webrtc/system_wrappers/source/condition_variable_event_win.cc - src - Git at Google

 /*
 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/include/critical_section_wrapper.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(CRITICAL_SECTION* crit_sect) {
   SleepCS(crit_sect, INFINITE);
 }

 bool ConditionVariableEventWin::SleepCS(CRITICAL_SECTION* 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_);

   LeaveCriticalSection(crit_sect);
   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(crit_sect);
   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
	/*
	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/include/critical_section_wrapper.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(CRITICAL_SECTION* crit_sect) {
	SleepCS(crit_sect, INFINITE);
	}

	bool ConditionVariableEventWin::SleepCS(CRITICAL_SECTION* 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_);

	LeaveCriticalSection(crit_sect);
	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(crit_sect);
	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