1 files changed, 154 insertions, 0 deletions

diff --git a/src/stable/counterevent.h b/src/stable/counterevent.h
new file mode 100644
index 0000000..e7ad7a1
--- /dev/null
+++ b/src/stable/counterevent.h
@@ -0,0 +1,154 @@
+/*
+ * Copyright (C) 2007-2019 Xagasoft, All rights reserved.
+ *
+ * This file is part of the libbu++ library and is released under the
+ * terms of the license contained in the file LICENSE.
+ */
+
+#ifndef BU_COUNTER_EVENT_H
+#define BU_COUNTER_EVENT_H
+
+#include <pthread.h>
+
+#include "bu/mutex.h"
+#include "bu/condition.h"
+
+namespace Bu
+{
+    /**
+     * Represents a true/false state that controls thread synchronization. This
+     * is primarilly intended to control the synchronization state of
+     * multithreaded services. For example, telling all threads when to exit.
+     *
+     * An Event is either set or unset. If the Event is unset then it can be
+     * waited on for something to happen. As soon as the Event is set all
+     * waiting threads are released and new requests to wait are ignored until
+     * the Event is cleared again.
+     *
+     * Threads can also be woken up without setting the Event, which may be
+     * handy in certain circumstances.
+     *@ingroup Threading
+     */
+    class CounterEvent
+    {
+    public:
+        CounterEvent() :
+            iCount( 0 )
+        {
+        }
+        
+        ~CounterEvent()
+        {
+        }
+
+        /**
+         * Wait indefinitely for the Event to trigger. If the event is already
+         * set, then return immediately.  It's important to note that this may
+         * return at any time, not only when the Event is set, so examining the
+         * return value is important.
+         *@returns the set status of the Event.
+         */
+        int wait()
+        {
+            cBlock.lock();
+            if( iCount == 0 )
+            {
+                cBlock.unlock();
+                return iCount;
+            }
+            cBlock.wait();
+            int iRet = iCount;
+            cBlock.unlock();
+            return iRet;
+        }
+
+        /**
+         * Wait for up to nSec seconds and nUSec nanoseconds for the event to
+         * trigger. If the Event is already set then return immediately.
+         *@returns the set status of the Event.
+         */
+        int wait( int nSec, int nUSec )
+        {
+            cBlock.lock();
+            if( iCount == 0 )
+            {
+                cBlock.unlock();
+                return iCount;
+            }
+            cBlock.wait( nSec, nUSec );
+            bool iRet = iCount;
+            cBlock.unlock();
+            return iRet;
+        }
+
+        /**
+         * Allow one of the waiting threads to unlock without updating the set
+         * state of the Event.
+         */
+        void unblockOne()
+        {
+            cBlock.lock();
+            cBlock.signal();
+            cBlock.unlock();
+        }
+
+        /**
+         * Allow all waiting threads to unlock and proceed without updating the
+         * set state of the Event.
+         */
+        void unblockAll()
+        {
+            cBlock.lock();
+            cBlock.broadcast();
+            cBlock.unlock();
+        }
+
+        /**
+         * Find out if the Event is in the set state or not.
+         *@returns True if set, false otherwise.
+         */
+        bool isZero()
+        {
+            cBlock.lock();
+            bool bRet = (iCount == 0);
+            cBlock.unlock();
+            return bRet;
+        }
+
+        /**
+         * Sets the Event's state to true and triggers all waiting threads.
+         */
+        void decrement()
+        {
+            cBlock.lock();
+            iCount--; if( iCount < 0 ) iCount = 0;
+            if( iCount == 0 )
+                cBlock.broadcast();
+            cBlock.unlock();
+        }
+
+        void increment()
+        {
+            cBlock.lock();
+            iCount++;
+            cBlock.unlock();
+        }
+        
+        /**
+         * Sets the Event's state to false. This does NOT trigger any waiting
+         * threads.
+         */
+        void clear()
+        {
+            cBlock.lock();
+            iCount = 0;
+            cBlock.unlock();
+        }
+
+    private:
+        Condition cBlock;   /**< The condition for blocking dequeues. */
+        int iCount;
+    };
+}
+
+#endif