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/**
* 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.constraint;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.regex.Pattern;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.util.Pair;
/**
* Utilities for adding/removing constraints from a table.
*
* Constraints can be added on table load time, via the {@link HTableDescriptor}.
*
* NOTE: this class is NOT thread safe. Concurrent setting/enabling/disabling of
* constraints can cause constraints to be run at incorrect times or not at all.
*/
@InterfaceAudience.Private
public final class Constraints {
private static final int DEFAULT_PRIORITY = -1;
private Constraints() {
}
private static final Log LOG = LogFactory.getLog(Constraints.class);
private static final String CONSTRAINT_HTD_KEY_PREFIX = "constraint $";
private static final Pattern CONSTRAINT_HTD_ATTR_KEY_PATTERN = Pattern
.compile(CONSTRAINT_HTD_KEY_PREFIX, Pattern.LITERAL);
// configuration key for if the constraint is enabled
private static final String ENABLED_KEY = "_ENABLED";
// configuration key for the priority
private static final String PRIORITY_KEY = "_PRIORITY";
// smallest priority a constraiNt can have
private static final long MIN_PRIORITY = 0L;
// ensure a priority less than the smallest we could intentionally set
private static final long UNSET_PRIORITY = MIN_PRIORITY - 1;
private static String COUNTER_KEY = "hbase.constraint.counter";
/**
* Enable constraints on a table.
*
* Currently, if you attempt to add a constraint to the table, then
* Constraints will automatically be turned on.
*
* @param desc
* table description to add the processor
* @throws IOException
* If the {@link ConstraintProcessor} CP couldn't be added to the
* table.
*/
public static void enable(HTableDescriptor desc) throws IOException {
// if the CP has already been loaded, do nothing
String clazz = ConstraintProcessor.class.getName();
if (desc.hasCoprocessor(clazz)) {
return;
}
// add the constrain processor CP to the table
desc.addCoprocessor(clazz);
}
/**
* Turn off processing constraints for a given table, even if constraints have
* been turned on or added.
*
* @param desc
* {@link HTableDescriptor} where to disable {@link Constraint
* Constraints}.
*/
public static void disable(HTableDescriptor desc) {
desc.removeCoprocessor(ConstraintProcessor.class.getName());
}
/**
* Remove all {@link Constraint Constraints} that have been added to the table
* and turn off the constraint processing.
*
* All {@link Configuration Configurations} and their associated
* {@link Constraint} are removed.
*
* @param desc
* {@link HTableDescriptor} to remove {@link Constraint Constraints}
* from.
*/
public static void remove(HTableDescriptor desc) {
// disable constraints
disable(desc);
// remove all the constraint settings
List keys = new ArrayList();
// loop through all the key, values looking for constraints
for (Map.Entry e : desc
.getValues().entrySet()) {
String key = Bytes.toString((e.getKey().get()));
String[] className = CONSTRAINT_HTD_ATTR_KEY_PATTERN.split(key);
if (className.length == 2) {
keys.add(e.getKey());
}
}
// now remove all the keys we found
for (ImmutableBytesWritable key : keys) {
desc.remove(key);
}
}
/**
* Check to see if the Constraint is currently set.
*
* @param desc
* {@link HTableDescriptor} to check
* @param clazz
* {@link Constraint} class to check for.
* @return true if the {@link Constraint} is present, even if it is
* disabled. false otherwise.
*/
public static boolean has(HTableDescriptor desc,
Class clazz) {
return getKeyValueForClass(desc, clazz) != null;
}
/**
* Get the kv {@link Entry} in the descriptor for the specified class
*
* @param desc
* {@link HTableDescriptor} to read
* @param clazz
* to search for
* @return the {@link Pair} of in the table, if that class is
* present. null otherwise.
*/
private static Pair getKeyValueForClass(
HTableDescriptor desc, Class clazz) {
// get the serialized version of the constraint
String key = serializeConstraintClass(clazz);
String value = desc.getValue(key);
return value == null ? null : new Pair(key, value);
}
/**
* Add configuration-less constraints to the table.
*
* This will overwrite any configuration associated with the previous
* constraint of the same class.
*
* Each constraint, when added to the table, will have a specific priority,
* dictating the order in which the {@link Constraint} will be run. A
* {@link Constraint} earlier in the list will be run before those later in
* the list. The same logic applies between two Constraints over time (earlier
* added is run first on the regionserver).
*
* @param desc
* {@link HTableDescriptor} to add {@link Constraint Constraints}
* @param constraints
* {@link Constraint Constraints} to add. All constraints are
* considered automatically enabled on add
* @throws IOException
* If constraint could not be serialized/added to table
*/
public static void add(HTableDescriptor desc,
Class... constraints) throws IOException {
// make sure constraints are enabled
enable(desc);
long priority = getNextPriority(desc);
// store each constraint
for (Class clazz : constraints) {
addConstraint(desc, clazz, null, priority++);
}
updateLatestPriority(desc, priority);
}
/**
* Add constraints and their associated configurations to the table.
*
* Adding the same constraint class twice will overwrite the first
* constraint's configuration
*
* Each constraint, when added to the table, will have a specific priority,
* dictating the order in which the {@link Constraint} will be run. A
* {@link Constraint} earlier in the list will be run before those later in
* the list. The same logic applies between two Constraints over time (earlier
* added is run first on the regionserver).
*
* @param desc
* {@link HTableDescriptor} to add a {@link Constraint}
* @param constraints
* {@link Pair} of a {@link Constraint} and its associated
* {@link Configuration}. The Constraint will be configured on load
* with the specified configuration.All constraints are considered
* automatically enabled on add
* @throws IOException
* if any constraint could not be deserialized. Assumes if 1
* constraint is not loaded properly, something has gone terribly
* wrong and that all constraints need to be enforced.
*/
public static void add(HTableDescriptor desc,
Pair, Configuration>... constraints)
throws IOException {
enable(desc);
long priority = getNextPriority(desc);
for (Pair, Configuration> pair : constraints) {
addConstraint(desc, pair.getFirst(), pair.getSecond(), priority++);
}
updateLatestPriority(desc, priority);
}
/**
* Add a {@link Constraint} to the table with the given configuration
*
* Each constraint, when added to the table, will have a specific priority,
* dictating the order in which the {@link Constraint} will be run. A
* {@link Constraint} added will run on the regionserver before those added to
* the {@link HTableDescriptor} later.
*
* @param desc
* table descriptor to the constraint to
* @param constraint
* to be added
* @param conf
* configuration associated with the constraint
* @throws IOException
* if any constraint could not be deserialized. Assumes if 1
* constraint is not loaded properly, something has gone terribly
* wrong and that all constraints need to be enforced.
*/
public static void add(HTableDescriptor desc,
Class constraint, Configuration conf)
throws IOException {
enable(desc);
long priority = getNextPriority(desc);
addConstraint(desc, constraint, conf, priority++);
updateLatestPriority(desc, priority);
}
/**
* Write the raw constraint and configuration to the descriptor.
*
* This method takes care of creating a new configuration based on the passed
* in configuration and then updating that with enabled and priority of the
* constraint.
*
* When a constraint is added, it is automatically enabled.
*/
private static void addConstraint(HTableDescriptor desc,
Class clazz, Configuration conf, long priority)
throws IOException {
writeConstraint(desc, serializeConstraintClass(clazz),
configure(conf, true, priority));
}
/**
* Setup the configuration for a constraint as to whether it is enabled and
* its priority
*
* @param conf
* on which to base the new configuration
* @param enabled
* true if it should be run
* @param priority
* relative to other constraints
* @return a new configuration, storable in the {@link HTableDescriptor}
*/
private static Configuration configure(Configuration conf, boolean enabled,
long priority) {
// create the configuration to actually be stored
// clone if possible, but otherwise just create an empty configuration
Configuration toWrite = conf == null ? new Configuration()
: new Configuration(conf);
// update internal properties
toWrite.setBooleanIfUnset(ENABLED_KEY, enabled);
// set if unset long
if (toWrite.getLong(PRIORITY_KEY, UNSET_PRIORITY) == UNSET_PRIORITY) {
toWrite.setLong(PRIORITY_KEY, priority);
}
return toWrite;
}
/**
* Just write the class to a String representation of the class as a key for
* the {@link HTableDescriptor}
*
* @param clazz
* Constraint class to convert to a {@link HTableDescriptor} key
* @return key to store in the {@link HTableDescriptor}
*/
private static String serializeConstraintClass(
Class clazz) {
String constraintClazz = clazz.getName();
return CONSTRAINT_HTD_KEY_PREFIX + constraintClazz;
}
/**
* Write the given key and associated configuration to the
* {@link HTableDescriptor}
*/
private static void writeConstraint(HTableDescriptor desc, String key,
Configuration conf) throws IOException {
// store the key and conf in the descriptor
desc.setValue(key, serializeConfiguration(conf));
}
/**
* Write the configuration to a String
*
* @param conf
* to write
* @return String representation of that configuration
* @throws IOException
*/
private static String serializeConfiguration(Configuration conf)
throws IOException {
// write the configuration out to the data stream
ByteArrayOutputStream bos = new ByteArrayOutputStream();
DataOutputStream dos = new DataOutputStream(bos);
conf.writeXml(dos);
dos.flush();
byte[] data = bos.toByteArray();
return Bytes.toString(data);
}
/**
* Read the {@link Configuration} stored in the byte stream.
*
* @param bytes
* to read from
* @return A valid configuration
*/
private static Configuration readConfiguration(byte[] bytes)
throws IOException {
ByteArrayInputStream is = new ByteArrayInputStream(bytes);
Configuration conf = new Configuration(false);
conf.addResource(is);
return conf;
}
/**
* Read in the configuration from the String encoded configuration
*
* @param bytes
* to read from
* @return A valid configuration
* @throws IOException
* if the configuration could not be read
*/
private static Configuration readConfiguration(String bytes)
throws IOException {
return readConfiguration(Bytes.toBytes(bytes));
}
private static long getNextPriority(HTableDescriptor desc) {
String value = desc.getValue(COUNTER_KEY);
long priority;
// get the current priority
if (value == null) {
priority = MIN_PRIORITY;
} else {
priority = Long.parseLong(value) + 1;
}
return priority;
}
private static void updateLatestPriority(HTableDescriptor desc, long priority) {
// update the max priority
desc.setValue(COUNTER_KEY, Long.toString(priority));
}
/**
* Update the configuration for the {@link Constraint}; does not change the
* order in which the constraint is run.
*
* @param desc
* {@link HTableDescriptor} to update
* @param clazz
* {@link Constraint} to update
* @param configuration
* to update the {@link Constraint} with.
* @throws IOException
* if the Constraint was not stored correctly
* @throws IllegalArgumentException
* if the Constraint was not present on this table.
*/
public static void setConfiguration(HTableDescriptor desc,
Class clazz, Configuration configuration)
throws IOException, IllegalArgumentException {
// get the entry for this class
Pair e = getKeyValueForClass(desc, clazz);
if (e == null) {
throw new IllegalArgumentException("Constraint: " + clazz.getName()
+ " is not associated with this table.");
}
// clone over the configuration elements
Configuration conf = new Configuration(configuration);
// read in the previous info about the constraint
Configuration internal = readConfiguration(e.getSecond());
// update the fields based on the previous settings
conf.setIfUnset(ENABLED_KEY, internal.get(ENABLED_KEY));
conf.setIfUnset(PRIORITY_KEY, internal.get(PRIORITY_KEY));
// update the current value
writeConstraint(desc, e.getFirst(), conf);
}
/**
* Remove the constraint (and associated information) for the table
* descriptor.
*
* @param desc
* {@link HTableDescriptor} to modify
* @param clazz
* {@link Constraint} class to remove
*/
public static void remove(HTableDescriptor desc,
Class clazz) {
String key = serializeConstraintClass(clazz);
desc.remove(key);
}
/**
* Enable the given {@link Constraint}. Retains all the information (e.g.
* Configuration) for the {@link Constraint}, but makes sure that it gets
* loaded on the table.
*
* @param desc
* {@link HTableDescriptor} to modify
* @param clazz
* {@link Constraint} to enable
* @throws IOException
* If the constraint cannot be properly deserialized
*/
public static void enableConstraint(HTableDescriptor desc,
Class clazz) throws IOException {
changeConstraintEnabled(desc, clazz, true);
}
/**
* Disable the given {@link Constraint}. Retains all the information (e.g.
* Configuration) for the {@link Constraint}, but it just doesn't load the
* {@link Constraint} on the table.
*
* @param desc
* {@link HTableDescriptor} to modify
* @param clazz
* {@link Constraint} to disable.
* @throws IOException
* if the constraint cannot be found
*/
public static void disableConstraint(HTableDescriptor desc,
Class clazz) throws IOException {
changeConstraintEnabled(desc, clazz, false);
}
/**
* Change the whether the constraint (if it is already present) is enabled or
* disabled.
*/
private static void changeConstraintEnabled(HTableDescriptor desc,
Class clazz, boolean enabled) throws IOException {
// get the original constraint
Pair entry = getKeyValueForClass(desc, clazz);
if (entry == null) {
throw new IllegalArgumentException("Constraint: " + clazz.getName()
+ " is not associated with this table. You can't enable it!");
}
// create a new configuration from that conf
Configuration conf = readConfiguration(entry.getSecond());
// set that it is enabled
conf.setBoolean(ENABLED_KEY, enabled);
// write it back out
writeConstraint(desc, entry.getFirst(), conf);
}
/**
* Check to see if the given constraint is enabled.
*
* @param desc
* {@link HTableDescriptor} to check.
* @param clazz
* {@link Constraint} to check for
* @return true if the {@link Constraint} is present and enabled.
* false otherwise.
* @throws IOException
* If the constraint has improperly stored in the table
*/
public static boolean enabled(HTableDescriptor desc,
Class clazz) throws IOException {
// get the kv
Pair entry = getKeyValueForClass(desc, clazz);
// its not enabled so just return false. In fact, its not even present!
if (entry == null) {
return false;
}
// get the info about the constraint
Configuration conf = readConfiguration(entry.getSecond());
return conf.getBoolean(ENABLED_KEY, false);
}
/**
* Get the constraints stored in the table descriptor
*
* @param desc
* To read from
* @param classloader
* To use when loading classes. If a special classloader is used on a
* region, for instance, then that should be the classloader used to
* load the constraints. This could also apply to unit-testing
* situation, where want to ensure that class is reloaded or not.
* @return List of configured {@link Constraint Constraints}
* @throws IOException
* if any part of reading/arguments fails
*/
static List getConstraints(HTableDescriptor desc,
ClassLoader classloader) throws IOException {
List constraints = new ArrayList();
// loop through all the key, values looking for constraints
for (Map.Entry e : desc
.getValues().entrySet()) {
// read out the constraint
String key = Bytes.toString(e.getKey().get()).trim();
String[] className = CONSTRAINT_HTD_ATTR_KEY_PATTERN.split(key);
if (className.length == 2) {
key = className[1];
if (LOG.isDebugEnabled()) {
LOG.debug("Loading constraint:" + key);
}
// read in the rest of the constraint
Configuration conf;
try {
conf = readConfiguration(e.getValue().get());
} catch (IOException e1) {
// long that we don't have a valid configuration stored, and move on.
LOG.warn("Corrupted configuration found for key:" + key
+ ", skipping it.");
continue;
}
// if it is not enabled, skip it
if (!conf.getBoolean(ENABLED_KEY, false)) {
if (LOG.isDebugEnabled())
LOG.debug("Constraint: " + key + " is DISABLED - skipping it");
// go to the next constraint
continue;
}
try {
// add the constraint, now that we expect it to be valid.
Class clazz = classloader.loadClass(key)
.asSubclass(Constraint.class);
Constraint constraint = clazz.newInstance();
constraint.setConf(conf);
constraints.add(constraint);
} catch (ClassNotFoundException e1) {
throw new IOException(e1);
} catch (InstantiationException e1) {
throw new IOException(e1);
} catch (IllegalAccessException e1) {
throw new IOException(e1);
}
}
}
// sort them, based on the priorities
Collections.sort(constraints, constraintComparator);
return constraints;
}
private static final Comparator constraintComparator = new Comparator() {
@Override
public int compare(Constraint c1, Constraint c2) {
// compare the priorities of the constraints stored in their configuration
return Long.compare(c1.getConf().getLong(PRIORITY_KEY, DEFAULT_PRIORITY),
c2.getConf().getLong(PRIORITY_KEY, DEFAULT_PRIORITY));
}
};
}