Method global_transaction_handler

plugins/traffic_dump/transaction_data.cc:398–534

Transaction handler: writes headers to the log file using AIO

// Transaction handler: writes headers to the log file using AIO
int
TransactionData::global_transaction_handler(TSCont /* contp ATS_UNUSED */, TSEvent event, void *edata)
{
  TSHttpTxn txnp = static_cast<TSHttpTxn>(edata);

  // Retrieve SessionData
  TSHttpSsn    ssnp    = TSHttpTxnSsnGet(txnp);
  SessionData *ssnData = static_cast<SessionData *>(TSUserArgGet(ssnp, SessionData::get_session_arg_index()));

  // If no valid ssnData, continue transaction as if nothing happened. This transaction
  // must be filtered out by our filter criteria.
  if (!ssnData) {
    Dbg(dbg_ctl, "session_txn_handler(): No ssnData found. Abort.");
    TSHttpTxnReenable(txnp, TS_EVENT_HTTP_CONTINUE);
    return TS_SUCCESS;
  }

  switch (event) {
  case TS_EVENT_HTTP_TXN_START: {
    // We will piece together JSON content accumulated across several hooks of
    // the transaction. The catch is that hooks across transactions in a
    // session may fire interleaved in HTTP/2. Thus, in order to get
    // non-garbled JSON content, we accumulate the data for an entire
    // transaction and write that atomically once the transaction is completed.
    TransactionData *txnData = new TransactionData(txnp, ssnData->get_http_version_in_client_stack());
    TSUserArgSet(txnp, transaction_arg_index, txnData);
    // Get UUID
    char uuid[TS_CRUUID_STRING_LEN + 1];
    TSAssert(TS_SUCCESS == TSClientRequestUuidGet(txnp, uuid));
    std::string_view uuid_view{uuid, strnlen(uuid, TS_CRUUID_STRING_LEN)};

    // Generate per transaction json records
    txnData->_txn_json += "{";
    // "connection-time":(number)
    TSHRTime start_time;
    TSHttpTxnMilestoneGet(txnp, TS_MILESTONE_UA_BEGIN, &start_time);
    txnData->_txn_json += "\"connection-time\":" + std::to_string(start_time);

    // "uuid":(string)
    // The uuid is a header field for each message in the transaction. Use the
    // "all" node to apply to each message.
    std::string_view name  = "uuid";
    txnData->_txn_json    += R"(,"all":{"headers":{"fields":[)" + json_entry_array(name, uuid_view);
    txnData->_txn_json    += "]}}";
    break;
  }

  case TS_EVENT_HTTP_READ_REQUEST_HDR: {
    TransactionData *txnData = static_cast<TransactionData *>(TSUserArgGet(txnp, transaction_arg_index));
    if (!txnData) {
      TSError("[%s] No transaction data found for the header hook we registered for.", traffic_dump::debug_tag);
      break;
    }
    // This hook is registered globally, not at TS_EVENT_HTTP_SSN_START in
    // global_session_handler(). As such, this handler will be called with every
    // transaction. However, we infer that we are dumping this transaction
    // because there is a ssnData associated with it.