RepositoryMapCache.java

package sk.stuba.fiit.perconik.activity.listeners.git;

import java.io.File;
import java.util.Map.Entry;
import java.util.concurrent.ConcurrentMap;

import org.eclipse.jgit.lib.Repository;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.collect.Maps.immutableEntry;
import static com.google.common.collect.Maps.newConcurrentMap;

final class RepositoryMapCache<K, V> {
  private final ConcurrentMap<Entry<File, K>, V> map;

  RepositoryMapCache() {
    this.map = newConcurrentMap();
  }

  boolean load(final Repository repository, final K key, final V value) {
    return this.map.putIfAbsent(immutableEntry(repository.getDirectory(), key), checkNotNull(value)) == null;
  }

  V update(final Repository repository, final K key, final V value) {
    V previous = this.map.replace(immutableEntry(repository.getDirectory(), key), checkNotNull(value));

    return !value.equals(previous) ? previous : null;
  }

  @Override
  public String toString() {
    return this.map.toString();
  }
}