content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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 accord.api;
  
  import java.util.function.Supplier;
  
  import javax.annotation.Nullable;
  
  import accord.local.Command;
  import accord.local.SafeCommandStore;
  import accord.local.StoreParticipants;
  import accord.primitives.Participants;
  import accord.primitives.Route;
  import accord.primitives.Status;
  import accord.primitives.Timestamp;
  import accord.primitives.TxnId;
  
  import static accord.utils.Invariants.illegalState;
  
  public interface ViolationHandler
  {
      /**
       * For use by implementations to decide what to do about timestamp inconsistency, i.e. two different timestamps
       * committed for the same transaction. This is a protocol consistency violation, potentially leading to non-linearizable
       * histories. In test cases this is used to fail the transaction, whereas in real systems this likely will be used for
       * reporting the violation, as it is no more correct at this point to refuse the operation than it is to complete it.
       *
       * Should throw an exception if the inconsistent timestamp should not be applied
       */
      default void onTimestampViolation(@Nullable SafeCommandStore safeStore, Command command, Participants<?> otherParticipants, @Nullable Route<?> otherRoute, Timestamp otherExecuteAt) { throw illegalState(timestampViolationMessage(safeStore, command, otherParticipants, otherRoute, otherExecuteAt)); }
      default void onTimestampViolation(@Nullable SafeCommandStore safeStore, Command command, StoreParticipants otherParticipants, Timestamp otherExecuteAt) { onTimestampViolation(safeStore, command, otherParticipants.owns(), otherParticipants.route(), otherExecuteAt); }
  
      default void onDependencyViolation(Participants<?> participants, TxnId notWitnessed, Timestamp notWitnessedExecuteAt, TxnId by, Timestamp byExecuteAt) { throw illegalState(dependencyViolationMessage(participants, notWitnessed, notWitnessedExecuteAt, by, byExecuteAt)); }
  
      static String timestampViolationMessage(@Nullable SafeCommandStore safeStore, Command command, Participants<?> otherParticipants, @Nullable Route<?> otherRoute, Timestamp otherExecuteAt)
      {
          String message = "Linearizability violation for " + command.txnId() + " on " + otherParticipants + (otherRoute != null && otherRoute.size() != otherParticipants.size() ? " (" + otherRoute + ')' : "") + ": "
                 + command.txnId() + " has already been " + (command.is(Status.Invalidated) ? " invalidated " : " committed with timestamp " + command.executeAt())
                 + " and is now being " + (otherExecuteAt.equals(Timestamp.NONE) ? " invalidated)" : " committed with timestamp " + otherExecuteAt);
          if (safeStore != null)
          {
              message += ". RedundantBefore={";
              Participants<?> participants = Participants.merge(Participants.merge(otherParticipants, (Participants)otherRoute), command.route());
              message += safeStore.redundantBefore().foldlWithBounds(participants, (b, m, s, e) -> (m.isEmpty() ? "[" : ", [") + s + ',' + e + "]:" + b, "", ignore -> false) + '}';
          }
          return message;
      }
  
      static String dependencyViolationMessage(Participants<?> participants, TxnId notWitnessed, Timestamp notWitnessedExecuteAt, TxnId by, Timestamp byExecuteAt)
      {
          return "Linearizability violation on " + participants + ": "
                 + notWitnessed + " is committed to execute (at " + notWitnessedExecuteAt + ") before "
                 + by + " that should witness it but has already applied (at " + byExecuteAt + ')';
  
      }
  
      class ViolationHandlerHolder
      {
          private static volatile Supplier<ViolationHandler> global = () -> new ViolationHandler() {};
          public static ViolationHandler get() { return global.get(); }
          public static void set(Supplier<ViolationHandler> agent) { global = agent; }
      }
  }
  