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1ca3348ed4
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>
78 lines
2.7 KiB
C
78 lines
2.7 KiB
C
/*
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* Copyright (c) 2008, 2009, 2010, 2011, 2013 Nicira, Inc.
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*
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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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*
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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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*/
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/* High-level wrapper around the "poll" system call.
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*
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* The intended usage is for each thread's main loop to go about its business
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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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* 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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#ifndef POLL_LOOP_H
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#define POLL_LOOP_H 1
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#include <poll.h>
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#include "util.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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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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* 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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void poll_fd_wait_at(int fd, short int events, const char *where);
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#define poll_fd_wait(fd, events) poll_fd_wait_at(fd, events, SOURCE_LOCATOR)
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#ifdef _WIN32
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#define poll_wevent_wait(wevent) poll_wevent_wait_at(wevent, SOURCE_LOCATOR)
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#endif /* _WIN32 */
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void poll_timer_wait_at(long long int msec, const char *where);
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#define poll_timer_wait(msec) poll_timer_wait_at(msec, SOURCE_LOCATOR)
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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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poll_timer_wait_until_at(msec, SOURCE_LOCATOR)
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void poll_immediate_wake_at(const char *where);
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#define poll_immediate_wake() poll_immediate_wake_at(SOURCE_LOCATOR)
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/* Wait until an event occurs. */
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void poll_block(void);
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#ifdef __cplusplus
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}
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#endif
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#endif /* poll-loop.h */
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