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package com.salesforce.hbase.index.write;
import java.io.IOException;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.atomic.AtomicBoolean;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.Stoppable;
import org.apache.hadoop.hbase.client.Mutation;
import org.apache.hadoop.hbase.coprocessor.RegionCoprocessorEnvironment;
import org.apache.hadoop.hbase.util.Pair;
import com.google.common.collect.ArrayListMultimap;
import com.google.common.collect.Multimap;
import com.salesforce.hbase.index.exception.IndexWriteException;
import com.salesforce.hbase.index.table.HTableInterfaceReference;
import com.salesforce.hbase.index.util.ImmutableBytesPtr;
/**
* Do the actual work of writing to the index tables. Ensures that if we do fail to write to the
* index table that we cleanly kill the region/server to ensure that the region's WAL gets replayed.
* <p>
* We attempt to do the index updates in parallel using a backing threadpool. All threads are daemon
* threads, so it will not block the region from shutting down.
*/
public class IndexWriter implements Stoppable {
private static final Log LOG = LogFactory.getLog(IndexWriter.class);
private static final String INDEX_COMMITTER_CONF_KEY = "index.writer.commiter.class";
public static final String INDEX_FAILURE_POLICY_CONF_KEY = "index.writer.failurepolicy.class";
private AtomicBoolean stopped = new AtomicBoolean(false);
private IndexCommitter writer;
private IndexFailurePolicy failurePolicy;
/**
* @throws IOException if the {@link IndexWriter} or {@link IndexFailurePolicy} cannot be
* instantiated
*/
public IndexWriter(RegionCoprocessorEnvironment env, String name) throws IOException {
this(getCommitter(env), getFailurePolicy(env), env, name);
}
public static IndexCommitter getCommitter(RegionCoprocessorEnvironment env) throws IOException {
Configuration conf = env.getConfiguration();
try {
IndexCommitter committer =
conf.getClass(INDEX_COMMITTER_CONF_KEY, ParallelWriterIndexCommitter.class,
IndexCommitter.class).newInstance();
return committer;
} catch (InstantiationException e) {
throw new IOException(e);
} catch (IllegalAccessException e) {
throw new IOException(e);
}
}
public static IndexFailurePolicy getFailurePolicy(RegionCoprocessorEnvironment env)
throws IOException {
Configuration conf = env.getConfiguration();
try {
IndexFailurePolicy committer =
conf.getClass(INDEX_FAILURE_POLICY_CONF_KEY, KillServerOnFailurePolicy.class,
IndexFailurePolicy.class).newInstance();
return committer;
} catch (InstantiationException e) {
throw new IOException(e);
} catch (IllegalAccessException e) {
throw new IOException(e);
}
}
/**
* Directly specify the {@link IndexCommitter} and {@link IndexFailurePolicy}. Both are expected
* to be fully setup before calling.
* @param committer
* @param policy
* @param env
*/
public IndexWriter(IndexCommitter committer, IndexFailurePolicy policy,
RegionCoprocessorEnvironment env, String name) {
this(committer, policy);
this.writer.setup(this, env, name);
this.failurePolicy.setup(this, env);
}
/**
* Create an {@link IndexWriter} with an already setup {@link IndexCommitter} and
* {@link IndexFailurePolicy}.
* @param committer to write updates
* @param policy to handle failures
*/
IndexWriter(IndexCommitter committer, IndexFailurePolicy policy) {
this.writer = committer;
this.failurePolicy = policy;
}
/**
* Write the mutations to their respective table.
* <p>
* This method is blocking and could potentially cause the writer to block for a long time as we
* write the index updates. When we return depends on the specified {@link IndexCommitter}.
* <p>
* If update fails, we pass along the failure to the installed {@link IndexFailurePolicy}, which
* then decides how to handle the failure. By default, we use a {@link KillServerOnFailurePolicy},
* which ensures that the server crashes when an index write fails, ensuring that we get WAL
* replay of the index edits.
* @param indexUpdates Updates to write
* @throws IOException
*/
public void writeAndKillYourselfOnFailure(Collection<Pair<Mutation, byte[]>> indexUpdates) throws IOException {
// convert the strings to htableinterfaces to which we can talk and group by TABLE
Multimap<HTableInterfaceReference, Mutation> toWrite = resolveTableReferences(indexUpdates);
writeAndKillYourselfOnFailure(toWrite);
}
/**
* see {@link #writeAndKillYourselfOnFailure(Collection)}.
* @param toWrite
* @throws IOException
*/
public void writeAndKillYourselfOnFailure(Multimap<HTableInterfaceReference, Mutation> toWrite) throws IOException {
try {
write(toWrite);
if (LOG.isTraceEnabled()) {
LOG.trace("Done writing all index updates!\n\t" + toWrite);
}
} catch (Exception e) {
this.failurePolicy.handleFailure(toWrite, e);
}
}
/**
* Write the mutations to their respective table.
* <p>
* This method is blocking and could potentially cause the writer to block for a long time as we
* write the index updates. We only return when either:
* <ol>
* <li>All index writes have returned, OR</li>
* <li>Any single index write has failed</li>
* </ol>
* We attempt to quickly determine if any write has failed and not write to the remaining indexes
* to ensure a timely recovery of the failed index writes.
* @param toWrite Updates to write
* @throws IndexWriteException if we cannot successfully write to the index. Whether or not we
* stop early depends on the {@link IndexCommitter}.
*/
public void write(Collection<Pair<Mutation, byte[]>> toWrite) throws IndexWriteException {
write(resolveTableReferences(toWrite));
}
/**
* see {@link #write(Collection)}
* @param toWrite
* @throws IndexWriteException
*/
public void write(Multimap<HTableInterfaceReference, Mutation> toWrite)
throws IndexWriteException {
this.writer.write(toWrite);
}
/**
* Convert the passed index updates to {@link HTableInterfaceReference}s.
* @param indexUpdates from the index builder
* @return pairs that can then be written by an {@link IndexWriter}.
*/
public static Multimap<HTableInterfaceReference, Mutation> resolveTableReferences(
Collection<Pair<Mutation, byte[]>> indexUpdates) {
Multimap<HTableInterfaceReference, Mutation> updates = ArrayListMultimap
.<HTableInterfaceReference, Mutation> create();
// simple map to make lookups easy while we build the map of tables to create
Map<ImmutableBytesPtr, HTableInterfaceReference> tables =
new HashMap<ImmutableBytesPtr, HTableInterfaceReference>(updates.size());
for (Pair<Mutation, byte[]> entry : indexUpdates) {
byte[] tableName = entry.getSecond();
ImmutableBytesPtr ptr = new ImmutableBytesPtr(tableName);
HTableInterfaceReference table = tables.get(ptr);
if (table == null) {
table = new HTableInterfaceReference(ptr);
tables.put(ptr, table);
}
updates.put(table, entry.getFirst());
}
return updates;
}
@Override
public void stop(String why) {
if (!this.stopped.compareAndSet(false, true)) {
// already stopped
return;
}
LOG.debug("Stopping because " + why);
this.writer.stop(why);
this.failurePolicy.stop(why);
}
@Override
public boolean isStopped() {
return this.stopped.get();
}
}