/**
* Copyright (C) 2009 - present by OpenGamma Inc. and the OpenGamma group of companies
*
* Please see distribution for license.
*/
package com.opengamma.id;
import java.util.concurrent.atomic.AtomicLong;
import com.google.common.base.Supplier;
import com.opengamma.util.ArgumentChecker;
/**
* A supplier of unique identifiers.
* <p>
* A unique identifier consists of a scheme, value and version.
* This class creates unique identifiers for a fixed scheme name, where each
* value is an incrementing number. The values are created in a thread-safe way.
* The version will always be null.
* <p>
* This class is thread-safe and not externally mutable.
*/
public class UniqueIdSupplier implements Supplier<UniqueId> {
/**
* The scheme.
*/
private final String _scheme;
/**
* The generator of identifiers.
*/
private final AtomicLong _idCount = new AtomicLong();
/**
* Creates an instance specifying the scheme.
*
* @param scheme the scheme, not empty
*/
public UniqueIdSupplier(final String scheme) {
ArgumentChecker.notEmpty(scheme, "scheme");
_scheme = scheme;
}
//-------------------------------------------------------------------------
/**
* Generates the next unique identifier.
*
* @return the next unique identifier, not null
*/
public UniqueId get() {
final long id = _idCount.incrementAndGet();
return UniqueId.of(_scheme, Long.toString(id));
}
/**
* Generates the next unique identifier prefixing the value.
*
* @param valuePrefix the prefix for the value, not null
* @return the next unique identifier, not null
*/
public UniqueId getWithValuePrefix(final String valuePrefix) {
final long id = _idCount.incrementAndGet();
return UniqueId.of(_scheme, valuePrefix + Long.toString(id));
}
//-------------------------------------------------------------------------
@Override
public String toString() {
return "UniqueIdSupplier[" + _scheme + "]";
}
}