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/*
* Copyright 2004-2014 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (http://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.Collections;
import java.util.Comparator;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import org.h2.api.DatabaseEventListener;
import org.h2.api.ErrorCode;
import org.h2.command.ddl.Analyze;
import org.h2.command.ddl.CreateTableData;
import org.h2.constraint.Constraint;
import org.h2.constraint.ConstraintReferential;
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.index.MultiVersionIndex;
import org.h2.message.DbException;
import org.h2.message.Trace;
import org.h2.mvstore.db.MVTableEngine.Store;
import org.h2.mvstore.db.TransactionStore.Transaction;
import org.h2.result.Row;
import org.h2.result.SortOrder;
import org.h2.schema.SchemaObject;
import org.h2.table.Column;
import org.h2.table.IndexColumn;
import org.h2.table.Table;
import org.h2.table.TableBase;
import org.h2.util.MathUtils;
import org.h2.util.New;
import org.h2.value.DataType;
import org.h2.value.Value;
/**
* A table stored in a MVStore.
*/
public class MVTable extends TableBase {
private MVPrimaryIndex primaryIndex;
private final ArrayList indexes = New.arrayList();
private long lastModificationId;
private volatile Session lockExclusiveSession;
// using a ConcurrentHashMap as a set
private final ConcurrentHashMap lockSharedSessions =
new ConcurrentHashMap();
/**
* 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 int changesSinceAnalyze;
private int nextAnalyze;
private boolean containsLargeObject;
private Column rowIdColumn;
private final TransactionStore store;
public MVTable(CreateTableData data, MVTableEngine.Store store) {
super(data);
nextAnalyze = database.getSettings().analyzeAuto;
this.store = store.getTransactionStore();
this.isHidden = data.isHidden;
for (Column col : getColumns()) {
if (DataType.isLargeObject(col.getType())) {
containsLargeObject = true;
}
}
traceLock = database.getTrace(Trace.LOCK);
}
/**
* Initialize the table.
*
* @param session the session
*/
void init(Session session) {
primaryIndex = new MVPrimaryIndex(session.getDatabase(), 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) {
return false;
}
if (!forceLockEvenInMvcc && database.isMultiVersion()) {
// 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 (getLockSyncObject()) {
if (!exclusive && lockSharedSessions.containsKey(session)) {
return true;
}
session.setWaitForLock(this, Thread.currentThread());
waitingSessions.addLast(session);
try {
doLock1(session, lockMode, exclusive);
} finally {
session.setWaitForLock(null, null);
waitingSessions.remove(session);
}
}
return false;
}
/**
* The the object on which to synchronize and wait on. For the
* multi-threaded mode, this is this object, but for non-multi-threaded, it
* is the database, as in this case all operations are synchronized on the
* database object.
*
* @return the lock sync object
*/
private Object getLockSyncObject() {
if (database.isMultiThreaded()) {
return this;
}
return database;
}
private void doLock1(Session session, int lockMode, boolean exclusive) {
traceLock(session, exclusive, "requesting for");
// 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.currentTimeMillis();
if (max == 0) {
// try at least one more time
max = now + session.getLockTimeout();
} else if (now >= max) {
traceLock(session, exclusive,
"timeout after " + session.getLockTimeout());
throw DbException.get(ErrorCode.LOCK_TIMEOUT_1, getName());
}
try {
traceLock(session, exclusive, "waiting for");
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, max - now);
if (sleep == 0) {
sleep = 1;
}
getLockSyncObject().wait(sleep);
} catch (InterruptedException e) {
// ignore
}
}
}
private boolean doLock2(Session session, int lockMode, boolean exclusive) {
if (exclusive) {
if (lockExclusiveSession == null) {
if (lockSharedSessions.isEmpty()) {
traceLock(session, exclusive, "added for");
session.addLock(this);
lockExclusiveSession = session;
return true;
} else if (lockSharedSessions.size() == 1 &&
lockSharedSessions.containsKey(session)) {
traceLock(session, exclusive, "add (upgraded) for ");
lockExclusiveSession = session;
return true;
}
}
} else {
if (lockExclusiveSession == null) {
if (lockMode == Constants.LOCK_MODE_READ_COMMITTED) {
if (!database.isMultiThreaded() &&
!database.isMultiVersion()) {
// READ_COMMITTED: a read lock is acquired,
// but released immediately after the operation
// is complete.
// When allowing only one thread, no lock is
// required.
// Row level locks work like read committed.
return true;
}
}
if (!lockSharedSessions.containsKey(session)) {
traceLock(session, exclusive, "ok");
session.addLock(this);
lockSharedSessions.put(session, session);
}
return true;
}
}
return false;
}
private static String getDeadlockDetails(ArrayList sessions, boolean exclusive) {
// We add the thread details here to make it easier for customers to
// match up these error messages with their own logs.
StringBuilder buff = new StringBuilder();
for (Session s : sessions) {
Table lock = s.getWaitForLock();
Thread thread = s.getWaitForLockThread();
buff.append("\nSession ").append(s.toString())
.append(" on thread ").append(thread.getName())
.append(" is waiting to lock ").append(lock.toString())
.append(exclusive ? " (exclusive)" : " (shared)")
.append(" while locking ");
int i = 0;
for (Table t : s.getLocks()) {
if (i++ > 0) {
buff.append(", ");
}
buff.append(t.toString());
if (t instanceof MVTable) {
if (((MVTable) t).lockExclusiveSession == s) {
buff.append(" (exclusive)");
} else {
buff.append(" (shared)");
}
}
}
buff.append('.');
}
return buff.toString();
}
@Override
public ArrayList checkDeadlock(Session session, Session clash,
Set visited) {
// only one deadlock check at any given time
synchronized (MVTable.class) {
if (clash == null) {
// verification is started
clash = session;
visited = New.hashSet();
} else if (clash == session) {
// we found a circle where this session is involved
return New.arrayList();
} else if (visited.contains(session)) {
// we have already checked this session.
// there is a circle, but the sessions in the circle need to
// find it out themselves
return null;
}
visited.add(session);
ArrayList error = null;
for (Session s : lockSharedSessions.keySet()) {
if (s == session) {
// it doesn't matter if we have locked the object already
continue;
}
Table t = s.getWaitForLock();
if (t != null) {
error = t.checkDeadlock(s, clash, visited);
if (error != null) {
error.add(session);
break;
}
}
}
// take a local copy so we don't see inconsistent data, since we are
// not locked while checking the lockExclusiveSession value
Session copyOfLockExclusiveSession = lockExclusiveSession;
if (error == null && copyOfLockExclusiveSession != null) {
Table t = copyOfLockExclusiveSession.getWaitForLock();
if (t != null) {
error = t.checkDeadlock(copyOfLockExclusiveSession, clash,
visited);
if (error != null) {
error.add(session);
}
}
}
return error;
}
}
private void traceLock(Session session, boolean exclusive, String s) {
if (traceLock.isDebugEnabled()) {
traceLock.debug("{0} {1} {2} {3}", session.getId(),
exclusive ? "exclusive write lock" : "shared read lock", s,
getName());
}
}
@Override
public boolean isLockedExclusively() {
return lockExclusiveSession != null;
}
@Override
public boolean isLockedExclusivelyBy(Session session) {
return lockExclusiveSession == session;
}
@Override
public void unlock(Session s) {
if (database != null) {
traceLock(s, lockExclusiveSession == s, "unlock");
if (lockExclusiveSession == s) {
lockExclusiveSession = null;
}
synchronized (getLockSyncObject()) {
if (lockSharedSessions.size() > 0) {
lockSharedSessions.remove(s);
}
if (!waitingSessions.isEmpty()) {
getLockSyncObject().notifyAll();
}
}
}
}
@Override
public boolean canTruncate() {
if (getCheckForeignKeyConstraints() &&
database.getReferentialIntegrity()) {
ArrayList constraints = getConstraints();
if (constraints != null) {
for (int i = 0, size = constraints.size(); i < size; i++) {
Constraint c = constraints.get(i);
if (!(c.getConstraintType().equals(Constraint.REFERENTIAL))) {
continue;
}
ConstraintReferential ref = (ConstraintReferential) c;
if (ref.getRefTable() == this) {
return false;
}
}
}
}
return true;
}
@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;
mainIndexColumn = getMainIndexColumn(indexType, cols);
if (database.isStarting()) {
if (store.store.hasMap("index." + indexId)) {
mainIndexColumn = -1;
}
} else if (primaryIndex.getRowCountMax() != 0) {
mainIndexColumn = -1;
}
if (mainIndexColumn != -1) {
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().getMvStore() == 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().getMvStore();
int bufferSize = database.getMaxMemoryRows() / 2;
ArrayList buffer = New.arrayList(bufferSize);
String n = getName() + ":" + index.getName();
int t = MathUtils.convertLongToInt(total);
ArrayList bufferNames = New.arrayList();
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.size() > 0) {
String mapName = store.nextTemporaryMapName();
index.addRowsToBuffer(buffer, mapName);
bufferNames.add(mapName);
buffer.clear();
index.addBufferedRows(bufferNames);
} else {
addRowsToIndex(session, buffer, index);
}
if (SysProperties.CHECK && 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 (SysProperties.CHECK && remaining != 0) {
DbException.throwInternalError("rowcount remaining=" + remaining +
" " + getName());
}
}
private int getMainIndexColumn(IndexType indexType, IndexColumn[] cols) {
if (primaryIndex.getMainIndexColumn() != -1) {
return -1;
}
if (!indexType.isPrimaryKey() || cols.length != 1) {
return -1;
}
IndexColumn first = cols[0];
if (first.sortType != SortOrder.ASCENDING) {
return -1;
}
switch (first.column.getType()) {
case Value.BYTE:
case Value.SHORT:
case Value.INT:
case Value.LONG:
break;
default:
return -1;
}
return first.column.getColumnId();
}
private static void addRowsToIndex(Session session, ArrayList list,
Index index) {
sortRows(list, index);
for (Row row : list) {
index.add(session, row);
}
list.clear();
}
private static void sortRows(ArrayList list, final Index index) {
Collections.sort(list, new Comparator() {
@Override
public int compare(Row r1, Row r2) {
return index.compareRows(r1, r2);
}
});
}
@Override
public void removeRow(Session session, Row row) {
lastModificationId = database.getNextModificationDataId();
Transaction t = getTransaction(session);
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) {
t.rollbackToSavepoint(savepoint);
throw DbException.convert(e);
}
analyzeIfRequired(session);
}
@Override
public void truncate(Session session) {
lastModificationId = database.getNextModificationDataId();
for (int i = indexes.size() - 1; i >= 0; i--) {
Index index = indexes.get(i);
index.truncate(session);
}
changesSinceAnalyze = 0;
}
@Override
public void addRow(Session session, Row row) {
lastModificationId = database.getNextModificationDataId();
Transaction t = getTransaction(session);
long savepoint = t.setSavepoint();
try {
for (int i = 0, size = indexes.size(); i < size; i++) {
Index index = indexes.get(i);
index.add(session, row);
}
} catch (Throwable e) {
t.rollbackToSavepoint(savepoint);
DbException de = DbException.convert(e);
if (de.getErrorCode() == ErrorCode.DUPLICATE_KEY_1) {
for (int j = 0; j < indexes.size(); j++) {
Index index = indexes.get(j);
if (index.getIndexType().isUnique() &&
index instanceof MultiVersionIndex) {
MultiVersionIndex mv = (MultiVersionIndex) index;
if (mv.isUncommittedFromOtherSession(session, row)) {
throw DbException.get(
ErrorCode.CONCURRENT_UPDATE_1,
index.getName());
}
}
}
}
throw de;
}
analyzeIfRequired(session);
}
private void analyzeIfRequired(Session session) {
if (nextAnalyze == 0 || nextAnalyze > changesSinceAnalyze++) {
return;
}
changesSinceAnalyze = 0;
int n = 2 * nextAnalyze;
if (n > 0) {
nextAnalyze = n;
}
int rows = session.getDatabase().getSettings().analyzeSample / 10;
Analyze.analyzeTable(session, this, rows, false);
}
@Override
public void checkSupportAlter() {
// ok
}
@Override
public String getTableType() {
return Table.TABLE;
}
@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;
}
public boolean getContainsLargeObject() {
return containsLargeObject;
}
@Override
public boolean isDeterministic() {
return true;
}
@Override
public boolean canGetRowCount() {
return true;
}
@Override
public boolean canDrop() {
return true;
}
@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.getMvStore().removeTable(this);
super.removeChildrenAndResources(session);
// go backwards because database.removeIndex will
// call table.removeIndex
while (indexes.size() > 1) {
Index index = indexes.get(1);
if (index.getName() != null) {
database.removeSchemaObject(session, index);
}
// needed for session temporary indexes
indexes.remove(index);
}
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());
}
}
}
primaryIndex.remove(session);
database.removeMeta(session, getId());
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();
}
@Override
public void checkRename() {
// ok
}
/**
* Get the transaction to use for this session.
*
* @param session the session
* @return the transaction
*/
Transaction getTransaction(Session session) {
if (session == null) {
// TODO need to commit/rollback the transaction
return store.begin();
}
return session.getTransaction();
}
@Override
public Column getRowIdColumn() {
if (rowIdColumn == null) {
rowIdColumn = new Column(Column.ROWID, Value.LONG);
rowIdColumn.setTable(this, -1);
}
return rowIdColumn;
}
@Override
public String toString() {
return getSQL();
}
@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) {
lastModificationId = database.getNextModificationDataId();
}
}
}
