rpc Txn (TxnRequest) returns (TxnResponse) { }

message TxnRequest {
    // List of tests to perform before transaction
    repeated Compare compare = 1;
    // List of operations to perform when all tests succeed
    repeated RequestOp success = 2;
    // List of operations to perform when any test fails
    repeated RequestOp failure = 3;
}

message Compare {

    enum CompareResult {
        EQUAL = 0;
        GREATER = 1;
        LESS = 2;
        NOT_EQUAL = 3;
    }

    enum CompareTarget {
        VERSION = 0;
        CREATE = 1;
        MOD = 2;
        VALUE = 3;
        LEASE = 4;
    }

    CompareResult result = 1;
    CompareTarget target = 2;

    bytes key = 3;
    oneof target_union {
        int64 version = 4;
        int64 create_revision = 5;
        int64 mod_revision = 6;
        bytes value = 7;
        int64 lease = 8;
    }

    // Can compare key range rather than just one key
    bytes range_end = 64;
}

message RequestOp {
    oneof request {
        RangeRequest request_range = 1;
        PutRequest request_put = 2;
        DeleteRangeRequest request_delete_range = 3;
        TxnRequest request_txn = 4;
    }
}

message TxnResponse {
    ResponseHeader header = 1;
    bool succeeded = 2;
    repeated ResponseOp responses = 3;
}