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/*
 * Copyright 2004-2019 H2 Group. Multiple-Licensed under the MPL 2.0,
 * and the EPL 1.0 (https://h2database.com/html/license.html).
 * Initial Developer: H2 Group
 */
package org.h2.pagestore;

import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.BitSet;
import java.util.Collections;
import java.util.HashMap;
import java.util.concurrent.TimeUnit;
import java.util.zip.CRC32;

import org.h2.api.ErrorCode;
import org.h2.command.CommandInterface;
import org.h2.command.ddl.CreateTableData;
import org.h2.engine.Constants;
import org.h2.engine.Database;
import org.h2.engine.Session;
import org.h2.engine.SysProperties;
import org.h2.index.Cursor;
import org.h2.index.Index;
import org.h2.index.IndexType;
import org.h2.message.DbException;
import org.h2.message.Trace;
import org.h2.pagestore.db.PageBtreeIndex;
import org.h2.pagestore.db.PageBtreeLeaf;
import org.h2.pagestore.db.PageBtreeNode;
import org.h2.pagestore.db.PageDataIndex;
import org.h2.pagestore.db.PageDataLeaf;
import org.h2.pagestore.db.PageDataNode;
import org.h2.pagestore.db.PageDataOverflow;
import org.h2.pagestore.db.PageDelegateIndex;
import org.h2.pagestore.db.PageIndex;
import org.h2.pagestore.db.PageStoreTable;
import org.h2.result.Row;
import org.h2.schema.Schema;
import org.h2.store.Data;
import org.h2.store.FileStore;
import org.h2.store.InDoubtTransaction;
import org.h2.store.fs.FileUtils;
import org.h2.table.Column;
import org.h2.table.IndexColumn;
import org.h2.table.Table;
import org.h2.table.TableType;
import org.h2.util.Cache;
import org.h2.util.CacheLRU;
import org.h2.util.CacheObject;
import org.h2.util.CacheWriter;
import org.h2.util.IntArray;
import org.h2.util.IntIntHashMap;
import org.h2.util.StringUtils;
import org.h2.value.CompareMode;
import org.h2.value.Value;
import org.h2.value.ValueInt;
import org.h2.value.ValueString;

/**
 * This class represents a file that is organized as a number of pages. Page 0
 * contains a static file header, and pages 1 and 2 both contain the variable
 * file header (page 2 is a copy of page 1 and is only read if the checksum of
 * page 1 is invalid). The format of page 0 is:
 * 
    *
  • 0-47: file header (3 time "-- H2 0.5/B -- \n")
  • *
  • 48-51: page size in bytes (512 - 32768, must be a power of 2)
  • *
  • 52: write version (read-only if larger than 1)
  • *
  • 53: read version (opening fails if larger than 1)
  • *
* The format of page 1 and 2 is: *
    *
  • CRC32 of the remaining data: int (0-3)
  • *
  • write counter (incremented on each write): long (4-11)
  • *
  • log trunk key: int (12-15)
  • *
  • log trunk page (0 for none): int (16-19)
  • *
  • log data page (0 for none): int (20-23)
  • *
* Page 3 contains the first free list page. * Page 4 contains the meta table root page. */ public class PageStore implements CacheWriter { // TODO test running out of disk space (using a special file system) // TODO unused pages should be freed once in a while // TODO node row counts are incorrect (it's not splitting row counts) // TODO after opening the database, delay writing until required // TODO optimization: try to avoid allocating a byte array per page // TODO optimization: check if calling Data.getValueLen slows things down // TODO order pages so that searching for a key only seeks forward // TODO optimization: update: only log the key and changed values // TODO index creation: use less space (ordered, split at insertion point) // TODO detect circles in linked lists // (input stream, free list, extend pages...) // at runtime and recovery // TODO remove trace or use isDebugEnabled // TODO recover tool: support syntax to delete a row with a key // TODO don't store default values (store a special value) // TODO check for file size (exception if not exact size expected) // TODO online backup using bsdiff /** * The smallest possible page size. */ public static final int PAGE_SIZE_MIN = 64; /** * The biggest possible page size. */ public static final int PAGE_SIZE_MAX = 32768; /** * This log mode means the transaction log is not used. */ public static final int LOG_MODE_OFF = 0; /** * This log mode means the transaction log is used and FileDescriptor.sync() * is called for each checkpoint. This is the default level. */ public static final int LOG_MODE_SYNC = 2; private static final int PAGE_ID_FREE_LIST_ROOT = 3; private static final int PAGE_ID_META_ROOT = 4; private static final int MIN_PAGE_COUNT = 5; private static final int INCREMENT_KB = 1024; private static final int INCREMENT_PERCENT_MIN = 35; private static final int READ_VERSION = 3; private static final int WRITE_VERSION = 3; private static final int META_TYPE_DATA_INDEX = 0; private static final int META_TYPE_BTREE_INDEX = 1; private static final int META_TABLE_ID = -1; private static final int COMPACT_BLOCK_SIZE = 1536; private final Database database; private final Trace trace; private final String fileName; private FileStore file; private String accessMode; private int pageSize = Constants.DEFAULT_PAGE_SIZE; private int pageSizeShift; private long writeCountBase, writeCount, readCount; private int logKey, logFirstTrunkPage, logFirstDataPage; private final Cache cache; private int freeListPagesPerList; private boolean recoveryRunning; private boolean ignoreBigLog; /** * The index to the first free-list page that potentially has free space. */ private int firstFreeListIndex; /** * The file size in bytes. */ private long fileLength; /** * Number of pages (including free pages). */ private int pageCount; private PageLog log; private Schema metaSchema; private PageStoreTable metaTable; private PageDataIndex metaIndex; private final IntIntHashMap metaRootPageId = new IntIntHashMap(); private final HashMap metaObjects = new HashMap<>(); private HashMap tempObjects; /** * The map of reserved pages, to ensure index head pages * are not used for regular data during recovery. The key is the page id, * and the value the latest transaction position where this page is used. */ private HashMap reservedPages; private boolean isNew; private long maxLogSize = Constants.DEFAULT_MAX_LOG_SIZE; private final Session pageStoreSession; /** * Each free page is marked with a set bit. */ private final BitSet freed = new BitSet(); private final ArrayList freeLists = new ArrayList<>(); private boolean recordPageReads; private ArrayList recordedPagesList; private IntIntHashMap recordedPagesIndex; /** * The change count is something like a "micro-transaction-id". * It is used to ensure that changed pages are not written to the file * before the current operation is not finished. This is only a problem * when using a very small cache size. The value starts at 1 so that * pages with change count 0 can be evicted from the cache. */ private long changeCount = 1; private Data emptyPage; private long logSizeBase; private HashMap statistics; private int logMode = LOG_MODE_SYNC; private boolean lockFile; private boolean readMode; private int backupLevel; /** * Create a new page store object. * * @param database the database * @param fileName the file name * @param accessMode the access mode * @param cacheSizeDefault the default cache size */ public PageStore(Database database, String fileName, String accessMode, int cacheSizeDefault) { this.fileName = fileName; this.accessMode = accessMode; this.database = database; trace = database.getTrace(Trace.PAGE_STORE); // if (fileName.endsWith("X.h2.db")) // trace.setLevel(TraceSystem.DEBUG); String cacheType = database.getCacheType(); this.cache = CacheLRU.getCache(this, cacheType, cacheSizeDefault); pageStoreSession = new Session(database, null, 0); } /** * Start collecting statistics. */ public void statisticsStart() { statistics = new HashMap<>(); } /** * Stop collecting statistics. * * @return the statistics */ public HashMap statisticsEnd() { HashMap result = statistics; statistics = null; return result; } private void statisticsIncrement(String key) { if (statistics != null) { Integer old = statistics.get(key); statistics.put(key, old == null ? 1 : old + 1); } } /** * Copy the next page to the output stream. * * @param pageId the page to copy * @param out the output stream * @return the new position, or -1 if there is no more data to copy */ public synchronized int copyDirect(int pageId, OutputStream out) throws IOException { byte[] buffer = new byte[pageSize]; if (pageId >= pageCount) { return -1; } file.seek((long) pageId << pageSizeShift); file.readFullyDirect(buffer, 0, pageSize); readCount++; out.write(buffer, 0, pageSize); return pageId + 1; } /** * Open the file and read the header. */ public synchronized void open() { try { metaRootPageId.put(META_TABLE_ID, PAGE_ID_META_ROOT); if (FileUtils.exists(fileName)) { long length = FileUtils.size(fileName); if (length < MIN_PAGE_COUNT * PAGE_SIZE_MIN) { if (database.isReadOnly()) { throw DbException.get( ErrorCode.FILE_CORRUPTED_1, fileName + " length: " + length); } // the database was not fully created openNew(); } else { openExisting(); } } else { openNew(); } } catch (DbException e) { close(); throw e; } } private void openNew() { setPageSize(pageSize); freeListPagesPerList = PageFreeList.getPagesAddressed(pageSize); file = database.openFile(fileName, accessMode, false); lockFile(); recoveryRunning = true; writeStaticHeader(); writeVariableHeader(); log = new PageLog(this); increaseFileSize(MIN_PAGE_COUNT); openMetaIndex(); logFirstTrunkPage = allocatePage(); log.openForWriting(logFirstTrunkPage, false); isNew = true; recoveryRunning = false; increaseFileSize(); } private void lockFile() { if (lockFile) { if (!file.tryLock()) { throw DbException.get( ErrorCode.DATABASE_ALREADY_OPEN_1, fileName); } } } private void openExisting() { try { file = database.openFile(fileName, accessMode, true); } catch (DbException e) { if (e.getErrorCode() == ErrorCode.IO_EXCEPTION_2) { if (e.getMessage().contains("locked")) { // in Windows, you can't open a locked file // (in other operating systems, you can) // the exact error message is: // "The process cannot access the file because // another process has locked a portion of the file" throw DbException.get( ErrorCode.DATABASE_ALREADY_OPEN_1, e, fileName); } } throw e; } lockFile(); readStaticHeader(); freeListPagesPerList = PageFreeList.getPagesAddressed(pageSize); fileLength = file.length(); pageCount = (int) (fileLength / pageSize); if (pageCount < MIN_PAGE_COUNT) { if (database.isReadOnly()) { throw DbException.get(ErrorCode.FILE_CORRUPTED_1, fileName + " pageCount: " + pageCount); } file.releaseLock(); file.close(); FileUtils.delete(fileName); openNew(); return; } readVariableHeader(); log = new PageLog(this); log.openForReading(logKey, logFirstTrunkPage, logFirstDataPage); boolean isEmpty = recover(); if (!database.isReadOnly()) { readMode = true; if (!isEmpty || !SysProperties.MODIFY_ON_WRITE || tempObjects != null) { openForWriting(); removeOldTempIndexes(); } } } private void openForWriting() { if (!readMode || database.isReadOnly()) { return; } readMode = false; recoveryRunning = true; log.free(); logFirstTrunkPage = allocatePage(); log.openForWriting(logFirstTrunkPage, false); recoveryRunning = false; freed.set(0, pageCount, true); checkpoint(); } private void removeOldTempIndexes() { if (tempObjects != null) { metaObjects.putAll(tempObjects); for (PageIndex index: tempObjects.values()) { if (index.getTable().isTemporary()) { index.truncate(pageStoreSession); index.remove(pageStoreSession); } } pageStoreSession.commit(true); tempObjects = null; } metaObjects.clear(); metaObjects.put(-1, metaIndex); } private void writeIndexRowCounts() { for (PageIndex index: metaObjects.values()) { index.writeRowCount(); } } private void writeBack() { ArrayList list = cache.getAllChanged(); Collections.sort(list); for (CacheObject cacheObject : list) { writeBack(cacheObject); } } /** * Flush all pending changes to disk, and switch the new transaction log. */ public synchronized void checkpoint() { trace.debug("checkpoint"); if (log == null || readMode || database.isReadOnly() || backupLevel > 0) { // the file was never fully opened, or is read-only, // or checkpoint is currently disabled return; } database.checkPowerOff(); writeIndexRowCounts(); log.checkpoint(); writeBack(); int firstUncommittedSection = getFirstUncommittedSection(); log.removeUntil(firstUncommittedSection); // write back the free list writeBack(); // ensure the free list is backed up again log.checkpoint(); if (trace.isDebugEnabled()) { trace.debug("writeFree"); } byte[] test = new byte[16]; byte[] empty = new byte[pageSize]; for (int i = PAGE_ID_FREE_LIST_ROOT; i < pageCount; i++) { if (isUsed(i)) { freed.clear(i); } else if (!freed.get(i)) { if (trace.isDebugEnabled()) { trace.debug("free " + i); } file.seek((long) i << pageSizeShift); file.readFully(test, 0, 16); if (test[0] != 0) { file.seek((long) i << pageSizeShift); file.write(empty, 0, pageSize); writeCount++; } freed.set(i); } } } /** * Shrink the file so there are no empty pages at the end. * * @param compactMode 0 if no compacting should happen, otherwise * TransactionCommand.SHUTDOWN_COMPACT or TransactionCommand.SHUTDOWN_DEFRAG */ public synchronized void compact(int compactMode) { if (!database.getSettings().pageStoreTrim) { return; } if (SysProperties.MODIFY_ON_WRITE && readMode && compactMode == 0) { return; } openForWriting(); // find the last used page int lastUsed = -1; for (int i = getFreeListId(pageCount); i >= 0; i--) { lastUsed = getFreeList(i).getLastUsed(); if (lastUsed != -1) { break; } } // open a new log at the very end // (to be truncated later) writeBack(); log.free(); recoveryRunning = true; try { logFirstTrunkPage = lastUsed + 1; allocatePage(logFirstTrunkPage); log.openForWriting(logFirstTrunkPage, true); // ensure the free list is backed up again log.checkpoint(); } finally { recoveryRunning = false; } long start = System.nanoTime(); boolean isCompactFully = compactMode == CommandInterface.SHUTDOWN_COMPACT; boolean isDefrag = compactMode == CommandInterface.SHUTDOWN_DEFRAG; if (database.getSettings().defragAlways) { isCompactFully = isDefrag = true; } int maxCompactTime = database.getSettings().maxCompactTime; int maxMove = database.getSettings().maxCompactCount; if (isCompactFully || isDefrag) { maxCompactTime = Integer.MAX_VALUE; maxMove = Integer.MAX_VALUE; } int blockSize = isCompactFully ? COMPACT_BLOCK_SIZE : 1; int firstFree = MIN_PAGE_COUNT; for (int x = lastUsed, j = 0; x > MIN_PAGE_COUNT && j < maxMove; x -= blockSize) { for (int full = x - blockSize + 1; full <= x; full++) { if (full > MIN_PAGE_COUNT && isUsed(full)) { synchronized (this) { firstFree = getFirstFree(firstFree); if (firstFree == -1 || firstFree >= full) { j = maxMove; break; } if (compact(full, firstFree)) { j++; long now = System.nanoTime(); if (now > start + TimeUnit.MILLISECONDS.toNanos(maxCompactTime)) { j = maxMove; break; } } } } } } if (isDefrag) { log.checkpoint(); writeBack(); cache.clear(); ArrayList tables = database.getAllTablesAndViews(false); recordedPagesList = new ArrayList<>(); recordedPagesIndex = new IntIntHashMap(); recordPageReads = true; Session sysSession = database.getSystemSession(); for (Table table : tables) { if (!table.isTemporary() && TableType.TABLE == table.getTableType()) { Index scanIndex = table.getScanIndex(sysSession); Cursor cursor = scanIndex.find(sysSession, null, null); while (cursor.next()) { cursor.get(); } for (Index index : table.getIndexes()) { if (index != scanIndex && index.canScan()) { cursor = index.find(sysSession, null, null); while (cursor.next()) { // the data is already read } } } } } recordPageReads = false; int target = MIN_PAGE_COUNT - 1; int temp = 0; for (int i = 0, size = recordedPagesList.size(); i < size; i++) { log.checkpoint(); writeBack(); int source = recordedPagesList.get(i); Page pageSource = getPage(source); if (!pageSource.canMove()) { continue; } while (true) { Page pageTarget = getPage(++target); if (pageTarget == null || pageTarget.canMove()) { break; } } if (target == source) { continue; } temp = getFirstFree(temp); if (temp == -1) { DbException.throwInternalError("no free page for defrag"); } cache.clear(); swap(source, target, temp); int index = recordedPagesIndex.get(target); if (index != IntIntHashMap.NOT_FOUND) { recordedPagesList.set(index, source); recordedPagesIndex.put(source, index); } recordedPagesList.set(i, target); recordedPagesIndex.put(target, i); } recordedPagesList = null; recordedPagesIndex = null; } // TODO can most likely be simplified checkpoint(); log.checkpoint(); writeIndexRowCounts(); log.checkpoint(); writeBack(); commit(pageStoreSession); writeBack(); log.checkpoint(); log.free(); // truncate the log recoveryRunning = true; try { setLogFirstPage(++logKey, 0, 0); } finally { recoveryRunning = false; } writeBack(); for (int i = getFreeListId(pageCount); i >= 0; i--) { lastUsed = getFreeList(i).getLastUsed(); if (lastUsed != -1) { break; } } int newPageCount = lastUsed + 1; if (newPageCount < pageCount) { freed.set(newPageCount, pageCount, false); } pageCount = newPageCount; // the easiest way to remove superfluous entries freeLists.clear(); trace.debug("pageCount: " + pageCount); long newLength = (long) pageCount << pageSizeShift; if (file.length() != newLength) { file.setLength(newLength); writeCount++; } } private int getFirstFree(int start) { int free = -1; for (int id = getFreeListId(start); start < pageCount; id++) { free = getFreeList(id).getFirstFree(start); if (free != -1) { break; } } return free; } private void swap(int a, int b, int free) { if (a < MIN_PAGE_COUNT || b < MIN_PAGE_COUNT) { System.out.println(isUsed(a) + " " + isUsed(b)); DbException.throwInternalError("can't swap " + a + " and " + b); } Page f = (Page) cache.get(free); if (f != null) { DbException.throwInternalError("not free: " + f); } if (trace.isDebugEnabled()) { trace.debug("swap " + a + " and " + b + " via " + free); } Page pageA = null; if (isUsed(a)) { pageA = getPage(a); if (pageA != null) { pageA.moveTo(pageStoreSession, free); } free(a); } if (free != b) { if (isUsed(b)) { Page pageB = getPage(b); if (pageB != null) { pageB.moveTo(pageStoreSession, a); } free(b); } if (pageA != null) { f = getPage(free); if (f != null) { f.moveTo(pageStoreSession, b); } free(free); } } } private boolean compact(int full, int free) { if (full < MIN_PAGE_COUNT || free == -1 || free >= full || !isUsed(full)) { return false; } Page f = (Page) cache.get(free); if (f != null) { DbException.throwInternalError("not free: " + f); } Page p = getPage(full); if (p == null) { freePage(full); } else if (p instanceof PageStreamData || p instanceof PageStreamTrunk) { if (p.getPos() < log.getMinPageId()) { // an old transaction log page // probably a leftover from a crash freePage(full); } } else { if (trace.isDebugEnabled()) { trace.debug("move " + p.getPos() + " to " + free); } try { p.moveTo(pageStoreSession, free); } finally { if (++changeCount < 0) { throw DbException.throwInternalError( "changeCount has wrapped"); } } } return true; } /** * Read a page from the store. * * @param pageId the page id * @return the page */ public synchronized Page getPage(int pageId) { Page p = (Page) cache.get(pageId); if (p != null) { return p; } Data data = createData(); readPage(pageId, data); int type = data.readByte(); if (type == Page.TYPE_EMPTY) { return null; } data.readShortInt(); data.readInt(); if (!checksumTest(data.getBytes(), pageId, pageSize)) { throw DbException.get(ErrorCode.FILE_CORRUPTED_1, "wrong checksum"); } switch (type & ~Page.FLAG_LAST) { case Page.TYPE_FREE_LIST: p = PageFreeList.read(this, data, pageId); break; case Page.TYPE_DATA_LEAF: { int indexId = data.readVarInt(); PageIndex idx = metaObjects.get(indexId); if (idx == null) { throw DbException.get(ErrorCode.FILE_CORRUPTED_1, "index not found " + indexId); } if (!(idx instanceof PageDataIndex)) { throw DbException.get(ErrorCode.FILE_CORRUPTED_1, "not a data index " + indexId + " " + idx); } PageDataIndex index = (PageDataIndex) idx; if (statistics != null) { statisticsIncrement(index.getTable().getName() + "." + index.getName() + " read"); } p = PageDataLeaf.read(index, data, pageId); break; } case Page.TYPE_DATA_NODE: { int indexId = data.readVarInt(); PageIndex idx = metaObjects.get(indexId); if (idx == null) { throw DbException.get(ErrorCode.FILE_CORRUPTED_1, "index not found " + indexId); } if (!(idx instanceof PageDataIndex)) { throw DbException.get(ErrorCode.FILE_CORRUPTED_1, "not a data index " + indexId + " " + idx); } PageDataIndex index = (PageDataIndex) idx; if (statistics != null) { statisticsIncrement(index.getTable().getName() + "." + index.getName() + " read"); } p = PageDataNode.read(index, data, pageId); break; } case Page.TYPE_DATA_OVERFLOW: { p = PageDataOverflow.read(this, data, pageId); if (statistics != null) { statisticsIncrement("overflow read"); } break; } case Page.TYPE_BTREE_LEAF: { int indexId = data.readVarInt(); PageIndex idx = metaObjects.get(indexId); if (idx == null) { throw DbException.get(ErrorCode.FILE_CORRUPTED_1, "index not found " + indexId); } if (!(idx instanceof PageBtreeIndex)) { throw DbException.get(ErrorCode.FILE_CORRUPTED_1, "not a btree index " + indexId + " " + idx); } PageBtreeIndex index = (PageBtreeIndex) idx; if (statistics != null) { statisticsIncrement(index.getTable().getName() + "." + index.getName() + " read"); } p = PageBtreeLeaf.read(index, data, pageId); break; } case Page.TYPE_BTREE_NODE: { int indexId = data.readVarInt(); PageIndex idx = metaObjects.get(indexId); if (idx == null) { throw DbException.get(ErrorCode.FILE_CORRUPTED_1, "index not found " + indexId); } if (!(idx instanceof PageBtreeIndex)) { throw DbException.get(ErrorCode.FILE_CORRUPTED_1, "not a btree index " + indexId + " " + idx); } PageBtreeIndex index = (PageBtreeIndex) idx; if (statistics != null) { statisticsIncrement(index.getTable().getName() + "." + index.getName() + " read"); } p = PageBtreeNode.read(index, data, pageId); break; } case Page.TYPE_STREAM_TRUNK: p = PageStreamTrunk.read(this, data, pageId); break; case Page.TYPE_STREAM_DATA: p = PageStreamData.read(this, data, pageId); break; default: throw DbException.get(ErrorCode.FILE_CORRUPTED_1, "page=" + pageId + " type=" + type); } cache.put(p); return p; } private int getFirstUncommittedSection() { trace.debug("getFirstUncommittedSection"); Session[] sessions = database.getSessions(true); int firstUncommittedSection = log.getLogSectionId(); for (Session session : sessions) { int firstUncommitted = session.getFirstUncommittedLog(); if (firstUncommitted != Session.LOG_WRITTEN) { if (firstUncommitted < firstUncommittedSection) { firstUncommittedSection = firstUncommitted; } } } return firstUncommittedSection; } private void readStaticHeader() { file.seek(FileStore.HEADER_LENGTH); Data page = Data.create(database, new byte[PAGE_SIZE_MIN - FileStore.HEADER_LENGTH], false); file.readFully(page.getBytes(), 0, PAGE_SIZE_MIN - FileStore.HEADER_LENGTH); readCount++; setPageSize(page.readInt()); int writeVersion = page.readByte(); int readVersion = page.readByte(); if (readVersion > READ_VERSION) { throw DbException.get( ErrorCode.FILE_VERSION_ERROR_1, fileName); } if (writeVersion > WRITE_VERSION) { close(); database.setReadOnly(true); accessMode = "r"; file = database.openFile(fileName, accessMode, true); } } private void readVariableHeader() { Data page = createData(); for (int i = 1;; i++) { if (i == 3) { throw DbException.get( ErrorCode.FILE_CORRUPTED_1, fileName); } page.reset(); readPage(i, page); CRC32 crc = new CRC32(); crc.update(page.getBytes(), 4, pageSize - 4); int expected = (int) crc.getValue(); int got = page.readInt(); if (expected == got) { writeCountBase = page.readLong(); logKey = page.readInt(); logFirstTrunkPage = page.readInt(); logFirstDataPage = page.readInt(); break; } } } /** * Set the page size. The size must be a power of two. This method must be * called before opening. * * @param size the page size */ public void setPageSize(int size) { if (size < PAGE_SIZE_MIN || size > PAGE_SIZE_MAX) { throw DbException.get(ErrorCode.FILE_CORRUPTED_1, fileName + " pageSize: " + size); } boolean good = false; int shift = 0; for (int i = 1; i <= size;) { if (size == i) { good = true; break; } shift++; i += i; } if (!good) { throw DbException.get(ErrorCode.FILE_CORRUPTED_1, fileName); } pageSize = size; emptyPage = createData(); pageSizeShift = shift; } private void writeStaticHeader() { Data page = Data.create(database, new byte[pageSize - FileStore.HEADER_LENGTH], false); page.writeInt(pageSize); page.writeByte((byte) WRITE_VERSION); page.writeByte((byte) READ_VERSION); file.seek(FileStore.HEADER_LENGTH); file.write(page.getBytes(), 0, pageSize - FileStore.HEADER_LENGTH); writeCount++; } /** * Set the trunk page and data page id of the log. * * @param logKey the log key of the trunk page * @param trunkPageId the trunk page id * @param dataPageId the data page id */ void setLogFirstPage(int logKey, int trunkPageId, int dataPageId) { if (trace.isDebugEnabled()) { trace.debug("setLogFirstPage key: " + logKey + " trunk: "+ trunkPageId +" data: " + dataPageId); } this.logKey = logKey; this.logFirstTrunkPage = trunkPageId; this.logFirstDataPage = dataPageId; writeVariableHeader(); } private void writeVariableHeader() { trace.debug("writeVariableHeader"); if (logMode == LOG_MODE_SYNC) { file.sync(); } Data page = createData(); page.writeInt(0); page.writeLong(getWriteCountTotal()); page.writeInt(logKey); page.writeInt(logFirstTrunkPage); page.writeInt(logFirstDataPage); CRC32 crc = new CRC32(); crc.update(page.getBytes(), 4, pageSize - 4); page.setInt(0, (int) crc.getValue()); file.seek(pageSize); file.write(page.getBytes(), 0, pageSize); file.seek(pageSize + pageSize); file.write(page.getBytes(), 0, pageSize); // don't increment the write counter, because it was just written } /** * Close the file without further writing. */ public synchronized void close() { trace.debug("close"); if (log != null) { log.close(); log = null; } if (file != null) { try { file.releaseLock(); file.close(); } finally { file = null; } } } @Override public synchronized void flushLog() { if (file != null) { log.flush(); } } /** * Flush the transaction log and sync the file. */ public synchronized void sync() { if (file != null) { log.flush(); file.sync(); } } @Override public Trace getTrace() { return trace; } @Override public synchronized void writeBack(CacheObject obj) { Page record = (Page) obj; if (trace.isDebugEnabled()) { trace.debug("writeBack " + record); } record.write(); record.setChanged(false); } /** * Write an undo log entry if required. * * @param page the page * @param old the old data (if known) or null */ public synchronized void logUndo(Page page, Data old) { if (logMode == LOG_MODE_OFF) { return; } checkOpen(); database.checkWritingAllowed(); if (!recoveryRunning) { int pos = page.getPos(); if (!log.getUndo(pos)) { if (old == null) { old = readPage(pos); } openForWriting(); log.addUndo(pos, old); } } } /** * Update a page. * * @param page the page */ public synchronized void update(Page page) { if (trace.isDebugEnabled()) { if (!page.isChanged()) { trace.debug("updateRecord " + page.toString()); } } checkOpen(); database.checkWritingAllowed(); page.setChanged(true); int pos = page.getPos(); if (SysProperties.CHECK && !recoveryRunning) { // ensure the undo entry is already written if (logMode != LOG_MODE_OFF) { log.addUndo(pos, null); } } allocatePage(pos); cache.update(pos, page); } private int getFreeListId(int pageId) { return (pageId - PAGE_ID_FREE_LIST_ROOT) / freeListPagesPerList; } private PageFreeList getFreeListForPage(int pageId) { return getFreeList(getFreeListId(pageId)); } private PageFreeList getFreeList(int i) { PageFreeList list = null; if (i < freeLists.size()) { list = freeLists.get(i); if (list != null) { return list; } } int p = PAGE_ID_FREE_LIST_ROOT + i * freeListPagesPerList; while (p >= pageCount) { increaseFileSize(); } if (p < pageCount) { list = (PageFreeList) getPage(p); } if (list == null) { list = PageFreeList.create(this, p); cache.put(list); } while (freeLists.size() <= i) { freeLists.add(null); } freeLists.set(i, list); return list; } private void freePage(int pageId) { int index = getFreeListId(pageId); PageFreeList list = getFreeList(index); firstFreeListIndex = Math.min(index, firstFreeListIndex); list.free(pageId); } /** * Set the bit of an already allocated page. * * @param pageId the page to allocate */ void allocatePage(int pageId) { PageFreeList list = getFreeListForPage(pageId); list.allocate(pageId); } private boolean isUsed(int pageId) { return getFreeListForPage(pageId).isUsed(pageId); } /** * Allocate a number of pages. * * @param list the list where to add the allocated pages * @param pagesToAllocate the number of pages to allocate * @param exclude the exclude list * @param after all allocated pages are higher than this page */ void allocatePages(IntArray list, int pagesToAllocate, BitSet exclude, int after) { list.ensureCapacity(list.size() + pagesToAllocate); for (int i = 0; i < pagesToAllocate; i++) { int page = allocatePage(exclude, after); after = page; list.add(page); } } /** * Allocate a page. * * @return the page id */ public synchronized int allocatePage() { openForWriting(); int pos = allocatePage(null, 0); if (!recoveryRunning) { if (logMode != LOG_MODE_OFF) { log.addUndo(pos, emptyPage); } } return pos; } private int allocatePage(BitSet exclude, int first) { int page; for (int i = firstFreeListIndex;; i++) { PageFreeList list = getFreeList(i); page = list.allocate(exclude, first); if (page >= 0) { firstFreeListIndex = i; break; } } while (page >= pageCount) { increaseFileSize(); } if (trace.isDebugEnabled()) { // trace.debug("allocatePage " + pos); } return page; } private void increaseFileSize() { int increment = INCREMENT_KB * 1024 / pageSize; int percent = pageCount * INCREMENT_PERCENT_MIN / 100; if (increment < percent) { increment = (1 + (percent / increment)) * increment; } int max = database.getSettings().pageStoreMaxGrowth; if (max < increment) { increment = max; } increaseFileSize(increment); } private void increaseFileSize(int increment) { for (int i = pageCount; i < pageCount + increment; i++) { freed.set(i); } pageCount += increment; long newLength = (long) pageCount << pageSizeShift; file.setLength(newLength); writeCount++; fileLength = newLength; } /** * Add a page to the free list. The undo log entry must have been written. * * @param pageId the page id */ public synchronized void free(int pageId) { free(pageId, true); } /** * Add a page to the free list. * * @param pageId the page id * @param undo if the undo record must have been written */ void free(int pageId, boolean undo) { if (trace.isDebugEnabled()) { // trace.debug("free " + pageId + " " + undo); } cache.remove(pageId); if (SysProperties.CHECK && !recoveryRunning && undo) { // ensure the undo entry is already written if (logMode != LOG_MODE_OFF) { log.addUndo(pageId, null); } } freePage(pageId); if (recoveryRunning) { writePage(pageId, createData()); if (reservedPages != null && reservedPages.containsKey(pageId)) { // re-allocate the page if it is used later on again int latestPos = reservedPages.get(pageId); if (latestPos > log.getLogPos()) { allocatePage(pageId); } } } } /** * Add a page to the free list. The page is not used, therefore doesn't need * to be overwritten. * * @param pageId the page id */ void freeUnused(int pageId) { if (trace.isDebugEnabled()) { trace.debug("freeUnused " + pageId); } cache.remove(pageId); freePage(pageId); freed.set(pageId); } /** * Create a data object. * * @return the data page. */ public Data createData() { return Data.create(database, new byte[pageSize], false); } /** * Read a page. * * @param pos the page id * @return the page */ public synchronized Data readPage(int pos) { Data page = createData(); readPage(pos, page); return page; } /** * Read a page. * * @param pos the page id * @param page the page */ void readPage(int pos, Data page) { if (recordPageReads) { if (pos >= MIN_PAGE_COUNT && recordedPagesIndex.get(pos) == IntIntHashMap.NOT_FOUND) { recordedPagesIndex.put(pos, recordedPagesList.size()); recordedPagesList.add(pos); } } if (pos < 0 || pos >= pageCount) { throw DbException.get(ErrorCode.FILE_CORRUPTED_1, pos + " of " + pageCount); } file.seek((long) pos << pageSizeShift); file.readFully(page.getBytes(), 0, pageSize); readCount++; } /** * Get the page size. * * @return the page size */ public int getPageSize() { return pageSize; } /** * Get the number of pages (including free pages). * * @return the page count */ public int getPageCount() { return pageCount; } /** * Write a page. * * @param pageId the page id * @param data the data */ public synchronized void writePage(int pageId, Data data) { if (pageId <= 0) { DbException.throwInternalError("write to page " + pageId); } byte[] bytes = data.getBytes(); if (SysProperties.CHECK) { boolean shouldBeFreeList = (pageId - PAGE_ID_FREE_LIST_ROOT) % freeListPagesPerList == 0; boolean isFreeList = bytes[0] == Page.TYPE_FREE_LIST; if (bytes[0] != 0 && shouldBeFreeList != isFreeList) { throw DbException.throwInternalError(); } } checksumSet(bytes, pageId); file.seek((long) pageId << pageSizeShift); file.write(bytes, 0, pageSize); writeCount++; } /** * Remove a page from the cache. * * @param pageId the page id */ public synchronized void removeFromCache(int pageId) { cache.remove(pageId); } Database getDatabase() { return database; } /** * Run recovery. * * @return whether the transaction log was empty */ private boolean recover() { trace.debug("log recover"); recoveryRunning = true; boolean isEmpty = true; isEmpty &= log.recover(PageLog.RECOVERY_STAGE_UNDO); if (reservedPages != null) { for (int r : reservedPages.keySet()) { if (trace.isDebugEnabled()) { trace.debug("reserve " + r); } allocatePage(r); } } isEmpty &= log.recover(PageLog.RECOVERY_STAGE_ALLOCATE); openMetaIndex(); readMetaData(); isEmpty &= log.recover(PageLog.RECOVERY_STAGE_REDO); boolean setReadOnly = false; if (!database.isReadOnly()) { if (log.getInDoubtTransactions().isEmpty()) { log.recoverEnd(); int firstUncommittedSection = getFirstUncommittedSection(); log.removeUntil(firstUncommittedSection); } else { setReadOnly = true; } } PageDataIndex systemTable = (PageDataIndex) metaObjects.get(0); isNew = systemTable == null; for (PageIndex index : metaObjects.values()) { if (index.getTable().isTemporary()) { // temporary indexes are removed after opening if (tempObjects == null) { tempObjects = new HashMap<>(); } tempObjects.put(index.getId(), index); } else { index.close(pageStoreSession); } } allocatePage(PAGE_ID_META_ROOT); writeIndexRowCounts(); recoveryRunning = false; reservedPages = null; writeBack(); // clear the cache because it contains pages with closed indexes cache.clear(); freeLists.clear(); metaObjects.clear(); metaObjects.put(-1, metaIndex); if (setReadOnly) { database.setReadOnly(true); } trace.debug("log recover done"); return isEmpty; } /** * A record is added to a table, or removed from a table. * * @param session the session * @param tableId the table id * @param row the row to add * @param add true if the row is added, false if it is removed */ public synchronized void logAddOrRemoveRow(Session session, int tableId, Row row, boolean add) { if (logMode != LOG_MODE_OFF) { if (!recoveryRunning) { log.logAddOrRemoveRow(session, tableId, row, add); } } } /** * Mark a committed transaction. * * @param session the session */ public synchronized void commit(Session session) { checkOpen(); openForWriting(); log.commit(session.getId()); long size = log.getSize(); if (size - logSizeBase > maxLogSize / 2) { int firstSection = log.getLogFirstSectionId(); checkpoint(); int newSection = log.getLogSectionId(); if (newSection - firstSection <= 2) { // one section is always kept, and checkpoint // advances two sections each time it is called return; } long newSize = log.getSize(); if (newSize < size || size < maxLogSize) { ignoreBigLog = false; return; } if (!ignoreBigLog) { ignoreBigLog = true; trace.error(null, "Transaction log could not be truncated; size: " + (newSize / 1024 / 1024) + " MB"); } logSizeBase = log.getSize(); } } /** * Prepare a transaction. * * @param session the session * @param transaction the name of the transaction */ public synchronized void prepareCommit(Session session, String transaction) { log.prepareCommit(session, transaction); } /** * Check whether this is a new database. * * @return true if it is */ public boolean isNew() { return isNew; } /** * Reserve the page if this is a index root page entry. * * @param logPos the redo log position * @param tableId the table id * @param row the row */ void allocateIfIndexRoot(int logPos, int tableId, Row row) { if (tableId == META_TABLE_ID) { int rootPageId = row.getValue(3).getInt(); if (reservedPages == null) { reservedPages = new HashMap<>(); } reservedPages.put(rootPageId, logPos); } } /** * Redo a delete in a table. * * @param tableId the object id of the table * @param key the key of the row to delete */ void redoDelete(int tableId, long key) { Index index = metaObjects.get(tableId); PageDataIndex scan = (PageDataIndex) index; Row row = scan.getRowWithKey(key); if (row == null || row.getKey() != key) { trace.error(null, "Entry not found: " + key + " found instead: " + row + " - ignoring"); return; } redo(tableId, row, false); } /** * Redo a change in a table. * * @param tableId the object id of the table * @param row the row * @param add true if the record is added, false if deleted */ void redo(int tableId, Row row, boolean add) { if (tableId == META_TABLE_ID) { if (add) { addMeta(row, pageStoreSession, true); } else { removeMeta(row); } } Index index = metaObjects.get(tableId); if (index == null) { throw DbException.throwInternalError( "Table not found: " + tableId + " " + row + " " + add); } Table table = index.getTable(); if (add) { table.addRow(pageStoreSession, row); } else { table.removeRow(pageStoreSession, row); } } /** * Redo a truncate. * * @param tableId the object id of the table */ void redoTruncate(int tableId) { Index index = metaObjects.get(tableId); Table table = index.getTable(); table.truncate(pageStoreSession); } private void openMetaIndex() { CreateTableData data = new CreateTableData(); ArrayList cols = data.columns; cols.add(new Column("ID", Value.INT)); cols.add(new Column("TYPE", Value.INT)); cols.add(new Column("PARENT", Value.INT)); cols.add(new Column("HEAD", Value.INT)); cols.add(new Column("OPTIONS", Value.STRING)); cols.add(new Column("COLUMNS", Value.STRING)); metaSchema = new Schema(database, 0, "", null, true); data.schema = metaSchema; data.tableName = "PAGE_INDEX"; data.id = META_TABLE_ID; data.temporary = false; data.persistData = true; data.persistIndexes = true; data.create = false; data.session = pageStoreSession; metaTable = new PageStoreTable(data); metaIndex = (PageDataIndex) metaTable.getScanIndex( pageStoreSession); metaObjects.clear(); metaObjects.put(-1, metaIndex); } private void readMetaData() { Cursor cursor = metaIndex.find(pageStoreSession, null, null); // first, create all tables while (cursor.next()) { Row row = cursor.get(); int type = row.getValue(1).getInt(); if (type == META_TYPE_DATA_INDEX) { addMeta(row, pageStoreSession, false); } } // now create all secondary indexes // otherwise the table might not be created yet cursor = metaIndex.find(pageStoreSession, null, null); while (cursor.next()) { Row row = cursor.get(); int type = row.getValue(1).getInt(); if (type != META_TYPE_DATA_INDEX) { addMeta(row, pageStoreSession, false); } } } private void removeMeta(Row row) { int id = row.getValue(0).getInt(); PageIndex index = metaObjects.get(id); index.getTable().removeIndex(index); if (index instanceof PageBtreeIndex || index instanceof PageDelegateIndex) { if (index.isTemporary()) { pageStoreSession.removeLocalTempTableIndex(index); } else { index.getSchema().remove(index); } } index.remove(pageStoreSession); metaObjects.remove(id); } private void addMeta(Row row, Session session, boolean redo) { int id = row.getValue(0).getInt(); int type = row.getValue(1).getInt(); int parent = row.getValue(2).getInt(); int rootPageId = row.getValue(3).getInt(); String[] options = StringUtils.arraySplit( row.getValue(4).getString(), ',', false); String columnList = row.getValue(5).getString(); String[] columns = StringUtils.arraySplit(columnList, ',', false); Index meta; if (trace.isDebugEnabled()) { trace.debug("addMeta id="+ id +" type=" + type + " root=" + rootPageId + " parent=" + parent + " columns=" + columnList); } if (redo && rootPageId != 0) { // ensure the page is empty, but not used by regular data writePage(rootPageId, createData()); allocatePage(rootPageId); } metaRootPageId.put(id, rootPageId); if (type == META_TYPE_DATA_INDEX) { CreateTableData data = new CreateTableData(); if (columns == null) { throw DbException.throwInternalError(row.toString()); } for (int i = 0, len = columns.length; i < len; i++) { Column col = new Column("C" + i, Value.INT); data.columns.add(col); } data.schema = metaSchema; data.tableName = "T" + id; data.id = id; data.temporary = options[2].equals("temp"); data.persistData = true; data.persistIndexes = true; data.create = false; data.session = session; PageStoreTable table = new PageStoreTable(data); boolean binaryUnsigned = SysProperties.SORT_BINARY_UNSIGNED; if (options.length > 3) { binaryUnsigned = Boolean.parseBoolean(options[3]); } boolean uuidUnsigned = SysProperties.SORT_UUID_UNSIGNED; if (options.length > 4) { uuidUnsigned = Boolean.parseBoolean(options[4]); } CompareMode mode = CompareMode.getInstance( options[0], Integer.parseInt(options[1]), binaryUnsigned, uuidUnsigned); table.setCompareMode(mode); meta = table.getScanIndex(session); } else { Index p = metaObjects.get(parent); if (p == null) { throw DbException.get(ErrorCode.FILE_CORRUPTED_1, "Table not found:" + parent + " for " + row + " meta:" + metaObjects); } PageStoreTable table = (PageStoreTable) p.getTable(); Column[] tableCols = table.getColumns(); int len = columns.length; IndexColumn[] cols = new IndexColumn[len]; for (int i = 0; i < len; i++) { String c = columns[i]; IndexColumn ic = new IndexColumn(); int idx = c.indexOf('/'); if (idx >= 0) { String s = c.substring(idx + 1); ic.sortType = Integer.parseInt(s); c = c.substring(0, idx); } ic.column = tableCols[Integer.parseInt(c)]; cols[i] = ic; } IndexType indexType; if (options[3].equals("d")) { indexType = IndexType.createPrimaryKey(true, false); Column[] tableColumns = table.getColumns(); for (IndexColumn indexColumn : cols) { tableColumns[indexColumn.column.getColumnId()].setNullable(false); } } else { indexType = IndexType.createNonUnique(true); } meta = table.addIndex(session, "I" + id, id, cols, indexType, false, null); } metaObjects.put(id, (PageIndex) meta); } /** * Add an index to the in-memory index map. * * @param index the index */ public synchronized void addIndex(PageIndex index) { metaObjects.put(index.getId(), index); } /** * Add the meta data of an index. * * @param index the index to add * @param session the session */ public void addMeta(PageIndex index, Session session) { Table table = index.getTable(); if (SysProperties.CHECK) { if (!table.isTemporary()) { // to prevent ABBA locking problems, we need to always take // the Database lock before we take the PageStore lock synchronized (database) { synchronized (this) { database.verifyMetaLocked(session); } } } } synchronized (this) { int type = index instanceof PageDataIndex ? META_TYPE_DATA_INDEX : META_TYPE_BTREE_INDEX; IndexColumn[] columns = index.getIndexColumns(); StringBuilder builder = new StringBuilder(); for (int i = 0, length = columns.length; i < length; i++) { if (i > 0) { builder.append(','); } IndexColumn col = columns[i]; int id = col.column.getColumnId(); builder.append(id); int sortType = col.sortType; if (sortType != 0) { builder.append('/').append(sortType); } } String columnList = builder.toString(); CompareMode mode = table.getCompareMode(); StringBuilder options = new StringBuilder().append(mode.getName()).append(',').append(mode.getStrength()) .append(','); if (table.isTemporary()) { options.append("temp"); } options.append(','); if (index instanceof PageDelegateIndex) { options.append('d'); } options.append(',').append(mode.isBinaryUnsigned()).append(',').append(mode.isUuidUnsigned()); Row row = metaTable.getTemplateRow(); row.setValue(0, ValueInt.get(index.getId())); row.setValue(1, ValueInt.get(type)); row.setValue(2, ValueInt.get(table.getId())); row.setValue(3, ValueInt.get(index.getRootPageId())); row.setValue(4, ValueString.get(options.toString())); row.setValue(5, ValueString.get(columnList)); row.setKey(index.getId() + 1); metaIndex.add(session, row); } } /** * Remove the meta data of an index. * * @param index the index to remove * @param session the session */ public void removeMeta(Index index, Session session) { if (SysProperties.CHECK) { if (!index.getTable().isTemporary()) { // to prevent ABBA locking problems, we need to always take // the Database lock before we take the PageStore lock synchronized (database) { synchronized (this) { database.verifyMetaLocked(session); } } } } synchronized (this) { if (!recoveryRunning) { removeMetaIndex(index, session); metaObjects.remove(index.getId()); } } } private void removeMetaIndex(Index index, Session session) { int key = index.getId() + 1; Row row = metaIndex.getRow(session, key); if (row.getKey() != key) { throw DbException.get(ErrorCode.FILE_CORRUPTED_1, "key: " + key + " index: " + index + " table: " + index.getTable() + " row: " + row); } metaIndex.remove(session, row); } /** * Set the maximum transaction log size in megabytes. * * @param maxSize the new maximum log size */ public void setMaxLogSize(long maxSize) { this.maxLogSize = maxSize; } /** * Commit or rollback a prepared transaction after opening a database with * in-doubt transactions. * * @param sessionId the session id * @param pageId the page where the transaction was prepared * @param commit if the transaction should be committed */ public synchronized void setInDoubtTransactionState(int sessionId, int pageId, boolean commit) { boolean old = database.isReadOnly(); try { database.setReadOnly(false); log.setInDoubtTransactionState(sessionId, pageId, commit); } finally { database.setReadOnly(old); } } /** * Get the list of in-doubt transaction. * * @return the list */ public ArrayList getInDoubtTransactions() { return log.getInDoubtTransactions(); } /** * Check whether the recovery process is currently running. * * @return true if it is */ public boolean isRecoveryRunning() { return recoveryRunning; } private void checkOpen() { if (file == null) { throw DbException.get(ErrorCode.DATABASE_IS_CLOSED); } } /** * Get the file write count since the database was created. * * @return the write count */ public long getWriteCountTotal() { return writeCount + writeCountBase; } /** * Get the file write count since the database was opened. * * @return the write count */ public long getWriteCount() { return writeCount; } /** * Get the file read count since the database was opened. * * @return the read count */ public long getReadCount() { return readCount; } /** * A table is truncated. * * @param session the session * @param tableId the table id */ public synchronized void logTruncate(Session session, int tableId) { if (!recoveryRunning) { openForWriting(); log.logTruncate(session, tableId); } } /** * Get the root page of an index. * * @param indexId the index id * @return the root page */ public int getRootPageId(int indexId) { return metaRootPageId.get(indexId); } public Cache getCache() { return cache; } private void checksumSet(byte[] d, int pageId) { int ps = pageSize; int type = d[0]; if (type == Page.TYPE_EMPTY) { return; } int s1 = 255 + (type & 255), s2 = 255 + s1; s2 += s1 += d[6] & 255; s2 += s1 += d[(ps >> 1) - 1] & 255; s2 += s1 += d[ps >> 1] & 255; s2 += s1 += d[ps - 2] & 255; s2 += s1 += d[ps - 1] & 255; d[1] = (byte) (((s1 & 255) + (s1 >> 8)) ^ pageId); d[2] = (byte) (((s2 & 255) + (s2 >> 8)) ^ (pageId >> 8)); } /** * Check if the stored checksum is correct * @param d the data * @param pageId the page id * @param pageSize the page size * @return true if it is correct */ public static boolean checksumTest(byte[] d, int pageId, int pageSize) { int s1 = 255 + (d[0] & 255), s2 = 255 + s1; s2 += s1 += d[6] & 255; s2 += s1 += d[(pageSize >> 1) - 1] & 255; s2 += s1 += d[pageSize >> 1] & 255; s2 += s1 += d[pageSize - 2] & 255; s2 += s1 += d[pageSize - 1] & 255; return d[1] == (byte) (((s1 & 255) + (s1 >> 8)) ^ pageId) && d[2] == (byte) (((s2 & 255) + (s2 >> 8)) ^ (pageId >> 8)); } /** * Increment the change count. To be done after the operation has finished. */ public void incrementChangeCount() { if (++changeCount < 0) { throw DbException.throwInternalError("changeCount has wrapped"); } } /** * Get the current change count. The first value is 1 * * @return the change count */ public long getChangeCount() { return changeCount; } public void setLogMode(int logMode) { this.logMode = logMode; } public int getLogMode() { return logMode; } public void setLockFile(boolean lockFile) { this.lockFile = lockFile; } public BitSet getObjectIds() { BitSet f = new BitSet(); Cursor cursor = metaIndex.find(pageStoreSession, null, null); while (cursor.next()) { Row row = cursor.get(); int id = row.getValue(0).getInt(); if (id > 0) { f.set(id); } } return f; } public Session getPageStoreSession() { return pageStoreSession; } public synchronized void setBackup(boolean start) { backupLevel += start ? 1 : -1; } public synchronized void setMaxCacheMemory(int size) { cache.setMaxMemory(size); } }