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// Copyright 2010 Google 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.google.gwtorm.nosql;
import com.google.gwtorm.client.Access;
import com.google.gwtorm.client.Key;
import com.google.gwtorm.client.OrmException;
import com.google.gwtorm.client.ResultSet;
import com.google.gwtorm.client.impl.AbstractAccess;
import com.google.gwtorm.protobuf.ProtobufCodec;
/** Internal base class for implementations of {@link Access}. */
public abstract class NoSqlAccess<T, K extends Key<?>> extends
AbstractAccess<T, K> {
protected NoSqlAccess(final NoSqlSchema s) {
}
/**
* Scan a range of keys from the data rows and return any matching objects.
*
* @param fromKey key to start the scan on. This is inclusive.
* @param toKey key to stop the scan on. This is exclusive.
* @param limit maximum number of results to return.
* @return result set for the requested range. The result set may be lazily
* filled, or filled completely.
* @throws OrmException an error occurred preventing the scan from completing.
*/
protected abstract ResultSet<T> scanPrimaryKey(byte[] fromKey, byte[] toKey,
int limit) throws OrmException;
/**
* Scan a range of keys and return any matching objects.
* <p>
* All NoSQL implementations must provide their own variant of this method.
* <p>
* To fetch a single record with a scan, set {@code toKey} to the same array
* as {@code fromKey}, but append a trailing NUL byte (0x00). The caller
* should validate that the returned ResultSet contains no more than 1 row.
*
* @param index definition of the index the scan occurs over.
* @param fromKey key to start the scan on. This is inclusive.
* @param toKey key to stop the scan on. This is exclusive.
* @param limit maximum number of results to return.
* @return result set for the requested range. The result set may be lazily
* filled, or filled completely.
* @throws OrmException an error occurred preventing the scan from completing.
*/
protected abstract ResultSet<T> scanIndex(IndexFunction<T> index,
byte[] fromKey, byte[] toKey, int limit) throws OrmException;
// -- These are all provided by AccessGen when it builds a subclass --
/** @return encoder/decoder for the object data. */
protected abstract ProtobufCodec<T> getObjectCodec();
/**
* Get the indexes that support query functions.
* <p>
* This array may be a subset of the total query functions. This can occur
* when two or more queries can be efficiently answered by performing a range
* scan over the same index.
*
* @return indexes needed to support queries.
*/
protected abstract IndexFunction<T>[] getIndexes();
/**
* Encode the primary key of the object.
*
* @param dst builder the key components will be added into.
* @param key the object primary key.
*/
protected abstract void encodePrimaryKey(IndexKeyBuilder dst, K key);
}
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