first pass at cache

unit-tests/cache_t.cc

@@ -0,0 +1,144 @@
+#include "cache.h"
+
+#define BOOST_TEST_MODULE CacheTests
+#include <boost/test/included/unit_test.hpp>
+
+#include <boost/shared_ptr.hpp>
+
+using namespace boost;
+using namespace base;
+using namespace std;
+
+//----------------------------------------------------------------
+
+namespace {
+	struct Thing {
+		Thing()
+			: key_(0),
+			  desc_("default constructed") {
+		}
+
+		Thing(unsigned n)
+			: key_(n),
+			  desc_("foo bar") {
+		}
+
+		unsigned key_;
+		string desc_;
+	};
+
+	struct ThingTraits {
+		typedef unsigned key_type;
+		typedef Thing value_type;
+
+		static key_type get_key(value_type const &t) {
+			return t.key_;
+		}
+	};
+
+	struct SharedThingTraits {
+		typedef unsigned key_type;
+		typedef shared_ptr<Thing> value_type;
+
+		static key_type get_key(value_type const &p) {
+			return p->key_;
+		}
+	};
+}
+
+//----------------------------------------------------------------
+
+BOOST_AUTO_TEST_CASE(cache_creation)
+{
+	cache<ThingTraits> c(16);
+}
+
+BOOST_AUTO_TEST_CASE(cache_caches)
+{
+	unsigned const COUNT = 16;
+	cache<ThingTraits> c(COUNT);
+
+	for (unsigned i = 0; i < COUNT; i++)
+		c.insert(Thing(i));
+
+	for (unsigned i = 0; i < COUNT; i++)
+		BOOST_ASSERT(c.get(i));
+}
+
+BOOST_AUTO_TEST_CASE(cache_drops_elements)
+{
+	unsigned const COUNT = 1024;
+	unsigned const CACHE_SIZE = 16;
+	cache<ThingTraits> c(CACHE_SIZE);
+
+	for (unsigned i = 0; i < COUNT; i++)
+		c.insert(Thing(i));
+
+	for (unsigned i = 0; i < COUNT - CACHE_SIZE; i++)
+		BOOST_ASSERT(!c.get(i));
+
+	for (unsigned i = COUNT - CACHE_SIZE; i < COUNT; i++)
+		BOOST_ASSERT(c.get(i));
+}
+
+BOOST_AUTO_TEST_CASE(held_entries_count_towards_the_cache_limit)
+{
+	unsigned const CACHE_SIZE = 16;
+	cache<ThingTraits> c(CACHE_SIZE);
+
+	unsigned i;
+	for (i = 0; i < CACHE_SIZE; i++) {
+		c.insert(Thing(i));
+		c.get(i);
+	}
+
+	BOOST_CHECK_THROW(c.insert(Thing(i)), runtime_error);
+}
+
+BOOST_AUTO_TEST_CASE(put_works)
+{
+	unsigned const CACHE_SIZE = 16;
+	cache<ThingTraits> c(CACHE_SIZE);
+
+	unsigned i;
+	for (i = 0; i < CACHE_SIZE; i++) {
+		c.insert(Thing(i));
+		c.get(i);
+		c.put(Thing(i));
+	}
+
+	// should succeed
+	c.insert(Thing(i));
+}
+
+BOOST_AUTO_TEST_CASE(multiple_gets_works)
+{
+	unsigned const CACHE_SIZE = 16;
+	cache<ThingTraits> c(CACHE_SIZE);
+
+	unsigned i;
+	for (i = 0; i < CACHE_SIZE; i++) {
+		c.insert(Thing(i));
+		c.get(i);
+		c.get(i);
+		c.put(Thing(i));
+	}
+
+	BOOST_CHECK_THROW(c.insert(Thing(i)), runtime_error);
+}
+
+BOOST_AUTO_TEST_CASE(shared_ptr_cache_works)
+{
+	unsigned const CACHE_SIZE = 16;
+	cache<SharedThingTraits> c(CACHE_SIZE);
+
+	for (unsigned i = 0; i < CACHE_SIZE; i++) {
+		c.insert(shared_ptr<Thing>(new Thing(i)));
+		optional<shared_ptr<Thing> > maybe_ptr = c.get(i);
+
+		BOOST_ASSERT(maybe_ptr);
+		BOOST_ASSERT((*maybe_ptr)->key_ == i);
+	}
+}
+
+//----------------------------------------------------------------