/**
* 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.hdfs.client;
import java.io.BufferedOutputStream;
import java.io.Closeable;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import org.apache.hadoop.classification.InterfaceAudience;
import java.io.IOException;
import java.nio.MappedByteBuffer;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.TreeMap;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;
import org.apache.commons.lang.mutable.MutableBoolean;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hdfs.ExtendedBlockId;
import org.apache.hadoop.hdfs.DFSConfigKeys;
import org.apache.hadoop.hdfs.client.ShortCircuitReplica;
import org.apache.hadoop.hdfs.ShortCircuitShm.Slot;
import org.apache.hadoop.hdfs.net.DomainPeer;
import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
import org.apache.hadoop.hdfs.protocol.datatransfer.Sender;
import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.ReleaseShortCircuitAccessResponseProto;
import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.Status;
import org.apache.hadoop.hdfs.protocolPB.PBHelper;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.ipc.RetriableException;
import org.apache.hadoop.net.unix.DomainSocket;
import org.apache.hadoop.net.unix.DomainSocketWatcher;
import org.apache.hadoop.security.token.SecretManager.InvalidToken;
import org.apache.hadoop.util.StringUtils;
import org.apache.hadoop.util.Time;
import org.apache.hadoop.util.Waitable;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Preconditions;
import com.google.common.util.concurrent.ThreadFactoryBuilder;
/**
* The ShortCircuitCache tracks things which the client needs to access
* HDFS block files via short-circuit.
*
* These things include: memory-mapped regions, file descriptors, and shared
* memory areas for communicating with the DataNode.
*/
@InterfaceAudience.Private
public class ShortCircuitCache implements Closeable {
public static final Log LOG = LogFactory.getLog(ShortCircuitCache.class);
/**
* Expiry thread which makes sure that the file descriptors get closed
* after a while.
*/
private class CacheCleaner implements Runnable, Closeable {
private ScheduledFuture<?> future;
/**
* Run the CacheCleaner thread.
*
* Whenever a thread requests a ShortCircuitReplica object, we will make
* sure it gets one. That ShortCircuitReplica object can then be re-used
* when another thread requests a ShortCircuitReplica object for the same
* block. So in that sense, there is no maximum size to the cache.
*
* However, when a ShortCircuitReplica object is unreferenced by the
* thread(s) that are using it, it becomes evictable. There are two
* separate eviction lists-- one for mmaped objects, and another for
* non-mmaped objects. We do this in order to avoid having the regular
* files kick the mmaped files out of the cache too quickly. Reusing
* an already-existing mmap gives a huge performance boost, since the
* page table entries don't have to be re-populated. Both the mmap
* and non-mmap evictable lists have maximum sizes and maximum lifespans.
*/
@Override
public void run() {
ShortCircuitCache.this.lock.lock();
try {
if (ShortCircuitCache.this.closed) return;
long curMs = Time.monotonicNow();
if (LOG.isDebugEnabled()) {
LOG.debug(this + ": cache cleaner running at " + curMs);
}
int numDemoted = demoteOldEvictableMmaped(curMs);
int numPurged = 0;
Long evictionTimeNs = Long.valueOf(0);
while (true) {
Entry<Long, ShortCircuitReplica> entry =
evictableMmapped.ceilingEntry(evictionTimeNs);
if (entry == null) break;
evictionTimeNs = entry.getKey();
long evictionTimeMs =
TimeUnit.MILLISECONDS.convert(evictionTimeNs, TimeUnit.NANOSECONDS);
if (evictionTimeMs + maxNonMmappedEvictableLifespanMs >= curMs) break;
ShortCircuitReplica replica = entry.getValue();
if (LOG.isTraceEnabled()) {
LOG.trace("CacheCleaner: purging " + replica + ": " +
StringUtils.getStackTrace(Thread.currentThread()));
}
purge(replica);
numPurged++;
}
if (LOG.isDebugEnabled()) {
LOG.debug(this + ": finishing cache cleaner run started at " +
curMs + ". Demoted " + numDemoted + " mmapped replicas; " +
"purged " + numPurged + " replicas.");
}
} finally {
ShortCircuitCache.this.lock.unlock();
}
}
@Override
public void close() throws IOException {
if (future != null) {
future.cancel(false);
}
}
public void setFuture(ScheduledFuture<?> future) {
this.future = future;
}
/**
* Get the rate at which this cleaner thread should be scheduled.
*
* We do this by taking the minimum expiration time and dividing by 4.
*
* @return the rate in milliseconds at which this thread should be
* scheduled.
*/
public long getRateInMs() {
long minLifespanMs =
Math.min(maxNonMmappedEvictableLifespanMs,
maxEvictableMmapedLifespanMs);
long sampleTimeMs = minLifespanMs / 4;
return (sampleTimeMs < 1) ? 1 : sampleTimeMs;
}
}
/**
* A task which asks the DataNode to release a short-circuit shared memory
* slot. If successful, this will tell the DataNode to stop monitoring
* changes to the mlock status of the replica associated with the slot.
* It will also allow us (the client) to re-use this slot for another
* replica. If we can't communicate with the DataNode for some reason,
* we tear down the shared memory segment to avoid being in an inconsistent
* state.
*/
private class SlotReleaser implements Runnable {
/**
* The slot that we need to release.
*/
private final Slot slot;
SlotReleaser(Slot slot) {
this.slot = slot;
}
@Override
public void run() {
if (LOG.isTraceEnabled()) {
LOG.trace(ShortCircuitCache.this + ": about to release " + slot);
}
final DfsClientShm shm = (DfsClientShm)slot.getShm();
final DomainSocket shmSock = shm.getPeer().getDomainSocket();
DomainSocket sock = null;
DataOutputStream out = null;
final String path = shmSock.getPath();
boolean success = false;
try {
sock = DomainSocket.connect(path);
out = new DataOutputStream(
new BufferedOutputStream(sock.getOutputStream()));
new Sender(out).releaseShortCircuitFds(slot.getSlotId());
DataInputStream in = new DataInputStream(sock.getInputStream());
ReleaseShortCircuitAccessResponseProto resp =
ReleaseShortCircuitAccessResponseProto.parseFrom(
PBHelper.vintPrefixed(in));
if (resp.getStatus() != Status.SUCCESS) {
String error = resp.hasError() ? resp.getError() : "(unknown)";
throw new IOException(resp.getStatus().toString() + ": " + error);
}
if (LOG.isTraceEnabled()) {
LOG.trace(ShortCircuitCache.this + ": released " + slot);
}
success = true;
} catch (IOException e) {
LOG.error(ShortCircuitCache.this + ": failed to release " +
"short-circuit shared memory slot " + slot + " by sending " +
"ReleaseShortCircuitAccessRequestProto to " + path +
". Closing shared memory segment.", e);
} finally {
if (success) {
shmManager.freeSlot(slot);
} else {
shm.getEndpointShmManager().shutdown(shm);
}
IOUtils.cleanup(LOG, sock, out);
}
}
}
public interface ShortCircuitReplicaCreator {
/**
* Attempt to create a ShortCircuitReplica object.
*
* This callback will be made without holding any locks.
*
* @return a non-null ShortCircuitReplicaInfo object.
*/
ShortCircuitReplicaInfo createShortCircuitReplicaInfo();
}
/**
* Lock protecting the cache.
*/
private final ReentrantLock lock = new ReentrantLock();
/**
* The executor service that runs the cacheCleaner.
*/
private final ScheduledThreadPoolExecutor cleanerExecutor
= new ScheduledThreadPoolExecutor(1, new ThreadFactoryBuilder().
setDaemon(true).setNameFormat("ShortCircuitCache_Cleaner").
build());
/**
* The executor service that runs the cacheCleaner.
*/
private final ScheduledThreadPoolExecutor releaserExecutor
= new ScheduledThreadPoolExecutor(1, new ThreadFactoryBuilder().
setDaemon(true).setNameFormat("ShortCircuitCache_SlotReleaser").
build());
/**
* A map containing all ShortCircuitReplicaInfo objects, organized by Key.
* ShortCircuitReplicaInfo objects may contain a replica, or an InvalidToken
* exception.
*/
private final HashMap<ExtendedBlockId, Waitable<ShortCircuitReplicaInfo>>
replicaInfoMap = new HashMap<ExtendedBlockId,
Waitable<ShortCircuitReplicaInfo>>();
/**
* The CacheCleaner. We don't create this and schedule it until it becomes
* necessary.
*/
private CacheCleaner cacheCleaner;
/**
* Tree of evictable elements.
*
* Maps (unique) insertion time in nanoseconds to the element.
*/
private final TreeMap<Long, ShortCircuitReplica> evictable =
new TreeMap<Long, ShortCircuitReplica>();
/**
* Maximum total size of the cache, including both mmapped and
* no$-mmapped elements.
*/
private final int maxTotalSize;
/**
* Non-mmaped elements older than this will be closed.
*/
private long maxNonMmappedEvictableLifespanMs;
/**
* Tree of mmaped evictable elements.
*
* Maps (unique) insertion time in nanoseconds to the element.
*/
private final TreeMap<Long, ShortCircuitReplica> evictableMmapped =
new TreeMap<Long, ShortCircuitReplica>();
/**
* Maximum number of mmaped evictable elements.
*/
private int maxEvictableMmapedSize;
/**
* Mmaped elements older than this will be closed.
*/
private final long maxEvictableMmapedLifespanMs;
/**
* The minimum number of milliseconds we'll wait after an unsuccessful
* mmap attempt before trying again.
*/
private final long mmapRetryTimeoutMs;
/**
* How long we will keep replicas in the cache before declaring them
* to be stale.
*/
private final long staleThresholdMs;
/**
* True if the ShortCircuitCache is closed.
*/
private boolean closed = false;
/**
* Number of existing mmaps associated with this cache.
*/
private int outstandingMmapCount = 0;
/**
* Manages short-circuit shared memory segments for the client.
*/
private final DfsClientShmManager shmManager;
/**
* Create a {@link ShortCircuitCache} object from a {@link Configuration}
*/
public static ShortCircuitCache fromConf(Configuration conf) {
return new ShortCircuitCache(
conf.getInt(DFSConfigKeys.DFS_CLIENT_READ_SHORTCIRCUIT_STREAMS_CACHE_SIZE_KEY,
DFSConfigKeys.DFS_CLIENT_READ_SHORTCIRCUIT_STREAMS_CACHE_SIZE_DEFAULT),
conf.getLong(DFSConfigKeys.DFS_CLIENT_READ_SHORTCIRCUIT_STREAMS_CACHE_EXPIRY_MS_KEY,
DFSConfigKeys.DFS_CLIENT_READ_SHORTCIRCUIT_STREAMS_CACHE_EXPIRY_MS_DEFAULT),
conf.getInt(DFSConfigKeys.DFS_CLIENT_MMAP_CACHE_SIZE,
DFSConfigKeys.DFS_CLIENT_MMAP_CACHE_SIZE_DEFAULT),
conf.getLong(DFSConfigKeys.DFS_CLIENT_MMAP_CACHE_TIMEOUT_MS,
DFSConfigKeys.DFS_CLIENT_MMAP_CACHE_TIMEOUT_MS_DEFAULT),
conf.getLong(DFSConfigKeys.DFS_CLIENT_MMAP_RETRY_TIMEOUT_MS,
DFSConfigKeys.DFS_CLIENT_MMAP_RETRY_TIMEOUT_MS_DEFAULT),
conf.getLong(DFSConfigKeys.DFS_CLIENT_SHORT_CIRCUIT_REPLICA_STALE_THRESHOLD_MS,
DFSConfigKeys.DFS_CLIENT_SHORT_CIRCUIT_REPLICA_STALE_THRESHOLD_MS_DEFAULT),
conf.getInt(DFSConfigKeys.DFS_SHORT_CIRCUIT_SHARED_MEMORY_WATCHER_INTERRUPT_CHECK_MS,
DFSConfigKeys.DFS_SHORT_CIRCUIT_SHARED_MEMORY_WATCHER_INTERRUPT_CHECK_MS_DEFAULT));
}
public ShortCircuitCache(int maxTotalSize, long maxNonMmappedEvictableLifespanMs,
int maxEvictableMmapedSize, long maxEvictableMmapedLifespanMs,
long mmapRetryTimeoutMs, long staleThresholdMs, int shmInterruptCheckMs) {
Preconditions.checkArgument(maxTotalSize >= 0);
this.maxTotalSize = maxTotalSize;
Preconditions.checkArgument(maxNonMmappedEvictableLifespanMs >= 0);
this.maxNonMmappedEvictableLifespanMs = maxNonMmappedEvictableLifespanMs;
Preconditions.checkArgument(maxEvictableMmapedSize >= 0);
this.maxEvictableMmapedSize = maxEvictableMmapedSize;
Preconditions.checkArgument(maxEvictableMmapedLifespanMs >= 0);
this.maxEvictableMmapedLifespanMs = maxEvictableMmapedLifespanMs;
this.mmapRetryTimeoutMs = mmapRetryTimeoutMs;
this.staleThresholdMs = staleThresholdMs;
DfsClientShmManager shmManager = null;
if ((shmInterruptCheckMs > 0) &&
(DomainSocketWatcher.getLoadingFailureReason() == null)) {
try {
shmManager = new DfsClientShmManager(shmInterruptCheckMs);
} catch (IOException e) {
LOG.error("failed to create ShortCircuitShmManager", e);
}
}
this.shmManager = shmManager;
}
public long getMmapRetryTimeoutMs() {
return mmapRetryTimeoutMs;
}
public long getStaleThresholdMs() {
return staleThresholdMs;
}
/**
* Increment the reference count of a replica, and remove it from any free
* list it may be in.
*
* You must hold the cache lock while calling this function.
*
* @param replica The replica we're removing.
*/
private void ref(ShortCircuitReplica replica) {
lock.lock();
try {
Preconditions.checkArgument(replica.refCount > 0,
"can't ref " + replica + " because its refCount reached " +
replica.refCount);
Long evictableTimeNs = replica.getEvictableTimeNs();
replica.refCount++;
if (evictableTimeNs != null) {
String removedFrom = removeEvictable(replica);
if (LOG.isTraceEnabled()) {
LOG.trace(this + ": " + removedFrom +
" no longer contains " + replica + ". refCount " +
(replica.refCount - 1) + " -> " + replica.refCount +
StringUtils.getStackTrace(Thread.currentThread()));
}
} else if (LOG.isTraceEnabled()) {
LOG.trace(this + ": replica refCount " +
(replica.refCount - 1) + " -> " + replica.refCount +
StringUtils.getStackTrace(Thread.currentThread()));
}
} finally {
lock.unlock();
}
}
/**
* Unreference a replica.
*
* You must hold the cache lock while calling this function.
*
* @param replica The replica being unreferenced.
*/
void unref(ShortCircuitReplica replica) {
lock.lock();
try {
// If the replica is stale, but we haven't purged it yet, let's do that.
// It would be a shame to evict a non-stale replica so that we could put
// a stale one into the cache.
if ((!replica.purged) && replica.isStale()) {
purge(replica);
}
String addedString = "";
boolean shouldTrimEvictionMaps = false;
int newRefCount = --replica.refCount;
if (newRefCount == 0) {
// Close replica, since there are no remaining references to it.
Preconditions.checkArgument(replica.purged,
"Replica " + replica + " reached a refCount of 0 without " +
"being purged");
replica.close();
} else if (newRefCount == 1) {
Preconditions.checkState(null == replica.getEvictableTimeNs(),
"Replica " + replica + " had a refCount higher than 1, " +
"but was still evictable (evictableTimeNs = " +
replica.getEvictableTimeNs() + ")");
if (!replica.purged) {
// Add the replica to the end of an eviction list.
// Eviction lists are sorted by time.
if (replica.hasMmap()) {
insertEvictable(System.nanoTime(), replica, evictableMmapped);
addedString = "added to evictableMmapped, ";
} else {
insertEvictable(System.nanoTime(), replica, evictable);
addedString = "added to evictable, ";
}
shouldTrimEvictionMaps = true;
}
} else {
Preconditions.checkArgument(replica.refCount >= 0,
"replica's refCount went negative (refCount = " +
replica.refCount + " for " + replica + ")");
}
if (LOG.isTraceEnabled()) {
LOG.trace(this + ": unref replica " + replica +
": " + addedString + " refCount " +
(newRefCount + 1) + " -> " + newRefCount +
StringUtils.getStackTrace(Thread.currentThread()));
}
if (shouldTrimEvictionMaps) {
trimEvictionMaps();
}
} finally {
lock.unlock();
}
}
/**
* Demote old evictable mmaps into the regular eviction map.
*
* You must hold the cache lock while calling this function.
*
* @param now Current time in monotonic milliseconds.
* @return Number of replicas demoted.
*/
private int demoteOldEvictableMmaped(long now) {
int numDemoted = 0;
boolean needMoreSpace = false;
Long evictionTimeNs = Long.valueOf(0);
while (true) {
Entry<Long, ShortCircuitReplica> entry =
evictableMmapped.ceilingEntry(evictionTimeNs);
if (entry == null) break;
evictionTimeNs = entry.getKey();
long evictionTimeMs =
TimeUnit.MILLISECONDS.convert(evictionTimeNs, TimeUnit.NANOSECONDS);
if (evictionTimeMs + maxEvictableMmapedLifespanMs >= now) {
if (evictableMmapped.size() < maxEvictableMmapedSize) {
break;
}
needMoreSpace = true;
}
ShortCircuitReplica replica = entry.getValue();
if (LOG.isTraceEnabled()) {
String rationale = needMoreSpace ? "because we need more space" :
"because it's too old";
LOG.trace("demoteOldEvictable: demoting " + replica + ": " +
rationale + ": " +
StringUtils.getStackTrace(Thread.currentThread()));
}
removeEvictable(replica, evictableMmapped);
munmap(replica);
insertEvictable(evictionTimeNs, replica, evictable);
numDemoted++;
}
return numDemoted;
}
/**
* Trim the eviction lists.
*/
private void trimEvictionMaps() {
long now = Time.monotonicNow();
demoteOldEvictableMmaped(now);
while (true) {
long evictableSize = evictable.size();
long evictableMmappedSize = evictableMmapped.size();
if (evictableSize + evictableMmappedSize <= maxTotalSize) {
return;
}
ShortCircuitReplica replica;
if (evictableSize == 0) {
replica = evictableMmapped.firstEntry().getValue();
} else {
replica = evictable.firstEntry().getValue();
}
if (LOG.isTraceEnabled()) {
LOG.trace(this + ": trimEvictionMaps is purging " + replica +
StringUtils.getStackTrace(Thread.currentThread()));
}
purge(replica);
}
}
/**
* Munmap a replica, updating outstandingMmapCount.
*
* @param replica The replica to munmap.
*/
private void munmap(ShortCircuitReplica replica) {
replica.munmap();
outstandingMmapCount--;
}
/**
* Remove a replica from an evictable map.
*
* @param replica The replica to remove.
* @return The map it was removed from.
*/
private String removeEvictable(ShortCircuitReplica replica) {
if (replica.hasMmap()) {
removeEvictable(replica, evictableMmapped);
return "evictableMmapped";
} else {
removeEvictable(replica, evictable);
return "evictable";
}
}
/**
* Remove a replica from an evictable map.
*
* @param replica The replica to remove.
* @param map The map to remove it from.
*/
private void removeEvictable(ShortCircuitReplica replica,
TreeMap<Long, ShortCircuitReplica> map) {
Long evictableTimeNs = replica.getEvictableTimeNs();
Preconditions.checkNotNull(evictableTimeNs);
ShortCircuitReplica removed = map.remove(evictableTimeNs);
Preconditions.checkState(removed == replica,
"failed to make " + replica + " unevictable");
replica.setEvictableTimeNs(null);
}
/**
* Insert a replica into an evictable map.
*
* If an element already exists with this eviction time, we add a nanosecond
* to it until we find an unused key.
*
* @param evictionTimeNs The eviction time in absolute nanoseconds.
* @param replica The replica to insert.
* @param map The map to insert it into.
*/
private void insertEvictable(Long evictionTimeNs,
ShortCircuitReplica replica, TreeMap<Long, ShortCircuitReplica> map) {
while (map.containsKey(evictionTimeNs)) {
evictionTimeNs++;
}
Preconditions.checkState(null == replica.getEvictableTimeNs());
Long time = Long.valueOf(evictionTimeNs);
replica.setEvictableTimeNs(time);
map.put(time, replica);
}
/**
* Purge a replica from the cache.
*
* This doesn't necessarily close the replica, since there may be
* outstanding references to it. However, it does mean the cache won't
* hand it out to anyone after this.
*
* You must hold the cache lock while calling this function.
*
* @param replica The replica being removed.
*/
private void purge(ShortCircuitReplica replica) {
boolean removedFromInfoMap = false;
String evictionMapName = null;
Preconditions.checkArgument(!replica.purged);
replica.purged = true;
Waitable<ShortCircuitReplicaInfo> val = replicaInfoMap.get(replica.key);
if (val != null) {
ShortCircuitReplicaInfo info = val.getVal();
if ((info != null) && (info.getReplica() == replica)) {
replicaInfoMap.remove(replica.key);
removedFromInfoMap = true;
}
}
Long evictableTimeNs = replica.getEvictableTimeNs();
if (evictableTimeNs != null) {
evictionMapName = removeEvictable(replica);
}
if (LOG.isTraceEnabled()) {
StringBuilder builder = new StringBuilder();
builder.append(this).append(": ").append(": purged ").
append(replica).append(" from the cache.");
if (removedFromInfoMap) {
builder.append(" Removed from the replicaInfoMap.");
}
if (evictionMapName != null) {
builder.append(" Removed from ").append(evictionMapName);
}
LOG.trace(builder.toString());
}
unref(replica);
}
/**
* Fetch or create a replica.
*
* You must hold the cache lock while calling this function.
*
* @param key Key to use for lookup.
* @param creator Replica creator callback. Will be called without
* the cache lock being held.
*
* @return Null if no replica could be found or created.
* The replica, otherwise.
*/
public ShortCircuitReplicaInfo fetchOrCreate(ExtendedBlockId key,
ShortCircuitReplicaCreator creator) {
Waitable<ShortCircuitReplicaInfo> newWaitable = null;
lock.lock();
try {
ShortCircuitReplicaInfo info = null;
do {
if (closed) {
if (LOG.isTraceEnabled()) {
LOG.trace(this + ": can't fetchOrCreate " + key +
" because the cache is closed.");
}
return null;
}
Waitable<ShortCircuitReplicaInfo> waitable = replicaInfoMap.get(key);
if (waitable != null) {
try {
info = fetch(key, waitable);
} catch (RetriableException e) {
if (LOG.isDebugEnabled()) {
LOG.debug(this + ": retrying " + e.getMessage());
}
continue;
}
}
} while (false);
if (info != null) return info;
// We need to load the replica ourselves.
newWaitable = new Waitable<ShortCircuitReplicaInfo>(lock.newCondition());
replicaInfoMap.put(key, newWaitable);
} finally {
lock.unlock();
}
return create(key, creator, newWaitable);
}
/**
* Fetch an existing ReplicaInfo object.
*
* @param key The key that we're using.
* @param waitable The waitable object to wait on.
* @return The existing ReplicaInfo object, or null if there is
* none.
*
* @throws RetriableException If the caller needs to retry.
*/
private ShortCircuitReplicaInfo fetch(ExtendedBlockId key,
Waitable<ShortCircuitReplicaInfo> waitable) throws RetriableException {
// Another thread is already in the process of loading this
// ShortCircuitReplica. So we simply wait for it to complete.
ShortCircuitReplicaInfo info;
try {
if (LOG.isTraceEnabled()) {
LOG.trace(this + ": found waitable for " + key);
}
info = waitable.await();
} catch (InterruptedException e) {
LOG.info(this + ": interrupted while waiting for " + key);
Thread.currentThread().interrupt();
throw new RetriableException("interrupted");
}
if (info.getInvalidTokenException() != null) {
LOG.warn(this + ": could not get " + key + " due to InvalidToken " +
"exception.", info.getInvalidTokenException());
return info;
}
ShortCircuitReplica replica = info.getReplica();
if (replica == null) {
LOG.warn(this + ": failed to get " + key);
return info;
}
if (replica.purged) {
// Ignore replicas that have already been purged from the cache.
throw new RetriableException("Ignoring purged replica " +
replica + ". Retrying.");
}
// Check if the replica is stale before using it.
// If it is, purge it and retry.
if (replica.isStale()) {
LOG.info(this + ": got stale replica " + replica + ". Removing " +
"this replica from the replicaInfoMap and retrying.");
// Remove the cache's reference to the replica. This may or may not
// trigger a close.
purge(replica);
throw new RetriableException("ignoring stale replica " + replica);
}
ref(replica);
return info;
}
private ShortCircuitReplicaInfo create(ExtendedBlockId key,
ShortCircuitReplicaCreator creator,
Waitable<ShortCircuitReplicaInfo> newWaitable) {
// Handle loading a new replica.
ShortCircuitReplicaInfo info = null;
try {
if (LOG.isTraceEnabled()) {
LOG.trace(this + ": loading " + key);
}
info = creator.createShortCircuitReplicaInfo();
} catch (RuntimeException e) {
LOG.warn(this + ": failed to load " + key, e);
}
if (info == null) info = new ShortCircuitReplicaInfo();
lock.lock();
try {
if (info.getReplica() != null) {
// On success, make sure the cache cleaner thread is running.
if (LOG.isTraceEnabled()) {
LOG.trace(this + ": successfully loaded " + info.getReplica());
}
startCacheCleanerThreadIfNeeded();
// Note: new ShortCircuitReplicas start with a refCount of 2,
// indicating that both this cache and whoever requested the
// creation of the replica hold a reference. So we don't need
// to increment the reference count here.
} else {
// On failure, remove the waitable from the replicaInfoMap.
Waitable<ShortCircuitReplicaInfo> waitableInMap = replicaInfoMap.get(key);
if (waitableInMap == newWaitable) replicaInfoMap.remove(key);
if (info.getInvalidTokenException() != null) {
LOG.warn(this + ": could not load " + key + " due to InvalidToken " +
"exception.", info.getInvalidTokenException());
} else {
LOG.warn(this + ": failed to load " + key);
}
}
newWaitable.provide(info);
} finally {
lock.unlock();
}
return info;
}
private void startCacheCleanerThreadIfNeeded() {
if (cacheCleaner == null) {
cacheCleaner = new CacheCleaner();
long rateMs = cacheCleaner.getRateInMs();
ScheduledFuture<?> future =
cleanerExecutor.scheduleAtFixedRate(cacheCleaner, rateMs, rateMs,
TimeUnit.MILLISECONDS);
cacheCleaner.setFuture(future);
if (LOG.isDebugEnabled()) {
LOG.debug(this + ": starting cache cleaner thread which will run " +
"every " + rateMs + " ms");
}
}
}
ClientMmap getOrCreateClientMmap(ShortCircuitReplica replica,
boolean anchored) {
Condition newCond;
lock.lock();
try {
while (replica.mmapData != null) {
if (replica.mmapData instanceof MappedByteBuffer) {
ref(replica);
MappedByteBuffer mmap = (MappedByteBuffer)replica.mmapData;
return new ClientMmap(replica, mmap, anchored);
} else if (replica.mmapData instanceof Long) {
long lastAttemptTimeMs = (Long)replica.mmapData;
long delta = Time.monotonicNow() - lastAttemptTimeMs;
if (delta < staleThresholdMs) {
if (LOG.isTraceEnabled()) {
LOG.trace(this + ": can't create client mmap for " +
replica + " because we failed to " +
"create one just " + delta + "ms ago.");
}
return null;
}
if (LOG.isTraceEnabled()) {
LOG.trace(this + ": retrying client mmap for " + replica +
", " + delta + " ms after the previous failure.");
}
} else if (replica.mmapData instanceof Condition) {
Condition cond = (Condition)replica.mmapData;
cond.awaitUninterruptibly();
} else {
Preconditions.checkState(false, "invalid mmapData type " +
replica.mmapData.getClass().getName());
}
}
newCond = lock.newCondition();
replica.mmapData = newCond;
} finally {
lock.unlock();
}
MappedByteBuffer map = replica.loadMmapInternal();
lock.lock();
try {
if (map == null) {
replica.mmapData = Long.valueOf(Time.monotonicNow());
newCond.signalAll();
return null;
} else {
outstandingMmapCount++;
replica.mmapData = map;
ref(replica);
newCond.signalAll();
return new ClientMmap(replica, map, anchored);
}
} finally {
lock.unlock();
}
}
/**
* Close the cache and free all associated resources.
*/
@Override
public void close() {
try {
lock.lock();
if (closed) return;
closed = true;
LOG.info(this + ": closing");
maxNonMmappedEvictableLifespanMs = 0;
maxEvictableMmapedSize = 0;
// Close and join cacheCleaner thread.
IOUtils.cleanup(LOG, cacheCleaner);
// Purge all replicas.
while (true) {
Entry<Long, ShortCircuitReplica> entry = evictable.firstEntry();
if (entry == null) break;
purge(entry.getValue());
}
while (true) {
Entry<Long, ShortCircuitReplica> entry = evictableMmapped.firstEntry();
if (entry == null) break;
purge(entry.getValue());
}
} finally {
lock.unlock();
}
IOUtils.cleanup(LOG, shmManager);
}
@VisibleForTesting // ONLY for testing
public interface CacheVisitor {
void visit(int numOutstandingMmaps,
Map<ExtendedBlockId, ShortCircuitReplica> replicas,
Map<ExtendedBlockId, InvalidToken> failedLoads,
Map<Long, ShortCircuitReplica> evictable,
Map<Long, ShortCircuitReplica> evictableMmapped);
}
@VisibleForTesting // ONLY for testing
public void accept(CacheVisitor visitor) {
lock.lock();
try {
Map<ExtendedBlockId, ShortCircuitReplica> replicas =
new HashMap<ExtendedBlockId, ShortCircuitReplica>();
Map<ExtendedBlockId, InvalidToken> failedLoads =
new HashMap<ExtendedBlockId, InvalidToken>();
for (Entry<ExtendedBlockId, Waitable<ShortCircuitReplicaInfo>> entry :
replicaInfoMap.entrySet()) {
Waitable<ShortCircuitReplicaInfo> waitable = entry.getValue();
if (waitable.hasVal()) {
if (waitable.getVal().getReplica() != null) {
replicas.put(entry.getKey(), waitable.getVal().getReplica());
} else {
// The exception may be null here, indicating a failed load that
// isn't the result of an invalid block token.
failedLoads.put(entry.getKey(),
waitable.getVal().getInvalidTokenException());
}
}
}
if (LOG.isDebugEnabled()) {
StringBuilder builder = new StringBuilder();
builder.append("visiting ").append(visitor.getClass().getName()).
append("with outstandingMmapCount=").append(outstandingMmapCount).
append(", replicas=");
String prefix = "";
for (Entry<ExtendedBlockId, ShortCircuitReplica> entry : replicas.entrySet()) {
builder.append(prefix).append(entry.getValue());
prefix = ",";
}
prefix = "";
builder.append(", failedLoads=");
for (Entry<ExtendedBlockId, InvalidToken> entry : failedLoads.entrySet()) {
builder.append(prefix).append(entry.getValue());
prefix = ",";
}
prefix = "";
builder.append(", evictable=");
for (Entry<Long, ShortCircuitReplica> entry : evictable.entrySet()) {
builder.append(prefix).append(entry.getKey()).
append(":").append(entry.getValue());
prefix = ",";
}
prefix = "";
builder.append(", evictableMmapped=");
for (Entry<Long, ShortCircuitReplica> entry : evictableMmapped.entrySet()) {
builder.append(prefix).append(entry.getKey()).
append(":").append(entry.getValue());
prefix = ",";
}
LOG.debug(builder.toString());
}
visitor.visit(outstandingMmapCount, replicas, failedLoads,
evictable, evictableMmapped);
} finally {
lock.unlock();
}
}
@Override
public String toString() {
return "ShortCircuitCache(0x" +
Integer.toHexString(System.identityHashCode(this)) + ")";
}
/**
* Allocate a new shared memory slot.
*
* @param datanode The datanode to allocate a shm slot with.
* @param peer A peer connected to the datanode.
* @param usedPeer Will be set to true if we use up the provided peer.
* @param blockId The block id and block pool id of the block we're
* allocating this slot for.
* @param clientName The name of the DFSClient allocating the shared
* memory.
* @return Null if short-circuit shared memory is disabled;
* a short-circuit memory slot otherwise.
* @throws IOException An exception if there was an error talking to
* the datanode.
*/
public Slot allocShmSlot(DatanodeInfo datanode,
DomainPeer peer, MutableBoolean usedPeer,
ExtendedBlockId blockId, String clientName) throws IOException {
if (shmManager != null) {
return shmManager.allocSlot(datanode, peer, usedPeer,
blockId, clientName);
} else {
return null;
}
}
/**
* Free a slot immediately.
*
* ONLY use this if the DataNode is not yet aware of the slot.
*
* @param slot The slot to free.
*/
public void freeSlot(Slot slot) {
Preconditions.checkState(shmManager != null);
slot.makeInvalid();
shmManager.freeSlot(slot);
}
/**
* Schedule a shared memory slot to be released.
*
* @param slot The slot to release.
*/
public void scheduleSlotReleaser(Slot slot) {
Preconditions.checkState(shmManager != null);
releaserExecutor.execute(new SlotReleaser(slot));
}
@VisibleForTesting
public DfsClientShmManager getDfsClientShmManager() {
return shmManager;
}
}