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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.util.ArrayList;
import java.util.Arrays;
import java.util.BitSet;
import java.util.HashMap;
import org.h2.api.ErrorCode;
import org.h2.compress.CompressLZF;
import org.h2.engine.Session;
import org.h2.message.DbException;
import org.h2.message.Trace;
import org.h2.result.Row;
import org.h2.result.RowFactory;
import org.h2.store.Data;
import org.h2.store.DataReader;
import org.h2.store.InDoubtTransaction;
import org.h2.util.IntArray;
import org.h2.util.IntIntHashMap;
import org.h2.util.Utils;
import org.h2.value.Value;
import org.h2.value.ValueNull;
/**
* Transaction log mechanism. The stream contains a list of records. The data
* format for a record is:
*
*
type (0: no-op, 1: undo, 2: commit, ...)
*
data
*
* The transaction log is split into sections.
* A checkpoint starts a new section.
*/
public class PageLog {
/**
* No operation.
*/
public static final int NOOP = 0;
/**
* An undo log entry. Format: page id: varInt, size, page. Size 0 means
* uncompressed, size 1 means empty page, otherwise the size is the number
* of compressed bytes.
*/
public static final int UNDO = 1;
/**
* A commit entry of a session.
* Format: session id: varInt.
*/
public static final int COMMIT = 2;
/**
* A prepare commit entry for a session.
* Format: session id: varInt, transaction name: string.
*/
public static final int PREPARE_COMMIT = 3;
/**
* Roll back a prepared transaction.
* Format: session id: varInt.
*/
public static final int ROLLBACK = 4;
/**
* Add a record to a table.
* Format: session id: varInt, table id: varInt, row.
*/
public static final int ADD = 5;
/**
* Remove a record from a table.
* Format: session id: varInt, table id: varInt, row.
*/
public static final int REMOVE = 6;
/**
* Truncate a table.
* Format: session id: varInt, table id: varInt.
*/
public static final int TRUNCATE = 7;
/**
* Perform a checkpoint. The log section id is incremented.
* Format: -
*/
public static final int CHECKPOINT = 8;
/**
* Free a log page.
* Format: count: varInt, page ids: varInt
*/
public static final int FREE_LOG = 9;
/**
* The recovery stage to undo changes (re-apply the backup).
*/
static final int RECOVERY_STAGE_UNDO = 0;
/**
* The recovery stage to allocate pages used by the transaction log.
*/
static final int RECOVERY_STAGE_ALLOCATE = 1;
/**
* The recovery stage to redo operations.
*/
static final int RECOVERY_STAGE_REDO = 2;
private static final boolean COMPRESS_UNDO = true;
private final PageStore store;
private final Trace trace;
private Data writeBuffer;
private PageOutputStream pageOut;
private int firstTrunkPage;
private int firstDataPage;
private final Data dataBuffer;
private int logKey;
private int logSectionId, logPos;
private int firstSectionId;
private final CompressLZF compress;
private final byte[] compressBuffer;
/**
* If the bit is set, the given page was written to the current log section.
* The undo entry of these pages doesn't need to be written again.
*/
private BitSet undo = new BitSet();
/**
* The undo entry of those pages was written in any log section.
* These pages may not be used in the transaction log.
*/
private final BitSet undoAll = new BitSet();
/**
* The map of section ids (key) and data page where the section starts
* (value).
*/
private final IntIntHashMap logSectionPageMap = new IntIntHashMap();
/**
* The session state map.
* Only used during recovery.
*/
private HashMap sessionStates = new HashMap<>();
/**
* The map of pages used by the transaction log.
* Only used during recovery.
*/
private BitSet usedLogPages;
/**
* This flag is set while freeing up pages.
*/
private boolean freeing;
PageLog(PageStore store) {
this.store = store;
dataBuffer = store.createData();
trace = store.getTrace();
compress = new CompressLZF();
compressBuffer = new byte[store.getPageSize() * 2];
}
/**
* Open the log for writing. For an existing database, the recovery
* must be run first.
*
* @param newFirstTrunkPage the first trunk page
* @param atEnd whether only pages at the end of the file should be used
*/
void openForWriting(int newFirstTrunkPage, boolean atEnd) {
trace.debug("log openForWriting firstPage: " + newFirstTrunkPage);
this.firstTrunkPage = newFirstTrunkPage;
logKey++;
pageOut = new PageOutputStream(store,
newFirstTrunkPage, undoAll, logKey, atEnd);
pageOut.reserve(1);
// pageBuffer = new BufferedOutputStream(pageOut, 8 * 1024);
store.setLogFirstPage(logKey, newFirstTrunkPage,
pageOut.getCurrentDataPageId());
writeBuffer = store.createData();
}
/**
* Free up all pages allocated by the log.
*/
void free() {
if (trace.isDebugEnabled()) {
trace.debug("log free");
}
int currentDataPage = 0;
if (pageOut != null) {
currentDataPage = pageOut.getCurrentDataPageId();
pageOut.freeReserved();
}
try {
freeing = true;
int first = 0;
int loopDetect = 1024, loopCount = 0;
PageStreamTrunk.Iterator it = new PageStreamTrunk.Iterator(
store, firstTrunkPage);
while (firstTrunkPage != 0 && firstTrunkPage < store.getPageCount()) {
PageStreamTrunk t = it.next();
if (t == null) {
if (it.canDelete()) {
store.free(firstTrunkPage, false);
}
break;
}
if (loopCount++ >= loopDetect) {
first = t.getPos();
loopCount = 0;
loopDetect *= 2;
} else if (first != 0 && first == t.getPos()) {
throw DbException.throwInternalError(
"endless loop at " + t);
}
t.free(currentDataPage);
firstTrunkPage = t.getNextTrunk();
}
} finally {
freeing = false;
}
}
/**
* Open the log for reading.
*
* @param newLogKey the first expected log key
* @param newFirstTrunkPage the first trunk page
* @param newFirstDataPage the index of the first data page
*/
void openForReading(int newLogKey, int newFirstTrunkPage,
int newFirstDataPage) {
this.logKey = newLogKey;
this.firstTrunkPage = newFirstTrunkPage;
this.firstDataPage = newFirstDataPage;
}
/**
* Run one recovery stage. There are three recovery stages: 0: only the undo
* steps are run (restoring the state before the last checkpoint). 1: the
* pages that are used by the transaction log are allocated. 2: the
* committed operations are re-applied.
*
* @param stage the recovery stage
* @return whether the transaction log was empty
*/
boolean recover(int stage) {
if (trace.isDebugEnabled()) {
trace.debug("log recover stage: " + stage);
}
if (stage == RECOVERY_STAGE_ALLOCATE) {
PageInputStream in = new PageInputStream(store,
logKey, firstTrunkPage, firstDataPage);
usedLogPages = in.allocateAllPages();
in.close();
return true;
}
PageInputStream pageIn = new PageInputStream(store,
logKey, firstTrunkPage, firstDataPage);
DataReader in = new DataReader(pageIn);
int logId = 0;
Data data = store.createData();
boolean isEmpty = true;
try {
int pos = 0;
while (true) {
int x = in.readByte();
if (x < 0) {
break;
}
pos++;
isEmpty = false;
if (x == UNDO) {
int pageId = in.readVarInt();
int size = in.readVarInt();
if (size == 0) {
in.readFully(data.getBytes(), store.getPageSize());
} else if (size == 1) {
// empty
Arrays.fill(data.getBytes(), 0, store.getPageSize(), (byte) 0);
} else {
in.readFully(compressBuffer, size);
try {
compress.expand(compressBuffer, 0, size,
data.getBytes(), 0, store.getPageSize());
} catch (ArrayIndexOutOfBoundsException e) {
DbException.convertToIOException(e);
}
}
if (stage == RECOVERY_STAGE_UNDO) {
if (!undo.get(pageId)) {
if (trace.isDebugEnabled()) {
trace.debug("log undo {0}", pageId);
}
store.writePage(pageId, data);
undo.set(pageId);
undoAll.set(pageId);
} else {
if (trace.isDebugEnabled()) {
trace.debug("log undo skip {0}", pageId);
}
}
}
} else if (x == ADD) {
int sessionId = in.readVarInt();
int tableId = in.readVarInt();
Row row = readRow(store.getDatabase().getRowFactory(), in, data);
if (stage == RECOVERY_STAGE_UNDO) {
store.allocateIfIndexRoot(pos, tableId, row);
} else if (stage == RECOVERY_STAGE_REDO) {
if (isSessionCommitted(sessionId, logId, pos)) {
if (trace.isDebugEnabled()) {
trace.debug("log redo + table: " + tableId +
" s: " + sessionId + " " + row);
}
store.redo(tableId, row, true);
} else {
if (trace.isDebugEnabled()) {
trace.debug("log ignore s: " + sessionId +
" + table: " + tableId + " " + row);
}
}
}
} else if (x == REMOVE) {
int sessionId = in.readVarInt();
int tableId = in.readVarInt();
long key = in.readVarLong();
if (stage == RECOVERY_STAGE_REDO) {
if (isSessionCommitted(sessionId, logId, pos)) {
if (trace.isDebugEnabled()) {
trace.debug("log redo - table: " + tableId +
" s:" + sessionId + " key: " + key);
}
store.redoDelete(tableId, key);
} else {
if (trace.isDebugEnabled()) {
trace.debug("log ignore s: " + sessionId +
" - table: " + tableId + " " + key);
}
}
}
} else if (x == TRUNCATE) {
int sessionId = in.readVarInt();
int tableId = in.readVarInt();
if (stage == RECOVERY_STAGE_REDO) {
if (isSessionCommitted(sessionId, logId, pos)) {
if (trace.isDebugEnabled()) {
trace.debug("log redo truncate table: " + tableId);
}
store.redoTruncate(tableId);
} else {
if (trace.isDebugEnabled()) {
trace.debug("log ignore s: "+ sessionId +
" truncate table: " + tableId);
}
}
}
} else if (x == PREPARE_COMMIT) {
int sessionId = in.readVarInt();
String transaction = in.readString();
if (trace.isDebugEnabled()) {
trace.debug("log prepare commit " + sessionId + " " +
transaction + " pos: " + pos);
}
if (stage == RECOVERY_STAGE_UNDO) {
int page = pageIn.getDataPage();
setPrepareCommit(sessionId, page, transaction);
}
} else if (x == ROLLBACK) {
int sessionId = in.readVarInt();
if (trace.isDebugEnabled()) {
trace.debug("log rollback " + sessionId + " pos: " + pos);
}
// ignore - this entry is just informational
} else if (x == COMMIT) {
int sessionId = in.readVarInt();
if (trace.isDebugEnabled()) {
trace.debug("log commit " + sessionId + " pos: " + pos);
}
if (stage == RECOVERY_STAGE_UNDO) {
setLastCommitForSession(sessionId, logId, pos);
}
} else if (x == NOOP) {
// nothing to do
} else if (x == CHECKPOINT) {
logId++;
} else if (x == FREE_LOG) {
int count = in.readVarInt();
for (int i = 0; i < count; i++) {
int pageId = in.readVarInt();
if (stage == RECOVERY_STAGE_REDO) {
if (!usedLogPages.get(pageId)) {
store.free(pageId, false);
}
}
}
} else {
if (trace.isDebugEnabled()) {
trace.debug("log end");
break;
}
}
}
} catch (DbException e) {
if (e.getErrorCode() == ErrorCode.FILE_CORRUPTED_1) {
trace.debug("log recovery stopped");
} else {
throw e;
}
} catch (IOException e) {
trace.debug("log recovery completed");
}
undo = new BitSet();
if (stage == RECOVERY_STAGE_REDO) {
usedLogPages = null;
}
return isEmpty;
}
/**
* This method is called when a 'prepare commit' log entry is read when
* opening the database.
*
* @param sessionId the session id
* @param pageId the data page with the prepare entry
* @param transaction the transaction name, or null to rollback
*/
private void setPrepareCommit(int sessionId, int pageId, String transaction) {
SessionState state = getOrAddSessionState(sessionId);
PageStoreInDoubtTransaction doubt;
if (transaction == null) {
doubt = null;
} else {
doubt = new PageStoreInDoubtTransaction(store, sessionId, pageId,
transaction);
}
state.inDoubtTransaction = doubt;
}
/**
* Read a row from an input stream.
*
* @param rowFactory the row factory
* @param in the input stream
* @param data a temporary buffer
* @return the row
*/
public static Row readRow(RowFactory rowFactory, DataReader in, Data data) throws IOException {
long key = in.readVarLong();
int len = in.readVarInt();
data.reset();
data.checkCapacity(len);
in.readFully(data.getBytes(), len);
int columnCount = data.readVarInt();
Value[] values = new Value[columnCount];
for (int i = 0; i < columnCount; i++) {
values[i] = data.readValue();
}
Row row = rowFactory.createRow(values, Row.MEMORY_CALCULATE);
row.setKey(key);
return row;
}
/**
* Check if the undo entry was already written for the given page.
*
* @param pageId the page
* @return true if it was written
*/
boolean getUndo(int pageId) {
return undo.get(pageId);
}
/**
* Add an undo entry to the log. The page data is only written once until
* the next checkpoint.
*
* @param pageId the page id
* @param page the old page data
*/
void addUndo(int pageId, Data page) {
if (undo.get(pageId) || freeing) {
return;
}
if (trace.isDebugEnabled()) {
trace.debug("log undo " + pageId);
}
if (page == null) {
DbException.throwInternalError("Undo entry not written");
}
undo.set(pageId);
undoAll.set(pageId);
Data buffer = getBuffer();
buffer.writeByte((byte) UNDO);
buffer.writeVarInt(pageId);
if (page.getBytes()[0] == 0) {
buffer.writeVarInt(1);
} else {
int pageSize = store.getPageSize();
if (COMPRESS_UNDO) {
int size = compress.compress(page.getBytes(),
pageSize, compressBuffer, 0);
if (size < pageSize) {
buffer.writeVarInt(size);
buffer.checkCapacity(size);
buffer.write(compressBuffer, 0, size);
} else {
buffer.writeVarInt(0);
buffer.checkCapacity(pageSize);
buffer.write(page.getBytes(), 0, pageSize);
}
} else {
buffer.writeVarInt(0);
buffer.checkCapacity(pageSize);
buffer.write(page.getBytes(), 0, pageSize);
}
}
write(buffer);
}
private void freeLogPages(IntArray pages) {
if (trace.isDebugEnabled()) {
trace.debug("log frees " + pages.get(0) + ".." +
pages.get(pages.size() - 1));
}
Data buffer = getBuffer();
buffer.writeByte((byte) FREE_LOG);
int size = pages.size();
buffer.writeVarInt(size);
for (int i = 0; i < size; i++) {
buffer.writeVarInt(pages.get(i));
}
write(buffer);
}
private void write(Data data) {
pageOut.write(data.getBytes(), 0, data.length());
data.reset();
}
/**
* Mark a transaction as committed.
*
* @param sessionId the session
*/
void commit(int sessionId) {
if (trace.isDebugEnabled()) {
trace.debug("log commit s: " + sessionId);
}
if (store.getDatabase().getPageStore() == null) {
// database already closed
return;
}
Data buffer = getBuffer();
buffer.writeByte((byte) COMMIT);
buffer.writeVarInt(sessionId);
write(buffer);
if (store.getDatabase().getFlushOnEachCommit()) {
flush();
}
}
/**
* Prepare a transaction.
*
* @param session the session
* @param transaction the name of the transaction
*/
void prepareCommit(Session session, String transaction) {
if (trace.isDebugEnabled()) {
trace.debug("log prepare commit s: " + session.getId() + ", " + transaction);
}
if (store.getDatabase().getPageStore() == null) {
// database already closed
return;
}
// store it on a separate log page
int pageSize = store.getPageSize();
pageOut.flush();
pageOut.fillPage();
Data buffer = getBuffer();
buffer.writeByte((byte) PREPARE_COMMIT);
buffer.writeVarInt(session.getId());
buffer.writeString(transaction);
if (buffer.length() >= PageStreamData.getCapacity(pageSize)) {
throw DbException.getInvalidValueException(
"transaction name (too long)", transaction);
}
write(buffer);
// store it on a separate log page
flushOut();
pageOut.fillPage();
if (store.getDatabase().getFlushOnEachCommit()) {
flush();
}
}
/**
* 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
*/
void logAddOrRemoveRow(Session session, int tableId, Row row, boolean add) {
if (trace.isDebugEnabled()) {
trace.debug("log " + (add ? "+" : "-") +
" s: " + session.getId() + " table: " + tableId + " row: " + row);
}
session.addLogPos(logSectionId, logPos);
logPos++;
Data data = dataBuffer;
data.reset();
int columns = row.getColumnCount();
data.writeVarInt(columns);
data.checkCapacity(row.getByteCount(data));
if (session.isRedoLogBinaryEnabled()) {
for (int i = 0; i < columns; i++) {
data.writeValue(row.getValue(i));
}
} else {
for (int i = 0; i < columns; i++) {
Value v = row.getValue(i);
if (v.getValueType() == Value.BYTES) {
data.writeValue(ValueNull.INSTANCE);
} else {
data.writeValue(v);
}
}
}
Data buffer = getBuffer();
buffer.writeByte((byte) (add ? ADD : REMOVE));
buffer.writeVarInt(session.getId());
buffer.writeVarInt(tableId);
buffer.writeVarLong(row.getKey());
if (add) {
buffer.writeVarInt(data.length());
buffer.checkCapacity(data.length());
buffer.write(data.getBytes(), 0, data.length());
}
write(buffer);
}
/**
* A table is truncated.
*
* @param session the session
* @param tableId the table id
*/
void logTruncate(Session session, int tableId) {
if (trace.isDebugEnabled()) {
trace.debug("log truncate s: " + session.getId() + " table: " + tableId);
}
session.addLogPos(logSectionId, logPos);
logPos++;
Data buffer = getBuffer();
buffer.writeByte((byte) TRUNCATE);
buffer.writeVarInt(session.getId());
buffer.writeVarInt(tableId);
write(buffer);
}
/**
* Flush the transaction log.
*/
void flush() {
if (pageOut != null) {
flushOut();
}
}
/**
* Switch to a new log section.
*/
void checkpoint() {
Data buffer = getBuffer();
buffer.writeByte((byte) CHECKPOINT);
write(buffer);
undo = new BitSet();
logSectionId++;
logPos = 0;
pageOut.flush();
pageOut.fillPage();
int currentDataPage = pageOut.getCurrentDataPageId();
logSectionPageMap.put(logSectionId, currentDataPage);
}
int getLogSectionId() {
return logSectionId;
}
int getLogFirstSectionId() {
return firstSectionId;
}
int getLogPos() {
return logPos;
}
/**
* Remove all pages until the given log (excluding).
*
* @param firstUncommittedSection the first log section to keep
*/
void removeUntil(int firstUncommittedSection) {
if (firstUncommittedSection == 0) {
return;
}
int firstDataPageToKeep = logSectionPageMap.get(firstUncommittedSection);
firstTrunkPage = removeUntil(firstTrunkPage, firstDataPageToKeep);
store.setLogFirstPage(logKey, firstTrunkPage, firstDataPageToKeep);
while (firstSectionId < firstUncommittedSection) {
if (firstSectionId > 0) {
// there is no entry for log 0
logSectionPageMap.remove(firstSectionId);
}
firstSectionId++;
}
}
/**
* Remove all pages until the given data page.
*
* @param trunkPage the first trunk page
* @param firstDataPageToKeep the first data page to keep
* @return the trunk page of the data page to keep
*/
private int removeUntil(int trunkPage, int firstDataPageToKeep) {
trace.debug("log.removeUntil " + trunkPage + " " + firstDataPageToKeep);
int last = trunkPage;
while (true) {
Page p = store.getPage(trunkPage);
PageStreamTrunk t = (PageStreamTrunk) p;
if (t == null) {
throw DbException.throwInternalError(
"log.removeUntil not found: " + firstDataPageToKeep + " last " + last);
}
logKey = t.getLogKey();
last = t.getPos();
if (t.contains(firstDataPageToKeep)) {
return last;
}
trunkPage = t.getNextTrunk();
IntArray list = new IntArray();
list.add(t.getPos());
for (int i = 0;; i++) {
int next = t.getPageData(i);
if (next == -1) {
break;
}
list.add(next);
}
freeLogPages(list);
pageOut.free(t);
}
}
/**
* Close without further writing.
*/
void close() {
trace.debug("log close");
if (pageOut != null) {
pageOut.close();
pageOut = null;
}
writeBuffer = null;
}
/**
* Check if the session committed after than the given position.
*
* @param sessionId the session id
* @param logId the log id
* @param pos the position in the log
* @return true if it is committed
*/
private boolean isSessionCommitted(int sessionId, int logId, int pos) {
SessionState state = sessionStates.get(sessionId);
if (state == null) {
return false;
}
return state.isCommitted(logId, pos);
}
/**
* Set the last commit record for a session.
*
* @param sessionId the session id
* @param logId the log id
* @param pos the position in the log
*/
private void setLastCommitForSession(int sessionId, int logId, int pos) {
SessionState state = getOrAddSessionState(sessionId);
state.lastCommitLog = logId;
state.lastCommitPos = pos;
state.inDoubtTransaction = null;
}
/**
* Get the session state for this session. A new object is created if there
* is no session state yet.
*
* @param sessionId the session id
* @return the session state object
*/
private SessionState getOrAddSessionState(int sessionId) {
Integer key = sessionId;
SessionState state = sessionStates.get(key);
if (state == null) {
state = new SessionState();
sessionStates.put(key, state);
state.sessionId = sessionId;
}
return state;
}
long getSize() {
return pageOut == null ? 0 : pageOut.getSize();
}
ArrayList getInDoubtTransactions() {
ArrayList list = Utils.newSmallArrayList();
for (SessionState state : sessionStates.values()) {
PageStoreInDoubtTransaction in = state.inDoubtTransaction;
if (in != null) {
list.add(in);
}
}
return list;
}
/**
* Set the state of an in-doubt transaction.
*
* @param sessionId the session
* @param pageId the page where the commit was prepared
* @param commit whether the transaction should be committed
*/
void setInDoubtTransactionState(int sessionId, int pageId, boolean commit) {
PageStreamData d = (PageStreamData) store.getPage(pageId);
d.initWrite();
Data buff = store.createData();
buff.writeByte((byte) (commit ? COMMIT : ROLLBACK));
buff.writeVarInt(sessionId);
byte[] bytes = buff.getBytes();
d.write(bytes, 0, bytes.length);
bytes = new byte[d.getRemaining()];
d.write(bytes, 0, bytes.length);
d.write();
}
/**
* Called after the recovery has been completed.
*/
void recoverEnd() {
sessionStates = new HashMap<>();
}
private void flushOut() {
pageOut.flush();
}
private Data getBuffer() {
if (writeBuffer.length() == 0) {
return writeBuffer;
}
return store.createData();
}
/**
* Get the smallest possible page id used. This is the trunk page if only
* appending at the end of the file, or 0.
*
* @return the smallest possible page.
*/
int getMinPageId() {
return pageOut == null ? 0 : pageOut.getMinPageId();
}
}
