpretation is necessary. It
can be useful even if the Open vSwitch version is only approximately known.
In addition to the file and line, this commit adds, for wakeups caused by
file descriptors, information about the file descriptor itself: what kind
of file it is (regular file, directory, socket, etc.), the name of the file
(on Linux only), and the local and remote endpoints for socket file
descriptors.
Here are a few examples of the new output format:
932-ms timeout at ../ofproto/in-band.c:507
[POLLIN] on fd 20 (192.168.0.20:35388<->192.168.0.3:6633) at ../lib/stream-fd.c:149
[POLLIN] on fd 7 (FIFO pipe:[48049]) at ../lib/fatal-signal.c:168
2011-05-13 13:06:49 -07:00
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2013-07-29 15:24:45 -07:00
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void poll_immediate_wake_at(const char *where);
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2014-12-15 14:10:38 +01:00
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#define poll_immediate_wake() poll_immediate_wake_at(OVS_SOURCE_LOCATOR)
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2009-07-08 13:19:16 -07:00
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/* Wait until an event occurs. */
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void poll_block(void);
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2010-02-17 10:36:57 -05:00
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#ifdef __cplusplus
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}
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#endif
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2009-07-08 13:19:16 -07:00
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#endif /* poll-loop.h */
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