[HADOOP-24] make Configuration an interface

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Won't Fix
• Affects Version/s: 0.7.2
• Component/s: conf
• Assignee: Doug Cutting
• Reporter: Doug Cutting
• Created: 07/Feb/06 05:09
• Updated: 23/Apr/09 19:24
• Resolved: 15/Jan/09 17:27

Description

The Configuration class should become an interface, e.g.:

public interface Configuration {
String get(String nam);
String set(String name, String value);

int getInt(String name);
void setInt(String name, int value);
float getFloat(String name);
void setFloat(String name, float value);
//... other utility methods based on get(String) and set(String,String) ...
}

An abstract class named ConfigurationBase should be implemented as follows:

public abstract class ConfigurationBase implements Configuration {
abstract public String get(String nam);
abstract public String set(String name, String value);

public int getInt(String name)

{ ... implementation in terms of get(String) ... }
public void setInt(String name, int value) {... implementation in terms of set(String, String) ...}
public float getFloat(String name) { ... implementation in terms of get(String) ... }

public void setFloat(String name, float value)

{... implementation in terms of set(String, String) ...}

//... other utility methods based on get(String) and set(String,String) ...
}

A concrete, default implementation will be provided as follows:

public class ConfigurationImpl implements Writable extends ConfigurationBase {
private Properties properties;

// implement abstract methods from ConfigurationBase
public String get(String name)

{ ... implemented in terms of props ...}

public String set(String name, String value)

{ .. implemented in terms of props ... }

// Writable methods
public write(DataOutputStream out);
public readFields(DataInputStream in);

// permit chaining of configurations
public Configuration getDefaults();
public void setDefaults(Configuration defaults);
}

Only code which creates configurations should need to be updated, so this shouldn't be a huge change.

Issue Links

• is part of: HADOOP-3582 Improve how Hadoop gets configured