From ad8fb867c51daa6eb2888f6a6af3bb51b5f91cd3 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Wed, 23 Dec 2015 17:23:02 +0000
Subject: Add some missing features to resource handle for early release and
 reassignment

---
 libadhocutil/resourcePool.h                 |  4 ++++
 libadhocutil/resourcePool.impl.h            | 35 ++++++++++++++++++++++++++++-
 libadhocutil/unittests/testResourcePool.cpp | 17 +++++++++++++-
 3 files changed, 54 insertions(+), 2 deletions(-)

diff --git a/libadhocutil/resourcePool.h b/libadhocutil/resourcePool.h
index 5ccb516..f77f2a5 100644
--- a/libadhocutil/resourcePool.h
+++ b/libadhocutil/resourcePool.h
@@ -34,6 +34,10 @@ namespace AdHoc {
 			Resource * operator->() const;
 			/// Access to the resource.
 			Resource * get() const;
+			/// Release the resource back to the pool.
+			void release();
+			/// Cast to bool.
+			operator bool() const;
 
 			/// Get number of handles to this resource.
 			unsigned int handleCount() const;
diff --git a/libadhocutil/resourcePool.impl.h b/libadhocutil/resourcePool.impl.h
index 85a6d3d..269cd00 100644
--- a/libadhocutil/resourcePool.impl.h
+++ b/libadhocutil/resourcePool.impl.h
@@ -5,6 +5,8 @@
 #include "lockHelpers.h"
 #include "safeMapFind.h"
 
+#define ASSERT(expr) if(!expr) throw std::runtime_error(#expr)
+
 namespace AdHoc {
 	//
 	// ResourceHandle
@@ -27,13 +29,16 @@ namespace AdHoc {
 	template <typename R>
 	ResourceHandle<R>::~ResourceHandle()
 	{
-		decRef();
+		if (resource) {
+			decRef();
+		}
 	}
 
 	template <typename R>
 	unsigned int
 	ResourceHandle<R>::handleCount() const
 	{
+		ASSERT(resource);
 		return boost::get<2>(*resource);
 	}
 
@@ -41,20 +46,47 @@ namespace AdHoc {
 	R *
 	ResourceHandle<R>::get() const
 	{
+		ASSERT(resource);
 		return boost::get<0>(*resource);
 	}
 
+	template <typename R>
+	void
+	ResourceHandle<R>::release()
+	{
+		decRef();
+	}
+
+	template <typename R>
+	ResourceHandle<R>::operator bool() const
+	{
+		return resource;
+	}
+
 	template <typename R>
 	R *
 	ResourceHandle<R>::operator->() const
 	{
+		ASSERT(resource);
 		return boost::get<0>(*resource);
 	}
 
+	template <typename R>
+	void
+	ResourceHandle<R>::operator=(const ResourceHandle & rh)
+	{
+		if (resource) {
+			decRef();
+		}
+		resource = rh.resource;
+		incRef();
+	}
+
 	template <typename R>
 	void
 	ResourceHandle<R>::incRef() const
 	{
+		ASSERT(resource);
 		++boost::get<2>(*resource);
 	}
 
@@ -62,6 +94,7 @@ namespace AdHoc {
 	void
 	ResourceHandle<R>::decRef()
 	{
+		ASSERT(resource);
 		if (!--boost::get<2>(*resource)) {
 			if (std::uncaught_exception()) {
 				boost::get<1>(*resource)->discard(boost::get<0>(*resource));
diff --git a/libadhocutil/unittests/testResourcePool.cpp b/libadhocutil/unittests/testResourcePool.cpp
index 349ea00..411f1bb 100644
--- a/libadhocutil/unittests/testResourcePool.cpp
+++ b/libadhocutil/unittests/testResourcePool.cpp
@@ -58,7 +58,8 @@ BOOST_AUTO_TEST_CASE ( get )
 			BOOST_REQUIRE_EQUAL(2, MockResource::count);
 			BOOST_REQUIRE(r2.get());
 
-			auto r1a = r1;
+			auto r1a = r2;
+			r1a = r1;
 			BOOST_REQUIRE_EQUAL(2, pool.inUseCount());
 			BOOST_REQUIRE_EQUAL(0, pool.availableCount());
 			BOOST_REQUIRE_EQUAL(2, r1.handleCount());
@@ -67,6 +68,20 @@ BOOST_AUTO_TEST_CASE ( get )
 			BOOST_REQUIRE(r1.get());
 			BOOST_REQUIRE(r1a.get());
 			BOOST_REQUIRE_EQUAL(r1.get(), r1a.get());
+
+			BOOST_REQUIRE(r1a);
+			r1a.release();
+			if (!r1a) {
+				BOOST_REQUIRE(true);
+			}
+			BOOST_REQUIRE(!r1a);
+			BOOST_REQUIRE_THROW(r1a.get(), std::runtime_error);
+			r1a = r2;
+			BOOST_REQUIRE(r1a);
+			BOOST_REQUIRE_EQUAL(r2.get(), r1a.get());
+			if (r1a) {
+				BOOST_REQUIRE(true);
+			}
 		}
 
 		BOOST_REQUIRE_EQUAL(0, pool.inUseCount());
-- 
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