// 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.
syntax = "proto2";
package kudu.transactions;

option java_package = "org.apache.kudu.transactions";

// The following state changes are expected:
//
//     BeginCommit           FinalizeCommit        CompleteCommit
//   OPEN --> COMMIT_IN_PROGRESS --> FINALIZE_IN_PROGRESS --> COMMITTED
//
//     BeginCommit           BeginAbort            FinalizeAbort
//   OPEN --> COMMIT_IN_PROGRESS --> ABORT_IN_PROGRESS --> ABORTED
//
//     AbortTxn              FinalizeAbort
//   OPEN --> ABORT_IN_PROGRESS --> ABORTED
enum TxnStatePB {
  UNKNOWN = 0;
  // The transaction is open. Users can write to participants, and register new
  // participants.
  OPEN = 1;

  // A user or Kudu's transaction staleness tracker has signaled that the
  // transaction should be aborted. No further participants can be registered,
  // and the transaction can only be moved to the ABORTED state after sending
  // ABORT_TXN ops to all participants.
  ABORT_IN_PROGRESS = 5;

  // The transaction has been fully aborted -- all participants have
  // successfully replicated ABORT_TXN ops and cleared the transaction. No
  // further tasks are required to abort the transaction.
  ABORTED = 2;

  // The user has signaled that the transaction should be committed. No further
  // participants can be registered. The transaction may still be aborted if
  // prompted by a user or if sending any BEGIN_COMMIT op fails.
  COMMIT_IN_PROGRESS = 3;

  // Kudu has successfully sent BEGIN_COMMIT ops to all participants, and has
  // started sending FINALIZE_COMMIT ops to participants. The transaction can
  // only be moved to the COMMITTED state.
  FINALIZE_IN_PROGRESS = 6;

  // All FINALIZE_COMMIT ops have succeeded. No further tasks are required to
  // commit the transaction.
  COMMITTED = 4;
}

// Metadata encapsulating the status of a transaction.
message TxnStatusEntryPB {
  optional TxnStatePB state = 1;
  optional string user = 2;

  // Commit timestamp associated with this transaction.
  optional fixed64 commit_timestamp = 3;

  // The timestamp in seconds since the epoch that this transaction was
  // started.
  optional int64 start_timestamp = 4;

  // The timestamp in seconds since the epoch that this transaction had a state
  // change.
  optional int64 last_transition_timestamp = 5;
}

// Metadata encapsulating the existence of a transaction participant.
message TxnParticipantEntryPB {
  optional TxnStatePB state = 1;
}

// High-level metadata about a transaction. Serialized messages of this type
// are used to pass information on an already opened transaction among multiple
// Kudu clients (even if residing on different nodes), so they can issue write
// operations in the context of the same multi-row distributed transaction.
message TxnTokenPB {
  // Transaction identifier assigned to the transaction.
  optional int64 txn_id = 1;

  // The keep-alive interval (in milliseconds) to keep the transaction alive.
  // To avoid auto-aborting the transaction, TxnManager should receive
  // keep-alive heartbeats spaced by intervals equal or shorter than
  // 'keepalive_millis' milliseconds in duration.
  optional uint32 keepalive_millis = 2;

  // Whether the client should automatically send keepalive messages once
  // this token is deserialized into a runtime transaction handle.
  optional bool enable_keepalive = 3;
}