Crafting speedup

This greatly increases crafting performance, especially in worlds with many mods.

Approved by @kwolekr.

Introduces a hash-type-layered fall-through mechanism, where every layer specifies one hash algorithm,
and the "deeper the fall", the more collisions to expect for the algorithm. One Craft definition
only resides at one layer, which improves speed for lower layers (and a complete fail), due to most
craft definitions residing at high layers.

Due to the fall-through design, the undocumented behaviour that later craft recipes
override older ones had to be weaked up a bit, but craft recipes with the same hash and layer
will still override.

3 files changed, 349 insertions, 88 deletions

diff --git a/src/craftdef.cpp b/src/craftdef.cpp
index bca16a4c6..749490f62 100644
--- a/src/craftdef.cpp
+++ b/src/craftdef.cpp
@@ -27,10 +27,48 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "gamedef.h"
 #include "inventory.h"
 #include "util/serialize.h"
+#include "util/string.h"
 #include "util/numeric.h"
 #include "strfnd.h"
 #include "exceptions.h"
 
+inline bool isGroupRecipeStr(const std::string &rec_name)
+{
+	return str_starts_with(rec_name, std::string("group:"));
+}
+
+inline u64 getHashForString(const std::string &recipe_str)
+{
+	/*errorstream << "Hashing craft string  \"" << recipe_str << "\"";*/
+	return murmur_hash_64_ua(recipe_str.data(), recipe_str.length(), 0xdeadbeef);
+}
+
+static u64 getHashForGrid(CraftHashType type, const std::vector<std::string> &grid_names)
+{
+	switch (type) {
+		case CRAFT_HASH_TYPE_ITEM_NAMES: {
+			std::ostringstream os;
+			bool is_first = true;
+			for (size_t i = 0; i < grid_names.size(); i++) {
+				if (grid_names[i] != "") {
+					os << (is_first ? "" : "\n") << grid_names[i];
+					is_first = false;
+				}
+			}
+			return getHashForString(os.str());
+		} case CRAFT_HASH_TYPE_COUNT: {
+			u64 cnt = 0;
+			for (size_t i = 0; i < grid_names.size(); i++)
+				if (grid_names[i] != "")
+					cnt++;
+			return cnt;
+		} case CRAFT_HASH_TYPE_UNHASHED:
+			return 0;
+	}
+	// invalid CraftHashType
+	assert(false);
+}
+
 // Check if input matches recipe
 // Takes recipe groups into account
 static bool inputItemMatchesRecipe(const std::string &inp_name,
@@ -41,7 +79,7 @@ static bool inputItemMatchesRecipe(const std::string &inp_name,
 		return true;
 
 	// Group
-	if(rec_name.substr(0,6) == "group:" && idef->isKnown(inp_name)){
+	if (isGroupRecipeStr(rec_name) && idef->isKnown(inp_name)) {
 		const struct ItemDefinition &def = idef->get(inp_name);
 		Strfnd f(rec_name.substr(6));
 		bool all_groups_match = true;
@@ -405,8 +443,13 @@ bool CraftDefinitionShaped::check(const CraftInput &input, IGameDef *gamedef) co
 	if(!craftGetBounds(inp_names, inp_width, inp_min_x, inp_max_x, inp_min_y, inp_max_y))
 		return false;  // it was empty
 
+	std::vector<std::string> rec_names;
+	if (hash_inited)
+		rec_names = recipe_names;
+	else
+		rec_names = craftGetItemNames(recipe, gamedef);
+
 	// Get recipe item matrix
-	std::vector<std::string> rec_names = craftGetItemNames(recipe, gamedef);
 	unsigned int rec_width = width;
 	if(rec_width == 0)
 		return false;
@@ -462,6 +505,43 @@ void CraftDefinitionShaped::decrementInput(CraftInput &input, IGameDef *gamedef)
 	craftDecrementOrReplaceInput(input, replacements, gamedef);
 }
 
+CraftHashType CraftDefinitionShaped::getHashType() const
+{
+	assert(hash_inited); //pre-condition
+	bool has_group = false;
+	for (size_t i = 0; i < recipe_names.size(); i++) {
+		if (isGroupRecipeStr(recipe_names[i])) {
+			has_group = true;
+			break;
+		}
+	}
+	if (has_group)
+		return CRAFT_HASH_TYPE_COUNT;
+	else
+		return CRAFT_HASH_TYPE_ITEM_NAMES;
+}
+
+u64 CraftDefinitionShaped::getHash(CraftHashType type) const
+{
+	assert(hash_inited); //pre-condition
+	if ((type == CRAFT_HASH_TYPE_ITEM_NAMES) || (type == CRAFT_HASH_TYPE_COUNT)) {
+		std::vector<std::string> rec_names = recipe_names;
+		std::sort(rec_names.begin(), rec_names.end());
+		return getHashForGrid(type, rec_names);
+	} else {
+		//illegal hash type for this CraftDefinition (pre-condition)
+		assert(false);
+	}
+}
+
+void CraftDefinitionShaped::initHash(IGameDef *gamedef)
+{
+	if (hash_inited)
+		return;
+	hash_inited = true;
+	recipe_names = craftGetItemNames(recipe, gamedef);
+}
+
 std::string CraftDefinitionShaped::dump() const
 {
 	std::ostringstream os(std::ios::binary);
@@ -526,12 +606,18 @@ bool CraftDefinitionShapeless::check(const CraftInput &input, IGameDef *gamedef)
 		return false;
 	}
 
-	// Try with all permutations of the recipe
-	std::vector<std::string> recipe_copy = craftGetItemNames(recipe, gamedef);
-	// Start from the lexicographically first permutation (=sorted)
-	std::sort(recipe_copy.begin(), recipe_copy.end());
-	//while(std::prev_permutation(recipe_copy.begin(), recipe_copy.end())){}
-	do{
+	std::vector<std::string> recipe_copy;
+	if (hash_inited)
+		recipe_copy = recipe_names;
+	else {
+		recipe_copy = craftGetItemNames(recipe, gamedef);
+		std::sort(recipe_copy.begin(), recipe_copy.end());
+	}
+
+	// Try with all permutations of the recipe,
+	// start from the lexicographically first permutation (=sorted),
+	// recipe_names is pre-sorted
+	do {
 		// If all items match, the recipe matches
 		bool all_match = true;
 		//dstream<<"Testing recipe (output="<<output<<"):";
@@ -566,6 +652,42 @@ void CraftDefinitionShapeless::decrementInput(CraftInput &input, IGameDef *gamed
 	craftDecrementOrReplaceInput(input, replacements, gamedef);
 }
 
+CraftHashType CraftDefinitionShapeless::getHashType() const
+{
+	assert(hash_inited); //pre-condition
+	bool has_group = false;
+	for (size_t i = 0; i < recipe_names.size(); i++) {
+		if (isGroupRecipeStr(recipe_names[i])) {
+			has_group = true;
+			break;
+		}
+	}
+	if (has_group)
+		return CRAFT_HASH_TYPE_COUNT;
+	else
+		return CRAFT_HASH_TYPE_ITEM_NAMES;
+}
+
+u64 CraftDefinitionShapeless::getHash(CraftHashType type) const
+{
+	assert(hash_inited); //pre-condition
+	if (type == CRAFT_HASH_TYPE_ITEM_NAMES || type == CRAFT_HASH_TYPE_COUNT) {
+		return getHashForGrid(type, recipe_names);
+	} else {
+		//illegal hash type for this CraftDefinition (pre-condition)
+		assert(false);
+	}
+}
+
+void CraftDefinitionShapeless::initHash(IGameDef *gamedef)
+{
+	if (hash_inited)
+		return;
+	hash_inited = true;
+	recipe_names = craftGetItemNames(recipe, gamedef);
+	std::sort(recipe_names.begin(), recipe_names.end());
+}
+
 std::string CraftDefinitionShapeless::dump() const
 {
 	std::ostringstream os(std::ios::binary);
@@ -763,6 +885,34 @@ void CraftDefinitionCooking::decrementInput(CraftInput &input, IGameDef *gamedef
 	craftDecrementOrReplaceInput(input, replacements, gamedef);
 }
 
+CraftHashType CraftDefinitionCooking::getHashType() const
+{
+	if (isGroupRecipeStr(recipe_name))
+		return CRAFT_HASH_TYPE_COUNT;
+	else
+		return CRAFT_HASH_TYPE_ITEM_NAMES;
+}
+
+u64 CraftDefinitionCooking::getHash(CraftHashType type) const
+{
+	if (type == CRAFT_HASH_TYPE_ITEM_NAMES) {
+		return getHashForString(recipe_name);
+	} else if (type == CRAFT_HASH_TYPE_COUNT) {
+		return 1;
+	} else {
+		//illegal hash type for this CraftDefinition (pre-condition)
+		assert(false);
+	}
+}
+
+void CraftDefinitionCooking::initHash(IGameDef *gamedef)
+{
+	if (hash_inited)
+		return;
+	hash_inited = true;
+	recipe_name = craftGetItemName(recipe, gamedef);
+}
+
 std::string CraftDefinitionCooking::dump() const
 {
 	std::ostringstream os(std::ios::binary);
@@ -844,6 +994,33 @@ void CraftDefinitionFuel::decrementInput(CraftInput &input, IGameDef *gamedef) c
 	craftDecrementOrReplaceInput(input, replacements, gamedef);
 }
 
+CraftHashType CraftDefinitionFuel::getHashType() const
+{
+	if (isGroupRecipeStr(recipe_name))
+		return CRAFT_HASH_TYPE_COUNT;
+	else
+		return CRAFT_HASH_TYPE_ITEM_NAMES;
+}
+
+u64 CraftDefinitionFuel::getHash(CraftHashType type) const
+{
+	if (type == CRAFT_HASH_TYPE_ITEM_NAMES) {
+		return getHashForString(recipe_name);
+	} else if (type == CRAFT_HASH_TYPE_COUNT) {
+		return 1;
+	} else {
+		//illegal hash type for this CraftDefinition (pre-condition)
+		assert(false);
+	}
+}
+
+void CraftDefinitionFuel::initHash(IGameDef *gamedef)
+{
+	if (hash_inited)
+		return;
+	hash_inited = true;
+	recipe_name = craftGetItemName(recipe, gamedef);
+}
 std::string CraftDefinitionFuel::dump() const
 {
 	std::ostringstream os(std::ios::binary);
@@ -876,10 +1053,16 @@ void CraftDefinitionFuel::deSerializeBody(std::istream &is, int version)
 class CCraftDefManager: public IWritableCraftDefManager
 {
 public:
+	CCraftDefManager()
+	{
+		m_craft_defs.resize(craft_hash_type_max + 1);
+	}
+
 	virtual ~CCraftDefManager()
 	{
 		clear();
 	}
+
 	virtual bool getCraftResult(CraftInput &input, CraftOutput &output,
 			bool decrementInput, IGameDef *gamedef) const
 	{
@@ -888,47 +1071,55 @@ public:
 
 		// If all input items are empty, abort.
 		bool all_empty = true;
-		for(std::vector<ItemStack>::const_iterator
+		for (std::vector<ItemStack>::const_iterator
 				i = input.items.begin();
-				i != input.items.end(); i++)
-		{
-			if(!i->empty())
-			{
+				i != input.items.end(); i++) {
+			if (!i->empty()) {
 				all_empty = false;
 				break;
 			}
 		}
-		if(all_empty)
+		if (all_empty)
 			return false;
 
-		// Walk crafting definitions from back to front, so that later
-		// definitions can override earlier ones.
-		for(std::vector<CraftDefinition*>::const_reverse_iterator
-				i = m_craft_definitions.rbegin();
-				i != m_craft_definitions.rend(); i++)
-		{
-			CraftDefinition *def = *i;
+		std::vector<std::string> input_names;
+		input_names = craftGetItemNames(input.items, gamedef);
+		std::sort(input_names.begin(), input_names.end());
 
-			/*infostream<<"Checking "<<input.dump()<<std::endl
-					<<" against "<<def->dump()<<std::endl;*/
+		// Try hash types with increasing collision rate, and return if found.
+		for (int type = 0; type <= craft_hash_type_max; type++) {
+			u64 hash = getHashForGrid((CraftHashType) type, input_names);
 
-			try {
-				if(def->check(input, gamedef))
-				{
+			/*errorstream << "Checking type " << type << " with hash " << hash << std::endl;*/
+
+			// We'd like to do "const [...] hash_collisions = m_craft_defs[type][hash];"
+			// but that doesn't compile for some reason. This does.
+			std::map<u64, std::vector<CraftDefinition*> >::const_iterator
+				col_iter = (m_craft_defs[type]).find(hash);
+
+			if (col_iter == (m_craft_defs[type]).end())
+				continue;
+
+			const std::vector<CraftDefinition*> &hash_collisions = col_iter->second;
+			// Walk crafting definitions from back to front, so that later
+			// definitions can override earlier ones.
+			for (std::vector<CraftDefinition*>::const_reverse_iterator
+					i = hash_collisions.rbegin();
+					i != hash_collisions.rend(); i++) {
+				CraftDefinition *def = *i;
+
+				/*errorstream << "Checking " << input.dump() << std::endl
+					<< " against " << def->dump() << std::endl;*/
+
+				if (def->check(input, gamedef)) {
 					// Get output, then decrement input (if requested)
 					output = def->getOutput(input, gamedef);
-					if(decrementInput)
+					if (decrementInput)
 						def->decrementInput(input, gamedef);
+					/*errorstream << "Check RETURNS TRUE" << std::endl;*/
 					return true;
 				}
 			}
-			catch(SerializationError &e)
-			{
-				errorstream<<"getCraftResult: ERROR: "
-						<<"Serialization error in recipe "
-						<<def->dump()<<std::endl;
-				// then go on with the next craft definition
-			}
 		}
 		return false;
 	}
@@ -960,12 +1151,16 @@ public:
 	virtual std::string dump() const
 	{
 		std::ostringstream os(std::ios::binary);
-		os<<"Crafting definitions:\n";
-		for(std::vector<CraftDefinition*>::const_iterator
-				i = m_craft_definitions.begin();
-				i != m_craft_definitions.end(); i++)
-		{
-			os<<(*i)->dump()<<"\n";
+		os << "Crafting definitions:\n";
+		for (int type = 0; type <= craft_hash_type_max; type++) {
+			for (std::map<u64, std::vector<CraftDefinition*> >::const_iterator
+					i = (m_craft_defs[type]).begin();
+					i != (m_craft_defs[type]).end(); i++) {
+				for (std::vector<CraftDefinition*>::const_iterator
+						ii = i->second.begin(); ii != i->second.end(); ii++) {
+					os << "type " << type << " hash " << i->first << (*ii)->dump() << "\n";
+				}
+			}
 		}
 		return os.str();
 	}
@@ -973,7 +1168,7 @@ public:
 	{
 		verbosestream<<"registerCraft: registering craft definition: "
 				<<def->dump()<<std::endl;
-		m_craft_definitions.push_back(def);
+		m_craft_defs[(int) CRAFT_HASH_TYPE_UNHASHED][0].push_back(def);
 
 		CraftInput input;
 		std::string output_name = craftGetItemName(
@@ -982,48 +1177,41 @@ public:
 	}
 	virtual void clear()
 	{
-		for(std::vector<CraftDefinition*>::iterator
-				i = m_craft_definitions.begin();
-				i != m_craft_definitions.end(); i++){
-			delete *i;
+		for (int type = 0; type <= craft_hash_type_max; type++) {
+			for (std::map<u64, std::vector<CraftDefinition*> >::iterator
+					i = m_craft_defs[type].begin();
+					i != m_craft_defs[type].end(); i++) {
+				for (std::vector<CraftDefinition*>::iterator
+						ii = i->second.begin(); ii != i->second.end(); ii++) {
+					delete *ii;
+				}
+				i->second.clear();
+			}
+			m_craft_defs[type].clear();
 		}
-		m_craft_definitions.clear();
 		m_output_craft_definitions.clear();
 	}
-	virtual void serialize(std::ostream &os) const
+	virtual void initHashes(IGameDef *gamedef)
 	{
-		writeU8(os, 0); // version
-		u16 count = m_craft_definitions.size();
-		writeU16(os, count);
-		for(std::vector<CraftDefinition*>::const_iterator
-				i = m_craft_definitions.begin();
-				i != m_craft_definitions.end(); i++){
+		// Move the CraftDefs from the unhashed layer into layers higher up.
+		for (std::vector<CraftDefinition*>::iterator
+			i = (m_craft_defs[(int) CRAFT_HASH_TYPE_UNHASHED][0]).begin();
+			i != (m_craft_defs[(int) CRAFT_HASH_TYPE_UNHASHED][0]).end(); i++) {
 			CraftDefinition *def = *i;
-			// Serialize wrapped in a string
-			std::ostringstream tmp_os(std::ios::binary);
-			def->serialize(tmp_os);
-			os<<serializeString(tmp_os.str());
-		}
-	}
-	virtual void deSerialize(std::istream &is, IGameDef *gamedef)
-	{
-		// Clear everything
-		clear();
-		// Deserialize
-		int version = readU8(is);
-		if(version != 0) throw SerializationError(
-				"unsupported CraftDefManager version");
-		u16 count = readU16(is);
-		for(u16 i=0; i<count; i++){
-			// Deserialize a string and grab a CraftDefinition from it
-			std::istringstream tmp_is(deSerializeString(is), std::ios::binary);
-			CraftDefinition *def = CraftDefinition::deSerialize(tmp_is);
-			// Register
-			registerCraft(def, gamedef);
+
+			// Initialize and get the definition's hash
+			def->initHash(gamedef);
+			CraftHashType type = def->getHashType();
+			u64 hash = def->getHash(type);
+
+			// Enter the definition
+			m_craft_defs[type][hash].push_back(def);
 		}
+		m_craft_defs[(int) CRAFT_HASH_TYPE_UNHASHED][0].clear();
 	}
 private:
-	std::vector<CraftDefinition*> m_craft_definitions;
+	//TODO: change both maps to unordered_map when c++11 can be used
+	std::vector<std::map<u64, std::vector<CraftDefinition*> > > m_craft_defs;
 	std::map<std::string, std::vector<CraftDefinition*> > m_output_craft_definitions;
 };
 
diff --git a/src/craftdef.h b/src/craftdef.h
index 7902a2e27..cc7a0619c 100644
--- a/src/craftdef.h
+++ b/src/craftdef.h
@@ -44,6 +44,28 @@ enum CraftMethod
 };
 
 /*
+	The type a hash can be. The earlier a type is mentioned in this enum,
+	the earlier it is tried at crafting, and the less likely is a collision.
+	Changing order causes changes in behaviour, so know what you do.
+ */
+enum CraftHashType
+{
+	// Hashes the normalized names of the recipe's elements.
+	// Only recipes without group usage can be found here,
+	// because groups can't be guessed efficiently.
+	CRAFT_HASH_TYPE_ITEM_NAMES,
+
+	// Counts the non-empty slots.
+	CRAFT_HASH_TYPE_COUNT,
+
+	// This layer both spares an extra variable, and helps to retain (albeit rarely used) functionality. Maps to 0.
+	// Before hashes are "initialized", all hashes reside here, after initialisation, none are.
+	CRAFT_HASH_TYPE_UNHASHED
+
+};
+const int craft_hash_type_max = (int) CRAFT_HASH_TYPE_UNHASHED;
+
+/*
 	Input: The contents of the crafting slots, arranged in matrix form
 */
 struct CraftInput
@@ -135,8 +157,13 @@ public:
 	// Decreases count of every input item
 	virtual void decrementInput(CraftInput &input, IGameDef *gamedef) const=0;
 
-	virtual std::string dump() const=0;
+	virtual CraftHashType getHashType() const = 0;
+	virtual u64 getHash(CraftHashType type) const = 0;
+
+	// to be called after all mods are loaded, so that we catch all aliases
+	virtual void initHash(IGameDef *gamedef) = 0;
 
+	virtual std::string dump() const=0;
 protected:
 	virtual void serializeBody(std::ostream &os) const=0;
 	virtual void deSerializeBody(std::istream &is, int version)=0;
@@ -152,14 +179,15 @@ class CraftDefinitionShaped: public CraftDefinition
 {
 public:
 	CraftDefinitionShaped():
-		output(""), width(1), recipe(), replacements()
+		output(""), width(1), recipe(), hash_inited(false), replacements()
 	{}
 	CraftDefinitionShaped(
 			const std::string &output_,
 			unsigned int width_,
 			const std::vector<std::string> &recipe_,
 			const CraftReplacements &replacements_):
-		output(output_), width(width_), recipe(recipe_), replacements(replacements_)
+		output(output_), width(width_), recipe(recipe_),
+		hash_inited(false), replacements(replacements_)
 	{}
 	virtual ~CraftDefinitionShaped(){}
 
@@ -169,6 +197,11 @@ public:
 	virtual CraftInput getInput(const CraftOutput &output, IGameDef *gamedef) const;
 	virtual void decrementInput(CraftInput &input, IGameDef *gamedef) const;
 
+	virtual CraftHashType getHashType() const;
+	virtual u64 getHash(CraftHashType type) const;
+
+	virtual void initHash(IGameDef *gamedef);
+
 	virtual std::string dump() const;
 
 protected:
@@ -182,6 +215,10 @@ private:
 	unsigned int width;
 	// Recipe matrix (itemstrings)
 	std::vector<std::string> recipe;
+	// Recipe matrix (item names)
+	std::vector<std::string> recipe_names;
+	// bool indicating if initHash has been called already
+	bool hash_inited;
 	// Replacement items for decrementInput()
 	CraftReplacements replacements;
 };
@@ -195,13 +232,14 @@ class CraftDefinitionShapeless: public CraftDefinition
 {
 public:
 	CraftDefinitionShapeless():
-		output(""), recipe(), replacements()
+		output(""), recipe(), hash_inited(false), replacements()
 	{}
 	CraftDefinitionShapeless(
 			const std::string &output_,
 			const std::vector<std::string> &recipe_,
 			const CraftReplacements &replacements_):
-		output(output_), recipe(recipe_), replacements(replacements_)
+		output(output_), recipe(recipe_),
+		hash_inited(false), replacements(replacements_)
 	{}
 	virtual ~CraftDefinitionShapeless(){}
 
@@ -211,6 +249,11 @@ public:
 	virtual CraftInput getInput(const CraftOutput &output, IGameDef *gamedef) const;
 	virtual void decrementInput(CraftInput &input, IGameDef *gamedef) const;
 
+	virtual CraftHashType getHashType() const;
+	virtual u64 getHash(CraftHashType type) const;
+
+	virtual void initHash(IGameDef *gamedef);
+
 	virtual std::string dump() const;
 
 protected:
@@ -222,6 +265,10 @@ private:
 	std::string output;
 	// Recipe list (itemstrings)
 	std::vector<std::string> recipe;
+	// Recipe list (item names)
+	std::vector<std::string> recipe_names;
+	// bool indicating if initHash has been called already
+	bool hash_inited;
 	// Replacement items for decrementInput()
 	CraftReplacements replacements;
 };
@@ -249,6 +296,11 @@ public:
 	virtual CraftInput getInput(const CraftOutput &output, IGameDef *gamedef) const;
 	virtual void decrementInput(CraftInput &input, IGameDef *gamedef) const;
 
+	virtual CraftHashType getHashType() const { return CRAFT_HASH_TYPE_COUNT; }
+	virtual u64 getHash(CraftHashType type) const { return 2; }
+
+	virtual void initHash(IGameDef *gamedef) {}
+
 	virtual std::string dump() const;
 
 protected:
@@ -272,14 +324,15 @@ class CraftDefinitionCooking: public CraftDefinition
 {
 public:
 	CraftDefinitionCooking():
-		output(""), recipe(""), cooktime()
+		output(""), recipe(""), hash_inited(false), cooktime()
 	{}
 	CraftDefinitionCooking(
 			const std::string &output_,
 			const std::string &recipe_,
 			float cooktime_,
 			const CraftReplacements &replacements_):
-		output(output_), recipe(recipe_), cooktime(cooktime_), replacements(replacements_)
+		output(output_), recipe(recipe_), hash_inited(false),
+		cooktime(cooktime_), replacements(replacements_)
 	{}
 	virtual ~CraftDefinitionCooking(){}
 
@@ -289,6 +342,11 @@ public:
 	virtual CraftInput getInput(const CraftOutput &output, IGameDef *gamedef) const;
 	virtual void decrementInput(CraftInput &input, IGameDef *gamedef) const;
 
+	virtual CraftHashType getHashType() const;
+	virtual u64 getHash(CraftHashType type) const;
+
+	virtual void initHash(IGameDef *gamedef);
+
 	virtual std::string dump() const;
 
 protected:
@@ -300,6 +358,10 @@ private:
 	std::string output;
 	// Recipe itemstring
 	std::string recipe;
+	// Recipe item name
+	std::string recipe_name;
+	// bool indicating if initHash has been called already
+	bool hash_inited;
 	// Time in seconds
 	float cooktime;
 	// Replacement items for decrementInput()
@@ -314,12 +376,12 @@ class CraftDefinitionFuel: public CraftDefinition
 {
 public:
 	CraftDefinitionFuel():
-		recipe(""), burntime()
+		recipe(""), hash_inited(false), burntime()
 	{}
 	CraftDefinitionFuel(std::string recipe_,
 			float burntime_,
 			const CraftReplacements &replacements_):
-		recipe(recipe_), burntime(burntime_), replacements(replacements_)
+		recipe(recipe_), hash_inited(false), burntime(burntime_), replacements(replacements_)
 	{}
 	virtual ~CraftDefinitionFuel(){}
 
@@ -329,6 +391,11 @@ public:
 	virtual CraftInput getInput(const CraftOutput &output, IGameDef *gamedef) const;
 	virtual void decrementInput(CraftInput &input, IGameDef *gamedef) const;
 
+	virtual CraftHashType getHashType() const;
+	virtual u64 getHash(CraftHashType type) const;
+
+	virtual void initHash(IGameDef *gamedef);
+
 	virtual std::string dump() const;
 
 protected:
@@ -338,6 +405,10 @@ protected:
 private:
 	// Recipe itemstring
 	std::string recipe;
+	// Recipe item name
+	std::string recipe_name;
+	// bool indicating if initHash has been called already
+	bool hash_inited;
 	// Time in seconds
 	float burntime;
 	// Replacement items for decrementInput()
@@ -361,8 +432,6 @@ public:
 	
 	// Print crafting recipes for debugging
 	virtual std::string dump() const=0;
-
-	virtual void serialize(std::ostream &os) const=0;
 };
 
 class IWritableCraftDefManager : public ICraftDefManager
@@ -383,11 +452,12 @@ public:
 	// Add a crafting definition.
 	// After calling this, the pointer belongs to the manager.
 	virtual void registerCraft(CraftDefinition *def, IGameDef *gamedef) = 0;
+
 	// Delete all crafting definitions
 	virtual void clear()=0;
 
-	virtual void serialize(std::ostream &os) const=0;
-	virtual void deSerialize(std::istream &is, IGameDef *gamedef) = 0;
+	// To be called after all mods are loaded, so that we catch all aliases
+	virtual void initHashes(IGameDef *gamedef) = 0;
 };
 
 IWritableCraftDefManager* createCraftDefManager();
diff --git a/src/server.cpp b/src/server.cpp
index 1969a5946..4971e6f66 100644
--- a/src/server.cpp
+++ b/src/server.cpp
@@ -334,6 +334,9 @@ Server::Server(
 	// Perform pending node name resolutions
 	m_nodedef->runNodeResolverCallbacks();
 
+	// init the recipe hashes to speed up crafting
+	m_craftdef->initHashes(this);
+
 	// Initialize Environment
 	m_env = new ServerEnvironment(servermap, m_script, this, m_path_world);