com.graphhopper.storage.DataAccess Maven / Gradle / Ivy
/*
* Licensed to GraphHopper GmbH under one or more contributor
* license agreements. See the NOTICE file distributed with this work for
* additional information regarding copyright ownership.
*
* GraphHopper GmbH licenses this file to you 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.graphhopper.storage;
/**
* Abstraction of the underlying data structure with a unique id and location. To ensure that the id
* is unique use a Directory.attach or findAttach, if you don't need uniqueness call
* Directory.create. Current implementations are RAM and memory mapped access.
*
* Life cycle: (1) object creation, (2) configuration (e.g. segment size), (3) create or
* loadExisting, (4) usage and calling ensureCapacity if necessary, (5) close
*
*
* @author Peter Karich
*/
public interface DataAccess extends Storable {
/**
* The logical identification of this object.
*/
String getName();
/**
* Renames the underlying DataAccess object. (Flushing shouldn't be necessary before or
* afterwards)
*
*
* @throws IllegalStateException if a rename is not possible
*/
void rename(String newName);
/**
* Set 4 bytes at position 'bytePos' to the specified value
*/
void setInt(long bytePos, int value);
/**
* Get 4 bytes from position 'bytePos'
*/
int getInt(long bytePos);
/**
* Set 2 bytes at position 'index' to the specified value
*/
void setShort(long bytePos, short value);
/**
* Get 2 bytes from position 'index'
*/
short getShort(long bytePos);
/**
* Set bytes from position 'index' to the specified values
*/
void setBytes(long bytePos, byte[] values, int length);
/**
* Get bytes from position 'index'
*
* @param values acts as output
*/
void getBytes(long bytePos, byte[] values, int length);
void setByte(long currentPointer, byte value);
byte getByte(long currentPointer);
/**
* Set 4 bytes at the header space index to the specified value
*/
void setHeader(int bytePos, int value);
/**
* Get 4 bytes from the header at 'index'
*/
int getHeader(int bytePos);
/**
* The first time you use a DataAccess object after configuring it you need to call this method.
* After that first call you have to use ensureCapacity to ensure that enough space is reserved.
*/
@Override
DataAccess create(long bytes);
/**
* Ensures that the capacity of this object is at least the specified bytes. The first time you
* have to call 'create' instead.
*
*
* @return true if size was increased
* @see #create(long)
*/
boolean ensureCapacity(long bytes);
/**
* Copies the content from this object into the specified one.
*/
DataAccess copyTo(DataAccess da);
/**
* @return the size of one segment in bytes
*/
int getSegmentSize();
/**
* In order to increase allocated space one needs to layout the underlying storage in segments.
* This is how you can customize the size.
*/
DataAccess setSegmentSize(int bytes);
/**
* @return the number of segments.
*/
int getSegments();
/**
* @return the data access type of this object.
*/
DAType getType();
}