From 042b72bc172e7eb4e9ef7668ae28be6e7a3b4036 Mon Sep 17 00:00:00 2001
From: Tycho Bickerstaff <work.tycho@gmail.com>
Date: Thu, 2 Jan 2014 12:32:55 +0000
Subject: rewrote queue not to use promises for waits

---
 src/OSSupport/Promise.cpp | 54 -----------------------------------------------
 src/OSSupport/Promise.h   | 38 ---------------------------------
 src/OSSupport/Queue.h     | 24 ++++++++++-----------
 3 files changed, 11 insertions(+), 105 deletions(-)
 delete mode 100644 src/OSSupport/Promise.cpp
 delete mode 100644 src/OSSupport/Promise.h

(limited to 'src/OSSupport')

diff --git a/src/OSSupport/Promise.cpp b/src/OSSupport/Promise.cpp
deleted file mode 100644
index b31869334..000000000
--- a/src/OSSupport/Promise.cpp
+++ /dev/null
@@ -1,54 +0,0 @@
-
-#include "Globals.h"
-
-#include "Promise.h"
-
-cPromise * cPromise::WaitFor(cPromise * a_Promise) 
-{
-	return new cCombinedPromise(this, a_Promise);
-}
-
-cPromise * cPromise::CancelOn(volatile bool& cancelation) 
-{
-	return new cCancelablePromise(this, cancelation);
-}
-
-void cPromise::Wait()
-{
-	while(!IsCompleted()){}; //busywait best we can do until waitany
-}
-
-
-cCombinedPromise::cCombinedPromise(cPromise* a_left, cPromise* a_right) : 
-	cPromise(), 
-	m_left(a_left), 
-	m_right(a_right)
-{
-}
-
-cCombinedPromise::~cCombinedPromise()
-{
-}
-
-bool cCombinedPromise::IsCompleted()
-{
-	return m_left->IsCompleted() || m_right->IsCompleted();
-}
-
-cCancelablePromise::cCancelablePromise(cPromise* a_wrapped, volatile bool& a_cancel) : 
-	cPromise(), 
-	m_cancel(a_cancel),
-	m_wrapped(a_wrapped)
-{
-}
-
-cCancelablePromise::~cCancelablePromise ()
-{
-}
-
-bool cCancelablePromise::IsCompleted() 
-{
-	return m_cancel || m_wrapped->IsCompleted();
-}
-
-
diff --git a/src/OSSupport/Promise.h b/src/OSSupport/Promise.h
deleted file mode 100644
index 83d04860b..000000000
--- a/src/OSSupport/Promise.h
+++ /dev/null
@@ -1,38 +0,0 @@
-#pragma once
-
-class cCombinedPromise;
-
-
-class cPromise {
-	public:
-		cPromise() {}
-		virtual ~cPromise () {}
-		cPromise * WaitFor(cPromise * a_Promise);
-		cPromise * CancelOn(volatile bool& cancelationtoken);
-		void Wait();
-		virtual bool IsCompleted() = 0;
-		//TODO:Expose Events for waiting on
-};
-
-class cCombinedPromise : public cPromise {
-public:
-	cCombinedPromise(cPromise*, cPromise*);
-	~cCombinedPromise();
-	virtual bool IsCompleted();
-private:
-	cPromise* m_left;
-	cPromise* m_right;
-};
-
-class cCancelablePromise : public cPromise {
-public:
-	cCancelablePromise(cPromise*, volatile bool&);
-	~cCancelablePromise();
-	virtual bool IsCompleted();
-private:
-	volatile bool& m_cancel;
-	cPromise* m_wrapped;
-};
-
-
-
diff --git a/src/OSSupport/Queue.h b/src/OSSupport/Queue.h
index eb323b067..153e201c1 100644
--- a/src/OSSupport/Queue.h
+++ b/src/OSSupport/Queue.h
@@ -3,8 +3,6 @@
 
 #include <list>
 
-#include "../OSSupport/Promise.h"
-
 //this empty struct allows function inlining
 template<class T>
 struct cQueueFuncs 
@@ -52,6 +50,7 @@ public:
 		if (m_contents.size() == 0) return false;
 		item = m_contents.front();
 		m_contents.pop_front();
+		m_evtRemoved.Set();
 		return true;
 	}
 	ItemType DequeueItem()
@@ -62,10 +61,15 @@ public:
 			cCSUnlock Unlock(m_CS);
 			m_evtAdded.Wait();
 		}
-		return m_contents.pop_front();
+		ItemType item = m_contents.front();
+		m_contents.pop_front();
+		m_evtRemoved.Set();
+		return item;
 	}
-	cPromise* BlockTillEmpty() {
-		return new cEmptyQueuePromise(this);
+	void BlockTillEmpty() {
+		//There is a very slight race condition here if the load completes between the check
+		//and the wait.
+		while(!(Size() == 0)){m_evtRemoved.Wait();}
 	}
 	//can all be inlined when delete is a noop
 	void     Clear()
@@ -87,18 +91,12 @@ public:
 	{
 		cCSLock Lock(m_CS);
 		m_contents.remove(item);
+		m_evtRemoved.Set();
 	}
 
 private:
 	ListType m_contents;
 	cCriticalSection m_CS;
 	cEvent m_evtAdded;
-
-	class cEmptyQueuePromise : public cPromise {
-	public:
-		cEmptyQueuePromise(cQueue* a_Queue) : cPromise(), m_Queue(a_Queue)  {}
-		virtual bool IsCompleted() {return m_Queue->Size() != 0;}
-	private:
-		cQueue* m_Queue;
-	};
+	cEvent m_evtRemoved;
 };
-- 
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