java/com/google/gerrit/server/Sequence.java

// Copyright (C) 2023 The Android Open Source Project
//
// 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 com.google.gerrit.server;

import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.ElementType.PARAMETER;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

import com.google.common.collect.ImmutableList;
import com.google.inject.BindingAnnotation;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;

/**
 * An incrementing sequence that's used to assign new unique numbers for change, account and group
 * IDs.
 */
public interface Sequence {
  String NAME_ACCOUNTS = "accounts";
  String NAME_GROUPS = "groups";
  String NAME_CHANGES = "changes";

  /**
   * Some callers cannot get the normal {@link #NAME_ACCOUNTS} sequence injected because some
   * injected fields are not available at injection time. Allow for providing a light-weight
   * injected instance.
   */
  @BindingAnnotation
  @Target({FIELD, PARAMETER, METHOD})
  @Retention(RUNTIME)
  @interface LightweightAccounts {}

  /**
   * Some callers cannot get the normal {@link #NAME_GROUPS} sequence injected because some injected
   * fields are not available at injection time. Allow for providing a light-weight injected
   * instance.
   */
  @BindingAnnotation
  @Target({FIELD, PARAMETER, METHOD})
  @Retention(RUNTIME)
  @interface LightweightGroups {}

  enum SequenceType {
    ACCOUNTS,
    CHANGES,
    GROUPS;
  }

  /** Returns the next available sequence value and increments the sequence for the next call. */
  int next();

  /** Similar to {@link #next()} but returns a {@code count} of next available values. */
  ImmutableList<Integer> next(int count);

  /** Returns the next available sequence value. */
  int current();

  /** Returns the last sequence number that was assigned. */
  int last();

  /**
   * Stores a new {@code value} to be returned on the next calls for {@link #next()} or {@link
   * #current()}.
   */
  void storeNew(int value);
}