org.hbase.async.RegionInfo Maven / Gradle / Ivy
/*
* Copyright (C) 2010-2012 The Async HBase Authors. All rights reserved.
* This file is part of Async HBase.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* - Neither the name of the StumbleUpon nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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package org.hbase.async;
import java.util.Comparator;
import java.util.Arrays;
import com.google.protobuf.InvalidProtocolBufferException;
import com.google.protobuf.ByteString;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBuffers;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.hbase.async.generated.HBasePB;
import static org.hbase.async.HBaseClient.EMPTY_ARRAY;
/**
* Stores basic information about a region.
*/
final class RegionInfo implements Comparable {
private static final Logger LOG = LoggerFactory.getLogger(RegionInfo.class);
private final byte[] table;
// The region name is of the form:
// table_name,start_key,timestamp[.MD5.]
// So it contains the start_key.
private final byte[] region_name;
private final byte[] stop_key;
/**
* Constructor.
*/
public RegionInfo(final byte[] table,
final byte[] region_name,
final byte[] stop_key) {
this.table = table;
this.region_name = region_name;
if (stop_key.length == 0) {
this.stop_key = EMPTY_ARRAY;
} else {
this.stop_key = stop_key;
}
}
/** Returns the name of the table this region belongs to. */
public byte[] table() {
return table;
}
/** Returns the name of the region. */
public byte[] name() {
return region_name;
}
/** Returns the stop key (exclusive) of this region. */
public byte[] stopKey() {
return stop_key;
}
/**
* Returns the protobuf representation of this region.
*/
HBasePB.RegionSpecifier toProtobuf() {
return HBasePB.RegionSpecifier.newBuilder()
.setType(HBasePB.RegionSpecifier.RegionSpecifierType.REGION_NAME)
.setValue(ByteString.copyFrom(region_name))
.build();
}
/**
* Creates a new {@link RegionInfo} from a META {@link KeyValue}.
* @param kv The {@link KeyValue} to use, which is assumed to be from
* the cell {@code info:regioninfo} of a {@code .META.} region.
* @param out_start_key A (@code {new byte[1][]}).
* The start row of the region will be stored in {@code out_start_key[0]}.
* Think "pointer-to-pointer" in Java (yeah!).
* @return A newly created {@link RegionInfo}.
* If calling {@link #table} on the object returned gives a reference to
* {@link HBaseClient#EMPTY_ARRAY}, then the META entry indicates that the
* region has been split (and thus this entry shouldn't be used).
* @throws RegionOfflineException if the META entry indicates that the
* region is offline.
* @throws BrokenMetaException if the {@link KeyValue} seems invalid.
*/
static RegionInfo fromKeyValue(final KeyValue kv,
final byte[][] out_start_key) {
switch (kv.value()[0]) {
case 0: // pre 0.92 -- fall through.
case 1: // 0.92 to 0.94
return deserializeOldRegionInfo(kv, out_start_key);
case 80: // 0.95+
return deserializeProtobufRegionInfo(kv, out_start_key);
default:
throw new IllegalStateException("Unsupported region info version: "
+ kv.value()[0] + " in .META. entry: "
+ kv);
}
}
/**
* Creates a new {@link RegionInfo} from a pre-0.95 META {@link KeyValue}.
*/
private static RegionInfo
deserializeOldRegionInfo(final KeyValue kv, final byte[][] out_start_key) {
final ChannelBuffer buf = ChannelBuffers.wrappedBuffer(kv.value());
buf.readByte(); // Skip the version.
// version 1 was introduced in HBase 0.92 (see HBASE-451).
// The differences between v0 and v1 are irrelevant to us,
// as we only look at the first few fields, and they didn't
// change across these 2 versions.
final byte[] stop_key = HBaseRpc.readByteArray(buf);
final boolean offline = buf.readByte() != 0;
final long region_id = buf.readLong();
final byte[] region_name = HBaseRpc.readByteArray(buf);
// TODO(tsuna): Can we easily de-dup this array with another RegionInfo?
byte[] table;
try {
table = tableFromRegionName(region_name);
} catch (IllegalArgumentException e) {
throw BrokenMetaException.badKV(null, "an `info:regioninfo' cell"
+ " has a " + e.getMessage(), kv);
}
final boolean split = buf.readByte() != 0;
final byte[] start_key = HBaseRpc.readByteArray(buf);
// Table description and hash code are left, but we don't care.
if (LOG.isDebugEnabled()) {
LOG.debug("Got " + Bytes.pretty(table) + "'s region ["
+ Bytes.pretty(start_key) + '-'
+ Bytes.pretty(stop_key) + ") offline=" + offline
+ ", region_id=" + region_id + ", region_name="
+ Bytes.pretty(region_name) + ", split=" + split);
}
// RegionServers set both `offline' and `split' to `false' on the parent
// region after it's been split. We normally don't expect to ever observe
// such regions as any META lookup should find the new daughter regions.
// But just in case, we make sure to not throw an exception in this case.
if (offline && !split) {
throw new RegionOfflineException(region_name);
}
// If the region has been split, we put a special marker instead of
// the table name to indicate that this region has been split.
final RegionInfo region = new RegionInfo(split ? EMPTY_ARRAY : table,
region_name, stop_key);
out_start_key[0] = start_key;
return region;
}
/**
* Creates a new {@link RegionInfo} from a 0.95+ META {@link KeyValue}.
*/
private static RegionInfo
deserializeProtobufRegionInfo(final KeyValue kv, final byte[][] out_start_key) {
final byte[] value = kv.value();
final int magic = Bytes.getInt(value);
if (magic != HBaseClient.PBUF_MAGIC) {
throw BrokenMetaException.badKV(null, "the magic number is invalid", kv);
}
final HBasePB.RegionInfo pb;
try {
pb = HBasePB.RegionInfo.PARSER.parseFrom(value, 4, value.length - 4);
} catch (InvalidProtocolBufferException e) {
throw new BrokenMetaException("Failed to decode " + Bytes.pretty(value),
e);
}
final byte[] region_id = Long.toString(pb.getRegionId()).getBytes();
final byte[] table = Bytes.get(pb.getTableName().getQualifier());
final byte[] start_key = Bytes.get(pb.getStartKey());
final byte[] stop_key = Bytes.get(pb.getEndKey());
final byte[] region_name = kv.key();
final boolean offline = pb.getOffline();
final boolean split = pb.getSplit();
// XXX what to do with the `recovering' field?
if (offline && !split) {
throw new RegionOfflineException(region_name);
}
out_start_key[0] = start_key;
return new RegionInfo(split ? EMPTY_ARRAY : table, region_name, stop_key);
}
/**
* Given the name of a region, returns the name of the table it belongs to.
* @throws IllegalArgumentException if the name of the region is malformed.
*/
static byte[] tableFromRegionName(final byte[] region_name) {
int comma = 1; // Can't be at the beginning.
for (/**/; comma < region_name.length; comma++) {
if (region_name[comma] == ',') {
break;
}
}
if (comma == region_name.length) {
throw new IllegalArgumentException("Malformed region name, contains no"
+ " comma: " + Bytes.pretty(region_name));
}
return Arrays.copyOf(region_name, comma);
}
/**
* Given name of a region, returns its start key
* @throws IllegalArgumentException if the name of the region is malformed
* @param region_name Full region_name created in the constructor
* @return byte Array of the start key
*/
static byte[] startKeyFromRegionName(final byte[] region_name){
int key_begin = 0;
int key_end= 1;
int comma = 0;
for (/**/; key_end < region_name.length; key_end++) {
if (region_name[key_end] == ',') {
comma++;
if (comma == 1){
key_begin = key_end+1;
}
if (comma == 2){
break;
}
}
}
// If reached the end and the string being returned is not empty
if (key_end == region_name.length && (comma == 2)) {
throw new IllegalArgumentException("Malformed region name, not enough"
+ " commas: " + Bytes.pretty(region_name));
}
// Only return the string if region length is greater than 0
if (key_end - key_begin > 0 && region_name.length > 0){
return Arrays.copyOfRange(region_name, key_begin, key_end);
}
// Otherwise, return an empty string as start key aka this is the
// start key for the first region in the table.
else {
return EMPTY_ARRAY;
}
}
@Override
public int compareTo(final RegionInfo other) {
return Bytes.memcmp(region_name, other.region_name);
}
public boolean equals(final Object other) {
if (other == null || !(other instanceof RegionInfo)) {
return false;
}
return compareTo((RegionInfo) other) == 0;
}
public int hashCode() {
return Arrays.hashCode(table)
^ Arrays.hashCode(region_name)
^ Arrays.hashCode(stop_key);
}
/** Returns a hint as to how many bytes are needed for {@link #toString}. */
int stringSizeHint() {
return 48 // boilerplate
+ table.length + 2
// region_name and stop_key are likely to contain non-ascii characters,
// so let's multiply its length by 2 to avoid re-allocations.
+ region_name.length * 2
+ stop_key.length * 2;
}
public String toString() {
final StringBuilder buf = new StringBuilder(stringSizeHint());
toStringbuf(buf);
return buf.toString();
}
/** Like {@link #toString} but puts the output in the given buffer. */
void toStringbuf(final StringBuilder buf) {
buf.append("RegionInfo(table=");
if (table == EMPTY_ARRAY) {
buf.append("");
} else {
Bytes.pretty(buf, table);
}
buf.append(", region_name=");
Bytes.pretty(buf, region_name);
buf.append(", stop_key=");
Bytes.pretty(buf, stop_key);
buf.append(')');
}
/** Singleton to compare region names. */
static final RegionNameCmp REGION_NAME_CMP = new RegionNameCmp();
/**
* Comparator for region names.
* We can't just use {@link Bytes.MEMCMP} because it doesn't play nicely
* with the way META keys are built as the first region has an empty start
* key. Let's assume we know about those 2 regions in our cache:
*
* .META.,,1
* tableA,,1273018455182
*
* We're given an RPC to execute on {@code tableA}, row {@code \000} (1 byte
* row key containing a 0). If we use {@code memcmp} to sort the entries in
* the cache, when we search for the entry right before {@code tableA,\000,:}
* we'll erroneously find {@code .META.,,1} instead of the entry for first
* region of {@code tableA}.
*
* Since this scheme breaks natural ordering, we need this comparator to
* implement a special version of {@code memcmp} to handle this scenario.
*/
private static final class RegionNameCmp implements Comparator {
private RegionNameCmp() { // Can't instantiate outside of this class.
}
@Override
public int compare(final byte[] a, final byte[] b) {
final int length = Math.min(a.length, b.length);
if (a == b) { // Do this after accessing a.length and b.length
return 0; // in order to NPE if either a or b is null.
}
// Reminder: region names are of the form:
// table_name,start_key,timestamp[.MD5.]
// First compare the table names.
int i;
for (i = 0; i < length; i++) {
final byte ai = a[i]; // Saves one pointer deference every iteration.
final byte bi = b[i]; // Saves one pointer deference every iteration.
if (ai != bi) { // The name of the tables differ.
if (ai == ',') {
return -1001; // `a' has a smaller table name. a < b
} else if (bi == ',') {
return 1001; // `b' has a smaller table name. a > b
}
return (ai & 0xFF) - (bi & 0xFF); // "promote" to unsigned.
}
if (ai == ',') { // Remember: at this point ai == bi.
break; // We're done comparing the table names. They're equal.
}
}
// Now find the last comma in both `a' and `b'. We need to start the
// search from the end as the row key could have an arbitrary number of
// commas and we don't know its length.
final int a_comma = findCommaFromEnd(a, i);
final int b_comma = findCommaFromEnd(b, i);
// If either `a' or `b' is followed immediately by another comma, then
// they are the first region (it's the empty start key).
i++; // No need to check against `length', there MUST be more bytes.
// Compare keys.
final int first_comma = Math.min(a_comma, b_comma);
for (/*nothing*/; i < first_comma; i++) {
final byte ai = a[i];
final byte bi = b[i];
if (ai != bi) { // The keys differ.
return (ai & 0xFF) - (bi & 0xFF); // "promote" to unsigned.
}
}
if (a_comma < b_comma) {
return -1002; // `a' has a shorter key. a < b
} else if (b_comma < a_comma) {
return 1002; // `b' has a shorter key. a > b
}
// Keys have the same length and have compared identical. Compare the
// rest, which essentially means: use start code as a tie breaker.
for (/*nothing*/; i < length; i++) {
final byte ai = a[i];
final byte bi = b[i];
if (ai != bi) { // The start codes differ.
return (ai & 0xFF) - (bi & 0xFF); // "promote" to unsigned.
}
}
return a.length - b.length;
}
private static int findCommaFromEnd(final byte[] b, final int offset) {
for (int i = b.length - 1; i > offset; i--) {
if (b[i] == ',') {
return i;
}
}
throw new IllegalArgumentException("No comma found in " + Bytes.pretty(b)
+ " after offset " + offset);
}
}
}