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Diffstat (limited to 'webrtc/system_wrappers/source/condition_variable_event_win.cc')
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diff --git a/webrtc/system_wrappers/source/condition_variable_event_win.cc b/webrtc/system_wrappers/source/condition_variable_event_win.cc new file mode 100644 index 0000000..41b019d --- /dev/null +++ b/webrtc/system_wrappers/source/condition_variable_event_win.cc @@ -0,0 +1,195 @@ +/* +Source: +http://www1.cse.wustl.edu/~schmidt/ACE-copying.html + +License: +Copyright and Licensing Information for ACE(TM), TAO(TM), CIAO(TM), DAnCE(TM), +and CoSMIC(TM) + +ACE(TM), TAO(TM), CIAO(TM), DAnCE>(TM), and CoSMIC(TM) (henceforth referred to +as "DOC software") are copyrighted by Douglas C. Schmidt and his research +group at Washington University, University of California, Irvine, and +Vanderbilt University, Copyright (c) 1993-2009, all rights reserved. Since DOC +software is open-source, freely available software, you are free to use, +modify, copy, and distribute--perpetually and irrevocably--the DOC software +source code and object code produced from the source, as well as copy and +distribute modified versions of this software. You must, however, include this +copyright statement along with any code built using DOC software that you +release. No copyright statement needs to be provided if you just ship binary +executables of your software products. +You can use DOC software in commercial and/or binary software releases and are +under no obligation to redistribute any of your source code that is built +using DOC software. Note, however, that you may not misappropriate the DOC +software code, such as copyrighting it yourself or claiming authorship of the +DOC software code, in a way that will prevent DOC software from being +distributed freely using an open-source development model. You needn't inform +anyone that you're using DOC software in your software, though we encourage +you to let us know so we can promote your project in the DOC software success +stories. + +The ACE, TAO, CIAO, DAnCE, and CoSMIC web sites are maintained by the DOC +Group at the Institute for Software Integrated Systems (ISIS) and the Center +for Distributed Object Computing of Washington University, St. Louis for the +development of open-source software as part of the open-source software +community. Submissions are provided by the submitter ``as is'' with no +warranties whatsoever, including any warranty of merchantability, +noninfringement of third party intellectual property, or fitness for any +particular purpose. In no event shall the submitter be liable for any direct, +indirect, special, exemplary, punitive, or consequential damages, including +without limitation, lost profits, even if advised of the possibility of such +damages. Likewise, DOC software is provided as is with no warranties of any +kind, including the warranties of design, merchantability, and fitness for a +particular purpose, noninfringement, or arising from a course of dealing, +usage or trade practice. Washington University, UC Irvine, Vanderbilt +University, their employees, and students shall have no liability with respect +to the infringement of copyrights, trade secrets or any patents by DOC +software or any part thereof. Moreover, in no event will Washington +University, UC Irvine, or Vanderbilt University, their employees, or students +be liable for any lost revenue or profits or other special, indirect and +consequential damages. + +DOC software is provided with no support and without any obligation on the +part of Washington University, UC Irvine, Vanderbilt University, their +employees, or students to assist in its use, correction, modification, or +enhancement. A number of companies around the world provide commercial support +for DOC software, however. DOC software is Y2K-compliant, as long as the +underlying OS platform is Y2K-compliant. Likewise, DOC software is compliant +with the new US daylight savings rule passed by Congress as "The Energy Policy +Act of 2005," which established new daylight savings times (DST) rules for the +United States that expand DST as of March 2007. Since DOC software obtains +time/date and calendaring information from operating systems users will not be +affected by the new DST rules as long as they upgrade their operating systems +accordingly. + +The names ACE(TM), TAO(TM), CIAO(TM), DAnCE(TM), CoSMIC(TM), Washington +University, UC Irvine, and Vanderbilt University, may not be used to endorse +or promote products or services derived from this source without express +written permission from Washington University, UC Irvine, or Vanderbilt +University. This license grants no permission to call products or services +derived from this source ACE(TM), TAO(TM), CIAO(TM), DAnCE(TM), or CoSMIC(TM), +nor does it grant permission for the name Washington University, UC Irvine, or +Vanderbilt University to appear in their names. +*/ + +/* + * This source code contain modifications to the original source code + * which can be found here: + * http://www.cs.wustl.edu/~schmidt/win32-cv-1.html (section 3.2). + * Modifications: + * 1) Dynamic detection of native support for condition variables. + * 2) Use of WebRTC defined types and classes. Renaming of some functions. + * 3) Introduction of a second event for wake all functionality. This prevents + * a thread from spinning on the same condition variable, preventing other + * threads from waking up. + */ + +#include "webrtc/system_wrappers/source/condition_variable_event_win.h" +#include "webrtc/system_wrappers/source/critical_section_win.h" + +namespace webrtc { + +ConditionVariableEventWin::ConditionVariableEventWin() : eventID_(WAKEALL_0) { + memset(&num_waiters_[0], 0, sizeof(num_waiters_)); + + InitializeCriticalSection(&num_waiters_crit_sect_); + + events_[WAKEALL_0] = CreateEvent(NULL, // no security attributes + TRUE, // manual-reset, sticky event + FALSE, // initial state non-signaled + NULL); // no name for event + + events_[WAKEALL_1] = CreateEvent(NULL, // no security attributes + TRUE, // manual-reset, sticky event + FALSE, // initial state non-signaled + NULL); // no name for event + + events_[WAKE] = CreateEvent(NULL, // no security attributes + FALSE, // auto-reset, sticky event + FALSE, // initial state non-signaled + NULL); // no name for event +} + +ConditionVariableEventWin::~ConditionVariableEventWin() { + CloseHandle(events_[WAKE]); + CloseHandle(events_[WAKEALL_1]); + CloseHandle(events_[WAKEALL_0]); + + DeleteCriticalSection(&num_waiters_crit_sect_); +} + +void ConditionVariableEventWin::SleepCS(CriticalSectionWrapper& crit_sect) { + SleepCS(crit_sect, INFINITE); +} + +bool ConditionVariableEventWin::SleepCS(CriticalSectionWrapper& crit_sect, + unsigned long max_time_in_ms) { + EnterCriticalSection(&num_waiters_crit_sect_); + + // Get the eventID for the event that will be triggered by next + // WakeAll() call and start waiting for it. + const EventWakeUpType eventID = + (WAKEALL_0 == eventID_) ? WAKEALL_1 : WAKEALL_0; + + ++(num_waiters_[eventID]); + LeaveCriticalSection(&num_waiters_crit_sect_); + + CriticalSectionWindows* cs = + static_cast<CriticalSectionWindows*>(&crit_sect); + LeaveCriticalSection(&cs->crit); + HANDLE events[2]; + events[0] = events_[WAKE]; + events[1] = events_[eventID]; + const DWORD result = WaitForMultipleObjects(2, // Wait on 2 events. + events, + FALSE, // Wait for either. + max_time_in_ms); + + const bool ret_val = (result != WAIT_TIMEOUT); + + EnterCriticalSection(&num_waiters_crit_sect_); + --(num_waiters_[eventID]); + + // Last waiter should only be true for WakeAll(). WakeAll() correspond + // to position 1 in events[] -> (result == WAIT_OBJECT_0 + 1) + const bool last_waiter = (result == WAIT_OBJECT_0 + 1) && + (num_waiters_[eventID] == 0); + LeaveCriticalSection(&num_waiters_crit_sect_); + + if (last_waiter) { + // Reset/unset the WakeAll() event since all threads have been + // released. + ResetEvent(events_[eventID]); + } + + EnterCriticalSection(&cs->crit); + return ret_val; +} + +void ConditionVariableEventWin::Wake() { + EnterCriticalSection(&num_waiters_crit_sect_); + const bool have_waiters = (num_waiters_[WAKEALL_0] > 0) || + (num_waiters_[WAKEALL_1] > 0); + LeaveCriticalSection(&num_waiters_crit_sect_); + + if (have_waiters) { + SetEvent(events_[WAKE]); + } +} + +void ConditionVariableEventWin::WakeAll() { + EnterCriticalSection(&num_waiters_crit_sect_); + + // Update current WakeAll() event + eventID_ = (WAKEALL_0 == eventID_) ? WAKEALL_1 : WAKEALL_0; + + // Trigger current event + const EventWakeUpType eventID = eventID_; + const bool have_waiters = num_waiters_[eventID] > 0; + LeaveCriticalSection(&num_waiters_crit_sect_); + + if (have_waiters) { + SetEvent(events_[eventID]); + } +} + +} // namespace webrtc |