Add an activeobject manager to hold active objects (#7939)

* Add an activeobject manager to hold active objects
* Add unittests

15 files changed, 844 insertions, 320 deletions

diff --git a/src/activeobjectmgr.h b/src/activeobjectmgr.h
new file mode 100644
index 000000000..95e7d3344
--- /dev/null
+++ b/src/activeobjectmgr.h
@@ -0,0 +1,65 @@
+/*
+Minetest
+Copyright (C) 2010-2018 nerzhul, Loic BLOT <loic.blot@unix-experience.fr>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#pragma once
+
+#include <unordered_map>
+#include "irrlichttypes.h"
+
+class TestClientActiveObjectMgr;
+class TestServerActiveObjectMgr;
+
+template <typename T> class ActiveObjectMgr
+{
+	friend class ::TestClientActiveObjectMgr;
+	friend class ::TestServerActiveObjectMgr;
+
+public:
+	virtual void step(float dtime, const std::function<void(T *)> &f) = 0;
+	virtual bool registerObject(T *obj) = 0;
+	virtual void removeObject(u16 id) = 0;
+
+	T *getActiveObject(u16 id)
+	{
+		typename std::unordered_map<u16, T *>::const_iterator n =
+				m_active_objects.find(id);
+		return (n != m_active_objects.end() ? n->second : nullptr);
+	}
+
+protected:
+	u16 getFreeId() const
+	{
+		// try to reuse id's as late as possible
+		static thread_local u16 last_used_id = 0;
+		u16 startid = last_used_id;
+		while (!isFreeId(++last_used_id)) {
+			if (last_used_id == startid)
+				return 0;
+		}
+
+		return last_used_id;
+	}
+
+	bool isFreeId(u16 id) const
+	{
+		return id != 0 && m_active_objects.find(id) == m_active_objects.end();
+	}
+
+	std::unordered_map<u16, T *> m_active_objects;
+};
diff --git a/src/client/CMakeLists.txt b/src/client/CMakeLists.txt
index e24b73e80..140814911 100644
--- a/src/client/CMakeLists.txt
+++ b/src/client/CMakeLists.txt
@@ -25,6 +25,7 @@ set(client_SRCS
 	${CMAKE_CURRENT_SOURCE_DIR}/render/plain.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/render/sidebyside.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/render/stereo.cpp
+	${CMAKE_CURRENT_SOURCE_DIR}/activeobjectmgr.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/camera.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/client.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/clientenvironment.cpp
diff --git a/src/client/activeobjectmgr.cpp b/src/client/activeobjectmgr.cpp
new file mode 100644
index 000000000..4ed98d79b
--- /dev/null
+++ b/src/client/activeobjectmgr.cpp
@@ -0,0 +1,106 @@
+/*
+Minetest
+Copyright (C) 2010-2018 nerzhul, Loic BLOT <loic.blot@unix-experience.fr>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include <log.h>
+#include "profiler.h"
+#include "activeobjectmgr.h"
+
+namespace client
+{
+
+void ActiveObjectMgr::clear()
+{
+	// delete active objects
+	for (auto &active_object : m_active_objects) {
+		delete active_object.second;
+	}
+}
+
+void ActiveObjectMgr::step(
+		float dtime, const std::function<void(ClientActiveObject *)> &f)
+{
+	g_profiler->avg("Client::ActiveObjectMgr: num of objects",
+			m_active_objects.size());
+	for (auto &ao_it : m_active_objects) {
+		f(ao_it.second);
+	}
+}
+
+// clang-format off
+bool ActiveObjectMgr::registerObject(ClientActiveObject *obj)
+{
+	assert(obj); // Pre-condition
+	if (obj->getId() == 0) {
+		u16 new_id = getFreeId();
+		if (new_id == 0) {
+			infostream << "Client::ActiveObjectMgr::registerObject(): "
+					<< "no free id available" << std::endl;
+
+			delete obj;
+			return false;
+		}
+		obj->setId(new_id);
+	}
+
+	if (!isFreeId(obj->getId())) {
+		infostream << "Client::ActiveObjectMgr::registerObject(): "
+				<< "id is not free (" << obj->getId() << ")" << std::endl;
+		delete obj;
+		return false;
+	}
+	infostream << "Client::ActiveObjectMgr::registerObject(): "
+			<< "added (id=" << obj->getId() << ")" << std::endl;
+	m_active_objects[obj->getId()] = obj;
+	return true;
+}
+
+void ActiveObjectMgr::removeObject(u16 id)
+{
+	verbosestream << "Client::ActiveObjectMgr::removeObject(): "
+			<< "id=" << id << std::endl;
+	ClientActiveObject *obj = getActiveObject(id);
+	if (!obj) {
+		infostream << "Client::ActiveObjectMgr::removeObject(): "
+				<< "id=" << id << " not found" << std::endl;
+		return;
+	}
+
+	m_active_objects.erase(id);
+
+	obj->removeFromScene(true);
+	delete obj;
+}
+
+// clang-format on
+void ActiveObjectMgr::getActiveObjects(const v3f &origin, f32 max_d,
+		std::vector<DistanceSortedActiveObject> &dest)
+{
+	for (auto &ao_it : m_active_objects) {
+		ClientActiveObject *obj = ao_it.second;
+
+		f32 d = (obj->getPosition() - origin).getLength();
+
+		if (d > max_d)
+			continue;
+
+		dest.emplace_back(obj, d);
+	}
+}
+
+} // namespace client
diff --git a/src/client/activeobjectmgr.h b/src/client/activeobjectmgr.h
new file mode 100644
index 000000000..510b2d6e3
--- /dev/null
+++ b/src/client/activeobjectmgr.h
@@ -0,0 +1,41 @@
+/*
+Minetest
+Copyright (C) 2010-2018 nerzhul, Loic BLOT <loic.blot@unix-experience.fr>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#pragma once
+
+#include <functional>
+#include <vector>
+#include "../activeobjectmgr.h"
+#include "clientobject.h"
+
+namespace client
+{
+class ActiveObjectMgr : public ::ActiveObjectMgr<ClientActiveObject>
+{
+public:
+	void clear();
+	void step(float dtime,
+			const std::function<void(ClientActiveObject *)> &f) override;
+	bool registerObject(ClientActiveObject *obj) override;
+	void removeObject(u16 id) override;
+
+	void getActiveObjects(const v3f &origin, f32 max_d,
+			std::vector<DistanceSortedActiveObject> &dest);
+};
+} // namespace client
diff --git a/src/client/clientenvironment.cpp b/src/client/clientenvironment.cpp
index e2f24aaa3..7c2ec099c 100644
--- a/src/client/clientenvironment.cpp
+++ b/src/client/clientenvironment.cpp
@@ -53,10 +53,7 @@ ClientEnvironment::ClientEnvironment(ClientMap *map,
 
 ClientEnvironment::~ClientEnvironment()
 {
-	// delete active objects
-	for (auto &active_object : m_active_objects) {
-		delete active_object.second;
-	}
+	m_ao_manager.clear();
 
 	for (auto &simple_object : m_simple_objects) {
 		delete simple_object;
@@ -262,12 +259,10 @@ void ClientEnvironment::step(float dtime)
 		Step active objects and update lighting of them
 	*/
 
-	g_profiler->avg("CEnv: num of objects", m_active_objects.size());
 	bool update_lighting = m_active_object_light_update_interval.step(dtime, 0.21);
-	for (auto &ao_it : m_active_objects) {
-		ClientActiveObject* obj = ao_it.second;
+	auto cb_state = [this, dtime, update_lighting, day_night_ratio] (ClientActiveObject *cao) {
 		// Step object
-		obj->step(dtime, this);
+		cao->step(dtime, this);
 
 		if (update_lighting) {
 			// Update lighting
@@ -275,16 +270,18 @@ void ClientEnvironment::step(float dtime)
 			bool pos_ok;
 
 			// Get node at head
-			v3s16 p = obj->getLightPosition();
-			MapNode n = m_map->getNodeNoEx(p, &pos_ok);
+			v3s16 p = cao->getLightPosition();
+			MapNode n = this->m_map->getNodeNoEx(p, &pos_ok);
 			if (pos_ok)
 				light = n.getLightBlend(day_night_ratio, m_client->ndef());
 			else
 				light = blend_light(day_night_ratio, LIGHT_SUN, 0);
 
-			obj->updateLight(light);
+			cao->updateLight(light);
 		}
-	}
+	};
+
+	m_ao_manager.step(dtime, cb_state);
 
 	/*
 		Step and handle simple objects
@@ -319,14 +316,6 @@ GenericCAO* ClientEnvironment::getGenericCAO(u16 id)
 	return NULL;
 }
 
-ClientActiveObject* ClientEnvironment::getActiveObject(u16 id)
-{
-	auto n = m_active_objects.find(id);
-	if (n == m_active_objects.end())
-		return NULL;
-	return n->second;
-}
-
 bool isFreeClientActiveObjectId(const u16 id,
 	ClientActiveObjectMap &objects)
 {
@@ -336,7 +325,7 @@ bool isFreeClientActiveObjectId(const u16 id,
 
 u16 getFreeClientActiveObjectId(ClientActiveObjectMap &objects)
 {
-	//try to reuse id's as late as possible
+	// try to reuse id's as late as possible
 	static u16 last_used_id = 0;
 	u16 startid = last_used_id;
 	for(;;) {
@@ -351,43 +340,25 @@ u16 getFreeClientActiveObjectId(ClientActiveObjectMap &objects)
 
 u16 ClientEnvironment::addActiveObject(ClientActiveObject *object)
 {
-	assert(object); // Pre-condition
-	if(object->getId() == 0)
-	{
-		u16 new_id = getFreeClientActiveObjectId(m_active_objects);
-		if(new_id == 0)
-		{
-			infostream<<"ClientEnvironment::addActiveObject(): "
-				<<"no free ids available"<<std::endl;
-			delete object;
-			return 0;
-		}
-		object->setId(new_id);
-	}
-	if (!isFreeClientActiveObjectId(object->getId(), m_active_objects)) {
-		infostream<<"ClientEnvironment::addActiveObject(): "
-			<<"id is not free ("<<object->getId()<<")"<<std::endl;
-		delete object;
+	// Register object. If failed return zero id
+	if (!m_ao_manager.registerObject(object))
 		return 0;
-	}
-	infostream<<"ClientEnvironment::addActiveObject(): "
-		<<"added (id="<<object->getId()<<")"<<std::endl;
-	m_active_objects[object->getId()] = object;
+
 	object->addToScene(m_texturesource);
-	{ // Update lighting immediately
-		u8 light = 0;
-		bool pos_ok;
 
-		// Get node at head
-		v3s16 p = object->getLightPosition();
-		MapNode n = m_map->getNodeNoEx(p, &pos_ok);
-		if (pos_ok)
-			light = n.getLightBlend(getDayNightRatio(), m_client->ndef());
-		else
-			light = blend_light(getDayNightRatio(), LIGHT_SUN, 0);
+	// Update lighting immediately
+	u8 light = 0;
+	bool pos_ok;
 
-		object->updateLight(light);
-	}
+	// Get node at head
+	v3s16 p = object->getLightPosition();
+	MapNode n = m_map->getNodeNoEx(p, &pos_ok);
+	if (pos_ok)
+		light = n.getLightBlend(getDayNightRatio(), m_client->ndef());
+	else
+		light = blend_light(getDayNightRatio(), LIGHT_SUN, 0);
+
+	object->updateLight(light);
 	return object->getId();
 }
 
@@ -423,21 +394,6 @@ void ClientEnvironment::addActiveObject(u16 id, u8 type,
 	addActiveObject(obj);
 }
 
-void ClientEnvironment::removeActiveObject(u16 id)
-{
-	verbosestream<<"ClientEnvironment::removeActiveObject(): "
-		<<"id="<<id<<std::endl;
-	ClientActiveObject* obj = getActiveObject(id);
-	if (obj == NULL) {
-		infostream<<"ClientEnvironment::removeActiveObject(): "
-			<<"id="<<id<<" not found"<<std::endl;
-		return;
-	}
-	obj->removeFromScene(true);
-	delete obj;
-	m_active_objects.erase(id);
-}
-
 void ClientEnvironment::processActiveObjectMessage(u16 id, const std::string &data)
 {
 	ClientActiveObject *obj = getActiveObject(id);
@@ -485,21 +441,6 @@ void ClientEnvironment::damageLocalPlayer(u8 damage, bool handle_hp)
 	Client likes to call these
 */
 
-void ClientEnvironment::getActiveObjects(v3f origin, f32 max_d,
-	std::vector<DistanceSortedActiveObject> &dest)
-{
-	for (auto &ao_it : m_active_objects) {
-		ClientActiveObject* obj = ao_it.second;
-
-		f32 d = (obj->getPosition() - origin).getLength();
-
-		if (d > max_d)
-			continue;
-
-		dest.emplace_back(obj, d);
-	}
-}
-
 ClientEnvEvent ClientEnvironment::getClientEnvEvent()
 {
 	FATAL_ERROR_IF(m_client_event_queue.empty(),
diff --git a/src/client/clientenvironment.h b/src/client/clientenvironment.h
index 606070e3a..d167902d1 100644
--- a/src/client/clientenvironment.h
+++ b/src/client/clientenvironment.h
@@ -23,6 +23,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include <ISceneManager.h>
 #include "clientobject.h"
 #include "util/numeric.h"
+#include "activeobjectmgr.h"
 
 class ClientSimpleObject;
 class ClientMap;
@@ -87,7 +88,10 @@ public:
 	*/
 
 	GenericCAO* getGenericCAO(u16 id);
-	ClientActiveObject* getActiveObject(u16 id);
+	ClientActiveObject* getActiveObject(u16 id)
+	{
+		return m_ao_manager.getActiveObject(id);
+	}
 
 	/*
 		Adds an active object to the environment.
@@ -100,7 +104,10 @@ public:
 	u16 addActiveObject(ClientActiveObject *object);
 
 	void addActiveObject(u16 id, u8 type, const std::string &init_data);
-	void removeActiveObject(u16 id);
+	void removeActiveObject(u16 id)
+	{
+		m_ao_manager.removeObject(id);
+	}
 
 	void processActiveObjectMessage(u16 id, const std::string &data);
 
@@ -115,8 +122,11 @@ public:
 	*/
 
 	// Get all nearby objects
-	void getActiveObjects(v3f origin, f32 max_d,
-		std::vector<DistanceSortedActiveObject> &dest);
+	void getActiveObjects(const v3f &origin, f32 max_d,
+		std::vector<DistanceSortedActiveObject> &dest)
+	{
+		return m_ao_manager.getActiveObjects(origin, max_d, dest);
+	}
 
 	bool hasClientEnvEvents() const { return !m_client_event_queue.empty(); }
 
@@ -142,7 +152,7 @@ private:
 	ITextureSource *m_texturesource;
 	Client *m_client;
 	ClientScripting *m_script = nullptr;
-	ClientActiveObjectMap m_active_objects;
+	client::ActiveObjectMgr m_ao_manager;
 	std::vector<ClientSimpleObject*> m_simple_objects;
 	std::queue<ClientEnvEvent> m_client_event_queue;
 	IntervalLimiter m_active_object_light_update_interval;
diff --git a/src/server/CMakeLists.txt b/src/server/CMakeLists.txt
index b892e83b3..e964c69ff 100644
--- a/src/server/CMakeLists.txt
+++ b/src/server/CMakeLists.txt
@@ -1,3 +1,4 @@
 set(server_SRCS
+	${CMAKE_CURRENT_SOURCE_DIR}/activeobjectmgr.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/mods.cpp
 	PARENT_SCOPE)
diff --git a/src/server/activeobjectmgr.cpp b/src/server/activeobjectmgr.cpp
new file mode 100644
index 000000000..56febd76e
--- /dev/null
+++ b/src/server/activeobjectmgr.cpp
@@ -0,0 +1,167 @@
+/*
+Minetest
+Copyright (C) 2010-2018 nerzhul, Loic BLOT <loic.blot@unix-experience.fr>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include <log.h>
+#include "mapblock.h"
+#include "profiler.h"
+#include "activeobjectmgr.h"
+
+namespace server
+{
+
+void ActiveObjectMgr::clear(const std::function<bool(ServerActiveObject *, u16)> &cb)
+{
+	std::vector<u16> objects_to_remove;
+	for (auto &it : m_active_objects) {
+		if (cb(it.second, it.first)) {
+			// Id to be removed from m_active_objects
+			objects_to_remove.push_back(it.first);
+		}
+	}
+
+	// Remove references from m_active_objects
+	for (u16 i : objects_to_remove) {
+		m_active_objects.erase(i);
+	}
+}
+
+void ActiveObjectMgr::step(
+		float dtime, const std::function<void(ServerActiveObject *)> &f)
+{
+	g_profiler->avg("Server::ActiveObjectMgr: num of objects",
+			m_active_objects.size());
+	for (auto &ao_it : m_active_objects) {
+		f(ao_it.second);
+	}
+}
+
+// clang-format off
+bool ActiveObjectMgr::registerObject(ServerActiveObject *obj)
+{
+	assert(obj); // Pre-condition
+	if (obj->getId() == 0) {
+		u16 new_id = getFreeId();
+		if (new_id == 0) {
+			errorstream << "Server::ActiveObjectMgr::addActiveObjectRaw(): "
+					<< "no free id available" << std::endl;
+			if (obj->environmentDeletes())
+				delete obj;
+			return false;
+		}
+		obj->setId(new_id);
+	} else {
+		verbosestream << "Server::ActiveObjectMgr::addActiveObjectRaw(): "
+				<< "supplied with id " << obj->getId() << std::endl;
+	}
+
+	if (!isFreeId(obj->getId())) {
+		errorstream << "Server::ActiveObjectMgr::addActiveObjectRaw(): "
+				<< "id is not free (" << obj->getId() << ")" << std::endl;
+		if (obj->environmentDeletes())
+			delete obj;
+		return false;
+	}
+
+	if (objectpos_over_limit(obj->getBasePosition())) {
+		v3f p = obj->getBasePosition();
+		warningstream << "Server::ActiveObjectMgr::addActiveObjectRaw(): "
+				<< "object position (" << p.X << "," << p.Y << "," << p.Z
+				<< ") outside maximum range" << std::endl;
+		if (obj->environmentDeletes())
+			delete obj;
+		return false;
+	}
+
+	m_active_objects[obj->getId()] = obj;
+
+	verbosestream << "Server::ActiveObjectMgr::addActiveObjectRaw(): "
+			<< "Added id=" << obj->getId() << "; there are now "
+			<< m_active_objects.size() << " active objects." << std::endl;
+	return true;
+}
+
+void ActiveObjectMgr::removeObject(u16 id)
+{
+	verbosestream << "Server::ActiveObjectMgr::removeObject(): "
+			<< "id=" << id << std::endl;
+	ServerActiveObject *obj = getActiveObject(id);
+	if (!obj) {
+		infostream << "Server::ActiveObjectMgr::removeObject(): "
+				<< "id=" << id << " not found" << std::endl;
+		return;
+	}
+
+	m_active_objects.erase(id);
+	delete obj;
+}
+
+// clang-format on
+void ActiveObjectMgr::getObjectsInsideRadius(
+		const v3f &pos, float radius, std::vector<u16> &result)
+{
+	for (auto &activeObject : m_active_objects) {
+		ServerActiveObject *obj = activeObject.second;
+		u16 id = activeObject.first;
+		const v3f &objectpos = obj->getBasePosition();
+		if (objectpos.getDistanceFrom(pos) > radius)
+			continue;
+		result.push_back(id);
+	}
+}
+
+void ActiveObjectMgr::getAddedActiveObjectsAroundPos(const v3f &player_pos, f32 radius,
+		f32 player_radius, std::set<u16> &current_objects,
+		std::queue<u16> &added_objects)
+{
+	/*
+		Go through the object list,
+		- discard removed/deactivated objects,
+		- discard objects that are too far away,
+		- discard objects that are found in current_objects.
+		- add remaining objects to added_objects
+	*/
+	for (auto &ao_it : m_active_objects) {
+		u16 id = ao_it.first;
+
+		// Get object
+		ServerActiveObject *object = ao_it.second;
+		if (!object)
+			continue;
+
+		if (object->isGone())
+			continue;
+
+		f32 distance_f = object->getBasePosition().getDistanceFrom(player_pos);
+		if (object->getType() == ACTIVEOBJECT_TYPE_PLAYER) {
+			// Discard if too far
+			if (distance_f > player_radius && player_radius != 0)
+				continue;
+		} else if (distance_f > radius)
+			continue;
+
+		// Discard if already on current_objects
+		auto n = current_objects.find(id);
+		if (n != current_objects.end())
+			continue;
+		// Add to added_objects
+		added_objects.push(id);
+	}
+}
+
+} // namespace server
diff --git a/src/server/activeobjectmgr.h b/src/server/activeobjectmgr.h
new file mode 100644
index 000000000..a502ac6ed
--- /dev/null
+++ b/src/server/activeobjectmgr.h
@@ -0,0 +1,45 @@
+/*
+Minetest
+Copyright (C) 2010-2018 nerzhul, Loic BLOT <loic.blot@unix-experience.fr>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#pragma once
+
+#include <functional>
+#include <vector>
+#include "../activeobjectmgr.h"
+#include "serverobject.h"
+
+namespace server
+{
+class ActiveObjectMgr : public ::ActiveObjectMgr<ServerActiveObject>
+{
+public:
+	void clear(const std::function<bool(ServerActiveObject *, u16)> &cb);
+	void step(float dtime,
+			const std::function<void(ServerActiveObject *)> &f) override;
+	bool registerObject(ServerActiveObject *obj) override;
+	void removeObject(u16 id) override;
+
+	void getObjectsInsideRadius(
+			const v3f &pos, float radius, std::vector<u16> &result);
+
+	void getAddedActiveObjectsAroundPos(const v3f &player_pos, f32 radius,
+			f32 player_radius, std::set<u16> &current_objects,
+			std::queue<u16> &added_objects);
+};
+} // namespace server
diff --git a/src/serverenvironment.cpp b/src/serverenvironment.cpp
index efb93b9a2..4837449e6 100644
--- a/src/serverenvironment.cpp
+++ b/src/serverenvironment.cpp
@@ -1047,29 +1047,13 @@ bool ServerEnvironment::swapNode(v3s16 p, const MapNode &n)
 	return true;
 }
 
-void ServerEnvironment::getObjectsInsideRadius(std::vector<u16> &objects, v3f pos,
-	float radius)
-{
-	for (auto &activeObject : m_active_objects) {
-		ServerActiveObject* obj = activeObject.second;
-		u16 id = activeObject.first;
-		v3f objectpos = obj->getBasePosition();
-		if (objectpos.getDistanceFrom(pos) > radius)
-			continue;
-		objects.push_back(id);
-	}
-}
-
 void ServerEnvironment::clearObjects(ClearObjectsMode mode)
 {
 	infostream << "ServerEnvironment::clearObjects(): "
 		<< "Removing all active objects" << std::endl;
-	std::vector<u16> objects_to_remove;
-	for (auto &it : m_active_objects) {
-		u16 id = it.first;
-		ServerActiveObject* obj = it.second;
+	auto cb_removal = [this] (ServerActiveObject *obj, u16 id) {
 		if (obj->getType() == ACTIVEOBJECT_TYPE_PLAYER)
-			continue;
+			return false;
 
 		// Delete static object if block is loaded
 		deleteStaticFromBlock(obj, id, MOD_REASON_CLEAR_ALL_OBJECTS, true);
@@ -1077,7 +1061,7 @@ void ServerEnvironment::clearObjects(ClearObjectsMode mode)
 		// If known by some client, don't delete immediately
 		if (obj->m_known_by_count > 0) {
 			obj->m_pending_removal = true;
-			continue;
+			return false;
 		}
 
 		// Tell the object about removal
@@ -1088,14 +1072,11 @@ void ServerEnvironment::clearObjects(ClearObjectsMode mode)
 		// Delete active object
 		if (obj->environmentDeletes())
 			delete obj;
-		// Id to be removed from m_active_objects
-		objects_to_remove.push_back(id);
-	}
 
-	// Remove references from m_active_objects
-	for (u16 i : objects_to_remove) {
-		m_active_objects.erase(i);
-	}
+		return true;
+	};
+
+	m_ao_manager.clear(cb_removal);
 
 	// Get list of loaded blocks
 	std::vector<v3s16> loaded_blocks;
@@ -1386,32 +1367,28 @@ void ServerEnvironment::step(float dtime)
 	*/
 	{
 		ScopeProfiler sp(g_profiler, "SEnv: step act. objs avg", SPT_AVG);
-		//TimeTaker timer("Step active objects");
-
-		g_profiler->avg("SEnv: num of objects", m_active_objects.size());
 
 		// This helps the objects to send data at the same time
 		bool send_recommended = false;
 		m_send_recommended_timer += dtime;
-		if(m_send_recommended_timer > getSendRecommendedInterval())
-		{
+		if (m_send_recommended_timer > getSendRecommendedInterval()) {
 			m_send_recommended_timer -= getSendRecommendedInterval();
 			send_recommended = true;
 		}
 
-		for (auto &ao_it : m_active_objects) {
-			ServerActiveObject* obj = ao_it.second;
+		auto cb_state = [this, dtime, send_recommended] (ServerActiveObject *obj) {
 			if (obj->isGone())
-				continue;
+				return;
 
 			// Step object
 			obj->step(dtime, send_recommended);
 			// Read messages from object
 			while (!obj->m_messages_out.empty()) {
-				m_active_object_messages.push(obj->m_messages_out.front());
+				this->m_active_object_messages.push(obj->m_messages_out.front());
 				obj->m_messages_out.pop();
 			}
-		}
+		};
+		m_ao_manager.step(dtime, cb_state);
 	}
 
 	/*
@@ -1484,44 +1461,6 @@ void ServerEnvironment::deleteParticleSpawner(u32 id, bool remove_from_object)
 	}
 }
 
-ServerActiveObject* ServerEnvironment::getActiveObject(u16 id)
-{
-	ServerActiveObjectMap::const_iterator n = m_active_objects.find(id);
-	return (n != m_active_objects.end() ? n->second : NULL);
-}
-
-/**
- * Verify if id is a free active object id
- * @param id
- * @return true if slot is free
- */
-bool ServerEnvironment::isFreeServerActiveObjectId(u16 id) const
-{
-	if (id == 0)
-		return false;
-
-	return m_active_objects.find(id) == m_active_objects.end();
-}
-
-/**
- * Retrieve the first free ActiveObject ID
- * @return free activeobject ID or 0 if none was found
- */
-u16 ServerEnvironment::getFreeServerActiveObjectId()
-{
-	// try to reuse id's as late as possible
-	static u16 last_used_id = 0;
-	u16 startid = last_used_id;
-	for (;;) {
-		last_used_id++;
-		if (isFreeServerActiveObjectId(last_used_id))
-			return last_used_id;
-
-		if (last_used_id == startid)
-			return 0;
-	}
-}
-
 u16 ServerEnvironment::addActiveObject(ServerActiveObject *object)
 {
 	assert(object);	// Pre-condition
@@ -1542,43 +1481,11 @@ void ServerEnvironment::getAddedActiveObjects(PlayerSAO *playersao, s16 radius,
 	f32 radius_f = radius * BS;
 	f32 player_radius_f = player_radius * BS;
 
-	if (player_radius_f < 0)
-		player_radius_f = 0;
-	/*
-		Go through the object list,
-		- discard removed/deactivated objects,
-		- discard objects that are too far away,
-		- discard objects that are found in current_objects.
-		- add remaining objects to added_objects
-	*/
-	for (auto &ao_it : m_active_objects) {
-		u16 id = ao_it.first;
-
-		// Get object
-		ServerActiveObject *object = ao_it.second;
-		if (object == NULL)
-			continue;
+	if (player_radius_f < 0.0f)
+		player_radius_f = 0.0f;
 
-		if (object->isGone())
-			continue;
-
-		f32 distance_f = object->getBasePosition().
-			getDistanceFrom(playersao->getBasePosition());
-		if (object->getType() == ACTIVEOBJECT_TYPE_PLAYER) {
-			// Discard if too far
-			if (distance_f > player_radius_f && player_radius_f != 0)
-				continue;
-		} else if (distance_f > radius_f)
-			continue;
-
-		// Discard if already on current_objects
-		std::set<u16>::iterator n;
-		n = current_objects.find(id);
-		if(n != current_objects.end())
-			continue;
-		// Add to added_objects
-		added_objects.push(id);
-	}
+	m_ao_manager.getAddedActiveObjectsAroundPos(playersao->getBasePosition(), radius_f,
+		player_radius_f, current_objects, added_objects);
 }
 
 /*
@@ -1639,8 +1546,8 @@ void ServerEnvironment::setStaticForActiveObjectsInBlock(
 
 	for (auto &so_it : block->m_static_objects.m_active) {
 		// Get the ServerActiveObject counterpart to this StaticObject
-		ServerActiveObjectMap::const_iterator ao_it = m_active_objects.find(so_it.first);
-		if (ao_it == m_active_objects.end()) {
+		ServerActiveObject *sao = m_ao_manager.getActiveObject(so_it.first);
+		if (!sao) {
 			// If this ever happens, there must be some kind of nasty bug.
 			errorstream << "ServerEnvironment::setStaticForObjectsInBlock(): "
 				"Object from MapBlock::m_static_objects::m_active not found "
@@ -1648,7 +1555,6 @@ void ServerEnvironment::setStaticForActiveObjectsInBlock(
 			continue;
 		}
 
-		ServerActiveObject *sao = ao_it->second;
 		sao->m_static_exists = static_exists;
 		sao->m_static_block  = static_block;
 	}
@@ -1703,60 +1609,17 @@ void ServerEnvironment::getSelectedActiveObjects(
 u16 ServerEnvironment::addActiveObjectRaw(ServerActiveObject *object,
 	bool set_changed, u32 dtime_s)
 {
-	assert(object); // Pre-condition
-	if(object->getId() == 0){
-		u16 new_id = getFreeServerActiveObjectId();
-		if(new_id == 0)
-		{
-			errorstream<<"ServerEnvironment::addActiveObjectRaw(): "
-				<<"no free ids available"<<std::endl;
-			if(object->environmentDeletes())
-				delete object;
-			return 0;
-		}
-		object->setId(new_id);
-	}
-	else{
-		verbosestream<<"ServerEnvironment::addActiveObjectRaw(): "
-			<<"supplied with id "<<object->getId()<<std::endl;
-	}
-
-	if(!isFreeServerActiveObjectId(object->getId())) {
-		errorstream<<"ServerEnvironment::addActiveObjectRaw(): "
-			<<"id is not free ("<<object->getId()<<")"<<std::endl;
-		if(object->environmentDeletes())
-			delete object;
-		return 0;
-	}
-
-	if (objectpos_over_limit(object->getBasePosition())) {
-		v3f p = object->getBasePosition();
-		warningstream << "ServerEnvironment::addActiveObjectRaw(): "
-			<< "object position (" << p.X << "," << p.Y << "," << p.Z
-			<< ") outside maximum range" << std::endl;
-		if (object->environmentDeletes())
-			delete object;
+	if (!m_ao_manager.registerObject(object)) {
 		return 0;
 	}
 
-	/*infostream<<"ServerEnvironment::addActiveObjectRaw(): "
-			<<"added (id="<<object->getId()<<")"<<std::endl;*/
-
-	m_active_objects[object->getId()] = object;
-
-	verbosestream<<"ServerEnvironment::addActiveObjectRaw(): "
-		<<"Added id="<<object->getId()<<"; there are now "
-		<<m_active_objects.size()<<" active objects."
-		<<std::endl;
-
 	// Register reference in scripting api (must be done before post-init)
 	m_script->addObjectReference(object);
 	// Post-initialize object
 	object->addedToEnvironment(dtime_s);
 
 	// Add static data to block
-	if(object->isStaticAllowed())
-	{
+	if (object->isStaticAllowed()) {
 		// Add static object to active static list of the block
 		v3f objectpos = object->getBasePosition();
 		StaticObject s_obj(object, objectpos);
@@ -1787,24 +1650,19 @@ u16 ServerEnvironment::addActiveObjectRaw(ServerActiveObject *object,
 */
 void ServerEnvironment::removeRemovedObjects()
 {
-	std::vector<u16> objects_to_remove;
-	for (auto &ao_it : m_active_objects) {
-		u16 id = ao_it.first;
-		ServerActiveObject* obj = ao_it.second;
-
+	auto clear_cb = [this] (ServerActiveObject *obj, u16 id) {
 		// This shouldn't happen but check it
 		if (!obj) {
 			errorstream << "ServerEnvironment::removeRemovedObjects(): "
 					<< "NULL object found. id=" << id << std::endl;
-			objects_to_remove.push_back(id);
-			continue;
+			return true;
 		}
 
 		/*
 			We will handle objects marked for removal or deactivation
 		*/
 		if (!obj->isGone())
-			continue;
+			return false;
 
 		/*
 			Delete static data from block if removed
@@ -1815,7 +1673,7 @@ void ServerEnvironment::removeRemovedObjects()
 		// If still known by clients, don't actually remove. On some future
 		// invocation this will be 0, which is when removal will continue.
 		if(obj->m_known_by_count > 0)
-			continue;
+			return false;
 
 		/*
 			Move static data from active to stored if deactivated
@@ -1823,8 +1681,7 @@ void ServerEnvironment::removeRemovedObjects()
 		if (!obj->m_pending_removal && obj->m_static_exists) {
 			MapBlock *block = m_map->emergeBlock(obj->m_static_block, false);
 			if (block) {
-				std::map<u16, StaticObject>::iterator i =
-					block->m_static_objects.m_active.find(id);
+				const auto i = block->m_static_objects.m_active.find(id);
 				if (i != block->m_static_objects.m_active.end()) {
 					block->m_static_objects.m_stored.push_back(i->second);
 					block->m_static_objects.m_active.erase(id);
@@ -1848,15 +1705,13 @@ void ServerEnvironment::removeRemovedObjects()
 		m_script->removeObjectReference(obj);
 
 		// Delete
-		if(obj->environmentDeletes())
+		if (obj->environmentDeletes())
 			delete obj;
 
-		objects_to_remove.push_back(id);
-	}
-	// Remove references from m_active_objects
-	for (u16 i : objects_to_remove) {
-		m_active_objects.erase(i);
-	}
+		return true;
+	};
+
+	m_ao_manager.clear(clear_cb);
 }
 
 static void print_hexdump(std::ostream &o, const std::string &data)
@@ -1976,24 +1831,19 @@ void ServerEnvironment::activateObjects(MapBlock *block, u32 dtime_s)
 */
 void ServerEnvironment::deactivateFarObjects(bool _force_delete)
 {
-	std::vector<u16> objects_to_remove;
-	for (auto &ao_it : m_active_objects) {
+	auto cb_deactivate = [this, _force_delete] (ServerActiveObject *obj, u16 id) {
 		// force_delete might be overriden per object
 		bool force_delete = _force_delete;
 
-		ServerActiveObject* obj = ao_it.second;
-		assert(obj);
-
 		// Do not deactivate if static data creation not allowed
-		if(!force_delete && !obj->isStaticAllowed())
-			continue;
+		if (!force_delete && !obj->isStaticAllowed())
+			return false;
 
 		// removeRemovedObjects() is responsible for these
-		if(!force_delete && obj->isGone())
-			continue;
+		if (!force_delete && obj->isGone())
+			return false;
 
-		u16 id = ao_it.first;
-		v3f objectpos = obj->getBasePosition();
+		const v3f &objectpos = obj->getBasePosition();
 
 		// The block in which the object resides in
 		v3s16 blockpos_o = getNodeBlockPos(floatToInt(objectpos, BS));
@@ -2001,11 +1851,9 @@ void ServerEnvironment::deactivateFarObjects(bool _force_delete)
 		// If object's static data is stored in a deactivated block and object
 		// is actually located in an active block, re-save to the block in
 		// which the object is actually located in.
-		if(!force_delete &&
-			obj->m_static_exists &&
-			!m_active_blocks.contains(obj->m_static_block) &&
-			m_active_blocks.contains(blockpos_o))
-		{
+		if (!force_delete && obj->m_static_exists &&
+		   !m_active_blocks.contains(obj->m_static_block) &&
+		   m_active_blocks.contains(blockpos_o)) {
 			// Delete from block where object was located
 			deleteStaticFromBlock(obj, id, MOD_REASON_STATIC_DATA_REMOVED, false);
 
@@ -2013,16 +1861,16 @@ void ServerEnvironment::deactivateFarObjects(bool _force_delete)
 			// Save to block where object is located
 			saveStaticToBlock(blockpos_o, id, obj, s_obj, MOD_REASON_STATIC_DATA_ADDED);
 
-			continue;
+			return false;
 		}
 
 		// If block is still active, don't remove
-		if(!force_delete && m_active_blocks.contains(blockpos_o))
-			continue;
+		if (!force_delete && m_active_blocks.contains(blockpos_o))
+			return false;
 
 		verbosestream << "ServerEnvironment::deactivateFarObjects(): "
-				<< "deactivating object id=" << id << " on inactive block "
-				<< PP(blockpos_o) << std::endl;
+					  << "deactivating object id=" << id << " on inactive block "
+					  << PP(blockpos_o) << std::endl;
 
 		// If known by some client, don't immediately delete.
 		bool pending_delete = (obj->m_known_by_count > 0 && !force_delete);
@@ -2045,8 +1893,7 @@ void ServerEnvironment::deactivateFarObjects(bool _force_delete)
 				MapBlock *block = m_map->emergeBlock(obj->m_static_block, false);
 
 				if (block) {
-					std::map<u16, StaticObject>::iterator n =
-						block->m_static_objects.m_active.find(id);
+					const auto n = block->m_static_objects.m_active.find(id);
 					if (n != block->m_static_objects.m_active.end()) {
 						StaticObject static_old = n->second;
 
@@ -2085,18 +1932,18 @@ void ServerEnvironment::deactivateFarObjects(bool _force_delete)
 			If known by some client, set pending deactivation.
 			Otherwise delete it immediately.
 		*/
-		if(pending_delete && !force_delete)
-		{
+		if (pending_delete && !force_delete) {
 			verbosestream << "ServerEnvironment::deactivateFarObjects(): "
-					<< "object id=" << id << " is known by clients"
-					<< "; not deleting yet" << std::endl;
+						  << "object id=" << id << " is known by clients"
+						  << "; not deleting yet" << std::endl;
 
 			obj->m_pending_deactivation = true;
-			continue;
+			return false;
 		}
+
 		verbosestream << "ServerEnvironment::deactivateFarObjects(): "
-				<< "object id=" << id << " is not known by clients"
-				<< "; deleting" << std::endl;
+					  << "object id=" << id << " is not known by clients"
+					  << "; deleting" << std::endl;
 
 		// Tell the object about removal
 		obj->removingFromEnvironment();
@@ -2104,16 +1951,13 @@ void ServerEnvironment::deactivateFarObjects(bool _force_delete)
 		m_script->removeObjectReference(obj);
 
 		// Delete active object
-		if(obj->environmentDeletes())
+		if (obj->environmentDeletes())
 			delete obj;
-		// Id to be removed from m_active_objects
-		objects_to_remove.push_back(id);
-	}
 
-	// Remove references from m_active_objects
-	for (u16 i : objects_to_remove) {
-		m_active_objects.erase(i);
-	}
+		return true;
+	};
+
+	m_ao_manager.clear(cb_deactivate);
 }
 
 void ServerEnvironment::deleteStaticFromBlock(
diff --git a/src/serverenvironment.h b/src/serverenvironment.h
index b7a121adf..b883e0dc5 100644
--- a/src/serverenvironment.h
+++ b/src/serverenvironment.h
@@ -23,6 +23,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "environment.h"
 #include "mapnode.h"
 #include "settings.h"
+#include "server/activeobjectmgr.h"
 #include "util/numeric.h"
 #include <set>
 
@@ -243,7 +244,10 @@ public:
 		-------------------------------------------
 	*/
 
-	ServerActiveObject* getActiveObject(u16 id);
+	ServerActiveObject* getActiveObject(u16 id)
+	{
+		return m_ao_manager.getActiveObject(id);
+	}
 
 	/*
 		Add an active object to the environment.
@@ -255,19 +259,6 @@ public:
 	*/
 	u16 addActiveObject(ServerActiveObject *object);
 
-	/**
-	 * Verify if id is a free active object id
-	 * @param id
-	 * @return true if slot is free
-	 */
-	bool isFreeServerActiveObjectId(u16 id) const;
-
-	/**
-	 * Retrieve the first free ActiveObject ID
-	 * @return free activeobject ID or 0 if none was found
-	 */
-	u16 getFreeServerActiveObjectId();
-
 	/*
 		Add an active object as a static object to the corresponding
 		MapBlock.
@@ -331,7 +322,10 @@ public:
 	bool swapNode(v3s16 p, const MapNode &n);
 
 	// Find all active objects inside a radius around a point
-	void getObjectsInsideRadius(std::vector<u16> &objects, v3f pos, float radius);
+	void getObjectsInsideRadius(std::vector<u16> &objects, const v3f &pos, float radius)
+	{
+		return m_ao_manager.getObjectsInsideRadius(pos, radius, objects);
+	}
 
 	// Clear objects, loading and going through every MapBlock
 	void clearObjects(ClearObjectsMode mode);
@@ -438,10 +432,10 @@ private:
 	ServerScripting* m_script;
 	// Server definition
 	Server *m_server;
+	// Active Object Manager
+	server::ActiveObjectMgr m_ao_manager;
 	// World path
 	const std::string m_path_world;
-	// Active object list
-	ServerActiveObjectMap m_active_objects;
 	// Outgoing network message buffer for active objects
 	std::queue<ActiveObjectMessage> m_active_object_messages;
 	// Some timers
diff --git a/src/unittest/CMakeLists.txt b/src/unittest/CMakeLists.txt
index 3ffe1978e..993137939 100644
--- a/src/unittest/CMakeLists.txt
+++ b/src/unittest/CMakeLists.txt
@@ -21,6 +21,7 @@ set (UNITTEST_SRCS
 	${CMAKE_CURRENT_SOURCE_DIR}/test_random.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/test_schematic.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/test_serialization.cpp
+	${CMAKE_CURRENT_SOURCE_DIR}/test_serveractiveobjectmgr.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/test_server_shutdown_state.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/test_settings.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/test_socket.cpp
@@ -33,6 +34,7 @@ set (UNITTEST_SRCS
 	PARENT_SCOPE)
 
 set (UNITTEST_CLIENT_SRCS
+	${CMAKE_CURRENT_SOURCE_DIR}/test_clientactiveobjectmgr.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/test_eventmanager.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/test_gameui.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/test_keycode.cpp
diff --git a/src/unittest/test_clientactiveobjectmgr.cpp b/src/unittest/test_clientactiveobjectmgr.cpp
new file mode 100644
index 000000000..4d2846c8d
--- /dev/null
+++ b/src/unittest/test_clientactiveobjectmgr.cpp
@@ -0,0 +1,117 @@
+/*
+Minetest
+Copyright (C) 2018 nerzhul, Loic Blot <loic.blot@unix-experience.fr>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "client/activeobjectmgr.h"
+#include <algorithm>
+#include "test.h"
+
+#include "profiler.h"
+
+class TestClientActiveObject : public ClientActiveObject
+{
+public:
+	TestClientActiveObject() : ClientActiveObject(0, nullptr, nullptr) {}
+	~TestClientActiveObject() = default;
+	ActiveObjectType getType() const { return ACTIVEOBJECT_TYPE_TEST; }
+};
+
+class TestClientActiveObjectMgr : public TestBase
+{
+public:
+	TestClientActiveObjectMgr() { TestManager::registerTestModule(this); }
+	const char *getName() { return "TestClientActiveObjectMgr"; }
+
+	void runTests(IGameDef *gamedef);
+
+	void testFreeID();
+	void testRegisterObject();
+	void testRemoveObject();
+};
+
+static TestClientActiveObjectMgr g_test_instance;
+
+void TestClientActiveObjectMgr::runTests(IGameDef *gamedef)
+{
+	TEST(testFreeID);
+	TEST(testRegisterObject)
+	TEST(testRemoveObject)
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+void TestClientActiveObjectMgr::testFreeID()
+{
+	client::ActiveObjectMgr caomgr;
+	std::vector<u16> aoids;
+
+	u16 aoid = caomgr.getFreeId();
+	// Ensure it's not the same id
+	UASSERT(caomgr.getFreeId() != aoid);
+
+	aoids.push_back(aoid);
+
+	// Register basic objects, ensure we never found
+	for (u8 i = 0; i < UINT8_MAX; i++) {
+		// Register an object
+		auto tcao = new TestClientActiveObject();
+		caomgr.registerObject(tcao);
+		aoids.push_back(tcao->getId());
+
+		// Ensure next id is not in registered list
+		UASSERT(std::find(aoids.begin(), aoids.end(), caomgr.getFreeId()) ==
+				aoids.end());
+	}
+
+	caomgr.clear();
+}
+
+void TestClientActiveObjectMgr::testRegisterObject()
+{
+	client::ActiveObjectMgr caomgr;
+	auto tcao = new TestClientActiveObject();
+	UASSERT(caomgr.registerObject(tcao));
+
+	u16 id = tcao->getId();
+
+	auto tcaoToCompare = caomgr.getActiveObject(id);
+	UASSERT(tcaoToCompare->getId() == id);
+	UASSERT(tcaoToCompare == tcao);
+
+	tcao = new TestClientActiveObject();
+	UASSERT(caomgr.registerObject(tcao));
+	UASSERT(caomgr.getActiveObject(tcao->getId()) == tcao);
+	UASSERT(caomgr.getActiveObject(tcao->getId()) != tcaoToCompare);
+
+	caomgr.clear();
+}
+
+void TestClientActiveObjectMgr::testRemoveObject()
+{
+	client::ActiveObjectMgr caomgr;
+	auto tcao = new TestClientActiveObject();
+	UASSERT(caomgr.registerObject(tcao));
+
+	u16 id = tcao->getId();
+	UASSERT(caomgr.getActiveObject(id) != nullptr)
+
+	caomgr.removeObject(tcao->getId());
+	UASSERT(caomgr.getActiveObject(id) == nullptr)
+
+	caomgr.clear();
+}
diff --git a/src/unittest/test_serveractiveobjectmgr.cpp b/src/unittest/test_serveractiveobjectmgr.cpp
new file mode 100644
index 000000000..0806972ab
--- /dev/null
+++ b/src/unittest/test_serveractiveobjectmgr.cpp
@@ -0,0 +1,188 @@
+/*
+Minetest
+Copyright (C) 2018 nerzhul, Loic Blot <loic.blot@unix-experience.fr>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "server/activeobjectmgr.h"
+#include <algorithm>
+#include <queue>
+#include "test.h"
+
+#include "profiler.h"
+
+class TestServerActiveObject : public ServerActiveObject
+{
+public:
+	TestServerActiveObject(const v3f &p = v3f()) : ServerActiveObject(nullptr, p) {}
+	~TestServerActiveObject() = default;
+	ActiveObjectType getType() const override { return ACTIVEOBJECT_TYPE_TEST; }
+	bool getCollisionBox(aabb3f *toset) const override { return false; }
+	bool getSelectionBox(aabb3f *toset) const override { return false; }
+	bool collideWithObjects() const override { return false; }
+};
+
+class TestServerActiveObjectMgr : public TestBase
+{
+public:
+	TestServerActiveObjectMgr() { TestManager::registerTestModule(this); }
+	const char *getName() { return "TestServerActiveObjectMgr"; }
+
+	void runTests(IGameDef *gamedef);
+
+	void testFreeID();
+	void testRegisterObject();
+	void testRemoveObject();
+	void testGetObjectsInsideRadius();
+	void testGetAddedActiveObjectsAroundPos();
+};
+
+static TestServerActiveObjectMgr g_test_instance;
+
+void TestServerActiveObjectMgr::runTests(IGameDef *gamedef)
+{
+	TEST(testFreeID);
+	TEST(testRegisterObject)
+	TEST(testRemoveObject)
+	TEST(testGetObjectsInsideRadius);
+	TEST(testGetAddedActiveObjectsAroundPos);
+}
+
+void clearSAOMgr(server::ActiveObjectMgr *saomgr)
+{
+	auto clear_cb = [](ServerActiveObject *obj, u16 id) {
+		delete obj;
+		return true;
+	};
+	saomgr->clear(clear_cb);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+void TestServerActiveObjectMgr::testFreeID()
+{
+	server::ActiveObjectMgr saomgr;
+	std::vector<u16> aoids;
+
+	u16 aoid = saomgr.getFreeId();
+	// Ensure it's not the same id
+	UASSERT(saomgr.getFreeId() != aoid);
+
+	aoids.push_back(aoid);
+
+	// Register basic objects, ensure we never found
+	for (u8 i = 0; i < UINT8_MAX; i++) {
+		// Register an object
+		auto tsao = new TestServerActiveObject();
+		saomgr.registerObject(tsao);
+		aoids.push_back(tsao->getId());
+
+		// Ensure next id is not in registered list
+		UASSERT(std::find(aoids.begin(), aoids.end(), saomgr.getFreeId()) ==
+				aoids.end());
+	}
+
+	clearSAOMgr(&saomgr);
+}
+
+void TestServerActiveObjectMgr::testRegisterObject()
+{
+	server::ActiveObjectMgr saomgr;
+	auto tsao = new TestServerActiveObject();
+	UASSERT(saomgr.registerObject(tsao));
+
+	u16 id = tsao->getId();
+
+	auto tsaoToCompare = saomgr.getActiveObject(id);
+	UASSERT(tsaoToCompare->getId() == id);
+	UASSERT(tsaoToCompare == tsao);
+
+	tsao = new TestServerActiveObject();
+	UASSERT(saomgr.registerObject(tsao));
+	UASSERT(saomgr.getActiveObject(tsao->getId()) == tsao);
+	UASSERT(saomgr.getActiveObject(tsao->getId()) != tsaoToCompare);
+
+	clearSAOMgr(&saomgr);
+}
+
+void TestServerActiveObjectMgr::testRemoveObject()
+{
+	server::ActiveObjectMgr saomgr;
+	auto tsao = new TestServerActiveObject();
+	UASSERT(saomgr.registerObject(tsao));
+
+	u16 id = tsao->getId();
+	UASSERT(saomgr.getActiveObject(id) != nullptr)
+
+	saomgr.removeObject(tsao->getId());
+	UASSERT(saomgr.getActiveObject(id) == nullptr);
+
+	clearSAOMgr(&saomgr);
+}
+
+void TestServerActiveObjectMgr::testGetObjectsInsideRadius()
+{
+	server::ActiveObjectMgr saomgr;
+	static const v3f sao_pos[] = {
+			v3f(10, 40, 10),
+			v3f(740, 100, -304),
+			v3f(-200, 100, -304),
+			v3f(740, -740, -304),
+			v3f(1500, -740, -304),
+	};
+
+	for (const auto &p : sao_pos) {
+		saomgr.registerObject(new TestServerActiveObject(p));
+	}
+
+	std::vector<u16> result;
+	saomgr.getObjectsInsideRadius(v3f(), 50, result);
+	UASSERTCMP(int, ==, result.size(), 1);
+
+	result.clear();
+	saomgr.getObjectsInsideRadius(v3f(), 750, result);
+	UASSERTCMP(int, ==, result.size(), 2);
+
+	clearSAOMgr(&saomgr);
+}
+
+void TestServerActiveObjectMgr::testGetAddedActiveObjectsAroundPos()
+{
+	server::ActiveObjectMgr saomgr;
+	static const v3f sao_pos[] = {
+			v3f(10, 40, 10),
+			v3f(740, 100, -304),
+			v3f(-200, 100, -304),
+			v3f(740, -740, -304),
+			v3f(1500, -740, -304),
+	};
+
+	for (const auto &p : sao_pos) {
+		saomgr.registerObject(new TestServerActiveObject(p));
+	}
+
+	std::queue<u16> result;
+	std::set<u16> cur_objects;
+	saomgr.getAddedActiveObjectsAroundPos(v3f(), 100, 50, cur_objects, result);
+	UASSERTCMP(int, ==, result.size(), 1);
+
+	result = std::queue<u16>();
+	cur_objects.clear();
+	saomgr.getAddedActiveObjectsAroundPos(v3f(), 740, 50, cur_objects, result);
+	UASSERTCMP(int, ==, result.size(), 2);
+
+	clearSAOMgr(&saomgr);
+}
diff --git a/src/unittest/test_utilities.cpp b/src/unittest/test_utilities.cpp
index 112b53f0b..234f622d5 100644
--- a/src/unittest/test_utilities.cpp
+++ b/src/unittest/test_utilities.cpp
@@ -171,6 +171,8 @@ void TestUtilities::testWrapDegrees_0_360_v3f()
 void TestUtilities::testLowercase()
 {
 	UASSERT(lowercase("Foo bAR") == "foo bar");
+	UASSERT(lowercase("eeeeeeaaaaaaaaaaaààààà") == "eeeeeeaaaaaaaaaaaààààà");
+	UASSERT(lowercase("MINETEST-powa") == "minetest-powa");
 }