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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.mvstore.db;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicLong;
import org.h2.api.DatabaseEventListener;
import org.h2.api.ErrorCode;
import org.h2.command.ddl.CreateTableData;
import org.h2.engine.Constants;
import org.h2.engine.DbObject;
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.mvstore.DataUtils;
import org.h2.mvstore.db.MVTableEngine.Store;
import org.h2.mvstore.tx.Transaction;
import org.h2.mvstore.tx.TransactionStore;
import org.h2.result.Row;
import org.h2.result.SearchRow;
import org.h2.schema.SchemaObject;
import org.h2.table.Column;
import org.h2.table.IndexColumn;
import org.h2.table.RegularTable;
import org.h2.util.DebuggingThreadLocal;
import org.h2.util.MathUtils;
import org.h2.util.Utils;
/**
* A table stored in a MVStore.
*/
public class MVTable extends RegularTable {
/**
* The table name this thread is waiting to lock.
*/
public static final DebuggingThreadLocal WAITING_FOR_LOCK;
/**
* The table names this thread has exclusively locked.
*/
public static final DebuggingThreadLocal> EXCLUSIVE_LOCKS;
/**
* The tables names this thread has a shared lock on.
*/
public static final DebuggingThreadLocal> SHARED_LOCKS;
/**
* The type of trace lock events
*/
private enum TraceLockEvent{
TRACE_LOCK_OK("ok"),
TRACE_LOCK_WAITING_FOR("waiting for"),
TRACE_LOCK_REQUESTING_FOR("requesting for"),
TRACE_LOCK_TIMEOUT_AFTER("timeout after "),
TRACE_LOCK_UNLOCK("unlock"),
TRACE_LOCK_ADDED_FOR("added for"),
TRACE_LOCK_ADD_UPGRADED_FOR("add (upgraded) for ");
private final String eventText;
TraceLockEvent(String eventText) {
this.eventText = eventText;
}
public String getEventText() {
return eventText;
}
}
private static final String NO_EXTRA_INFO = "";
static {
if (SysProperties.THREAD_DEADLOCK_DETECTOR) {
WAITING_FOR_LOCK = new DebuggingThreadLocal<>();
EXCLUSIVE_LOCKS = new DebuggingThreadLocal<>();
SHARED_LOCKS = new DebuggingThreadLocal<>();
} else {
WAITING_FOR_LOCK = null;
EXCLUSIVE_LOCKS = null;
SHARED_LOCKS = null;
}
}
private MVPrimaryIndex primaryIndex;
private final ArrayList indexes = Utils.newSmallArrayList();
private final AtomicLong lastModificationId = new AtomicLong();
/**
* The queue of sessions waiting to lock the table. It is a FIFO queue to
* prevent starvation, since Java's synchronized locking is biased.
*/
private final ArrayDeque waitingSessions = new ArrayDeque<>();
private final Trace traceLock;
private final AtomicInteger changesUntilAnalyze;
private int nextAnalyze;
private final MVTableEngine.Store store;
private final TransactionStore transactionStore;
public MVTable(CreateTableData data, MVTableEngine.Store store) {
super(data);
nextAnalyze = database.getSettings().analyzeAuto;
changesUntilAnalyze = nextAnalyze <= 0 ? null : new AtomicInteger(nextAnalyze);
this.store = store;
this.transactionStore = store.getTransactionStore();
traceLock = database.getTrace(Trace.LOCK);
primaryIndex = new MVPrimaryIndex(database, this, getId(),
IndexColumn.wrap(getColumns()), IndexType.createScan(true));
indexes.add(primaryIndex);
}
public String getMapName() {
return primaryIndex.getMapName();
}
@Override
public boolean lock(Session session, boolean exclusive,
boolean forceLockEvenInMvcc) {
int lockMode = database.getLockMode();
if (lockMode == Constants.LOCK_MODE_OFF) {
session.registerTableAsUpdated(this);
return false;
}
if (!forceLockEvenInMvcc) {
// MVCC: update, delete, and insert use a shared lock.
// Select doesn't lock except when using FOR UPDATE and
// the system property h2.selectForUpdateMvcc
// is not enabled
if (exclusive) {
exclusive = false;
} else {
if (lockExclusiveSession == null) {
return false;
}
}
}
if (lockExclusiveSession == session) {
return true;
}
if (!exclusive && lockSharedSessions.containsKey(session)) {
return true;
}
synchronized (this) {
if (!exclusive && lockSharedSessions.containsKey(session)) {
return true;
}
session.setWaitForLock(this, Thread.currentThread());
if (SysProperties.THREAD_DEADLOCK_DETECTOR) {
WAITING_FOR_LOCK.set(getName());
}
waitingSessions.addLast(session);
try {
doLock1(session, lockMode, exclusive);
} finally {
session.setWaitForLock(null, null);
if (SysProperties.THREAD_DEADLOCK_DETECTOR) {
WAITING_FOR_LOCK.remove();
}
waitingSessions.remove(session);
}
}
return false;
}
private void doLock1(Session session, int lockMode, boolean exclusive) {
traceLock(session, exclusive, TraceLockEvent.TRACE_LOCK_REQUESTING_FOR, NO_EXTRA_INFO);
// don't get the current time unless necessary
long max = 0;
boolean checkDeadlock = false;
while (true) {
// if I'm the next one in the queue
if (waitingSessions.getFirst() == session) {
if (doLock2(session, lockMode, exclusive)) {
return;
}
}
if (checkDeadlock) {
ArrayList sessions = checkDeadlock(session, null, null);
if (sessions != null) {
throw DbException.get(ErrorCode.DEADLOCK_1,
getDeadlockDetails(sessions, exclusive));
}
} else {
// check for deadlocks from now on
checkDeadlock = true;
}
long now = System.nanoTime();
if (max == 0) {
// try at least one more time
max = now + TimeUnit.MILLISECONDS.toNanos(session.getLockTimeout());
} else if (now >= max) {
traceLock(session, exclusive,
TraceLockEvent.TRACE_LOCK_TIMEOUT_AFTER, NO_EXTRA_INFO+session.getLockTimeout());
throw DbException.get(ErrorCode.LOCK_TIMEOUT_1, getName());
}
try {
traceLock(session, exclusive, TraceLockEvent.TRACE_LOCK_WAITING_FOR, NO_EXTRA_INFO);
if (database.getLockMode() == Constants.LOCK_MODE_TABLE_GC) {
for (int i = 0; i < 20; i++) {
long free = Runtime.getRuntime().freeMemory();
System.gc();
long free2 = Runtime.getRuntime().freeMemory();
if (free == free2) {
break;
}
}
}
// don't wait too long so that deadlocks are detected early
long sleep = Math.min(Constants.DEADLOCK_CHECK,
TimeUnit.NANOSECONDS.toMillis(max - now));
if (sleep == 0) {
sleep = 1;
}
wait(sleep);
} catch (InterruptedException e) {
// ignore
}
}
}
private boolean doLock2(Session session, int lockMode, boolean exclusive) {
if (lockExclusiveSession == null) {
if (exclusive) {
if (lockSharedSessions.isEmpty()) {
traceLock(session, exclusive, TraceLockEvent.TRACE_LOCK_ADDED_FOR, NO_EXTRA_INFO);
session.registerTableAsLocked(this);
lockExclusiveSession = session;
if (SysProperties.THREAD_DEADLOCK_DETECTOR) {
if (EXCLUSIVE_LOCKS.get() == null) {
EXCLUSIVE_LOCKS.set(new ArrayList());
}
EXCLUSIVE_LOCKS.get().add(getName());
}
return true;
} else if (lockSharedSessions.size() == 1 &&
lockSharedSessions.containsKey(session)) {
traceLock(session, exclusive, TraceLockEvent.TRACE_LOCK_ADD_UPGRADED_FOR, NO_EXTRA_INFO);
lockExclusiveSession = session;
if (SysProperties.THREAD_DEADLOCK_DETECTOR) {
if (EXCLUSIVE_LOCKS.get() == null) {
EXCLUSIVE_LOCKS.set(new ArrayList());
}
EXCLUSIVE_LOCKS.get().add(getName());
}
return true;
}
} else {
if (lockSharedSessions.putIfAbsent(session, session) == null) {
traceLock(session, exclusive, TraceLockEvent.TRACE_LOCK_OK, NO_EXTRA_INFO);
session.registerTableAsLocked(this);
if (SysProperties.THREAD_DEADLOCK_DETECTOR) {
ArrayList list = SHARED_LOCKS.get();
if (list == null) {
list = new ArrayList<>();
SHARED_LOCKS.set(list);
}
list.add(getName());
}
}
return true;
}
}
return false;
}
private void traceLock(Session session, boolean exclusive, TraceLockEvent eventEnum, String extraInfo) {
if (traceLock.isDebugEnabled()) {
traceLock.debug("{0} {1} {2} {3} {4}", session.getId(),
exclusive ? "exclusive write lock" : "shared read lock", eventEnum.getEventText(),
getName(), extraInfo);
}
}
@Override
public void unlock(Session s) {
if (database != null) {
boolean wasLocked = lockExclusiveSession == s;
traceLock(s, wasLocked, TraceLockEvent.TRACE_LOCK_UNLOCK, NO_EXTRA_INFO);
if (wasLocked) {
lockSharedSessions.remove(s);
lockExclusiveSession = null;
if (SysProperties.THREAD_DEADLOCK_DETECTOR) {
if (EXCLUSIVE_LOCKS.get() != null) {
EXCLUSIVE_LOCKS.get().remove(getName());
}
}
} else {
wasLocked = lockSharedSessions.remove(s) != null;
if (SysProperties.THREAD_DEADLOCK_DETECTOR) {
if (SHARED_LOCKS.get() != null) {
SHARED_LOCKS.get().remove(getName());
}
}
}
if (wasLocked && !waitingSessions.isEmpty()) {
synchronized (this) {
notifyAll();
}
}
}
}
@Override
public void close(Session session) {
// ignore
}
@Override
public Row getRow(Session session, long key) {
return primaryIndex.getRow(session, key);
}
@Override
public Index addIndex(Session session, String indexName, int indexId,
IndexColumn[] cols, IndexType indexType, boolean create,
String indexComment) {
if (indexType.isPrimaryKey()) {
for (IndexColumn c : cols) {
Column column = c.column;
if (column.isNullable()) {
throw DbException.get(
ErrorCode.COLUMN_MUST_NOT_BE_NULLABLE_1,
column.getName());
}
column.setPrimaryKey(true);
}
}
boolean isSessionTemporary = isTemporary() && !isGlobalTemporary();
if (!isSessionTemporary) {
database.lockMeta(session);
}
MVIndex index;
int mainIndexColumn = primaryIndex.getMainIndexColumn() != SearchRow.ROWID_INDEX
? SearchRow.ROWID_INDEX : getMainIndexColumn(indexType, cols);
if (database.isStarting()) {
// if index does exists as a separate map it can't be a delegate
if (transactionStore.hasMap("index." + indexId)) {
// we can not reuse primary index
mainIndexColumn = SearchRow.ROWID_INDEX;
}
} else if (primaryIndex.getRowCountMax() != 0) {
mainIndexColumn = SearchRow.ROWID_INDEX;
}
if (mainIndexColumn != SearchRow.ROWID_INDEX) {
primaryIndex.setMainIndexColumn(mainIndexColumn);
index = new MVDelegateIndex(this, indexId, indexName, primaryIndex,
indexType);
} else if (indexType.isSpatial()) {
index = new MVSpatialIndex(session.getDatabase(), this, indexId,
indexName, cols, indexType);
} else {
index = new MVSecondaryIndex(session.getDatabase(), this, indexId,
indexName, cols, indexType);
}
if (index.needRebuild()) {
rebuildIndex(session, index, indexName);
}
index.setTemporary(isTemporary());
if (index.getCreateSQL() != null) {
index.setComment(indexComment);
if (isSessionTemporary) {
session.addLocalTempTableIndex(index);
} else {
database.addSchemaObject(session, index);
}
}
indexes.add(index);
setModified();
return index;
}
private void rebuildIndex(Session session, MVIndex index, String indexName) {
try {
if (session.getDatabase().getStore() == null ||
index instanceof MVSpatialIndex) {
// in-memory
rebuildIndexBuffered(session, index);
} else {
rebuildIndexBlockMerge(session, index);
}
} catch (DbException e) {
getSchema().freeUniqueName(indexName);
try {
index.remove(session);
} catch (DbException e2) {
// this could happen, for example on failure in the storage
// but if that is not the case it means
// there is something wrong with the database
trace.error(e2, "could not remove index");
throw e2;
}
throw e;
}
}
private void rebuildIndexBlockMerge(Session session, MVIndex index) {
if (index instanceof MVSpatialIndex) {
// the spatial index doesn't support multi-way merge sort
rebuildIndexBuffered(session, index);
}
// Read entries in memory, sort them, write to a new map (in sorted
// order); repeat (using a new map for every block of 1 MB) until all
// record are read. Merge all maps to the target (using merge sort;
// duplicates are detected in the target). For randomly ordered data,
// this should use relatively few write operations.
// A possible optimization is: change the buffer size from "row count"
// to "amount of memory", and buffer index keys instead of rows.
Index scan = getScanIndex(session);
long remaining = scan.getRowCount(session);
long total = remaining;
Cursor cursor = scan.find(session, null, null);
long i = 0;
Store store = session.getDatabase().getStore();
int bufferSize = database.getMaxMemoryRows() / 2;
ArrayList buffer = new ArrayList<>(bufferSize);
String n = getName() + ":" + index.getName();
int t = MathUtils.convertLongToInt(total);
ArrayList bufferNames = Utils.newSmallArrayList();
while (cursor.next()) {
Row row = cursor.get();
buffer.add(row);
database.setProgress(DatabaseEventListener.STATE_CREATE_INDEX, n,
MathUtils.convertLongToInt(i++), t);
if (buffer.size() >= bufferSize) {
sortRows(buffer, index);
String mapName = store.nextTemporaryMapName();
index.addRowsToBuffer(buffer, mapName);
bufferNames.add(mapName);
buffer.clear();
}
remaining--;
}
sortRows(buffer, index);
if (!bufferNames.isEmpty()) {
String mapName = store.nextTemporaryMapName();
index.addRowsToBuffer(buffer, mapName);
bufferNames.add(mapName);
buffer.clear();
index.addBufferedRows(bufferNames);
} else {
addRowsToIndex(session, buffer, index);
}
if (remaining != 0) {
DbException.throwInternalError("rowcount remaining=" + remaining +
" " + getName());
}
}
private void rebuildIndexBuffered(Session session, Index index) {
Index scan = getScanIndex(session);
long remaining = scan.getRowCount(session);
long total = remaining;
Cursor cursor = scan.find(session, null, null);
long i = 0;
int bufferSize = (int) Math.min(total, database.getMaxMemoryRows());
ArrayList buffer = new ArrayList<>(bufferSize);
String n = getName() + ":" + index.getName();
int t = MathUtils.convertLongToInt(total);
while (cursor.next()) {
Row row = cursor.get();
buffer.add(row);
database.setProgress(DatabaseEventListener.STATE_CREATE_INDEX, n,
MathUtils.convertLongToInt(i++), t);
if (buffer.size() >= bufferSize) {
addRowsToIndex(session, buffer, index);
}
remaining--;
}
addRowsToIndex(session, buffer, index);
if (remaining != 0) {
DbException.throwInternalError("rowcount remaining=" + remaining +
" " + getName());
}
}
@Override
public void removeRow(Session session, Row row) {
syncLastModificationIdWithDatabase();
Transaction t = session.getTransaction();
long savepoint = t.setSavepoint();
try {
for (int i = indexes.size() - 1; i >= 0; i--) {
Index index = indexes.get(i);
index.remove(session, row);
}
} catch (Throwable e) {
try {
t.rollbackToSavepoint(savepoint);
} catch (Throwable nested) {
e.addSuppressed(nested);
}
throw DbException.convert(e);
}
analyzeIfRequired(session);
}
@Override
public void truncate(Session session) {
syncLastModificationIdWithDatabase();
for (int i = indexes.size() - 1; i >= 0; i--) {
Index index = indexes.get(i);
index.truncate(session);
}
if (changesUntilAnalyze != null) {
changesUntilAnalyze.set(nextAnalyze);
}
}
@Override
public void addRow(Session session, Row row) {
syncLastModificationIdWithDatabase();
Transaction t = session.getTransaction();
long savepoint = t.setSavepoint();
try {
for (Index index : indexes) {
index.add(session, row);
}
} catch (Throwable e) {
try {
t.rollbackToSavepoint(savepoint);
} catch (Throwable nested) {
e.addSuppressed(nested);
}
throw DbException.convert(e);
}
analyzeIfRequired(session);
}
@Override
public void updateRow(Session session, Row oldRow, Row newRow) {
newRow.setKey(oldRow.getKey());
syncLastModificationIdWithDatabase();
Transaction t = session.getTransaction();
long savepoint = t.setSavepoint();
try {
for (Index index : indexes) {
index.update(session, oldRow, newRow);
}
} catch (Throwable e) {
try {
t.rollbackToSavepoint(savepoint);
} catch (Throwable nested) {
e.addSuppressed(nested);
}
throw DbException.convert(e);
}
analyzeIfRequired(session);
}
@Override
public Row lockRow(Session session, Row row) {
Row lockedRow = primaryIndex.lockRow(session, row);
if (lockedRow == null || !row.hasSharedData(lockedRow)) {
syncLastModificationIdWithDatabase();
}
return lockedRow;
}
private void analyzeIfRequired(Session session) {
if (changesUntilAnalyze != null) {
if (changesUntilAnalyze.decrementAndGet() == 0) {
if (nextAnalyze <= Integer.MAX_VALUE / 2) {
nextAnalyze *= 2;
}
changesUntilAnalyze.set(nextAnalyze);
session.markTableForAnalyze(this);
}
}
}
@Override
public Index getScanIndex(Session session) {
return primaryIndex;
}
@Override
public Index getUniqueIndex() {
return primaryIndex;
}
@Override
public ArrayList getIndexes() {
return indexes;
}
@Override
public long getMaxDataModificationId() {
return lastModificationId.get();
}
@Override
public void removeChildrenAndResources(Session session) {
if (containsLargeObject) {
// unfortunately, the data is gone on rollback
truncate(session);
database.getLobStorage().removeAllForTable(getId());
database.lockMeta(session);
}
database.getStore().removeTable(this);
super.removeChildrenAndResources(session);
// remove scan index (at position 0 on the list) last
while (indexes.size() > 1) {
Index index = indexes.get(1);
index.remove(session);
if (index.getName() != null) {
database.removeSchemaObject(session, index);
}
// needed for session temporary indexes
indexes.remove(index);
}
primaryIndex.remove(session);
indexes.clear();
if (SysProperties.CHECK) {
for (SchemaObject obj : database
.getAllSchemaObjects(DbObject.INDEX)) {
Index index = (Index) obj;
if (index.getTable() == this) {
DbException.throwInternalError("index not dropped: " +
index.getName());
}
}
}
close(session);
invalidate();
}
@Override
public long getRowCount(Session session) {
return primaryIndex.getRowCount(session);
}
@Override
public long getRowCountApproximation() {
return primaryIndex.getRowCountApproximation();
}
@Override
public long getDiskSpaceUsed() {
return primaryIndex.getDiskSpaceUsed();
}
/**
* Get a new transaction.
*
* @return the transaction
*/
Transaction getTransactionBegin() {
// TODO need to commit/rollback the transaction
return transactionStore.begin();
}
@Override
public boolean isMVStore() {
return true;
}
/**
* Mark the transaction as committed, so that the modification counter of
* the database is incremented.
*/
public void commit() {
if (database != null) {
syncLastModificationIdWithDatabase();
}
}
// Field lastModificationId can not be just a volatile, because window of opportunity
// between reading database's modification id and storing this value in the field
// could be exploited by another thread.
// Second thread may do the same with possibly bigger (already advanced)
// modification id, and when first thread finally updates the field, it will
// result in lastModificationId jumping back.
// This is, of course, unacceptable.
private void syncLastModificationIdWithDatabase() {
long nextModificationDataId = database.getNextModificationDataId();
long currentId;
do {
currentId = lastModificationId.get();
} while (nextModificationDataId > currentId &&
!lastModificationId.compareAndSet(currentId, nextModificationDataId));
}
/**
* Convert the illegal state exception to a database exception.
*
* @param e the illegal state exception
* @return the database exception
*/
DbException convertException(IllegalStateException e) {
int errorCode = DataUtils.getErrorCode(e.getMessage());
if (errorCode == DataUtils.ERROR_TRANSACTION_LOCKED) {
throw DbException.get(ErrorCode.CONCURRENT_UPDATE_1,
e, getName());
}
if (errorCode == DataUtils.ERROR_TRANSACTIONS_DEADLOCK) {
throw DbException.get(ErrorCode.DEADLOCK_1,
e, getName());
}
return store.convertIllegalStateException(e);
}
}
