org.apache.hadoop.hbase.zookeeper.ZKTable Maven / Gradle / Ivy
Show all versions of hbase Show documentation
/**
* Copyright 2010 The Apache Software Foundation
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.hbase.zookeeper;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.master.AssignmentManager;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.zookeeper.ZKUtil.ZKUtilOp;
import org.apache.zookeeper.KeeperException;
/**
* Helper class for table state tracking for use by {@link AssignmentManager}.
* Reads, caches and sets state up in zookeeper. If multiple read/write
* clients, will make for confusion. Read-only clients other than
* AssignmentManager interested in learning table state can use the
* read-only utility methods in {@link ZKTableReadOnly}.
*
* To save on trips to the zookeeper ensemble, internally we cache table
* state.
*/
public class ZKTable {
// A znode will exist under the table directory if it is in any of the
// following states: {@link TableState#ENABLING} , {@link TableState#DISABLING},
// or {@link TableState#DISABLED}. If {@link TableState#ENABLED}, there will
// be no entry for a table in zk. Thats how it currently works.
private static final Log LOG = LogFactory.getLog(ZKTable.class);
private final ZooKeeperWatcher watcher;
/**
* Cache of what we found in zookeeper so we don't have to go to zk ensemble
* for every query. Synchronize access rather than use concurrent Map because
* synchronization needs to span query of zk.
*/
private final Map cache =
new HashMap();
// TODO: Make it so always a table znode. Put table schema here as well as table state.
// Have watcher on table znode so all are notified of state or schema change.
/**
* States a Table can be in.
* Compatibility note: ENABLED does not exist in 0.92 releases. In 0.92, the absence of
* the znode indicates the table is enabled.
*/
public static enum TableState {
ENABLED,
DISABLED,
DISABLING,
ENABLING
};
public ZKTable(final ZooKeeperWatcher zkw) throws KeeperException {
super();
this.watcher = zkw;
populateTableStates();
}
/**
* Gets a list of all the tables set as disabled in zookeeper.
* @throws KeeperException
*/
private void populateTableStates()
throws KeeperException {
synchronized (this.cache) {
List children =
ZKUtil.listChildrenNoWatch(this.watcher, this.watcher.masterTableZNode);
if (children == null) return;
for (String child: children) {
TableState state = getTableState(this.watcher, child);
if (state != null) this.cache.put(child, state);
}
}
}
/**
* @param zkw
* @param child
* @return Null or {@link TableState} found in znode.
* @throws KeeperException
*/
private static TableState getTableState(final ZooKeeperWatcher zkw,
final String child)
throws KeeperException {
return ZKTableReadOnly.getTableState(zkw, zkw.masterTableZNode, child);
}
/**
* Sets the specified table as DISABLED in zookeeper. Fails silently if the
* table is already disabled in zookeeper. Sets no watches.
* @param tableName
* @throws KeeperException unexpected zookeeper exception
*/
public void setDisabledTable(String tableName)
throws KeeperException {
synchronized (this.cache) {
if (!isDisablingOrDisabledTable(tableName)) {
LOG.warn("Moving table " + tableName + " state to disabled but was " +
"not first in disabling state: " + this.cache.get(tableName));
}
setTableState(tableName, TableState.DISABLED);
}
}
/**
* Sets the specified table as DISABLING in zookeeper. Fails silently if the
* table is already disabled in zookeeper. Sets no watches.
* @param tableName
* @throws KeeperException unexpected zookeeper exception
*/
public void setDisablingTable(final String tableName)
throws KeeperException {
synchronized (this.cache) {
if (!isEnabledOrDisablingTable(tableName)) {
LOG.warn("Moving table " + tableName + " state to disabling but was " +
"not first in enabled state: " + this.cache.get(tableName));
}
setTableState(tableName, TableState.DISABLING);
}
}
/**
* Sets the specified table as ENABLING in zookeeper. Fails silently if the
* table is already disabled in zookeeper. Sets no watches.
* @param tableName
* @throws KeeperException unexpected zookeeper exception
*/
public void setEnablingTable(final String tableName)
throws KeeperException {
synchronized (this.cache) {
if (!isDisabledOrEnablingTable(tableName)) {
LOG.warn("Moving table " + tableName + " state to enabling but was " +
"not first in disabled state: " + this.cache.get(tableName));
}
setTableState(tableName, TableState.ENABLING);
}
}
/**
* Sets the specified table as ENABLING in zookeeper atomically
* If the table is already in ENABLING state, no operation is performed
* @param tableName
* @return if the operation succeeds or not
* @throws KeeperException unexpected zookeeper exception
*/
public boolean checkAndSetEnablingTable(final String tableName)
throws KeeperException {
synchronized (this.cache) {
if (isEnablingTable(tableName)) {
return false;
}
setTableState(tableName, TableState.ENABLING);
return true;
}
}
/**
* Sets the specified table as ENABLING in zookeeper atomically
* If the table isn't in DISABLED state, no operation is performed
* @param tableName
* @return if the operation succeeds or not
* @throws KeeperException unexpected zookeeper exception
*/
public boolean checkDisabledAndSetEnablingTable(final String tableName)
throws KeeperException {
synchronized (this.cache) {
if (!isDisabledTable(tableName)) {
return false;
}
setTableState(tableName, TableState.ENABLING);
return true;
}
}
/**
* Sets the specified table as DISABLING in zookeeper atomically
* If the table isn't in ENABLED state, no operation is performed
* @param tableName
* @return if the operation succeeds or not
* @throws KeeperException unexpected zookeeper exception
*/
public boolean checkEnabledAndSetDisablingTable(final String tableName)
throws KeeperException {
synchronized (this.cache) {
if (this.cache.get(tableName) != null && !isEnabledTable(tableName)) {
return false;
}
setTableState(tableName, TableState.DISABLING);
return true;
}
}
private void setTableState(final String tableName, final TableState state)
throws KeeperException {
String znode = ZKUtil.joinZNode(this.watcher.masterTableZNode, tableName);
if (ZKUtil.checkExists(this.watcher, znode) == -1) {
ZKUtil.createAndFailSilent(this.watcher, znode);
}
String znode92 = ZKUtil.joinZNode(this.watcher.masterTableZNode92, tableName);
boolean settingToEnabled = (state == TableState.ENABLED);
// 0.92 format znode differs in that it is deleted to represent ENABLED,
// so only create if we are not setting to enabled.
if (!settingToEnabled) {
if (ZKUtil.checkExists(this.watcher, znode92) == -1) {
ZKUtil.createAndFailSilent(this.watcher, znode92);
}
}
synchronized (this.cache) {
List ops = new LinkedList();
if (settingToEnabled) {
ops.add(ZKUtilOp.deleteNodeFailSilent(znode92));
}
else {
ops.add(ZKUtilOp.setData(znode92, Bytes.toBytes(state.toString())));
}
// If not running multi-update either because of configuration or failure,
// set the current format znode after the 0.92 format znode.
// This is so in the case of failure, the AssignmentManager is guaranteed to
// see the state was not applied, since it uses the current format znode internally.
ops.add(ZKUtilOp.setData(znode, Bytes.toBytes(state.toString())));
ZKUtil.multiOrSequential(this.watcher, ops, true);
this.cache.put(tableName, state);
}
}
public boolean isDisabledTable(final String tableName) {
return isTableState(tableName, TableState.DISABLED);
}
public boolean isDisablingTable(final String tableName) {
return isTableState(tableName, TableState.DISABLING);
}
public boolean isEnablingTable(final String tableName) {
return isTableState(tableName, TableState.ENABLING);
}
public boolean isEnabledTable(String tableName) {
return isTableState(tableName, TableState.ENABLED);
}
public boolean isDisablingOrDisabledTable(final String tableName) {
synchronized (this.cache) {
return isDisablingTable(tableName) || isDisabledTable(tableName);
}
}
public boolean isEnabledOrDisablingTable(final String tableName) {
synchronized (this.cache) {
return isEnabledTable(tableName) || isDisablingTable(tableName);
}
}
public boolean isDisabledOrEnablingTable(final String tableName) {
synchronized (this.cache) {
return isDisabledTable(tableName) || isEnablingTable(tableName);
}
}
private boolean isTableState(final String tableName, final TableState state) {
synchronized (this.cache) {
TableState currentState = this.cache.get(tableName);
return ZKTableReadOnly.isTableState(currentState, state);
}
}
/**
* Deletes the table in zookeeper. Fails silently if the
* table is not currently disabled in zookeeper. Sets no watches.
* @param tableName
* @throws KeeperException unexpected zookeeper exception
*/
public void setDeletedTable(final String tableName)
throws KeeperException {
synchronized (this.cache) {
List ops = new LinkedList();
ops.add(ZKUtilOp.deleteNodeFailSilent(
ZKUtil.joinZNode(this.watcher.masterTableZNode92, tableName)));
// If not running multi-update either because of configuration or failure,
// delete the current format znode after the 0.92 format znode. This is so in the case of
// failure, the AssignmentManager is guaranteed to see the table was not deleted, since it
// uses the current format znode internally.
ops.add(ZKUtilOp.deleteNodeFailSilent(
ZKUtil.joinZNode(this.watcher.masterTableZNode, tableName)));
ZKUtil.multiOrSequential(this.watcher, ops, true);
if (this.cache.remove(tableName) == null) {
LOG.warn("Moving table " + tableName + " state to deleted but was " +
"already deleted");
}
}
}
/**
* Sets the ENABLED state in the cache and creates or force updates a node to
* ENABLED state for the specified table
*
* @param tableName
* @throws KeeperException
*/
public void setEnabledTable(final String tableName) throws KeeperException {
setTableState(tableName, TableState.ENABLED);
}
/**
* check if table is present .
*
* @param tableName
* @return true if the table is present
*/
public boolean isTablePresent(final String tableName) {
synchronized (this.cache) {
TableState state = this.cache.get(tableName);
return !(state == null);
}
}
/**
* Gets a list of all the tables set as disabled in zookeeper.
* @return Set of disabled tables, empty Set if none
*/
public Set getDisabledTables() {
Set disabledTables = new HashSet();
synchronized (this.cache) {
Set tables = this.cache.keySet();
for (String table: tables) {
if (isDisabledTable(table)) disabledTables.add(table);
}
}
return disabledTables;
}
}