Introduce std::string_view into wider use (#14368)

src/database/database-dummy.cpp

@@ -25,7 +25,7 @@ Dummy database class
 #include "remoteplayer.h"
 
 
-bool Database_Dummy::saveBlock(const v3s16 &pos, const std::string &data)
+bool Database_Dummy::saveBlock(const v3s16 &pos, std::string_view data)
 {
 	m_database[getBlockAsInteger(pos)] = data;
 	return true;
@@ -128,11 +128,12 @@ bool Database_Dummy::hasModEntry(const std::string &modname, const std::string &
 }
 
 bool Database_Dummy::setModEntry(const std::string &modname,
-	const std::string &key, const std::string &value)
+	const std::string &key, std::string_view value)
 {
 	auto mod_pair = m_mod_storage_database.find(modname);
 	if (mod_pair == m_mod_storage_database.end()) {
-		m_mod_storage_database[modname] = StringMap({{key, value}});
+		auto &map = m_mod_storage_database[modname];
+		map[key] = value;
 	} else {
 		mod_pair->second[key] = value;
 	}

src/database/database-dummy.h

@@ -20,6 +20,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #pragma once
 
 #include <map>
+#include <set>
 #include <string>
 #include "database.h"
 #include "irrlichttypes.h"
@@ -27,7 +28,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 class Database_Dummy : public MapDatabase, public PlayerDatabase, public ModStorageDatabase
 {
 public:
-	bool saveBlock(const v3s16 &pos, const std::string &data);
+	bool saveBlock(const v3s16 &pos, std::string_view data);
 	void loadBlock(const v3s16 &pos, std::string *block);
 	bool deleteBlock(const v3s16 &pos);
 	void listAllLoadableBlocks(std::vector<v3s16> &dst);
@@ -43,7 +44,7 @@ public:
 			const std::string &key, std::string *value);
 	bool hasModEntry(const std::string &modname, const std::string &key);
 	bool setModEntry(const std::string &modname,
-			const std::string &key, const std::string &value);
+			const std::string &key,std::string_view value);
 	bool removeModEntry(const std::string &modname, const std::string &key);
 	bool removeModEntries(const std::string &modname);
 	void listMods(std::vector<std::string> *res);

src/database/database-files.cpp

@@ -428,13 +428,14 @@ bool ModStorageDatabaseFiles::hasModEntry(const std::string &modname, const std:
 }
 
 bool ModStorageDatabaseFiles::setModEntry(const std::string &modname,
-	const std::string &key, const std::string &value)
+	const std::string &key, std::string_view value)
 {
 	Json::Value *meta = getOrCreateJson(modname);
 	if (!meta)
 		return false;
 
-	(*meta)[key] = Json::Value(value);
+	Json::Value value_v(value.data(), value.data() + value.size());
+	(*meta)[key] = std::move(value_v);
 	m_modified.insert(modname);
 
 	return true;

src/database/database-files.h

@@ -84,7 +84,7 @@ public:
 		const std::string &key, std::string *value);
 	virtual bool hasModEntry(const std::string &modname, const std::string &key);
 	virtual bool setModEntry(const std::string &modname,
-		const std::string &key, const std::string &value);
+		const std::string &key, std::string_view value);
 	virtual bool removeModEntry(const std::string &modname, const std::string &key);
 	virtual bool removeModEntries(const std::string &modname);
 	virtual void listMods(std::vector<std::string> *res);

src/database/database-leveldb.cpp

@@ -53,10 +53,11 @@ Database_LevelDB::Database_LevelDB(const std::string &savedir)
 	m_database.reset(db);
 }
 
-bool Database_LevelDB::saveBlock(const v3s16 &pos, const std::string &data)
+bool Database_LevelDB::saveBlock(const v3s16 &pos, std::string_view data)
 {
+	leveldb::Slice data_s(data.data(), data.size());
 	leveldb::Status status = m_database->Put(leveldb::WriteOptions(),
-			i64tos(getBlockAsInteger(pos)), data);
+			i64tos(getBlockAsInteger(pos)), data_s);
 	if (!status.ok()) {
 		warningstream << "saveBlock: LevelDB error saving block "
 			<< pos << ": " << status.ToString() << std::endl;

src/database/database-leveldb.h

@@ -34,7 +34,7 @@ public:
 	Database_LevelDB(const std::string &savedir);
 	~Database_LevelDB() = default;
 
-	bool saveBlock(const v3s16 &pos, const std::string &data);
+	bool saveBlock(const v3s16 &pos, std::string_view data);
 	void loadBlock(const v3s16 &pos, std::string *block);
 	bool deleteBlock(const v3s16 &pos);
 	void listAllLoadableBlocks(std::vector<v3s16> &dst);

src/database/database-postgresql.cpp

@@ -223,7 +223,7 @@ void MapDatabasePostgreSQL::initStatements()
 		"SELECT posX, posY, posZ FROM blocks");
 }
 
-bool MapDatabasePostgreSQL::saveBlock(const v3s16 &pos, const std::string &data)
+bool MapDatabasePostgreSQL::saveBlock(const v3s16 &pos, std::string_view data)
 {
 	// Verify if we don't overflow the platform integer with the mapblock size
 	if (data.size() > INT_MAX) {
@@ -240,7 +240,7 @@ bool MapDatabasePostgreSQL::saveBlock(const v3s16 &pos, const std::string &data)
 	y = htonl(pos.Y);
 	z = htonl(pos.Z);
 
-	const void *args[] = { &x, &y, &z, data.c_str() };
+	const void *args[] = { &x, &y, &z, data.data() };
 	const int argLen[] = {
 		sizeof(x), sizeof(y), sizeof(z), (int)data.size()
 	};
@@ -940,11 +940,11 @@ bool ModStorageDatabasePostgreSQL::hasModEntry(const std::string &modname,
 }
 
 bool ModStorageDatabasePostgreSQL::setModEntry(const std::string &modname,
-	const std::string &key, const std::string &value)
+	const std::string &key, std::string_view value)
 {
 	verifyDatabase();
 
-	const void *args[] = { modname.c_str(), key.c_str(), value.c_str() };
+	const void *args[] = { modname.c_str(), key.c_str(), value.data() };
 	const int argLen[] = {
 		-1,
 		(int)MYMIN(key.size(), INT_MAX),

src/database/database-postgresql.h

@@ -120,7 +120,7 @@ public:
 	MapDatabasePostgreSQL(const std::string &connect_string);
 	virtual ~MapDatabasePostgreSQL() = default;
 
-	bool saveBlock(const v3s16 &pos, const std::string &data);
+	bool saveBlock(const v3s16 &pos, std::string_view data);
 	void loadBlock(const v3s16 &pos, std::string *block);
 	bool deleteBlock(const v3s16 &pos);
 	void listAllLoadableBlocks(std::vector<v3s16> &dst);
@@ -186,7 +186,7 @@ public:
 	bool getModEntry(const std::string &modname, const std::string &key, std::string *value);
 	bool hasModEntry(const std::string &modname, const std::string &key);
 	bool setModEntry(const std::string &modname,
-			const std::string &key, const std::string &value);
+			const std::string &key, std::string_view value);
 	bool removeModEntry(const std::string &modname, const std::string &key);
 	bool removeModEntries(const std::string &modname);
 	void listMods(std::vector<std::string> *res);

src/database/database-redis.cpp

@@ -91,12 +91,12 @@ void Database_Redis::endSave() {
 	freeReplyObject(reply);
 }
 
-bool Database_Redis::saveBlock(const v3s16 &pos, const std::string &data)
+bool Database_Redis::saveBlock(const v3s16 &pos, std::string_view data)
 {
 	std::string tmp = i64tos(getBlockAsInteger(pos));
 
 	redisReply *reply = static_cast<redisReply *>(redisCommand(ctx, "HSET %s %s %b",
-			hash.c_str(), tmp.c_str(), data.c_str(), data.size()));
+			hash.c_str(), tmp.c_str(), data.data(), data.size()));
 	if (!reply) {
 		warningstream << "saveBlock: redis command 'HSET' failed on "
 			"block " << pos << ": " << ctx->errstr << std::endl;

src/database/database-redis.h

@@ -38,7 +38,7 @@ public:
 	void beginSave();
 	void endSave();
 
-	bool saveBlock(const v3s16 &pos, const std::string &data);
+	bool saveBlock(const v3s16 &pos, std::string_view data);
 	void loadBlock(const v3s16 &pos, std::string *block);
 	bool deleteBlock(const v3s16 &pos);
 	void listAllLoadableBlocks(std::vector<v3s16> &dst);

src/database/database-sqlite3.cpp

@@ -258,7 +258,7 @@ bool MapDatabaseSQLite3::deleteBlock(const v3s16 &pos)
 	return good;
 }
 
-bool MapDatabaseSQLite3::saveBlock(const v3s16 &pos, const std::string &data)
+bool MapDatabaseSQLite3::saveBlock(const v3s16 &pos, std::string_view data)
 {
 	verifyDatabase();
 
@@ -283,13 +283,8 @@ void MapDatabaseSQLite3::loadBlock(const v3s16 &pos, std::string *block)
 		return;
 	}
 
-	const char *data = (const char *) sqlite3_column_blob(m_stmt_read, 0);
-	size_t len = sqlite3_column_bytes(m_stmt_read, 0);
-
-	if (data)
-		block->assign(data, len);
-	else
-		block->clear();
+	auto data = sqlite_to_blob(m_stmt_read, 0);
+	block->assign(data);
 
 	sqlite3_step(m_stmt_read);
 	// We should never get more than 1 row, so ok to reset
@@ -553,7 +548,7 @@ bool PlayerDatabaseSQLite3::loadPlayer(RemotePlayer *player, PlayerSAO *sao)
 		int_to_sqlite(m_stmt_player_load_inventory_items, 2, invId);
 		while (sqlite3_step(m_stmt_player_load_inventory_items) == SQLITE_ROW) {
 			const std::string itemStr = sqlite_to_string(m_stmt_player_load_inventory_items, 1);
-			if (itemStr.length() > 0) {
+			if (!itemStr.empty()) {
 				ItemStack stack;
 				stack.deSerialize(itemStr);
 				invList->changeItem(sqlite_to_uint(m_stmt_player_load_inventory_items, 0), stack);
@@ -567,7 +562,7 @@ bool PlayerDatabaseSQLite3::loadPlayer(RemotePlayer *player, PlayerSAO *sao)
 	str_to_sqlite(m_stmt_player_metadata_load, 1, sao->getPlayer()->getName());
 	while (sqlite3_step(m_stmt_player_metadata_load) == SQLITE_ROW) {
 		std::string attr = sqlite_to_string(m_stmt_player_metadata_load, 0);
-		std::string value = sqlite_to_string(m_stmt_player_metadata_load, 1);
+		auto value = sqlite_to_string_view(m_stmt_player_metadata_load, 1);
 
 		sao->getMeta().setString(attr, value);
 	}
@@ -592,7 +587,7 @@ void PlayerDatabaseSQLite3::listPlayers(std::vector<std::string> &res)
 	verifyDatabase();
 
 	while (sqlite3_step(m_stmt_player_list) == SQLITE_ROW)
-		res.push_back(sqlite_to_string(m_stmt_player_list, 0));
+		res.emplace_back(sqlite_to_string_view(m_stmt_player_list, 0));
 
 	sqlite3_reset(m_stmt_player_list);
 }
@@ -669,14 +664,14 @@ bool AuthDatabaseSQLite3::getAuth(const std::string &name, AuthEntry &res)
 		return false;
 	}
 	res.id = sqlite_to_uint(m_stmt_read, 0);
-	res.name = sqlite_to_string(m_stmt_read, 1);
-	res.password = sqlite_to_string(m_stmt_read, 2);
+	res.name = sqlite_to_string_view(m_stmt_read, 1);
+	res.password = sqlite_to_string_view(m_stmt_read, 2);
 	res.last_login = sqlite_to_int64(m_stmt_read, 3);
 	sqlite3_reset(m_stmt_read);
 
 	int64_to_sqlite(m_stmt_read_privs, 1, res.id);
 	while (sqlite3_step(m_stmt_read_privs) == SQLITE_ROW) {
-		res.privileges.emplace_back(sqlite_to_string(m_stmt_read_privs, 0));
+		res.privileges.emplace_back(sqlite_to_string_view(m_stmt_read_privs, 0));
 	}
 	sqlite3_reset(m_stmt_read_privs);
 
@@ -741,7 +736,7 @@ void AuthDatabaseSQLite3::listNames(std::vector<std::string> &res)
 	verifyDatabase();
 
 	while (sqlite3_step(m_stmt_list_names) == SQLITE_ROW) {
-		res.push_back(sqlite_to_string(m_stmt_list_names, 0));
+		res.emplace_back(sqlite_to_string_view(m_stmt_list_names, 0));
 	}
 	sqlite3_reset(m_stmt_list_names);
 }
@@ -815,11 +810,9 @@ void ModStorageDatabaseSQLite3::getModEntries(const std::string &modname, String
 
 	str_to_sqlite(m_stmt_get_all, 1, modname);
 	while (sqlite3_step(m_stmt_get_all) == SQLITE_ROW) {
-		const char *key_data = (const char *) sqlite3_column_blob(m_stmt_get_all, 0);
-		size_t key_len = sqlite3_column_bytes(m_stmt_get_all, 0);
-		const char *value_data = (const char *) sqlite3_column_blob(m_stmt_get_all, 1);
-		size_t value_len = sqlite3_column_bytes(m_stmt_get_all, 1);
-		(*storage)[std::string(key_data, key_len)] = std::string(value_data, value_len);
+		auto key = sqlite_to_blob(m_stmt_get_all, 0);
+		auto value = sqlite_to_blob(m_stmt_get_all, 1);
+		(*storage)[std::string(key)].assign(value);
 	}
 	sqlite3_vrfy(sqlite3_errcode(m_database), SQLITE_DONE);
 
@@ -833,9 +826,8 @@ void ModStorageDatabaseSQLite3::getModKeys(const std::string &modname,
 
 	str_to_sqlite(m_stmt_get_keys, 1, modname);
 	while (sqlite3_step(m_stmt_get_keys) == SQLITE_ROW) {
-		const char *key_data = (const char *) sqlite3_column_blob(m_stmt_get_keys, 0);
-		size_t key_len = sqlite3_column_bytes(m_stmt_get_keys, 0);
-		storage->emplace_back(key_data, key_len);
+		auto key = sqlite_to_blob(m_stmt_get_keys, 0);
+		storage->emplace_back(key);
 	}
 	sqlite3_vrfy(sqlite3_errcode(m_database), SQLITE_DONE);
 
@@ -852,9 +844,8 @@ bool ModStorageDatabaseSQLite3::getModEntry(const std::string &modname,
 		"Internal error: failed to bind query at " __FILE__ ":" TOSTRING(__LINE__));
 	bool found = sqlite3_step(m_stmt_get) == SQLITE_ROW;
 	if (found) {
-		const char *value_data = (const char *) sqlite3_column_blob(m_stmt_get, 0);
-		size_t value_len = sqlite3_column_bytes(m_stmt_get, 0);
-		value->assign(value_data, value_len);
+		auto sv = sqlite_to_blob(m_stmt_get, 0);
+		value->assign(sv);
 		sqlite3_step(m_stmt_get);
 	}
 
@@ -881,7 +872,7 @@ bool ModStorageDatabaseSQLite3::hasModEntry(const std::string &modname,
 }
 
 bool ModStorageDatabaseSQLite3::setModEntry(const std::string &modname,
-	const std::string &key, const std::string &value)
+	const std::string &key, std::string_view value)
 {
 	verifyDatabase();
 

src/database/database-sqlite3.h

@@ -44,14 +44,9 @@ protected:
 	void verifyDatabase();
 
 	// Convertors
-	inline void str_to_sqlite(sqlite3_stmt *s, int iCol, const std::string &str) const
+	inline void str_to_sqlite(sqlite3_stmt *s, int iCol, std::string_view str) const
 	{
-		sqlite3_vrfy(sqlite3_bind_text(s, iCol, str.c_str(), str.size(), NULL));
-	}
-
-	inline void str_to_sqlite(sqlite3_stmt *s, int iCol, const char *str) const
-	{
-		sqlite3_vrfy(sqlite3_bind_text(s, iCol, str, strlen(str), NULL));
+		sqlite3_vrfy(sqlite3_bind_text(s, iCol, str.data(), str.size(), NULL));
 	}
 
 	inline void int_to_sqlite(sqlite3_stmt *s, int iCol, int val) const
@@ -69,10 +64,28 @@ protected:
 		sqlite3_vrfy(sqlite3_bind_double(s, iCol, val));
 	}
 
-	inline std::string sqlite_to_string(sqlite3_stmt *s, int iCol)
+	// Note that the return value is only valid until the statement is stepped or reset.
+	inline std::string_view sqlite_to_string_view(sqlite3_stmt *s, int iCol)
 	{
 		const char* text = reinterpret_cast<const char*>(sqlite3_column_text(s, iCol));
-		return std::string(text ? text : "");
+		return text ? std::string_view(text) : std::string_view();
+	}
+
+	// Avoid using this in favor of `sqlite_to_string_view`.
+	inline std::string sqlite_to_string(sqlite3_stmt *s, int iCol)
+	{
+		return std::string(sqlite_to_string_view(s, iCol));
+	}
+
+	// Converts a BLOB-type column into a string_view (null byte safe).
+	// Note that the return value is only valid until the statement is stepped or reset.
+	inline std::string_view sqlite_to_blob(sqlite3_stmt *s, int iCol)
+	{
+		const char *data = reinterpret_cast<const char*>(sqlite3_column_blob(s, iCol));
+		if (!data)
+			return std::string_view();
+		size_t len = sqlite3_column_bytes(s, iCol);
+		return std::string_view(data, len);
 	}
 
 	inline s32 sqlite_to_int(sqlite3_stmt *s, int iCol)
@@ -107,13 +120,16 @@ protected:
 	}
 
 	// Query verifiers helpers
-	inline void sqlite3_vrfy(int s, const std::string &m = "", int r = SQLITE_OK) const
+	inline void sqlite3_vrfy(int s, std::string_view m = "", int r = SQLITE_OK) const
 	{
-		if (s != r)
-			throw DatabaseException(m + ": " + sqlite3_errmsg(m_database));
+		if (s != r) {
+			std::string msg(m);
+			msg.append(": ").append(sqlite3_errmsg(m_database));
+			throw DatabaseException(msg);
+		}
 	}
 
-	inline void sqlite3_vrfy(const int s, const int r, const std::string &m = "") const
+	inline void sqlite3_vrfy(const int s, const int r, std::string_view m = "") const
 	{
 		sqlite3_vrfy(s, m, r);
 	}
@@ -146,7 +162,7 @@ public:
 	MapDatabaseSQLite3(const std::string &savedir);
 	virtual ~MapDatabaseSQLite3();
 
-	bool saveBlock(const v3s16 &pos, const std::string &data);
+	bool saveBlock(const v3s16 &pos, std::string_view data);
 	void loadBlock(const v3s16 &pos, std::string *block);
 	bool deleteBlock(const v3s16 &pos);
 	void listAllLoadableBlocks(std::vector<v3s16> &dst);
@@ -245,7 +261,7 @@ public:
 		const std::string &key, std::string *value);
 	virtual bool hasModEntry(const std::string &modname, const std::string &key);
 	virtual bool setModEntry(const std::string &modname,
-		const std::string &key, const std::string &value);
+		const std::string &key,std::string_view value);
 	virtual bool removeModEntry(const std::string &modname, const std::string &key);
 	virtual bool removeModEntries(const std::string &modname);
 	virtual void listMods(std::vector<std::string> *res);

src/database/database.h

@@ -19,12 +19,11 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #pragma once
 
-#include <set>
 #include <string>
+#include <string_view>
 #include <vector>
 #include "irr_v3d.h"
 #include "irrlichttypes.h"
-#include "util/basic_macros.h"
 #include "util/string.h"
 
 class Database
@@ -40,7 +39,7 @@ class MapDatabase : public Database
 public:
 	virtual ~MapDatabase() = default;
 
-	virtual bool saveBlock(const v3s16 &pos, const std::string &data) = 0;
+	virtual bool saveBlock(const v3s16 &pos, std::string_view data) = 0;
 	virtual void loadBlock(const v3s16 &pos, std::string *block) = 0;
 	virtual bool deleteBlock(const v3s16 &pos) = 0;
 
@@ -97,7 +96,7 @@ public:
 	virtual bool getModEntry(const std::string &modname,
 		const std::string &key, std::string *value) = 0;
 	virtual bool setModEntry(const std::string &modname,
-		const std::string &key, const std::string &value) = 0;
+		const std::string &key, std::string_view value) = 0;
 	virtual bool removeModEntry(const std::string &modname, const std::string &key) = 0;
 	virtual bool removeModEntries(const std::string &modname) = 0;
 	virtual void listMods(std::vector<std::string> *res) = 0;