com.jcabi.dynamo.AwsIterator Maven / Gradle / Ivy
/**
* Copyright (c) 2012-2017, jcabi.com
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met: 1) Redistributions of source code must retain the above
* copyright notice, this list of conditions and the following
* disclaimer. 2) 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. 3) Neither the name of the jcabi.com 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
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* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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*/
package com.jcabi.dynamo;
import com.amazonaws.services.dynamodbv2.AmazonDynamoDB;
import com.amazonaws.services.dynamodbv2.model.AttributeValue;
import com.amazonaws.services.dynamodbv2.model.DeleteItemRequest;
import com.amazonaws.services.dynamodbv2.model.DeleteItemResult;
import com.amazonaws.services.dynamodbv2.model.ReturnConsumedCapacity;
import com.jcabi.aspects.Immutable;
import com.jcabi.aspects.Loggable;
import com.jcabi.immutable.Array;
import com.jcabi.log.Logger;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.concurrent.atomic.AtomicReference;
import lombok.EqualsAndHashCode;
import lombok.ToString;
/**
* Iterator of items in AWS SDK.
*
* The class is mutable and thread-safe.
*
* @author Yegor Bugayenko ([email protected])
* @version $Id: b85d9ab80c84c8135152c93bea18dfbad35e08a6 $
* @checkstyle ClassDataAbstractionCoupling (500 lines)
* @since 0.1
*/
@Loggable(Loggable.DEBUG)
@ToString
@EqualsAndHashCode
(
of = { "credentials", "conditions", "frame", "name", "keys", "valve" }
)
final class AwsIterator implements Iterator- {
/**
* AWS credentials.
*/
private final transient Credentials credentials;
/**
* Conditions.
*/
private final transient Conditions conditions;
/**
* Frame.
*/
private final transient AwsFrame frame;
/**
* Table name.
*/
private final transient String name;
/**
* List of primary keys in the table.
*/
private final transient Collection
keys;
/**
* Valve that loads dosages of items.
*/
private final transient Valve valve;
/**
* Last scan result (mutable).
*/
private final transient AtomicReference dosage;
/**
* Position inside the scan result, last seen, starts with -1 (mutable).
*/
private transient int position;
/**
* Public ctor.
* @param creds Credentials
* @param frm Frame object
* @param label Table name
* @param conds Conditions
* @param primary Primary keys of the table
* @param vlv Valve with items
* @checkstyle ParameterNumber (5 lines)
*/
AwsIterator(final Credentials creds, final AwsFrame frm,
final String label, final Conditions conds,
final Collection primary, final Valve vlv) {
this.credentials = creds;
this.frame = frm;
this.name = label;
this.conditions = conds;
this.keys = primary;
this.valve = vlv;
this.dosage = new AtomicReference();
this.position = -1;
}
@Override
public boolean hasNext() {
synchronized (this.dosage) {
if (this.dosage.get() == null) {
try {
this.dosage.set(
this.valve.fetch(
this.credentials,
this.name,
this.conditions,
this.keys
)
);
} catch (final IOException ex) {
throw new IllegalStateException(ex);
}
this.position = -1;
}
if (this.dosage.get().hasNext()
&& this.position + 1 >= this.dosage.get().items().size()) {
this.dosage.set(this.dosage.get().next());
this.position = -1;
}
return this.dosage.get().items().size() - this.position > 1;
}
}
@Override
public Item next() {
synchronized (this.dosage) {
if (!this.hasNext()) {
throw new NoSuchElementException(
String.format(
"no more items in the frame, position=%d",
this.position
)
);
}
++this.position;
return new AwsItem(
this.credentials,
this.frame,
this.name,
new Attributes(this.dosage.get().items().get(this.position)),
new Array(this.keys)
);
}
}
@Override
@SuppressWarnings("PMD.UseConcurrentHashMap")
public void remove() {
synchronized (this.dosage) {
final AmazonDynamoDB aws = this.credentials.aws();
try {
final Dosage prev = this.dosage.get();
final List> items =
new ArrayList>(prev.items());
final Map item =
items.remove(this.position);
final long start = System.currentTimeMillis();
final DeleteItemResult res = aws.deleteItem(
new DeleteItemRequest()
.withTableName(this.name)
.withKey(new Attributes(item).only(this.keys))
.withReturnConsumedCapacity(
ReturnConsumedCapacity.TOTAL
)
.withExpected(
new Attributes(item).only(this.keys).asKeys()
)
);
this.dosage.set(new AwsIterator.Fixed(prev, items));
--this.position;
Logger.info(
this,
"#remove(): item #%d removed from DynamoDB, %s, in %[ms]s",
this.position,
new PrintableConsumedCapacity(
res.getConsumedCapacity()
).print(),
System.currentTimeMillis() - start
);
} finally {
aws.shutdown();
}
}
}
/**
* Dosage with fixed list of items.
*/
@Immutable
private static final class Fixed implements Dosage {
/**
* List of items.
*/
private final transient Array> list;
/**
* Previous dosage.
*/
private final transient Dosage prev;
/**
* Ctor.
* @param dsg Dosage
* @param items Items
*/
Fixed(final Dosage dsg, final List> items) {
this.prev = dsg;
this.list = new Array>(items);
}
@Override
public List> items() {
return Collections.unmodifiableList(this.list);
}
@Override
public Dosage next() {
return this.prev.next();
}
@Override
public boolean hasNext() {
return this.prev.hasNext();
}
}
}