From 58841ef12f6cba1bb622353c1fcaa0e3c6fb46c9 Mon Sep 17 00:00:00 2001
From: Ilya Zhuravlev <zhuravlevilya@ya.ru>
Date: Tue, 23 Oct 2012 01:18:44 +0400
Subject: Add dummy and LevelDB database backends

---
 src/map.cpp | 263 +++++++++---------------------------------------------------
 1 file changed, 39 insertions(+), 224 deletions(-)

(limited to 'src/map.cpp')

diff --git a/src/map.cpp b/src/map.cpp
index 457db14da..e2191f9e1 100644
--- a/src/map.cpp
+++ b/src/map.cpp
@@ -38,6 +38,12 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "emerge.h"
 #include "mapgen_v6.h"
 #include "biome.h"
+#include "database.h"
+#include "database-dummy.h"
+#include "database-sqlite3.h"
+#if USE_LEVELDB
+#include "database-leveldb.h"
+#endif
 
 #define PP(x) "("<<(x).X<<","<<(x).Y<<","<<(x).Z<<")"
 
@@ -2401,10 +2407,7 @@ s16 Map::getHumidity(v3s16 p)
 ServerMap::ServerMap(std::string savedir, IGameDef *gamedef, EmergeManager *emerge):
 	Map(dout_server, gamedef),
 	m_seed(0),
-	m_map_metadata_changed(true),
-	m_database(NULL),
-	m_database_read(NULL),
-	m_database_write(NULL)
+	m_map_metadata_changed(true)
 {
 	verbosestream<<__FUNCTION_NAME<<std::endl;
 
@@ -2435,6 +2438,28 @@ ServerMap::ServerMap(std::string savedir, IGameDef *gamedef, EmergeManager *emer
 		Try to load map; if not found, create a new one.
 	*/
 
+	// Determine which database backend to use
+	std::string conf_path = savedir + DIR_DELIM + "world.mt";
+	Settings conf;
+	bool succeeded = conf.readConfigFile(conf_path.c_str());
+	if (!succeeded || !conf.exists("backend")) {
+		// fall back to sqlite3
+		dbase = new Database_SQLite3(this, savedir);
+		conf.set("backend", "sqlite3");
+	} else {
+		std::string backend = conf.get("backend");
+		if (backend == "dummy")
+			dbase = new Database_Dummy(this);
+		else if (backend == "sqlite3")
+			dbase = new Database_SQLite3(this, savedir);
+		#if USE_LEVELDB
+		else if (backend == "leveldb")
+			dbase = new Database_LevelDB(this, savedir);
+		#endif
+		else
+			throw BaseException("Unknown map backend");
+	}
+
 	m_savedir = savedir;
 	m_map_saving_enabled = false;
 
@@ -2526,12 +2551,7 @@ ServerMap::~ServerMap()
 	/*
 		Close database if it was opened
 	*/
-	if(m_database_read)
-		sqlite3_finalize(m_database_read);
-	if(m_database_write)
-		sqlite3_finalize(m_database_write);
-	if(m_database)
-		sqlite3_close(m_database);
+	delete(dbase);
 
 #if 0
 	/*
@@ -3167,81 +3187,12 @@ plan_b:
 	//return (s16)level;
 }
 
-void ServerMap::createDatabase() {
-	int e;
-	assert(m_database);
-	e = sqlite3_exec(m_database,
-		"CREATE TABLE IF NOT EXISTS `blocks` ("
-			"`pos` INT NOT NULL PRIMARY KEY,"
-			"`data` BLOB"
-		");"
-	, NULL, NULL, NULL);
-	if(e == SQLITE_ABORT)
-		throw FileNotGoodException("Could not create database structure");
-	else
-		infostream<<"ServerMap: Database structure was created";
-}
-
-void ServerMap::verifyDatabase() {
-	if(m_database)
-		return;
-
-	{
-		std::string dbp = m_savedir + DIR_DELIM + "map.sqlite";
-		bool needs_create = false;
-		int d;
-
-		/*
-			Open the database connection
-		*/
-
-		createDirs(m_savedir);
-
-		if(!fs::PathExists(dbp))
-			needs_create = true;
-
-		d = sqlite3_open_v2(dbp.c_str(), &m_database, SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE, NULL);
-		if(d != SQLITE_OK) {
-			infostream<<"WARNING: Database failed to open: "<<sqlite3_errmsg(m_database)<<std::endl;
-			throw FileNotGoodException("Cannot open database file");
-		}
-
-		if(needs_create)
-			createDatabase();
-
-		d = sqlite3_prepare(m_database, "SELECT `data` FROM `blocks` WHERE `pos`=? LIMIT 1", -1, &m_database_read, NULL);
-		if(d != SQLITE_OK) {
-			infostream<<"WARNING: Database read statment failed to prepare: "<<sqlite3_errmsg(m_database)<<std::endl;
-			throw FileNotGoodException("Cannot prepare read statement");
-		}
-
-		d = sqlite3_prepare(m_database, "REPLACE INTO `blocks` VALUES(?, ?)", -1, &m_database_write, NULL);
-		if(d != SQLITE_OK) {
-			infostream<<"WARNING: Database write statment failed to prepare: "<<sqlite3_errmsg(m_database)<<std::endl;
-			throw FileNotGoodException("Cannot prepare write statement");
-		}
-
-		d = sqlite3_prepare(m_database, "SELECT `pos` FROM `blocks`", -1, &m_database_list, NULL);
-		if(d != SQLITE_OK) {
-			infostream<<"WARNING: Database list statment failed to prepare: "<<sqlite3_errmsg(m_database)<<std::endl;
-			throw FileNotGoodException("Cannot prepare read statement");
-		}
-
-		infostream<<"ServerMap: Database opened"<<std::endl;
-	}
-}
-
 bool ServerMap::loadFromFolders() {
-	if(!m_database && !fs::PathExists(m_savedir + DIR_DELIM + "map.sqlite"))
+	if(!dbase->Initialized() && !fs::PathExists(m_savedir + DIR_DELIM + "map.sqlite")) // ?
 		return true;
 	return false;
 }
 
-sqlite3_int64 ServerMap::getBlockAsInteger(const v3s16 pos) {
-	return (sqlite3_int64)pos.Z*16777216 +
-		(sqlite3_int64)pos.Y*4096 + (sqlite3_int64)pos.X;
-}
-
 void ServerMap::createDirs(std::string path)
 {
 	if(fs::CreateAllDirs(path) == false)
@@ -3414,50 +3365,13 @@ void ServerMap::save(ModifiedState save_level)
 	}
 }
 
-static s32 unsignedToSigned(s32 i, s32 max_positive)
-{
-	if(i < max_positive)
-		return i;
-	else
-		return i - 2*max_positive;
-}
-
-// modulo of a negative number does not work consistently in C
-static sqlite3_int64 pythonmodulo(sqlite3_int64 i, sqlite3_int64 mod)
-{
-	if(i >= 0)
-		return i % mod;
-	return mod - ((-i) % mod);
-}
-
-v3s16 ServerMap::getIntegerAsBlock(sqlite3_int64 i)
-{
-	s32 x = unsignedToSigned(pythonmodulo(i, 4096), 2048);
-	i = (i - x) / 4096;
-	s32 y = unsignedToSigned(pythonmodulo(i, 4096), 2048);
-	i = (i - y) / 4096;
-	s32 z = unsignedToSigned(pythonmodulo(i, 4096), 2048);
-	return v3s16(x,y,z);
-}
-
 void ServerMap::listAllLoadableBlocks(std::list<v3s16> &dst)
 {
 	if(loadFromFolders()){
 		errorstream<<"Map::listAllLoadableBlocks(): Result will be missing "
 				<<"all blocks that are stored in flat files"<<std::endl;
 	}
-
-	{
-		verifyDatabase();
-
-		while(sqlite3_step(m_database_list) == SQLITE_ROW)
-		{
-			sqlite3_int64 block_i = sqlite3_column_int64(m_database_list, 0);
-			v3s16 p = getIntegerAsBlock(block_i);
-			//dstream<<"block_i="<<block_i<<" p="<<PP(p)<<std::endl;
-			dst.push_back(p);
-		}
-	}
+	dbase->listAllLoadableBlocks(dst);
 }
 
 void ServerMap::listAllLoadedBlocks(std::list<v3s16> &dst)
@@ -3743,88 +3657,16 @@ bool ServerMap::loadSectorFull(v2s16 p2d)
 #endif
 
 void ServerMap::beginSave() {
-	verifyDatabase();
-	if(sqlite3_exec(m_database, "BEGIN;", NULL, NULL, NULL) != SQLITE_OK)
-		infostream<<"WARNING: beginSave() failed, saving might be slow.";
+	dbase->beginSave();
 }
 
 void ServerMap::endSave() {
-	verifyDatabase();
-	if(sqlite3_exec(m_database, "COMMIT;", NULL, NULL, NULL) != SQLITE_OK)
-		infostream<<"WARNING: endSave() failed, map might not have saved.";
+	dbase->endSave();
 }
 
 void ServerMap::saveBlock(MapBlock *block)
 {
-	DSTACK(__FUNCTION_NAME);
-	/*
-		Dummy blocks are not written
-	*/
-	if(block->isDummy())
-	{
-		/*v3s16 p = block->getPos();
-		infostream<<"ServerMap::saveBlock(): WARNING: Not writing dummy block "
-				<<"("<<p.X<<","<<p.Y<<","<<p.Z<<")"<<std::endl;*/
-		return;
-	}
-
-	// Format used for writing
-	u8 version = SER_FMT_VER_HIGHEST_WRITE;
-	// Get destination
-	v3s16 p3d = block->getPos();
-
-
-#if 0
-	v2s16 p2d(p3d.X, p3d.Z);
-	std::string sectordir = getSectorDir(p2d);
-
-	createDirs(sectordir);
-
-	std::string fullpath = sectordir+DIR_DELIM+getBlockFilename(p3d);
-	std::ofstream o(fullpath.c_str(), std::ios_base::binary);
-	if(o.good() == false)
-		throw FileNotGoodException("Cannot open block data");
-#endif
-	/*
-		[0] u8 serialization version
-		[1] data
-	*/
-
-	verifyDatabase();
-
-	std::ostringstream o(std::ios_base::binary);
-
-	o.write((char*)&version, 1);
-
-	// Write basic data
-	block->serialize(o, version, true);
-
-	// Write block to database
-
-	std::string tmp = o.str();
-	const char *bytes = tmp.c_str();
-
-	bool success = true;
-	if(sqlite3_bind_int64(m_database_write, 1, getBlockAsInteger(p3d)) != SQLITE_OK) {
-		infostream<<"WARNING: Block position failed to bind: "<<sqlite3_errmsg(m_database)<<std::endl;
-		success = false;
-	}
-	if(sqlite3_bind_blob(m_database_write, 2, (void *)bytes, o.tellp(), NULL) != SQLITE_OK) { // TODO this mught not be the right length
-		infostream<<"WARNING: Block data failed to bind: "<<sqlite3_errmsg(m_database)<<std::endl;
-		success = false;
-	}
-	int written = sqlite3_step(m_database_write);
-	if(written != SQLITE_DONE) {
-		errorstream<<"WARNING: Block failed to save ("<<p3d.X<<", "<<p3d.Y<<", "<<p3d.Z<<") "
-				<<sqlite3_errmsg(m_database)<<std::endl;
-		success = false;
-	}
-	// Make ready for later reuse
-	sqlite3_reset(m_database_write);
-
-	// We just wrote it to the disk so clear modified flag
-	if (success)
-		block->resetModified();
+  dbase->saveBlock(block);
 }
 
 void ServerMap::loadBlock(std::string sectordir, std::string blockfile, MapSector *sector, bool save_after_load)
@@ -3978,38 +3820,11 @@ MapBlock* ServerMap::loadBlock(v3s16 blockpos)
 
 	v2s16 p2d(blockpos.X, blockpos.Z);
 
-	if(!loadFromFolders()) {
-		verifyDatabase();
-
-		if(sqlite3_bind_int64(m_database_read, 1, getBlockAsInteger(blockpos)) != SQLITE_OK)
-			infostream<<"WARNING: Could not bind block position for load: "
-				<<sqlite3_errmsg(m_database)<<std::endl;
-		if(sqlite3_step(m_database_read) == SQLITE_ROW) {
-			/*
-				Make sure sector is loaded
-			*/
-			MapSector *sector = createSector(p2d);
-
-			/*
-				Load block
-			*/
-			const char * data = (const char *)sqlite3_column_blob(m_database_read, 0);
-			size_t len = sqlite3_column_bytes(m_database_read, 0);
-
-			std::string datastr(data, len);
+	MapBlock *ret;
 
-			loadBlock(&datastr, blockpos, sector, false);
-
-			sqlite3_step(m_database_read);
-			// We should never get more than 1 row, so ok to reset
-			sqlite3_reset(m_database_read);
-
-			return getBlockNoCreateNoEx(blockpos);
-		}
-		sqlite3_reset(m_database_read);
-
-		// Not found in database, try the files
-	}
+	ret = dbase->loadBlock(blockpos);
+	if (ret) return (ret);
+	// Not found in database, try the files
 
 	// The directory layout we're going to load from.
 	//  1 - original sectors/xxxxzzzz/
-- 
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