transaction_message.h

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/* Copyright (c) 2013, 2024, Oracle and/or its affiliates.
 
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   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.
 
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   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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#ifndef TRANSACTION_MESSAGE_INCLUDED
#define TRANSACTION_MESSAGE_INCLUDED
 
#include "plugin/group_replication/include/plugin_messages/transaction_message_interface.h"
 
/*
  @class Transaction_message
  Class to convey the serialized contents of the TCLE
 */
class Transaction_message : public Transaction_message_interface {
 public:
  enum enum_payload_item_type {
    // This type should not be used anywhere.
    PIT_UNKNOWN = 0,
 
    // Length of the payload item: variable
    PIT_TRANSACTION_DATA = 1,
 
    // Length of the payload item: 8 bytes
    PIT_SENT_TIMESTAMP = 2,
 
    // No valid type codes can appear after this one.
    PIT_MAX = 3
  };
 
  /**
   Constructor
 
   @param[in] payload_capacity  The transaction data size
   */
  Transaction_message(uint64_t payload_capacity);
  ~Transaction_message() override;
 
  /**
     Overrides Basic_ostream::write().
     Transaction_message is a Basic_ostream, which appends
     data into the a Gcs_message_data.
 
     @param[in] buffer  where the data will be read
     @param[in] length  the length of the data to write
 
     @return returns false if succeeds, otherwise true is returned.
  */
  bool write(const unsigned char *buffer, my_off_t length) override;
 
  /**
     Length of the message.
 
     @return message length
  */
  uint64_t length() override;
 
  /**
     Get the Gcs_message_data object, which contains the serialized
     transaction data.
     The internal Gcs_message_data is nullified, to avoid further usage
     of this Transaction object and the caller receives a pointer to the
     previously internal Gcs_message_data, which whom it is now responsible.
 
     @return the serialized transaction data in a Gcs_message_data object
  */
  Gcs_message_data *get_message_data_and_reset() override;
 
  /**
    Return the time at which the message contained in the buffer was sent.
    @see Metrics_handler::get_current_time()
 
    @param[in] buffer            the buffer to decode from.
    @param[in] length            the buffer length
 
    @return the time on which the message was sent.
  */
  static uint64_t get_sent_timestamp(const unsigned char *buffer,
                                     size_t length);
 
 protected:
  /*
   Implementation of the template methods
   */
  void encode_payload(std::vector<unsigned char> *buffer) const override;
  void decode_payload(const unsigned char *buffer,
                      const unsigned char *) override;
 
 private:
  Gcs_message_data *m_gcs_message_data{nullptr};
  static const uint64_t s_sent_timestamp_pit_size;
};
 
#endif /* TRANSACTION_MESSAGE_INCLUDED */