io.zeebe.logstreams.spi.SnapshotController Maven / Gradle / Ivy

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/*
 * Copyright © 2017 camunda services GmbH ([email protected])
 *
 * 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
 *
 *     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 io.zeebe.logstreams.spi;

import io.zeebe.db.ZeebeDb;
import io.zeebe.logstreams.state.StateSnapshotMetadata;
import java.util.function.Predicate;

public interface SnapshotController extends AutoCloseable {
  /**
   * Takes a snapshot based on the given metadata: - last successful processed event - last written
   * event (regardless of whether or not it is committed) - term of the last written event
   *
   * @param metadata current state metadata
   */
  void takeSnapshot(StateSnapshotMetadata metadata) throws Exception;

  /**
   * Recovers the state from the latest snapshot and returns the corresponding metadata. The
   * metadata is used by the StreamProcessController to know where to seek to in the log stream.
   * Defaults to: (-1, -1, term)
   *
   * @param commitPosition current log stream commit position
   * @return recovered state metadata
   */
  StateSnapshotMetadata recover(
      long commitPosition, int term, Predicate filter) throws Exception;

  /**
   * Recovers the state from the latest snapshot.
   *
   * @return recovered state metadata
   * @throws Exception
   */
  StateSnapshotMetadata recoverFromLatestSnapshot() throws Exception;

  ZeebeDb openDb();

  /**
   * Purges all snapshots which return true for the given matcher.
   *
   * @param matcher predicate used to match
   */
  void purgeAll(Predicate matcher) throws Exception;

  /** Purges all snapshots. */
  default void purgeAll() throws Exception {
    purgeAll(s -> true);
  }

  /**
   * Purges old and invalid snapshots. Should be done once we are sure we can discard other
   * snapshots, e.g. during recovery.
   *
   * @param metadata last taken/recovered snapshot metadata
   */
  default void purgeAllExcept(StateSnapshotMetadata metadata) throws Exception {
    purgeAll(s -> !s.equals(metadata));
  }
}