From 8a4dadd30ad8d6554a23259bb251b5c41e2e92e1 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Mon, 28 Dec 2015 19:40:01 +0000
Subject: Support testing a resource validity on return to the pool

---
 libadhocutil/resourcePool.h                 |  4 +++-
 libadhocutil/resourcePool.impl.h            | 18 +++++++++++++++---
 libadhocutil/unittests/testResourcePool.cpp | 28 ++++++++++++++++++++++++----
 3 files changed, 42 insertions(+), 8 deletions(-)

diff --git a/libadhocutil/resourcePool.h b/libadhocutil/resourcePool.h
index 9d8c625..26517bf 100644
--- a/libadhocutil/resourcePool.h
+++ b/libadhocutil/resourcePool.h
@@ -83,8 +83,10 @@ namespace AdHoc {
 			virtual Resource * createResource() const = 0;
 			/// Destroy an existing resource (defaults to delete).
 			virtual void destroyResource(Resource *) const throw();
-			/// Test a cached resource is still suitable for use (defaults to no-op).
+			/// Test a cached resource is still suitable for use before re-use (defaults to no-op).
 			virtual void testResource(const Resource *) const;
+			/// Test a cached resource is still suitable for use on return (defaults to no-op).
+			virtual void returnTestResource(const Resource *) const;
 
 		private:
 			typedef std::list<Resource *> Available;
diff --git a/libadhocutil/resourcePool.impl.h b/libadhocutil/resourcePool.impl.h
index dfdd72d..f49a548 100644
--- a/libadhocutil/resourcePool.impl.h
+++ b/libadhocutil/resourcePool.impl.h
@@ -145,6 +145,12 @@ namespace AdHoc {
 	{
 	}
 
+	template <typename R>
+	void
+	ResourcePool<R>::returnTestResource(const R *) const
+	{
+	}
+
 	template <typename R>
 	unsigned int
 	ResourcePool<R>::inUseCount() const
@@ -248,10 +254,16 @@ namespace AdHoc {
 	{
 		Lock(lock);
 		removeFrom(r, inUse);
-		if (available.size() < keep) {
-			available.push_back(r);
+		try {
+			returnTestResource(r);
+			if (available.size() < keep) {
+				available.push_back(r);
+			}
+			else {
+				destroyResource(r);
+			}
 		}
-		else {
+		catch (...) {
 			destroyResource(r);
 		}
 		poolSize.notify();
diff --git a/libadhocutil/unittests/testResourcePool.cpp b/libadhocutil/unittests/testResourcePool.cpp
index d7547d4..2b3389f 100644
--- a/libadhocutil/unittests/testResourcePool.cpp
+++ b/libadhocutil/unittests/testResourcePool.cpp
@@ -38,9 +38,7 @@ class TRPSmall : public AdHoc::ResourcePool<MockResource> {
 		}
 };
 
-class TRPFail : public AdHoc::ResourcePool<MockResource> {
-	public:
-		TRPFail() : AdHoc::ResourcePool<MockResource>(3, 1) { }
+class TRPCreateFail : public TRPSmall {
 	protected:
 		MockResource * createResource() const override
 		{
@@ -48,6 +46,14 @@ class TRPFail : public AdHoc::ResourcePool<MockResource> {
 		}
 };
 
+class TRPReturnFail : public TRPSmall {
+	protected:
+		void returnTestResource(const MockResource *) const override
+		{
+			throw std::exception();
+		}
+};
+
 BOOST_AUTO_TEST_CASE ( get )
 {
 	{
@@ -323,7 +329,7 @@ BOOST_AUTO_TEST_CASE( test )
 
 BOOST_AUTO_TEST_CASE( createFail )
 {
-	TRPFail pool;
+	TRPCreateFail pool;
 	BOOST_REQUIRE_EQUAL(0, MockResource::count);
 	BOOST_REQUIRE_EQUAL(0, pool.availableCount());
 	BOOST_REQUIRE_EQUAL(0, pool.inUseCount());
@@ -343,3 +349,17 @@ BOOST_AUTO_TEST_CASE( createFail )
 	BOOST_REQUIRE_EQUAL(3, pool.freeCount());
 }
 
+BOOST_AUTO_TEST_CASE( returnFail )
+{
+	TRPReturnFail pool;
+	{
+		auto rh = pool.get();
+		BOOST_REQUIRE_EQUAL(0, pool.availableCount());
+		BOOST_REQUIRE_EQUAL(1, pool.inUseCount());
+		BOOST_REQUIRE_EQUAL(2, pool.freeCount());
+	}
+	BOOST_REQUIRE_EQUAL(0, pool.availableCount());
+	BOOST_REQUIRE_EQUAL(0, pool.inUseCount());
+	BOOST_REQUIRE_EQUAL(3, pool.freeCount());
+}
+
-- 
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