com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapperConfig Maven / Gradle / Ivy
/*
* Copyright 2011-2014 Amazon Technologies, 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://aws.amazon.com/apache2.0
*
* This file 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.amazonaws.services.dynamodbv2.datamodeling;
import com.amazonaws.metrics.RequestMetricCollector;
/**
* Immutable configuration object for service call behavior. An instance of this
* configuration is supplied to every {@link DynamoDBMapper} at construction; if
* not provided explicitly, {@link DynamoDBMapperConfig#DEFAULT} is used. New
* instances can be given to the mapper object on individual save, load, and
* delete operations to override the defaults. For example:
*
*
* DynamoDBMapper mapper = new DynamoDBMapper(dynamoDBClient);
* // Force this read to be consistent
* DomainClass obj = mapper.load(DomainClass.class, key, new DynamoDBMapperConfig(ConsistentReads.CONSISTENT));
* // Force this save operation to use putItem rather than updateItem
* mapper.save(obj, new DynamoDBMapperConfig(SaveBehavior.CLOBBER));
* // Save the object into a different table
* mapper.save(obj, new DynamoDBMapperConfig(new TableNameOverride("AnotherTable")));
* // Delete the object even if the version field is out of date
* mapper.delete(obj, new DynamoDBMapperConfig(SaveBehavior.CLOBBER));
*
*/
public class DynamoDBMapperConfig {
/**
* Enumeration of behaviors for the save operation.
*/
public static enum SaveBehavior {
/**
* UPDATE will not affect unmodeled attributes on a save operation and a
* null value for the modeled attribute will remove it from that item in
* DynamoDB.
*
* Because of the limitation of updateItem request, the implementation
* of UPDATE will send a putItem request when a key-only object is being
* saved, and it will send another updateItem request if the given
* key(s) already exists in the table.
*
* By default, the mapper uses UPDATE.
*/
UPDATE,
/**
* UPDATE_SKIP_NULL_ATTRIBUTES is similar to UPDATE, except that it
* ignores any null value attribute(s) and will NOT remove them from
* that item in DynamoDB. It also guarantees to send only one single
* updateItem request, no matter the object is key-only or not.
*/
UPDATE_SKIP_NULL_ATTRIBUTES,
/**
* CLOBBER will clear and replace all attributes, included unmodeled
* ones, (delete and recreate) on save. Versioned field constraints will
* also be disregarded.
*/
CLOBBER,
/**
* APPEND_SET treats scalar attributes (String, Number, Binary) the same
* as UPDATE_SKIP_NULL_ATTRIBUTES does. However, for set attributes, it
* will append to the existing attribute value, instead of overriding
* it. Caller needs to make sure that the modeled attribute type matches
* the existing set type, otherwise it would result in a service
* exception.
*/
APPEND_SET
};
/**
* Enumeration of consistent read behavior.
*
* CONSISTENT uses consistent reads, EVENTUAL does not. Consistent reads
* have implications for performance and billing; see the service
* documentation for details.
*
* By default, the mapper uses eventual consistency.
*/
public static enum ConsistentReads {
CONSISTENT, EVENTUAL
};
/**
* Enumeration of pagination loading strategy.
*/
public static enum PaginationLoadingStrategy {
/**
* Paginated list is lazily loaded when possible, and all loaded results
* are kept in the memory.
*
* By default, the mapper uses LAZY_LOADING.
*/
LAZY_LOADING,
/**
* Only supports using iterator to read from the paginated list. All
* other list operations will return UnsupportedOperationException
* immediately. During the iteration, the list will clear all the
* previous results before loading the next page, so that the list will
* keep at most one page of the loaded results in memory. This also
* means the list could only be iterated once.
*
* Use this configuration to reduce the memory overhead when handling
* large DynamoDB items.
*/
ITERATION_ONLY,
/**
* Paginated list will eagerly load all the paginated results from
* DynamoDB as soon as the list is initialized.
*/
EAGER_LOADING
}
/**
* Allows overriding the table name declared on a domain class by the
* {@link DynamoDBTable} annotation.
*/
public static final class TableNameOverride {
private final String tableNameOverride;
private final String tableNamePrefix;
/**
* Returns a new {@link TableNameOverride} object that will prepend the
* given string to every table name.
*/
public static TableNameOverride withTableNamePrefix(String tableNamePrefix) {
return new TableNameOverride(null, tableNamePrefix);
}
/**
* Returns a new {@link TableNameOverride} object that will replace
* every table name in requests with the given string.
*/
public static TableNameOverride withTableNameReplacement(String tableNameReplacement) {
return new TableNameOverride(tableNameReplacement, null);
}
private TableNameOverride(String tableNameOverride, String tableNamePrefix) {
this.tableNameOverride = tableNameOverride;
this.tableNamePrefix = tableNamePrefix;
}
/**
* @see TableNameOverride#withTableNameReplacement(String)
*/
public TableNameOverride(String tableNameOverride) {
this(tableNameOverride, null);
}
/**
* Returns the table name to use for all requests. Exclusive with
* {@link TableNameOverride#getTableNamePrefix()}
*
* @see DynamoDBMapperConfig#getTableNameOverride()
*/
public String getTableName() {
return tableNameOverride;
}
/**
* Returns the table name prefix to prepend the table name for all
* requests. Exclusive with {@link TableNameOverride#getTableName()}
*
* @see DynamoDBMapperConfig#getTableNameOverride()
*/
public String getTableNamePrefix() {
return tableNamePrefix;
}
}
private final SaveBehavior saveBehavior;
private final ConsistentReads consistentReads;
private final TableNameOverride tableNameOverride;
private final PaginationLoadingStrategy paginationLoadingStrategy;
private final RequestMetricCollector requestMetricCollector;
/** Legacy constructor, using default PaginationLoadingStrategy **/
public DynamoDBMapperConfig(SaveBehavior saveBehavior,
ConsistentReads consistentReads, TableNameOverride tableNameOverride) {
this(saveBehavior, consistentReads, tableNameOverride, null, null);
}
/**
* Constructs a new configuration object with the save behavior, consistent
* read behavior, and table name override given.
*
* @param saveBehavior
* The {@link SaveBehavior} to use, or null for default.
* @param consistentReads
* The {@link ConsistentReads} to use, or null for default.
* @param tableNameOverride
* An override for the table name, or null for no override.
* @param paginationLoadingStrategy
* The pagination loading strategy, or null for default.
*/
public DynamoDBMapperConfig(SaveBehavior saveBehavior,
ConsistentReads consistentReads,
TableNameOverride tableNameOverride,
PaginationLoadingStrategy paginationLoadingStrategy) {
this(saveBehavior, consistentReads, tableNameOverride,
paginationLoadingStrategy, null);
}
/**
* Constructs a new configuration object with the save behavior, consistent
* read behavior, and table name override given.
*
* @param saveBehavior
* The {@link SaveBehavior} to use, or null for default.
* @param consistentReads
* The {@link ConsistentReads} to use, or null for default.
* @param tableNameOverride
* An override for the table name, or null for no override.
* @param paginationLoadingStrategy
* The pagination loading strategy, or null for default.
* @param requestMetricCollector
* optional request metric collector
*/
public DynamoDBMapperConfig(SaveBehavior saveBehavior,
ConsistentReads consistentReads,
TableNameOverride tableNameOverride,
PaginationLoadingStrategy paginationLoadingStrategy,
RequestMetricCollector requestMetricCollector) {
this.saveBehavior = saveBehavior;
this.consistentReads = consistentReads;
this.tableNameOverride = tableNameOverride;
this.paginationLoadingStrategy = paginationLoadingStrategy;
this.requestMetricCollector = requestMetricCollector;
}
/**
* Constructs a new configuration object with the save behavior given.
*/
public DynamoDBMapperConfig(SaveBehavior saveBehavior) {
this(saveBehavior, null, null, null);
}
/**
* Constructs a new configuration object with the consistent read behavior
* given.
*/
public DynamoDBMapperConfig(ConsistentReads consistentReads) {
this(null, consistentReads, null, null);
}
/**
* Constructs a new configuration object with the table name override given.
*/
public DynamoDBMapperConfig(TableNameOverride tableNameOverride) {
this(null, null, tableNameOverride, null);
}
/**
* Constructs a new configuration object with the pagination loading strategy given.
*/
public DynamoDBMapperConfig(PaginationLoadingStrategy paginationLoadingStrategy) {
this(null, null, null, paginationLoadingStrategy);
}
/**
* Constructs a new configuration object from two others: a set of defaults
* and a set of overrides. Any non-null overrides will be applied to the
* defaults.
*
* Used internally to merge the {@link DynamoDBMapperConfig} provided at
* construction with an overriding object for a particular operation.
*
* @param defaults
* The default mapper configuration values.
* @param overrides
* The overridden mapper configuration values. Any non-null
* config settings will be applied to the returned object.
*/
public DynamoDBMapperConfig(DynamoDBMapperConfig defaults, DynamoDBMapperConfig overrides) {
if ( overrides == null ) {
this.saveBehavior = defaults.getSaveBehavior();
this.consistentReads = defaults.getConsistentReads();
this.tableNameOverride = defaults.getTableNameOverride();
this.paginationLoadingStrategy = defaults.getPaginationLoadingStrategy();
this.requestMetricCollector = defaults.getRequestMetricCollector();
} else {
this.saveBehavior = overrides.getSaveBehavior() == null ? defaults.getSaveBehavior() : overrides
.getSaveBehavior();
this.consistentReads = overrides.getConsistentReads() == null ? defaults.getConsistentReads() : overrides
.getConsistentReads();
this.tableNameOverride = overrides.getTableNameOverride() == null ? defaults.getTableNameOverride()
: overrides.getTableNameOverride();
this.paginationLoadingStrategy = overrides.getPaginationLoadingStrategy() == null ? defaults.getPaginationLoadingStrategy()
: overrides.getPaginationLoadingStrategy();
this.requestMetricCollector = overrides.getRequestMetricCollector() == null ? defaults.getRequestMetricCollector()
: overrides.getRequestMetricCollector();
}
}
/**
* Returns the save behavior for this configuration.
*/
public SaveBehavior getSaveBehavior() {
return saveBehavior;
}
/**
* Returns the consistent read behavior for this configuration.
*/
public ConsistentReads getConsistentReads() {
return consistentReads;
}
/**
* Returns the table name override for this configuration. This value will
* override the table name specified in a {@link DynamoDBTable} annotation,
* either by replacing the table name entirely or else by pre-pending a
* string to each table name. This is useful for partitioning data in
* multiple tables at runtime.
*
* @see TableNameOverride#withTableNamePrefix(String)
* @see TableNameOverride#withTableNameReplacement(String)
*/
public TableNameOverride getTableNameOverride() {
return tableNameOverride;
}
/**
* Returns the pagination loading strategy for this configuration.
*/
public PaginationLoadingStrategy getPaginationLoadingStrategy() {
return paginationLoadingStrategy;
}
/**
* Returns the request metric collector or null if not specified.
*/
public RequestMetricCollector getRequestMetricCollector() {
return requestMetricCollector;
}
/**
* Default configuration uses UPDATE behavior for saves and EVENTUALly
* consistent reads, with no table name override and lazy-loading strategy.
*/
public static final DynamoDBMapperConfig DEFAULT = new DynamoDBMapperConfig(SaveBehavior.UPDATE,
ConsistentReads.EVENTUAL, null, PaginationLoadingStrategy.LAZY_LOADING);
}