BlockTypeRegistry: Initial skeleton

src/BlockTypeRegistry.cpp

@@ -0,0 +1,153 @@
+
+#include "Globals.h"
+#include "BlockTypeRegistry.h"
+
+
+
+
+////////////////////////////////////////////////////////////////////////////////
+// BlockInfo:
+
+BlockInfo::BlockInfo(
+	const AString & aPluginName,
+	const AString & aBlockTypeName,
+	std::shared_ptr<cBlockHandler> aHandler,
+	const std::map<AString, AString> & aHints,
+	const std::map<AString, BlockInfo::HintCallback> & aHintCallbacks
+):
+	mPluginName(aPluginName),
+	mBlockTypeName(aBlockTypeName),
+	mHandler(aHandler),
+	mHints(aHints),
+	mHintCallbacks(aHintCallbacks)
+{
+}
+
+
+
+
+
+AString BlockInfo::hintValue(
+	const AString & aHintName,
+	const BlockState & aBlockState
+)
+{
+	// Search the hint callbacks first:
+	auto itrC = mHintCallbacks.find(aHintName);
+	if (itrC != mHintCallbacks.end())
+	{
+		// Hint callback found, use it:
+		return itrC->second(mBlockTypeName, aBlockState);
+	}
+
+	// Search the static hints:
+	auto itr = mHints.find(aHintName);
+	if (itr != mHints.end())
+	{
+		// Hint found, use it:
+		return itr->second;
+	}
+
+	// Nothing found, return empty string:
+	return AString();
+}
+
+
+
+
+
+////////////////////////////////////////////////////////////////////////////////
+// BlockTypeRegistry:
+
+void BlockTypeRegistry::registerBlockType(
+	const AString & aPluginName,
+	const AString & aBlockTypeName,
+	std::shared_ptr<cBlockHandler> aHandler,
+	const std::map<AString, AString> & aHints,
+	const std::map<AString, BlockInfo::HintCallback> & aHintCallbacks
+)
+{
+	auto blockInfo = std::make_shared<BlockInfo>(aPluginName, aBlockTypeName, aHandler, aHints, aHintCallbacks);
+
+	// Check previous registrations:
+	cCSLock lock(mCSRegistry);
+	auto itr = mRegistry.find(aBlockTypeName);
+	if (itr != mRegistry.end())
+	{
+		if (itr->second->pluginName() != aPluginName)
+		{
+			throw AlreadyRegisteredException(itr->second, blockInfo);
+		}
+	}
+
+	// Store the registration:
+	mRegistry[aBlockTypeName] = blockInfo;
+}
+
+
+
+
+
+std::shared_ptr<BlockInfo> BlockTypeRegistry::blockInfo(const AString & aBlockTypeName)
+{
+	cCSLock lock(mCSRegistry);
+	auto itr = mRegistry.find(aBlockTypeName);
+	if (itr == mRegistry.end())
+	{
+		return nullptr;
+	}
+	return itr->second;
+}
+
+
+
+
+
+void BlockTypeRegistry::removeAllByPlugin(const AString & aPluginName)
+{
+	cCSLock lock(mCSRegistry);
+	for (auto itr = mRegistry.begin(); itr != mRegistry.end();)
+	{
+		if (itr->second->pluginName() == aPluginName)
+		{
+			itr = mRegistry.erase(itr);
+		}
+		else
+		{
+			++itr;
+		}
+	}
+}
+
+
+
+
+
+////////////////////////////////////////////////////////////////////////////////
+// BlockTypeRegistry::AlreadyRegisteredException:
+
+BlockTypeRegistry::AlreadyRegisteredException::AlreadyRegisteredException(
+	std::shared_ptr<BlockInfo> aPreviousRegistration,
+	std::shared_ptr<BlockInfo> aNewRegistration
+) :
+	Super(message(aPreviousRegistration, aNewRegistration)),
+	mPreviousRegistration(aPreviousRegistration),
+	mNewRegistration(aNewRegistration)
+{
+}
+
+
+
+
+
+AString BlockTypeRegistry::AlreadyRegisteredException::message(
+	std::shared_ptr<BlockInfo> aPreviousRegistration,
+	std::shared_ptr<BlockInfo> aNewRegistration
+)
+{
+	return Printf("Attempting to register BlockTypeName %s from plugin %s, while it is already registered in plugin %s",
+		aNewRegistration->blockTypeName().c_str(),
+		aNewRegistration->pluginName().c_str(),
+		aPreviousRegistration->pluginName().c_str()
+	);
+}

src/BlockTypeRegistry.h

@@ -0,0 +1,158 @@
+#pragma once
+
+
+
+
+
+#include <map>
+
+
+
+
+
+// fwd:
+class BlockState;
+
+
+
+
+
+/** Complete information about a single block type.
+The BlockTypeRegistry uses this structure to store the registered information. */
+class BlockInfo
+{
+public:
+
+	/** Callback is used to query block hints dynamically, based on the current BlockState.
+	Useful for example for redstone lamps that can be turned on or off. */
+	using HintCallback = std::function<AString(const AString & aTypeName, const BlockState & aBlockState)>;
+
+
+	/** Creates a new instance with the specified BlockTypeName and handler / hints / callbacks.
+	aPluginName specifies the name of the plugin to associate with the block type (to allow unload / reload). */
+	BlockInfo(
+		const AString & aPluginName,
+		const AString & aBlockTypeName,
+		std::shared_ptr<cBlockHandler> aHandler,
+		const std::map<AString, AString> & aHints = std::map<AString, AString>(),
+		const std::map<AString, HintCallback> & aHintCallbacks = std::map<AString, HintCallback>()
+	);
+
+
+	/** Retrieves the value associated with the specified hint for this specific BlockTypeName and BlockState.
+	Queries callbacks first, then hints if a callback doesn't exist.
+	Returns an empty string if hint not found at all. */
+	AString hintValue(
+		const AString & aHintName,
+		const BlockState & aBlockState
+	);
+
+	// Simple getters:
+	const AString & pluginName() const { return mPluginName; }
+	const AString & blockTypeName() const { return mBlockTypeName; }
+	std::shared_ptr<cBlockHandler> handler() const { return mHandler; }
+
+
+private:
+
+	/** The name of the plugin that registered the block. */
+	AString mPluginName;
+
+	/** The name of the block type, such as "minecraft:redstone_lamp" */
+	AString mBlockTypeName;
+
+	/** The callbacks to call for various interaction. */
+	std::shared_ptr<cBlockHandler> mHandler;
+
+	/** Optional hints for any subsystem to use, such as "IsSnowable" -> "1". */
+	std::map<AString, AString> mHints;
+
+	/** The callbacks for dynamic evaluation of hints, such as "LightValue" -> function(BlockTypeName, BlockState). */
+	std::map<AString, HintCallback> mHintCallbacks;
+};
+
+
+
+
+
+/** Stores information on all known block types.
+Can dynamically add and remove block types.
+Block types are identified using BlockTypeName.
+Supports unregistering and re-registering the same type by the same plugin.
+Stores the name of the plugin that registered the type, for better plugin error messages ("already registered in X")
+and so that we can unload and reload plugins. */
+class BlockTypeRegistry
+{
+public:
+	// fwd:
+	class AlreadyRegisteredException;
+
+
+	/** Creates an empty new instance of the block type registry */
+	BlockTypeRegistry() = default;
+
+	/** Registers the specified block type.
+	If the block type already exists and the plugin is the same, updates the registration.
+	If the block type already exists and the plugin is different, throws an AlreadyRegisteredException. */
+	void registerBlockType(
+		const AString & aPluginName,
+		const AString & aBlockTypeName,
+		std::shared_ptr<cBlockHandler> aHandler,
+		const std::map<AString, AString> & aHints = std::map<AString, AString>(),
+		const std::map<AString, BlockInfo::HintCallback> & aHintCallbacks = std::map<AString, BlockInfo::HintCallback>()
+	);
+
+	/** Returns the registration information for the specified BlockTypeName.
+	Returns nullptr if BlockTypeName not found. */
+	std::shared_ptr<BlockInfo> blockInfo(const AString & aBlockTypeName);
+
+	/** Removes all registrations done by the specified plugin. */
+	void removeAllByPlugin(const AString & aPluginName);
+
+
+private:
+
+	/** The actual block type registry.
+	Maps the BlockTypeName to the BlockInfo instance. */
+	std::map<AString, std::shared_ptr<BlockInfo>> mRegistry;
+
+	/** The CS that protects mRegistry against multithreaded access. */
+	cCriticalSection mCSRegistry;
+};
+
+
+
+
+
+/** The exception thrown from BlockTypeRegistry::registerBlockType() if the same block type is being registered from a different plugin. */
+class BlockTypeRegistry::AlreadyRegisteredException: public std::runtime_error
+{
+	using Super = std::runtime_error;
+
+public:
+
+	/** Creates a new instance of the exception that provides info on both the original registration and the newly attempted
+	registration that caused the failure. */
+	AlreadyRegisteredException(
+		std::shared_ptr<BlockInfo> aPreviousRegistration,
+		std::shared_ptr<BlockInfo> aNewRegistration
+	);
+
+	// Simple getters:
+	std::shared_ptr<BlockInfo> previousRegistration() const { return mPreviousRegistration; }
+	std::shared_ptr<BlockInfo> newRegistration()      const { return mNewRegistration; }
+
+
+private:
+
+	std::shared_ptr<BlockInfo> mPreviousRegistration;
+	std::shared_ptr<BlockInfo> mNewRegistration;
+
+
+	/** Returns the general exception message formatted by the two registrations.
+	The output is used when logging. */
+	static AString message(
+		std::shared_ptr<BlockInfo> aPreviousRegistration,
+		std::shared_ptr<BlockInfo> aNewRegistration
+	);
+};

src/CMakeLists.txt

@@ -17,6 +17,7 @@ SET (SRCS
 	BlockArea.cpp
 	BlockID.cpp
 	BlockInfo.cpp
+	BlockTypeRegistry.cpp
 	BrewingRecipes.cpp
 	Broadcaster.cpp
 	BoundingBox.cpp
@@ -84,6 +85,7 @@ SET (HDRS
 	BlockInServerPluginInterface.h
 	BlockInfo.h
 	BlockTracer.h
+	BlockTypeRegistry.h
 	BrewingRecipes.h
 	BoundingBox.h
 	BuildInfo.h

tests/BlockTypeRegistry/BlockTypeRegistryTest.cpp

@@ -0,0 +1,228 @@
+
+#include "Globals.h"
+#include <thread>
+#include "BlockTypeRegistry.h"
+#include "../TestHelpers.h"
+
+
+
+
+/** Dummy BlockState implementation */
+class BlockState
+{
+public:
+	BlockState() = default;
+};
+
+
+
+
+/** Dummy cBlockHandler implementation that allows simple checking for equality through mIdent. */
+class cBlockHandler
+{
+public:
+	cBlockHandler(UInt32 aIdent):
+		mIdent(aIdent)
+	{
+	}
+
+	UInt32 mIdent;
+};
+
+
+
+
+
+/** Tests simple block type name registration.
+Registers a block type, checks that the type is then registered. */
+static void testSimpleReg()
+{
+	LOGD("Testing simple registration...");
+
+	// Register the block type:
+	BlockTypeRegistry reg;
+	AString blockTypeName("test:block1");
+	AString pluginName("testPlugin");
+	AString hint1("testHint1");
+	AString hint1Value("value1");
+	std::shared_ptr<cBlockHandler> handler(new cBlockHandler(0x12345678));
+	std::map<AString, AString> hints = {{hint1, hint1Value}, {"testHint2", "value2"}};
+	std::map<AString, BlockInfo::HintCallback> hintCallbacks;
+	reg.registerBlockType(pluginName, blockTypeName, handler, hints, hintCallbacks);
+
+	// Query the registration:
+	auto blockInfo = reg.blockInfo(blockTypeName);
+	TEST_NOTEQUAL(blockInfo, nullptr);
+	TEST_EQUAL(blockInfo->blockTypeName(), blockTypeName);
+	TEST_EQUAL(blockInfo->pluginName(), pluginName);
+	TEST_EQUAL(blockInfo->handler(), handler);
+	TEST_EQUAL(blockInfo->hintValue(hint1, BlockState()), hint1Value);
+	TEST_EQUAL(blockInfo->hintValue("nonexistent", BlockState()), "");
+}
+
+
+
+
+
+/** Tests that the plugin-based information is used correctly for registration.
+Registers two different block types with two different plugins, then tries to re-register them from a different plugin.
+Finally removes the registration through removeAllByPlugin() and checks its success. */
+static void testPlugins()
+{
+	LOGD("Testing plugin-based checks / removal...");
+
+	// Register the block types:
+	BlockTypeRegistry reg;
+	AString blockTypeName1("test:block1");
+	AString pluginName1("testPlugin1");
+	AString hint1("testHint1");
+	AString hint1Value("value1");
+	std::shared_ptr<cBlockHandler> handler1(new cBlockHandler(1));
+	std::map<AString, AString> hints = {{hint1, hint1Value}, {"testHint2", "value2"}};
+	std::map<AString, BlockInfo::HintCallback> hintCallbacks;
+	reg.registerBlockType(pluginName1, blockTypeName1, handler1, hints, hintCallbacks);
+	AString blockTypeName2("test:block2");
+	AString pluginName2("testPlugin2");
+	std::shared_ptr<cBlockHandler> handler2(new cBlockHandler(2));
+	reg.registerBlockType(pluginName2, blockTypeName2, handler2, hints, hintCallbacks);
+
+	// Test the refusal to register under a different plugin:
+	TEST_THROWS(reg.registerBlockType(pluginName2, blockTypeName1, handler2, hints, hintCallbacks), BlockTypeRegistry::AlreadyRegisteredException);
+	TEST_EQUAL(reg.blockInfo(blockTypeName1)->handler()->mIdent, 1);  // Did we overwrite the old registration?
+	reg.registerBlockType(pluginName1, blockTypeName1, handler1, hints, hintCallbacks);  // Re-registering must succeed
+
+	// Unregister by plugin, then re-register from a different plugin:
+	reg.removeAllByPlugin(pluginName1);
+	TEST_EQUAL(reg.blockInfo(blockTypeName1), nullptr);  // Unregistered successfully
+	TEST_NOTEQUAL(reg.blockInfo(blockTypeName2), nullptr);  // Didn't unregister from the other plugin
+	std::shared_ptr<cBlockHandler> handler3(new cBlockHandler(3));
+	reg.registerBlockType(pluginName2, blockTypeName1, handler3, hints, hintCallbacks);
+	TEST_NOTEQUAL(reg.blockInfo(blockTypeName1), nullptr);  // Registered successfully
+	TEST_EQUAL(reg.blockInfo(blockTypeName1)->pluginName(), pluginName2);
+	TEST_EQUAL(reg.blockInfo(blockTypeName1)->handler()->mIdent, 3);
+	TEST_EQUAL(reg.blockInfo(blockTypeName2)->handler()->mIdent, 2);
+	reg.removeAllByPlugin(pluginName2);
+	TEST_EQUAL(reg.blockInfo(blockTypeName1), nullptr);  // Unregistered successfully
+	TEST_EQUAL(reg.blockInfo(blockTypeName2), nullptr);  // Unregistered successfully
+}
+
+
+
+
+/** Tests that the callback-based hints work properly. */
+static void testHintCallbacks()
+{
+	LOGD("Testing hint callbacks...");
+
+	// Register the block type:
+	BlockTypeRegistry reg;
+	AString blockTypeName("test:block1");
+	AString pluginName("testPlugin");
+	AString hint1("testHint1");
+	AString hint1Value("value1");
+	AString hc1("hintCallback1");
+	int callbackCount = 0;
+	auto callback1 = [&callbackCount](const AString & aBlockType, const BlockState & aBlockState)
+	{
+		callbackCount = callbackCount + 1;
+		return aBlockType + "_hint";
+	};
+	std::shared_ptr<cBlockHandler> handler(new cBlockHandler(0x12345678));
+	std::map<AString, AString> hints = {{hint1, hint1Value}, {"testHint2", "value2"}};
+	std::map<AString, BlockInfo::HintCallback> hintCallbacks = {{hc1, callback1}};
+	reg.registerBlockType(pluginName, blockTypeName, handler, hints, hintCallbacks);
+
+	// Check that querying the hint using a callback works:
+	TEST_EQUAL(reg.blockInfo(blockTypeName)->hintValue(hc1, BlockState()), blockTypeName + "_hint");
+	TEST_EQUAL(callbackCount, 1);  // Called exactly once
+}
+
+
+
+
+
+/** Tests whether thread-locking works properly by running two threads,
+one constantly (re-)registering and the other one constantly querying the same block type. */
+static void testThreadLocking()
+{
+	LOGD("Testing thread locking...");
+
+	// Register the block type:
+	BlockTypeRegistry reg;
+	AString blockTypeName("test:block1");
+	AString pluginName("testPlugin");
+	AString hint1("testHint1");
+	AString hint1Value("value1");
+	std::shared_ptr<cBlockHandler> handler(new cBlockHandler(0x12345678));
+	std::map<AString, AString> hints = {{hint1, hint1Value}, {"testHint2", "value2"}};
+	std::map<AString, BlockInfo::HintCallback> hintCallbacks;
+	reg.registerBlockType(pluginName, blockTypeName, handler, hints, hintCallbacks);
+
+	// Run the two threads for at least a second:
+	auto endTime = time(nullptr) + 2;
+	auto keepRegistering = [&]()
+	{
+		while (time(nullptr) < endTime)
+		{
+			reg.registerBlockType(pluginName, blockTypeName, handler, hints, hintCallbacks);
+		}
+	};
+	auto keepQuerying = [&]()
+	{
+		unsigned numQueries = 0;
+		while (time(nullptr) < endTime)
+		{
+			TEST_NOTEQUAL(reg.blockInfo(blockTypeName), nullptr);
+			numQueries += 1;
+		}
+		LOGD("%u queries have been executed", numQueries);
+	};
+	std::thread thr1(keepRegistering);
+	std::thread thr2(keepQuerying);
+	thr1.join();
+	thr2.join();
+}
+
+
+
+
+
+static void testBlockTypeRegistry()
+{
+	testSimpleReg();
+	testPlugins();
+	testHintCallbacks();
+	testThreadLocking();
+}
+
+
+
+
+
+int main()
+{
+	LOGD("BlockTypeRegistryTest started");
+
+	try
+	{
+		testBlockTypeRegistry();
+	}
+	catch (const TestException & exc)
+	{
+		LOGERROR("BlockTypeRegistryTest has failed, an unhandled exception was thrown: %s", exc.mMessage.c_str());
+		return 1;
+	}
+	catch (...)
+	{
+		LOGERROR("BlockTypeRegistryTest has failed, an unhandled exception was thrown.");
+		return 1;
+	}
+
+	LOGD("BlockTypeRegistryTest finished");
+
+	return 0;
+}
+
+
+
+

tests/BlockTypeRegistry/CMakeLists.txt

@@ -0,0 +1,40 @@
+cmake_minimum_required(VERSION 3.0.2)
+enable_testing()
+
+include_directories(${CMAKE_SOURCE_DIR}/src/)
+
+add_definitions(-DTEST_GLOBALS=1)
+
+
+
+
+
+# Define individual test executables:
+
+# BlockTypeRegistryTest: Verify that the BlockTypeRegistry class works as intended:
+add_executable(BlockTypeRegistryTest
+	BlockTypeRegistryTest.cpp
+	../TestHelpers.h
+	${CMAKE_SOURCE_DIR}/src/BlockTypeRegistry.cpp
+	${CMAKE_SOURCE_DIR}/src/StringUtils.cpp
+	${CMAKE_SOURCE_DIR}/src/OSSupport/CriticalSection.cpp
+)
+target_link_libraries(BlockTypeRegistryTest fmt::fmt)
+
+
+
+
+
+# Define individual tests:
+
+add_test(NAME BlockTypeRegistryTest COMMAND BlockTypeRegistryTest)
+
+
+
+
+
+# Put all the tests into a solution folder (MSVC):
+set_target_properties(
+	BlockTypeRegistryTest
+	PROPERTIES FOLDER Tests/BlockTypeRegistry
+)

tests/CMakeLists.txt

@@ -6,6 +6,7 @@ endif()
 
 add_definitions(-DTEST_GLOBALS=1)
 
+add_subdirectory(BlockTypeRegistry)
 add_subdirectory(BoundingBox)
 add_subdirectory(ByteBuffer)
 add_subdirectory(ChunkData)

tests/TestHelpers.h

@@ -0,0 +1,79 @@
+// Helper macros for writing exception-based tests
+
+
+
+
+/** The exception that is thrown if a test fails.
+It doesn't inherit from any type so that it is not possible to catch it by a mistake,
+it needs to be caught explicitly (used in the TEST_THROWS).
+It bears a single message that is to be displayed to stderr. */
+class TestException
+{
+public:
+	TestException(const AString & aMessage):
+		mMessage(aMessage)
+	{
+	}
+
+	AString mMessage;
+};
+
+
+
+
+
+/** Checks that the two values are equal; if not, throws a TestException. */
+#define TEST_EQUAL(VAL1, VAL2) \
+	if (VAL1 != VAL2) \
+	{ \
+		throw TestException(Printf("%s (line %d): Equality test failed: %s != %s", \
+			__FUNCTION__, __LINE__, \
+			#VAL1, #VAL2 \
+		)); \
+	}
+
+
+
+/** Checks that the two values are not equal; if they are, throws a TestException. */
+#define TEST_NOTEQUAL(VAL1, VAL2) \
+	if (VAL1 == VAL2) \
+	{ \
+		throw TestException(Printf("%s (line %d): Inequality test failed: %s == %s", \
+			__FUNCTION__, __LINE__, \
+			#VAL1, #VAL2 \
+		)); \
+	}
+
+
+
+/** Checks that the statement throws an exception of the specified class. */
+#define TEST_THROWS(Stmt, ExcClass) \
+	try \
+	{ \
+		Stmt; \
+		throw TestException(Printf("%s (line %d): Failed to throw an exception of type %s", \
+			__FUNCTION__, __LINE__, \
+			#ExcClass \
+		)); \
+	} \
+	catch (const ExcClass &) \
+	{ \
+		/* This is the expected case. */ \
+	} \
+	catch (const std::exception & exc) \
+	{ \
+		throw TestException(Printf("%s (line %d): An unexpected std::exception descendant was thrown, was expecting type %s. Message is: %s", \
+			__FUNCTION__, __LINE__, \
+			#ExcClass, exc.what() \
+		)); \
+	} \
+	catch (...) \
+	{ \
+		throw TestException(Printf("%s (line %d): An unexpected exception object was thrown, was expecting type %s", \
+			__FUNCTION__, __LINE__, \
+			#ExcClass \
+		)); \
+	}
+
+
+