Rework Settings to support arbitrary hierarchies (#11352)

7 files changed, 160 insertions, 67 deletions

diff --git a/src/httpfetch.cpp b/src/httpfetch.cpp
index 6137782ff..1307bfec3 100644
--- a/src/httpfetch.cpp
+++ b/src/httpfetch.cpp
@@ -761,10 +761,12 @@ void httpfetch_cleanup()
 {
 	verbosestream<<"httpfetch_cleanup: cleaning up"<<std::endl;
 
-	g_httpfetch_thread->stop();
-	g_httpfetch_thread->requestWakeUp();
-	g_httpfetch_thread->wait();
-	delete g_httpfetch_thread;
+	if (g_httpfetch_thread) {
+		g_httpfetch_thread->stop();
+		g_httpfetch_thread->requestWakeUp();
+		g_httpfetch_thread->wait();
+		delete g_httpfetch_thread;
+	}
 
 	curl_global_cleanup();
 }
diff --git a/src/main.cpp b/src/main.cpp
index 4a69f83b5..ffbdb7b5b 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -91,6 +91,7 @@ static void list_worlds(bool print_name, bool print_path);
 static bool setup_log_params(const Settings &cmd_args);
 static bool create_userdata_path();
 static bool init_common(const Settings &cmd_args, int argc, char *argv[]);
+static void uninit_common();
 static void startup_message();
 static bool read_config_file(const Settings &cmd_args);
 static void init_log_streams(const Settings &cmd_args);
@@ -201,6 +202,7 @@ int main(int argc, char *argv[])
 		errorstream << "Unittest support is not enabled in this binary. "
 			<< "If you want to enable it, compile project with BUILD_UNITTESTS=1 flag."
 			<< std::endl;
+		return 1;
 #endif
 	}
 #endif
@@ -236,9 +238,6 @@ int main(int argc, char *argv[])
 
 	print_modified_quicktune_values();
 
-	// Stop httpfetch thread (if started)
-	httpfetch_cleanup();
-
 	END_DEBUG_EXCEPTION_HANDLER
 
 	return retval;
@@ -486,13 +485,14 @@ static bool init_common(const Settings &cmd_args, int argc, char *argv[])
 	startup_message();
 	set_default_settings();
 
-	// Initialize sockets
 	sockets_init();
-	atexit(sockets_cleanup);
 
 	// Initialize g_settings
 	Settings::createLayer(SL_GLOBAL);
 
+	// Set cleanup callback(s) to run at process exit
+	atexit(uninit_common);
+
 	if (!read_config_file(cmd_args))
 		return false;
 
@@ -511,6 +511,17 @@ static bool init_common(const Settings &cmd_args, int argc, char *argv[])
 	return true;
 }
 
+static void uninit_common()
+{
+	httpfetch_cleanup();
+
+	sockets_cleanup();
+
+	// It'd actually be okay to leak these but we want to please valgrind...
+	for (int i = 0; i < (int)SL_TOTAL_COUNT; i++)
+		delete Settings::getLayer((SettingsLayer)i);
+}
+
 static void startup_message()
 {
 	infostream << PROJECT_NAME << " " << _("with")
diff --git a/src/map_settings_manager.cpp b/src/map_settings_manager.cpp
index 99e3cb0e6..7e86a9937 100644
--- a/src/map_settings_manager.cpp
+++ b/src/map_settings_manager.cpp
@@ -26,15 +26,24 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "map_settings_manager.h"
 
 MapSettingsManager::MapSettingsManager(const std::string &map_meta_path):
-	m_map_meta_path(map_meta_path)
+	m_map_meta_path(map_meta_path),
+	m_hierarchy(g_settings)
 {
-	m_map_settings = Settings::createLayer(SL_MAP, "[end_of_params]");
-	Mapgen::setDefaultSettings(Settings::getLayer(SL_DEFAULTS));
+	/*
+	 * We build our own hierarchy which falls back to the global one.
+	 * It looks as follows: (lowest prio first)
+	 * 0: whatever is picked up from g_settings (incl. engine defaults)
+	 * 1: defaults set by scripts (override_meta = false)
+	 * 2: settings present in map_meta.txt or overriden by scripts
+	 */
+	m_defaults = new Settings("", &m_hierarchy, 1);
+	m_map_settings = new Settings("[end_of_params]", &m_hierarchy, 2);
 }
 
 
 MapSettingsManager::~MapSettingsManager()
 {
+	delete m_defaults;
 	delete m_map_settings;
 	delete mapgen_params;
 }
@@ -43,14 +52,13 @@ MapSettingsManager::~MapSettingsManager()
 bool MapSettingsManager::getMapSetting(
 	const std::string &name, std::string *value_out)
 {
-	// Get from map_meta.txt, then try from all other sources
+	// Try getting it normally first
 	if (m_map_settings->getNoEx(name, *value_out))
 		return true;
 
-	// Compatibility kludge
+	// If not we may have to resolve some compatibility kludges
 	if (name == "seed")
 		return Settings::getLayer(SL_GLOBAL)->getNoEx("fixed_map_seed", *value_out);
-
 	return false;
 }
 
@@ -72,7 +80,7 @@ bool MapSettingsManager::setMapSetting(
 	if (override_meta)
 		m_map_settings->set(name, value);
 	else
-		Settings::getLayer(SL_GLOBAL)->set(name, value);
+		m_defaults->set(name, value);
 
 	return true;
 }
@@ -87,7 +95,7 @@ bool MapSettingsManager::setMapSettingNoiseParams(
 	if (override_meta)
 		m_map_settings->setNoiseParams(name, *value);
 	else
-		Settings::getLayer(SL_GLOBAL)->setNoiseParams(name, *value);
+		m_defaults->setNoiseParams(name, *value);
 
 	return true;
 }
@@ -146,15 +154,8 @@ MapgenParams *MapSettingsManager::makeMapgenParams()
 	if (mapgen_params)
 		return mapgen_params;
 
-	assert(m_map_settings != NULL);
-
-	// At this point, we have (in order of precedence):
-	// 1). SL_MAP containing map_meta.txt settings or
-	//     explicit overrides from scripts
-	// 2). SL_GLOBAL containing all user-specified config file
-	//     settings
-	// 3). SL_DEFAULTS containing any low-priority settings from
-	//     scripts, e.g. mods using Lua as an enhanced config file)
+	assert(m_map_settings);
+	assert(m_defaults);
 
 	// Now, get the mapgen type so we can create the appropriate MapgenParams
 	std::string mg_name;
diff --git a/src/map_settings_manager.h b/src/map_settings_manager.h
index 9258d3032..fa271268d 100644
--- a/src/map_settings_manager.h
+++ b/src/map_settings_manager.h
@@ -20,8 +20,8 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #pragma once
 
 #include <string>
+#include "settings.h"
 
-class Settings;
 struct NoiseParams;
 struct MapgenParams;
 
@@ -70,6 +70,8 @@ public:
 
 private:
 	std::string m_map_meta_path;
-	// TODO: Rename to "m_settings"
+
+	SettingsHierarchy m_hierarchy;
+	Settings *m_defaults;
 	Settings *m_map_settings;
 };
diff --git a/src/settings.cpp b/src/settings.cpp
index cff393e5f..0a9424994 100644
--- a/src/settings.cpp
+++ b/src/settings.cpp
@@ -33,35 +33,90 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include <cctype>
 #include <algorithm>
 
-Settings *g_settings = nullptr; // Populated in main()
+Settings *g_settings = nullptr;
+static SettingsHierarchy g_hierarchy;
 std::string g_settings_path;
 
-Settings *Settings::s_layers[SL_TOTAL_COUNT] = {0}; // Zeroed by compiler
 std::unordered_map<std::string, const FlagDesc *> Settings::s_flags;
 
+/* Settings hierarchy implementation */
 
-Settings *Settings::createLayer(SettingsLayer sl, const std::string &end_tag)
+SettingsHierarchy::SettingsHierarchy(Settings *fallback)
+{
+	layers.push_back(fallback);
+}
+
+
+Settings *SettingsHierarchy::getLayer(int layer) const
 {
-	if ((int)sl < 0 || sl >= SL_TOTAL_COUNT)
+	if (layer < 0 || layer >= layers.size())
 		throw BaseException("Invalid settings layer");
+	return layers[layer];
+}
+
 
-	Settings *&pos = s_layers[(size_t)sl];
+Settings *SettingsHierarchy::getParent(int layer) const
+{
+	assert(layer >= 0 && layer < layers.size());
+	// iterate towards the origin (0) to find the next fallback layer
+	for (int i = layer - 1; i >= 0; --i) {
+		if (layers[i])
+			return layers[i];
+	}
+
+	return nullptr;
+}
+
+
+void SettingsHierarchy::onLayerCreated(int layer, Settings *obj)
+{
+	if (layer < 0)
+		throw BaseException("Invalid settings layer");
+	if (layers.size() < layer+1)
+		layers.resize(layer+1);
+
+	Settings *&pos = layers[layer];
 	if (pos)
-		throw BaseException("Setting layer " + std::to_string(sl) + " already exists");
+		throw BaseException("Setting layer " + itos(layer) + " already exists");
+
+	pos = obj;
+	// This feels bad
+	if (this == &g_hierarchy && layer == (int)SL_GLOBAL)
+		g_settings = obj;
+}
+
+
+void SettingsHierarchy::onLayerRemoved(int layer)
+{
+	assert(layer >= 0 && layer < layers.size());
+	layers[layer] = nullptr;
+	if (this == &g_hierarchy && layer == (int)SL_GLOBAL)
+		g_settings = nullptr;
+}
 
-	pos = new Settings(end_tag);
-	pos->m_settingslayer = sl;
+/* Settings implementation */
 
-	if (sl == SL_GLOBAL)
-		g_settings = pos;
-	return pos;
+Settings *Settings::createLayer(SettingsLayer sl, const std::string &end_tag)
+{
+	return new Settings(end_tag, &g_hierarchy, (int)sl);
 }
 
 
 Settings *Settings::getLayer(SettingsLayer sl)
 {
 	sanity_check((int)sl >= 0 && sl < SL_TOTAL_COUNT);
-	return s_layers[(size_t)sl];
+	return g_hierarchy.layers[(int)sl];
+}
+
+
+Settings::Settings(const std::string &end_tag, SettingsHierarchy *h,
+		int settings_layer) :
+	m_end_tag(end_tag),
+	m_hierarchy(h),
+	m_settingslayer(settings_layer)
+{
+	if (m_hierarchy)
+		m_hierarchy->onLayerCreated(m_settingslayer, this);
 }
 
 
@@ -69,12 +124,8 @@ Settings::~Settings()
 {
 	MutexAutoLock lock(m_mutex);
 
-	if (m_settingslayer < SL_TOTAL_COUNT)
-		s_layers[(size_t)m_settingslayer] = nullptr;
-
-	// Compatibility
-	if (m_settingslayer == SL_GLOBAL)
-		g_settings = nullptr;
+	if (m_hierarchy)
+		m_hierarchy->onLayerRemoved(m_settingslayer);
 
 	clearNoLock();
 }
@@ -86,8 +137,8 @@ Settings & Settings::operator = (const Settings &other)
 		return *this;
 
 	// TODO: Avoid copying Settings objects. Make this private.
-	FATAL_ERROR_IF(m_settingslayer != SL_TOTAL_COUNT && other.m_settingslayer != SL_TOTAL_COUNT,
-		("Tried to copy unique Setting layer " + std::to_string(m_settingslayer)).c_str());
+	FATAL_ERROR_IF(m_hierarchy || other.m_hierarchy,
+		"Cannot copy or overwrite Settings object that belongs to a hierarchy");
 
 	MutexAutoLock lock(m_mutex);
 	MutexAutoLock lock2(other.m_mutex);
@@ -410,18 +461,7 @@ bool Settings::parseCommandLine(int argc, char *argv[],
 
 Settings *Settings::getParent() const
 {
-	// If the Settings object is within the hierarchy structure,
-	// iterate towards the origin (0) to find the next fallback layer
-	if (m_settingslayer >= SL_TOTAL_COUNT)
-		return nullptr;
-
-	for (int i = (int)m_settingslayer - 1; i >= 0; --i) {
-		if (s_layers[i])
-			return s_layers[i];
-	}
-
-	// No parent
-	return nullptr;
+	return m_hierarchy ? m_hierarchy->getParent(m_settingslayer) : nullptr;
 }
 
 
@@ -823,6 +863,8 @@ bool Settings::set(const std::string &name, const std::string &value)
 // TODO: Remove this function
 bool Settings::setDefault(const std::string &name, const std::string &value)
 {
+	FATAL_ERROR_IF(m_hierarchy != &g_hierarchy, "setDefault is only valid on "
+		"global settings");
 	return getLayer(SL_DEFAULTS)->set(name, value);
 }
 
diff --git a/src/settings.h b/src/settings.h
index e22d949d3..7791413b9 100644
--- a/src/settings.h
+++ b/src/settings.h
@@ -21,6 +21,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #include "irrlichttypes_bloated.h"
 #include "util/string.h"
+#include "util/basic_macros.h"
 #include <string>
 #include <list>
 #include <set>
@@ -60,14 +61,36 @@ enum SettingsParseEvent {
 	SPE_MULTILINE,
 };
 
+// Describes the global setting layers, SL_GLOBAL is where settings are read from
 enum SettingsLayer {
 	SL_DEFAULTS,
 	SL_GAME,
 	SL_GLOBAL,
-	SL_MAP,
 	SL_TOTAL_COUNT
 };
 
+// Implements the hierarchy a settings object may be part of
+class SettingsHierarchy {
+public:
+	/*
+	 * A settings object that may be part of another hierarchy can
+	 * occupy the index 0 as a fallback. If not set you can use 0 on your own.
+	 */
+	SettingsHierarchy(Settings *fallback = nullptr);
+
+	DISABLE_CLASS_COPY(SettingsHierarchy)
+
+	Settings *getLayer(int layer) const;
+
+private:
+	friend class Settings;
+	Settings *getParent(int layer) const;
+	void onLayerCreated(int layer, Settings *obj);
+	void onLayerRemoved(int layer);
+
+	std::vector<Settings*> layers;
+};
+
 struct ValueSpec {
 	ValueSpec(ValueType a_type, const char *a_help=NULL)
 	{
@@ -100,13 +123,15 @@ typedef std::unordered_map<std::string, SettingsEntry> SettingEntries;
 
 class Settings {
 public:
+	/* These functions operate on the global hierarchy! */
 	static Settings *createLayer(SettingsLayer sl, const std::string &end_tag = "");
 	static Settings *getLayer(SettingsLayer sl);
-	SettingsLayer getLayerType() const { return m_settingslayer; }
+	/**/
 
 	Settings(const std::string &end_tag = "") :
 		m_end_tag(end_tag)
 	{}
+	Settings(const std::string &end_tag, SettingsHierarchy *h, int settings_layer);
 	~Settings();
 
 	Settings & operator += (const Settings &other);
@@ -200,9 +225,9 @@ public:
 	// remove a setting
 	bool remove(const std::string &name);
 
-	/**************
-	 * Miscellany *
-	 **************/
+	/*****************
+	 * Miscellaneous *
+	 *****************/
 
 	void setDefault(const std::string &name, const FlagDesc *flagdesc, u32 flags);
 	const FlagDesc *getFlagDescFallback(const std::string &name) const;
@@ -214,6 +239,10 @@ public:
 
 	void removeSecureSettings();
 
+	// Returns the settings layer this object is.
+	// If within the global hierarchy you can cast this to enum SettingsLayer
+	inline int getLayer() const { return m_settingslayer; }
+
 private:
 	/***********************
 	 * Reading and writing *
@@ -257,7 +286,8 @@ private:
 	// All methods that access m_settings/m_defaults directly should lock this.
 	mutable std::mutex m_mutex;
 
-	static Settings *s_layers[SL_TOTAL_COUNT];
-	SettingsLayer m_settingslayer = SL_TOTAL_COUNT;
+	SettingsHierarchy *m_hierarchy = nullptr;
+	int m_settingslayer = -1;
+
 	static std::unordered_map<std::string, const FlagDesc *> s_flags;
 };
diff --git a/src/unittest/test_map_settings_manager.cpp b/src/unittest/test_map_settings_manager.cpp
index 81ca68705..17c31fe79 100644
--- a/src/unittest/test_map_settings_manager.cpp
+++ b/src/unittest/test_map_settings_manager.cpp
@@ -148,6 +148,11 @@ void TestMapSettingsManager::testMapSettingsManager()
 		check_noise_params(&dummy, &script_np_factor);
 	}
 
+	// The settings manager MUST leave user settings alone
+	mgr.setMapSetting("testname", "1");
+	mgr.setMapSetting("testname", "1", true);
+	UASSERT(!Settings::getLayer(SL_GLOBAL)->exists("testname"));
+
 	// Now make our Params and see if the values are correctly sourced
 	MapgenParams *params = mgr.makeMapgenParams();
 	UASSERT(params->mgtype == MAPGEN_V5);