content: /*
   * Copyright 2024-2025 the original author or authors.
   *
   * 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
   *
   *      https://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.alibaba.cloud.ai.graph.checkpoint;
  
  import com.alibaba.cloud.ai.graph.RunnableConfig;
  
  import java.util.Collection;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.Objects;
  import java.util.Optional;
  
  import static java.util.Optional.ofNullable;
  
  public interface BaseCheckpointSaver {
  
  	String THREAD_ID_DEFAULT = "$default";
  
  	record Tag(String threadId, Collection<Checkpoint> checkpoints) {
  		public Tag(String threadId, Collection<Checkpoint> checkpoints) {
  			this.threadId = threadId;
  			this.checkpoints = ofNullable(checkpoints).map(List::copyOf).orElseGet(List::of);
  		}
  	}
  
  	default Tag release(RunnableConfig config) throws Exception {
  		return null;
  	}
  
  	Collection<Checkpoint> list(RunnableConfig config);
  
  	Optional<Checkpoint> get(RunnableConfig config);
  
  	RunnableConfig put(RunnableConfig config, Checkpoint checkpoint) throws Exception;
  
  	boolean clear(RunnableConfig config);
  
  	default Optional<Checkpoint> getLast(LinkedList<Checkpoint> checkpoints, RunnableConfig config) {
  		return (checkpoints == null || checkpoints.isEmpty()) ? Optional.empty() : ofNullable(checkpoints.peek());
  	}
  
  	default LinkedList<Checkpoint> getLinkedList(List<Checkpoint> checkpoints) {
  		return Objects.nonNull(checkpoints) ? new LinkedList<>(checkpoints) : new LinkedList<>();
  	}
  
  }
  