From df3af60bb3f65e51b5b9e8340d0c2ad754e29a33 Mon Sep 17 00:00:00 2001
From: Mike Buland <eichlan@xagasoft.com>
Date: Tue, 18 Feb 2020 07:09:19 -0800
Subject: Event updates!  It's...like an actual Event now.

---
 src/stable/event.h | 87 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 84 insertions(+), 3 deletions(-)

(limited to 'src/stable')

diff --git a/src/stable/event.h b/src/stable/event.h
index db4f846..f12dc7d 100644
--- a/src/stable/event.h
+++ b/src/stable/event.h
@@ -16,12 +16,24 @@
 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 Event
     {
     public:
-        Event()
+        Event() :
+            bIsSet( false )
         {
         }
         
@@ -29,20 +41,50 @@ namespace Bu
         {
         }
 
-        void wait()
+        /**
+         * 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.
+         */
+        bool wait()
         {
             cBlock.lock();
+            if( bIsSet )
+            {
+                cBlock.unlock();
+                return true;
+            }
             cBlock.wait();
+            bool bRet = bIsSet;
             cBlock.unlock();
+            return bIsSet;
         }
 
-        void wait( int nSec, int nUSec )
+        /**
+         * 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.
+         */
+        bool wait( int nSec, int nUSec )
         {
             cBlock.lock();
+            if( bIsSet )
+            {
+                cBlock.unlock();
+                return true;
+            }
             cBlock.wait( nSec, nUSec );
+            bool bRet = bIsSet;
             cBlock.unlock();
+            return bIsSet;
         }
 
+        /**
+         * Allow one of the waiting threads to unlock without updating the set
+         * state of the Event.
+         */
         void unblockOne()
         {
             cBlock.lock();
@@ -50,6 +92,10 @@ namespace Bu
             cBlock.unlock();
         }
 
+        /**
+         * Allow all waiting threads to unlock and proceed without updating the
+         * set state of the Event.
+         */
         void unblockAll()
         {
             cBlock.lock();
@@ -57,8 +103,43 @@ namespace Bu
             cBlock.unlock();
         }
 
+        /**
+         * Find out if the Event is in the set state or not.
+         *@returns True if set, false otherwise.
+         */
+        bool isSet()
+        {
+            cBlock.lock();
+            bool bRet = bIsSet;
+            cBlock.unlock();
+            return bRet;
+        }
+
+        /**
+         * Sets the Event's state to true and triggers all waiting threads.
+         */
+        void set()
+        {
+            cBlock.lock();
+            bIsSet = true;
+            cBlock.broadcast();
+            cBlock.unlock();
+        }
+        
+        /**
+         * Sets the Event's state to false. This does NOT trigger any waiting
+         * threads.
+         */
+        void clear()
+        {
+            cBlock.lock();
+            bIsSet = false;
+            cBlock.unlock();
+        }
+
     private:
         Condition cBlock;   /**< The condition for blocking dequeues. */
+        bool bIsSet;
     };
 }
 
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