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/*
* Copyright 2017, 2018 IBM Corp. All Rights Reserved.
*
* Licensed 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 com.ibm.etcd.client.utils;
import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
import static com.ibm.etcd.client.GrpcClient.waitFor;
import com.ibm.etcd.api.ResponseOp;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.NavigableMap;
import java.util.NavigableSet;
import java.util.Set;
import java.util.concurrent.CancellationException;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ConcurrentSkipListMap;
import java.util.concurrent.ConcurrentSkipListSet;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.atomic.AtomicLong;
import java.util.function.Consumer;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import javax.annotation.concurrent.GuardedBy;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.google.common.collect.Iterators;
import com.google.common.util.concurrent.AbstractFuture;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.protobuf.ByteString;
import com.ibm.etcd.client.EtcdClient;
import com.ibm.etcd.client.FutureListener;
import com.ibm.etcd.client.GrpcClient;
import com.ibm.etcd.client.KeyUtils;
import com.ibm.etcd.client.kv.KvClient;
import com.ibm.etcd.client.kv.WatchUpdate;
import com.ibm.etcd.client.kv.KvClient.FluentWatchRequest;
import com.ibm.etcd.client.kv.KvClient.Watch;
import com.ibm.etcd.client.utils.RangeCache.Listener.EventType;
import com.ibm.etcd.client.watch.RevisionCompactedException;
import com.ibm.etcd.api.Compare;
import com.ibm.etcd.api.Compare.CompareResult;
import com.ibm.etcd.api.Compare.CompareTarget;
import com.ibm.etcd.api.CompareOrBuilder;
import com.ibm.etcd.api.DeleteRangeRequest;
import com.ibm.etcd.api.DeleteRangeResponse;
import com.ibm.etcd.api.Event;
import com.ibm.etcd.api.KeyValue;
import com.ibm.etcd.api.PutRequest;
import com.ibm.etcd.api.RangeRequest;
import com.ibm.etcd.api.RangeResponse;
import com.ibm.etcd.api.RequestOp;
import com.ibm.etcd.api.TxnRequest;
import com.ibm.etcd.api.TxnResponse;
import io.grpc.Status;
import io.grpc.Status.Code;
import io.grpc.stub.StreamObserver;
/**
* Auto-updated write-through lock-free cache for etcd3, supporting
* atomic compare-and-set updates.
*
* The cache must be started via the {@link #start()} method before
* it will populate and update itself with key/values from the
* specified range.
*
* Note that no range checking is done - the cache will not update
* itself with keys outside of the specified range, but it is possible
* to put, delete and getRemote keys outside of the range. This is not
* advised and may result in stale out-of-range key/values remaining
* in the cache.
*
*/
public class RangeCache implements AutoCloseable, Iterable {
protected static final Logger logger = LoggerFactory.getLogger(RangeCache.class);
public static final long TIMEOUT_MS = 3500L;
private final ByteString fromKey, toKey;
private final transient EtcdClient client;
private final KvClient kvClient;
private /*final*/ Watch watch;
private volatile boolean closed;
@GuardedBy("this")
private ListenableFuture startFuture;
private final ConcurrentMap entries;
// deletion queue is used to avoid race condition where a PUT is seen
// after a delete that it precedes
private final NavigableSet deletionQueue;
// Modified only from listenerExecutor context
private final AtomicLong seenUpToRev = new AtomicLong(0L);
public RangeCache(EtcdClient client, ByteString prefix) {
this(client, prefix, false, null);
}
public RangeCache(EtcdClient client, ByteString prefix, Executor listenerExecutor) {
this(client, prefix, false, listenerExecutor);
}
public RangeCache(EtcdClient client, ByteString prefix, boolean sorted) {
this(client, prefix, sorted, null);
}
public RangeCache(EtcdClient client, ByteString prefix, boolean sorted,
Executor listenerExecutor) {
// per etcd API spec: end == start+1 => prefix
this(client, prefix, KeyUtils.plusOne(prefix), sorted, listenerExecutor);
}
public RangeCache(EtcdClient client, ByteString fromKey, ByteString toKey, boolean sorted) {
this(client, fromKey, toKey, sorted, null);
}
public RangeCache(EtcdClient client, ByteString fromKey, ByteString toKey,
boolean sorted, Executor listenerExecutor) {
this.fromKey = fromKey;
this.toKey = toKey;
this.client = client;
this.kvClient = client.getKvClient();
this.entries = !sorted ? new ConcurrentHashMap<>(32,.75f,4)
: new ConcurrentSkipListMap<>(KeyUtils::compareByteStrings);
this.deletionQueue = new ConcurrentSkipListSet<>((kv1, kv2) -> {
int diff = Long.compare(kv1.getModRevision(), kv2.getModRevision());
return diff != 0 ? diff : KeyUtils.compareByteStrings(kv1.getKey(), kv2.getKey());
});
// This does not wrap if listenerExecutor is already a SerializedExecutor
this.listenerExecutor = GrpcClient.serialized(listenerExecutor != null
? listenerExecutor : client.getExecutor());
}
/**
* Start the cache. This must be called before the cache will
* automatically populate and update its internal state.
*
* @return a future which completes when the cache is fully
* initialized - i.e. when its contents reflects the state of
* the range at or after the time this method was called
*/
public synchronized ListenableFuture start() {
if (closed) {
throw new IllegalStateException("closed");
}
if (startFuture != null) {
throw new IllegalStateException("already started");
}
return startFuture = fullRefreshCache();
}
// internal method - should not be called while watch is active
protected ListenableFuture fullRefreshCache() {
ListenableFuture> rrfut;
long seenUpTo = seenUpToRev.get();
boolean firstTime = (seenUpTo == 0L);
if (firstTime || entries.size() <= 20) {
//TODO *maybe* chunking (for large caches)
ListenableFuture rrf = kvClient.get(fromKey).rangeEnd(toKey)
.backoffRetry(() -> !closed)
.timeout(300_000L).async(); // long timeout (5min) for large ranges
rrfut = Futures.transform(rrf, Collections::singletonList, directExecutor());
} else {
// in case the local cache is large, reduce data transfer by requesting
// just keys, and full key+value only for those modified since seenUpToRev
RangeRequest.Builder rangeReqBld = RangeRequest.newBuilder()
.setKey(fromKey).setRangeEnd(toKey);
RangeRequest newModsReq = rangeReqBld
.setMinModRevision(seenUpTo + 1).build();
RangeRequest otherKeysReq = rangeReqBld.clearMinModRevision()
.setMaxModRevision(seenUpTo).setKeysOnly(true).build();
ListenableFuture trf = kvClient.batch()
.get(newModsReq).get(otherKeysReq)
.backoffRetry(() -> !closed)
.timeout(300_000L).async(); // long timeout (5min) for large ranges
rrfut = Futures.transform(trf,
tr -> tr.getResponsesList().stream()
.map(ResponseOp::getResponseRange)
.collect(Collectors.toList()), directExecutor());
}
final class StartPromise extends SettableFuture implements Runnable {
// Reference to parent future (etcd range request) held here just
// to be able to propagate cancellation if that happens before it completes.
volatile ListenableFuture parent;
StartPromise(ListenableFuture parent) {
this.parent = parent;
parent.addListener(this, directExecutor());
}
@Override
public void run() {
// Ensure that we remove our reference to the "parent" future as soon
// as it completes, since RangeCache stores this promise in the
// startFuture field, and we want to allow the original future and its
// possibly-large value to be garbage collected.
parent = null;
}
@Override
protected void afterDone() {
if (!wasInterrupted()) {
return;
}
// propagate cancellation
final ListenableFuture p = parent;
if (p != null && p.cancel(true)) {
return;
}
Watch theWatch;
synchronized(RangeCache.this) {
theWatch = watch;
closed = true;
}
if (theWatch != null) {
theWatch.close();
}
}
}
final SettableFuture promise = new StartPromise(rrfut);
Futures.addCallback(rrfut, (FutureListener>) (rrs, err) -> {
if (rrs != null) try {
setupWatch(rrs, firstTime, promise);
return;
} catch (Throwable t) {
err = t;
}
promise.setException(err);
}, listenerExecutor);
return promise;
}
// called only from listenerExecutor context
private void setupWatch(List rrs, boolean firstTime, SettableFuture promise) {
if (closed) {
throw new CancellationException();
}
Set snapshot = firstTime && entries.isEmpty() ? null : new HashSet<>();
RangeResponse toUpdate = rrs.get(0);
if (toUpdate.getKvsCount() > 0) {
for (KeyValue kv : toUpdate.getKvsList()) {
if (snapshot != null) {
snapshot.add(kv.getKey());
}
offerUpdate(kv, true);
}
}
long snapshotRev = toUpdate.getHeader().getRevision();
if (firstTime) {
notifyListeners(EventType.INITIALIZED, null, true);
}
if (snapshot != null) {
if (rrs.size() > 1) {
for (KeyValue kv : rrs.get(1).getKvsList()) {
snapshot.add(kv.getKey());
}
}
// prune deleted entries
KeyValue.Builder kvBld = null;
for (ByteString key : entries.keySet()) {
if (!snapshot.contains(key)) {
if (kvBld == null) {
kvBld = KeyValue.newBuilder().setVersion(0L).setModRevision(snapshotRev);
}
offerUpdate(kvBld.setKey(key).build(), true);
}
}
}
revisionUpdate(snapshotRev);
StreamObserver watchObserver = new StreamObserver() {
@Override
public void onNext(WatchUpdate update) {
List events = update.getEvents();
int eventCount = events != null ? events.size() : 0;
if (eventCount > 0) {
for (Event event : events) {
KeyValue kv = event.getKv();
// event.getPrevKv(); //TBD
switch (event.getType()) {
case DELETE:
if (kv.getVersion() != 0L) {
kv = KeyValue.newBuilder(kv).setVersion(0L)
.clearValue().build();
}
// fall-thru
case PUT:
offerUpdate(kv, true);
break;
case UNRECOGNIZED: default:
logger.warn("Unrecognized event for key "
+ kv.getKey().toStringUtf8());
break;
}
}
}
revisionUpdate(eventCount == 0 ? update.getHeader().getRevision() - 1L
: events.get(eventCount - 1).getKv().getModRevision());
}
@Override
public void onCompleted() {
// should only happen after external close()
if (!closed) {
if (!client.isClosed()) {
logger.warn("Watch completed unexpectedly (not closed) (fromKey = "
+ fromKey.toStringUtf8() + ")");
}
close();
}
}
@Override
public void onError(Throwable t) {
if (closed) {
promise.setException(new CancellationException());
return;
}
boolean isDone = promise.isDone();
if (isDone && promise.isCancelled()) {
return;
}
if (!(t instanceof RevisionCompactedException)) {
logger.error("Watch failed with exception (fromKey = " +
fromKey.toStringUtf8() + ")", t);
promise.setException(t);
return;
}
// Refresh the cache, which will renew the watch
ListenableFuture refresh;
if (isDone) {
refresh = fullRefreshCache();
} else {
// If this is a watch creation failure, delay the attempt for 1 second
refresh = Futures.scheduleAsync(RangeCache.this::fullRefreshCache,
1L, TimeUnit.SECONDS, client.internalScheduledExecutor());
if (promise.setFuture(refresh)) {
refresh = null;
}
}
synchronized (RangeCache.this) {
if (!closed) {
if (refresh != null) {
startFuture = refresh;
refresh = null;
}
watch = null;
}
}
if (refresh == null) {
logger.warn("Performing full refresh (fromKey = " + fromKey.toStringUtf8() +
") following watch compaction error: " + t);
} else {
assert closed;
refresh.cancel(false);
}
}
};
FluentWatchRequest watchRequest = kvClient.watch(fromKey).rangeEnd(toKey) //.prevKv() //TODO TBD
.progressNotify().startRevision(snapshotRev + 1).executor(listenerExecutor);
Watch newWatch;
synchronized (RangeCache.this) {
if (closed) {
throw new CancellationException();
}
if (promise.isCancelled()) {
return;
}
watch = newWatch = watchRequest.start(watchObserver);
}
Futures.addCallback(newWatch, (FutureListener) (v, t) -> {
if (t != null && !newWatch.isCancelled()) {
// Error cases are handled by onError above
return;
}
if (!Boolean.TRUE.equals(v) && closed) {
promise.setException(new CancellationException());
} else {
promise.set(v);
}
}, directExecutor());
}
// called only from listenerExecutor context
protected void revisionUpdate(final long upToRev) {
if (seenUpToRev.get() >= upToRev) {
return;
}
seenUpToRev.lazySet(upToRev);
// process deletion queue up to upToRec
if (deletionQueue.isEmpty()) {
return;
}
for (Iterator it = deletionQueue.iterator(); it.hasNext();) {
KeyValue kv = it.next();
if (kv.getModRevision() > upToRev) {
return;
}
it.remove();
entries.remove(kv.getKey(), kv);
}
}
protected final List listeners = new CopyOnWriteArrayList<>();
protected final Executor listenerExecutor;
//TODO maybe take optional listener-specific executor
public void addListener(Listener listener) {
listeners.add(listener);
}
public boolean removeListener(Listener listener) {
return listeners.remove(listener);
}
/**
* Interface for listening to update events from
* the cache
*/
@FunctionalInterface
public interface Listener {
enum EventType {
/**
* Key added or modified
*/
UPDATED,
/**
* Key deleted
*/
DELETED,
/**
* Initial cache population complete (fired only once)
*/
INITIALIZED
}
/**
* @param type
* @param keyValue
*/
void event(EventType type, KeyValue keyValue);
}
protected void notifyListeners(EventType type, KeyValue keyValue,
boolean inListenerExecutor) {
if (!inListenerExecutor) {
listenerExecutor.execute(() -> notifyListeners(type, keyValue, true));
} else {
for (Listener l : listeners) try {
l.event(type, keyValue);
} catch (RuntimeException re) {
logger.warn("Listener threw exception for " + type + " event"
+ (keyValue != null ? " for key " + keyValue.getKey().toStringUtf8() : ""), re);
}
}
}
//------------------------------------
/**
* @deprecated this method now has no effect
*/
protected KeyValue offerExpiry(ByteString key) {
return get(key);
}
/**
* Assumed to not be called from watch/listener executor
*
* @return latest value, may or may not be the provided one
*/
protected KeyValue offerDelete(ByteString key, long modRevision) {
return offerUpdate(KeyValue.newBuilder().setKey(key)
.setVersion(0L).setModRevision(modRevision).build(), false);
}
/**
* @param keyValue
* @param watchThread if being called from background watch context
* @return the provided value, or a newer one
*/
protected KeyValue offerUpdate(final KeyValue keyValue, boolean watchThread) {
final long modRevision = keyValue.getModRevision();
if (modRevision <= seenUpToRev.get()) {
return kvOrNullIfDeleted(keyValue);
}
final ByteString key = keyValue.getKey();
final boolean isDeleted = isDeleted(keyValue);
// can only do this optimization in watch context, otherwise there's
// a possible (but unlikely) race with deletions
if (watchThread && !isDeleted) {
// optimized non-deletion path
KeyValue newKv = entries.merge(key, keyValue, (existKv,kv) ->
(kv.getModRevision() > existKv.getModRevision() ? kv : existKv));
if (newKv == keyValue) {
notifyListeners(EventType.UPDATED, keyValue, true);
}
return kvOrNullIfDeleted(newKv);
}
KeyValue existKv = entries.get(key);
for (;;) {
if (existKv != null) {
long existModRevision = existKv.getModRevision();
if (existModRevision >= modRevision) {
return kvOrNullIfDeleted(existKv);
}
KeyValue newKv = entries.computeIfPresent(key, (k,v) ->
(existModRevision == v.getModRevision() ? keyValue : v));
if (newKv != keyValue) {
existKv = newKv;
continue; // update failed
}
// update succeeded
boolean deletionReplaced = isDeleted(existKv);
if (deletionReplaced) {
deletionQueue.remove(existKv);
}
if (isDeleted) {
deletionQueue.add(keyValue);
if (!deletionReplaced) { // previous value
notifyListeners(EventType.DELETED, existKv, watchThread);
}
return null;
}
break; // added or updated
}
// here existKv == null
if (modRevision <= seenUpToRev.get()) {
return null;
}
//TODO in some cases it might be better to return null here
// when isDeleted == true, rather than inserting deletion record
// (e.g. when this comes from a getRemote() or keyExistsRemote() call)
if ((existKv = entries.putIfAbsent(key, keyValue)) == null) {
// update succeeded
if (isDeleted) {
deletionQueue.add(keyValue);
return null;
}
break; // added
}
}
notifyListeners(EventType.UPDATED, keyValue, false);
return keyValue;
}
protected static KeyValue kvOrNullIfDeleted(KeyValue fromCache) {
return isDeleted(fromCache) ? null : fromCache;
}
protected static boolean isDeleted(KeyValue kv) {
return kv == null || kv.getVersion() == 0L;
}
public KeyValue get(ByteString key) {
return key == null ? null : kvOrNullIfDeleted(entries.get(key));
}
/**
* @return the first KeyValue or null if empty
*/
public KeyValue getFirst() {
if (entries.isEmpty()) {
return null;
}
if (entries instanceof NavigableMap) {
@SuppressWarnings("unchecked")
Map.Entry first
= ((NavigableMap) entries).firstEntry();
return first != null ? first.getValue() : null;
}
Iterator it = entries.values().iterator();
return it.hasNext() ? it.next() : null;
}
protected KeyValue getRemote(ByteString key, boolean weak) {
if (key == null) {
return null;
}
//TODO -- async option
RangeResponse rr = kvClient.get(key)
.serializable(weak).timeout(TIMEOUT_MS).sync();
KeyValue kv = rr.getKvsCount() > 0 ? rr.getKvs(0) : null;
return kv != null ? offerUpdate(kv, false)
: offerDelete(key, rr.getHeader().getRevision());
}
public KeyValue getRemote(ByteString key) {
return getRemote(key, false);
}
public KeyValue getRemoteWeak(ByteString key) {
return getRemote(key, true);
}
public int size() {
int total = entries.size();
if (total > 0 && !deletionQueue.isEmpty()) {
// We need to exclude deletion records but can't just subtract
// deletionQueue.size() since it can contain "stale" records
// which persist until the next watch update flushes them
for (Iterator it = deletionQueue.iterator(); it.hasNext();) {
KeyValue deletion = it.next();
if (entries.get(deletion.getKey()) != deletion) {
it.remove();
} else if (--total == 0) {
return 0;
}
}
}
return total;
}
//TODO maybe add sizeRemote() ?
public boolean keyExists(ByteString key) {
// ensures deleted records (version == 0) aren't included
return get(key) != null;
}
public boolean keyExistsRemote(ByteString key) {
if (key == null) {
return false;
}
//TODO -- async
RangeResponse rr = kvClient.get(key).countOnly()
.timeout(TIMEOUT_MS).sync();
boolean exists = rr.getCount() > 0;
if (!exists) {
offerDelete(key, rr.getHeader().getRevision());
}
return exists;
}
/**
* Stores result of put operations
*/
public static final class PutResult {
private final boolean succ;
private final KeyValue kv;
public PutResult(boolean success, KeyValue kv) {
this.succ = success;
this.kv = kv;
}
public boolean succ() {
return succ;
}
public KeyValue kv() {
return kv;
}
public KeyValue existingOrNull() {
return succ ? null : kv;
}
@Override
public String toString() {
return "PutResult[succ=" + succ + ", kv=" + kv + "]";
}
}
/**
* Unconditional put. Can be used to unconditionally delete
* by passing a null value, but it's preferable to use
* {@link #delete(ByteString)} for this.
*
* @param key
* @param value value to put
* @return modRevision of updated keyValue
*/
public long put(ByteString key, ByteString value) {
return putNoGet(key, value, 0L, (CompareOrBuilder[]) null);
}
/**
* Multi-purpose put or delete, returns updated or existing KeyValue
*
* @param key
* @param value new value to put, or null to delete
* @param lease leaseId to associate value with if successful, or 0L for no lease
* @param conditions conditions which must all match to proceed, null or empty for unconditional
* @return PutResult
*/
public PutResult put(ByteString key, ByteString value, long lease,
CompareOrBuilder... conditions) {
TxnRequest treq = putTxn(key, value, true, lease, conditions);
//TODO -- async option
TxnResponse tr = kvClient.txnSync(treq, TIMEOUT_MS);
if (tr.getSucceeded()) {
if (value != null) {
KeyValue putValue = tr.getResponses(1).getResponseRange().getKvs(0);
offerUpdate(putValue, false);
return new PutResult(true, putValue);
} else {
offerDelete(key, tr.getHeader().getRevision());
return new PutResult(true, null);
}
} else {
// assert conditions != null && conditions.length > 0;
RangeResponse rr = tr.getResponses(0).getResponseRange();
KeyValue exist = rr.getKvsCount() > 0 ? offerUpdate(rr.getKvs(0), false) :
offerDelete(key, tr.getHeader().getRevision());
return new PutResult(false, exist);
}
}
/**
* @param key
* @param value new value to put, or null to delete
* @param modRev last-modified revision to match, or 0 for put-if-absent
* @return PutResult
*/
public PutResult put(ByteString key, ByteString value, long modRev) {
// return put(key, value, new Cmp(key, Cmp.Op.EQUAL, CmpTarget.modRevision(modRev)));
return put(key, value, 0L, modRevCompare(key, modRev));
}
/**
* @param key
* @param value new value to put, or null to delete
* @param leaseId leaseId to associate value with if successful, or 0L for no lease
* @param modRev last-modified revision to match, or 0 for put-if-absent
* @return PutResult
*/
public PutResult put(ByteString key, ByteString value, long leaseId, long modRev) {
return put(key, value, leaseId, modRevCompare(key, modRev));
}
/**
* Multi-purpose put or delete. If successful returns modRevision
* of updated keyValue or 0 if deleted
*
* @param key
* @param value new value to put, or null to delete
* @param lease leaseId to associate value with if successful, or 0L for no lease
* @param conditions conditions which must all match to proceed, null or empty for unconditional
* @return -1 if condition failed, else modRevision of updated keyValue
*/
public long putNoGet(ByteString key, ByteString value, long lease,
CompareOrBuilder... conditions) {
TxnRequest treq = putTxn(key, value, false, lease, conditions);
//TODO -- async option
TxnResponse tr = kvClient.txnSync(treq, TIMEOUT_MS);
if (!tr.getSucceeded()) {
return -1L;
} else if (value != null) {
KeyValue kv = tr.getResponses(1).getResponseRange().getKvs(0);
offerUpdate(kv, false);
return kv.getModRevision();
} else {
offerDelete(key, tr.getHeader().getRevision());
return 0L; //TODO TBD return modRevision or 0 in this case?
}
}
/**
* @param key
* @param value new value to put, or null to delete
* @param modRev last-modified revision to match, or 0 for put-if-absent
* @return -1 if condition failed, else modRevision of updated keyValue
*/
public long putNoGet(ByteString key, ByteString value, long modRev) {
return putNoGet(key, value, 0L, modRevCompare(key, modRev));
}
/**
* @param key
* @param value new value to put, or null to delete
* @param leaseId leaseId to associate value with if successful, or 0L for no lease
* @param modRev last-modified rev to match, or 0 for put-if-absent
* @return -1 if condition failed, else modRevision of updated keyValue
*/
public long putNoGet(ByteString key, ByteString value, long leaseId, long modRev) {
return putNoGet(key, value, leaseId, modRevCompare(key, modRev));
}
protected static Compare.Builder modRevCompare(ByteString key, long modRev) {
return Compare.newBuilder().setKey(key).setTarget(CompareTarget.MOD)
.setResult(CompareResult.EQUAL).setModRevision(modRev);
}
protected TxnRequest putTxn(ByteString key, ByteString value,
boolean getOnFail, long lease, CompareOrBuilder... conditions) {
TxnRequest.Builder tb = TxnRequest.newBuilder();
if (conditions != null && conditions.length > 0) {
for (CompareOrBuilder comp : conditions) {
if (comp instanceof Compare) {
tb.addCompare((Compare) comp);
} else {
tb.addCompare((Compare.Builder) comp);
}
}
} else {
getOnFail = false;
}
RequestOp.Builder bld = RequestOp.newBuilder();
RequestOp getOp = getOnFail || value != null ? getReq(bld, key) : null;
if (value != null) {
tb.addSuccess(putReq(bld, key, value, lease)).addSuccess(getOp);
} else {
tb.addSuccess(deleteReq(bld, key));
}
if (getOnFail) {
tb.addFailure(getOp);
}
return tb.build();
}
private static RequestOp getReq(RequestOp.Builder bld, ByteString key) {
return bld.setRequestRange(RangeRequest.newBuilder().setKey(key)).build();
}
private static RequestOp putReq(RequestOp.Builder bld, ByteString key,
ByteString value, long lease) {
return bld.setRequestPut(PutRequest.newBuilder().setKey(key)
.setValue(value).setLease(lease)).build();
}
private static RequestOp deleteReq(RequestOp.Builder bld, ByteString key) {
return bld.setRequestDeleteRange(DeleteRangeRequest.newBuilder().setKey(key)).build();
}
/**
* Unconditional delete
*
* @param key
* @return true if entry was deleted, false if already absent
*/
public boolean delete(ByteString key) {
//TODO -- async version
DeleteRangeResponse drr = kvClient.delete(key).timeout(TIMEOUT_MS).sync();
offerDelete(key, drr.getHeader().getRevision());
return drr.getDeleted() > 0;
}
/**
* Conditional delete
*
* @param key
* @param modRev
* @return true if entry was deleted, false if already absent
*/
public boolean delete(ByteString key, long modRev) {
return putNoGet(key, null, modRev) != -1L;
}
public Set keySet() {
return entries.keySet();
}
/**
* {@link Iterator#remove()} not supported on returned iterators
*
* @return an {@link Iterator} over the {@link KeyValue}s of this cache
*/
@Override
public Iterator iterator() {
// filtering iterator is unmodifiable
return Iterators.filter(entries.values().iterator(), kv -> !isDeleted(kv));
}
@Override
public void forEach(Consumer action) {
// avoid some allocations
entries.values().forEach(kv -> {
if (!isDeleted(kv)) {
action.accept(kv);
}
});
}
/**
* Iterator whose contents is guaranteed to be sequentially consistent
* with remote updates to the cached range.
*
* @return an {@link Iterator} over the {@link KeyValue}s of this cache
*/
public Iterator strongIterator() {
long seenUpTo = seenUpToRev.get();
if (seenUpTo == 0L) {
ListenableFuture startFut;
synchronized (this) {
startFut = startFuture;
}
if (startFut == null) {
// cache has not yet been started
return kvClient.get(fromKey).rangeEnd(toKey)
.timeout(120_000L).sync().getKvsList().iterator();
} else try {
startFut.get(2L, TimeUnit.MINUTES);
// now started
seenUpTo = seenUpToRev.get();
} catch (TimeoutException te) {
throw Status.DEADLINE_EXCEEDED.asRuntimeException();
} catch (ExecutionException e) {
throw Status.UNKNOWN.withCause(e).asRuntimeException();
} catch (InterruptedException|CancellationException e) {
throw Status.CANCELLED.withCause(e).asRuntimeException();
}
}
/*
* This logic is similar to that in fullRefreshCache(), but
* it includes an optimistic initial comparison of counts
* to identify cases where no deletions have been missed and
* thus a retrieval of all the keys isn't required.
*/
RangeRequest.Builder rangeReqBld = RangeRequest.newBuilder()
.setKey(fromKey).setRangeEnd(toKey);
RangeRequest curCountReq = rangeReqBld.setCountOnly(true)
.setMaxCreateRevision(seenUpTo).build();
RangeRequest seenCountReq = rangeReqBld.clearMaxCreateRevision()
.setRevision(seenUpTo).build(); // (countOnly still true here)
RangeRequest newModsReq = rangeReqBld.clearRevision().clearCountOnly()
.setMinModRevision(seenUpTo+1).build();
// first, attempt to get:
// 0- kvs modified since seenUpTo
// 1- current count excluding those created since seenUpTo
// 2- count at revision seenUpTo (this could potentially
// fail with compaction error, see below)
TxnResponse txnResp;
try {
txnResp = kvClient.batch().get(newModsReq).get(curCountReq)
.get(seenCountReq).timeout(8000L).sync();
} catch (RuntimeException e) {
Code code = Status.fromThrowable(e).getCode();
if (code != Code.OUT_OF_RANGE) {
throw e;
}
// if (2) above fails due to compaction, also retrieve all current keys
RangeRequest otherKeysReq = rangeReqBld.clearMinModRevision()
.setMaxModRevision(seenUpTo).setKeysOnly(true).build();
txnResp = kvClient.batch().get(newModsReq).get(otherKeysReq)
.timeout(60_000L).sync(); // longer timeout
}
long revNow = txnResp.getHeader().getRevision();
if (revNow > seenUpToRev.get()) {
RangeResponse newModKvs = txnResp.getResponses(0).getResponseRange();
List otherKeys;
if (txnResp.getResponsesCount() == 2) {
// this means we must have taken the compacted exception path above
otherKeys = txnResp.getResponses(1).getResponseRange().getKvsList();
} else if (txnResp.getResponses(1).getResponseRange().getCount() < // <- latest count
txnResp.getResponses(2).getResponseRange().getCount()) { // <- count at seenUpTo
// if counts don't match, there must have been deletions since seenUpTo,
// so additionally retrieve all current keys
RangeRequest otherKeysReq = rangeReqBld.clearMinModRevision()
.setMaxModRevision(seenUpTo).setKeysOnly(true).build();
otherKeys = waitFor(kvClient.get(otherKeysReq), 60_000L).getKvsList(); // longer timeout
} else {
otherKeys = null;
}
boolean newKvs = newModKvs.getKvsCount() > 0;
if (otherKeys != null) { // if this is true, there *might* be deletions to process
if (otherKeys.isEmpty() && !newKvs) {
return Collections.emptyIterator();
}
// bring cache up to date with recently deleted kvs
Set keys = Stream.concat(otherKeys.stream(), newModKvs.getKvsList().stream())
.map(kv -> kv.getKey()).collect(Collectors.toSet());
entries.values().stream().filter(kv -> kv.getModRevision() < revNow && !keys.contains(kv.getKey()))
.forEach(kv -> offerDelete(kv.getKey(), revNow));
}
// bring cache up to date with recently modified kvs
if (newKvs) {
newModKvs.getKvsList().forEach(kv -> offerUpdate(kv, false));
}
if (revNow > seenUpToRev.get()) {
listenerExecutor.execute(() -> revisionUpdate(revNow));
}
}
return iterator();
}
@Override
public synchronized void close() {
if (closed) {
return;
}
if (startFuture != null) {
if (watch != null) {
watch.close();
} else {
startFuture.addListener(() -> {
synchronized (RangeCache.this) {
if (watch != null) {
watch.close();
}
}
}, directExecutor());
}
}
closed = true;
}
public boolean isClosed() {
return closed;
}
static class SettableFuture extends AbstractFuture {
@Override
public boolean set(V value) {
return super.set(value);
}
@Override
public boolean setException(Throwable throwable) {
return super.setException(throwable);
}
@Override
public boolean setFuture(ListenableFuture future) {
return super.setFuture(future);
}
}
}