com.couchbase.client.java.datastructures.collections.CouchbaseQueue Maven / Gradle / Ivy
/*
* Copyright (c) 2016 Couchbase, Inc.
*
* 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.couchbase.client.java.datastructures.collections;
import java.util.AbstractQueue;
import java.util.Collection;
import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.Queue;
import com.couchbase.client.core.annotations.InterfaceAudience;
import com.couchbase.client.core.annotations.InterfaceStability;
import com.couchbase.client.core.message.ResponseStatus;
import com.couchbase.client.core.message.kv.subdoc.multi.Lookup;
import com.couchbase.client.core.message.kv.subdoc.multi.Mutation;
import com.couchbase.client.java.Bucket;
import com.couchbase.client.java.datastructures.collections.iterators.JsonArrayDocumentIterator;
import com.couchbase.client.java.document.JsonArrayDocument;
import com.couchbase.client.java.document.json.JsonArray;
import com.couchbase.client.java.document.json.JsonObject;
import com.couchbase.client.java.document.json.JsonValue;
import com.couchbase.client.java.error.CASMismatchException;
import com.couchbase.client.java.error.DocumentAlreadyExistsException;
import com.couchbase.client.java.error.subdoc.MultiMutationException;
import com.couchbase.client.java.subdoc.DocumentFragment;
/**
* A CouchbaseQueue is a {@link Queue} backed by a {@link Bucket Couchbase} document (more
* specifically a {@link JsonArrayDocument JSON array}).
*
* Note that as such, a CouchbaseQueue is restricted to the types that a {@link JsonArray JSON array}
* can contain. JSON objects and sub-arrays can be represented as {@link JsonObject} and {@link JsonArray}
* respectively. Null values are not allowed as they have special meaning for the {@link #peek()} and {@link #remove()}
* methods of a queue.
*
* @param the type of values in the queue.
*
* @author Simon Baslé
* @author Subhashni Balakrishnan
* @since 2.3.6
*/
@InterfaceStability.Committed
@InterfaceAudience.Public
public class CouchbaseQueue extends AbstractQueue {
private static final int MAX_OPTIMISTIC_LOCKING_ATTEMPTS = Integer.parseInt(System.getProperty("com.couchbase.datastructureCASRetryLimit", "10"));
private final String id;
private final Bucket bucket;
/**
* Create a new {@link Bucket Couchbase-backed} Queue, backed by the document identified by id
* in bucket. Note that if the document already exists, its content will be used as initial
* content for this collection. Otherwise it is created empty.
*
* @param id the id of the Couchbase document to back the queue.
* @param bucket the {@link Bucket} through which to interact with the document.
*/
public CouchbaseQueue(String id, Bucket bucket) {
this.bucket = bucket;
this.id = id;
try {
bucket.insert(JsonArrayDocument.create(id, JsonArray.empty()));
} catch (DocumentAlreadyExistsException ex) {
// Ignore concurrent creations, keep on moving.
}
}
/**
* Create a new {@link Bucket Couchbase-backed} Queue, backed by the document identified by id
* in bucket. Note that if the document already exists, its content is reset to the values
* provided.
*
* Note that if you don't provide any value as a vararg, the {@link #CouchbaseQueue(String, Bucket)}
* constructor will be invoked instead, which will use pre-existing values as content. To create a new
* Queue and force it to be empty, use {@link #CouchbaseQueue(String, Bucket, Collection)} with an empty
* collection.
*
* @param id the id of the Couchbase document to back the queue.
* @param bucket the {@link Bucket} through which to interact with the document.
* @param content vararg of the elements to initially store in the Queue.
*/
public CouchbaseQueue(String id, Bucket bucket, E... content) {
this.bucket = bucket;
this.id = id;
JsonArray array = JsonArray.create();
for (E e : content) {
if (!JsonValue.checkType(e)) {
throw new ClassCastException();
} else if (e == null) {
throw new NullPointerException();
}
array.add(e);
}
bucket.upsert(JsonArrayDocument.create(id, array));
}
/**
* Create a new {@link Bucket Couchbase-backed} Queue, backed by the document identified by id
* in bucket. Note that if the document already exists, its content is reset to the values
* provided in the content Collection.
*
* @param id the id of the Couchbase document to back the queue.
* @param bucket the {@link Bucket} through which to interact with the document.
* @param content collection of the elements to initially store in the Queue, in iteration order.
*/
public CouchbaseQueue(String id, Bucket bucket, Collection content) {
this.bucket = bucket;
this.id = id;
JsonArray array = JsonArray.create();
for (E e : content) {
if (!JsonValue.checkType(e)) {
throw new ClassCastException();
} else if (e == null) {
throw new NullPointerException();
}
array.add(e);
}
bucket.upsert(JsonArrayDocument.create(id, array));
}
@Override
public Iterator iterator() {
return new JsonArrayDocumentIterator(bucket, id);
}
@Override
public int size() {
//TODO in Spock, GET_COUNT should be available on subdoc
JsonArrayDocument current = bucket.get(id, JsonArrayDocument.class);
return current.content().size();
}
@Override
public void clear() {
bucket.upsert(JsonArrayDocument.create(id, JsonArray.empty()));
}
@Override
public boolean offer(E e) {
if (e == null) {
throw new NullPointerException("Unsupported null value");
}
if (!JsonValue.checkType(e)) {
throw new IllegalArgumentException("Unsupported value type.");
}
bucket.mutateIn(id).arrayPrepend("", e, false).execute();
return true;
}
@Override
public E poll() {
String idx = "[-1]"; //FIFO queue as offer uses ARRAY_PREPEND
for(int i = 0; i < MAX_OPTIMISTIC_LOCKING_ATTEMPTS; i++) {
try {
DocumentFragment current = bucket.lookupIn(id).get(idx).execute();
long returnCas = current.cas();
Object result = current.content(idx);
DocumentFragment updated = bucket.mutateIn(id).remove(idx).withCas(returnCas).execute();
return (E) result;
} catch (CASMismatchException ex) {
//will have to retry get-and-remove
} catch (MultiMutationException ex) {
if (ex.firstFailureStatus() == ResponseStatus.SUBDOC_PATH_NOT_FOUND) {
return null; //the queue is empty
}
throw ex;
}
}
throw new ConcurrentModificationException("Couldn't perform poll in less than " + MAX_OPTIMISTIC_LOCKING_ATTEMPTS + " iterations");
}
@Override
public E peek() {
try {
DocumentFragment current = bucket.lookupIn(id).get("[0]").execute();
Object result = current.content(0);
return (E) result;
} catch (MultiMutationException ex) {
if (ex.firstFailureStatus() == ResponseStatus.SUBDOC_PATH_NOT_FOUND) {
return null; //the queue is empty
}
throw ex;
}
}
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