Function state_handle_cache_lookup

example/plugins/c-api/protocol/TxnSM.cc:264–334

This function handle the cache lookup result. If MISS, try to open cache write_vc for writing. Otherwise, use the vc returned by the cache to read the data from the cache. */

   open cache write_vc for writing. Otherwise, use the vc returned
   by the cache to read the data from the cache. */
int
state_handle_cache_lookup(TSCont contp, TSEvent event, TSVConn vc)
{
  TxnSM  *txn_sm = static_cast<TxnSM *>(TSContDataGet(contp));
  int64_t response_size;
  int     ret_val;

  Dbg(dbg_ctl, "enter state_handle_cache_lookup");

  switch (event) {
  case TS_EVENT_CACHE_OPEN_READ:
    Dbg(dbg_ctl, "cache hit!!!");
    /* Cache hit. */

    /* Write log */
    ret_val = TSTextLogObjectWrite(protocol_plugin_log, "%s %s %d \n", txn_sm->q_file_name, txn_sm->q_server_name, 1);
    if (ret_val != TS_SUCCESS) {
      TSError("[%s] Fail to write into log", PLUGIN_NAME);
    }

    txn_sm->q_cache_vc       = vc;
    txn_sm->q_pending_action = nullptr;

    /* Get the size of the cached doc. */
    response_size = TSVConnCacheObjectSizeGet(txn_sm->q_cache_vc);

    /* Allocate IOBuffer to store data from the cache. */
    txn_sm->q_client_response_buffer = TSIOBufferCreate();
    if (!txn_sm->q_client_response_buffer) {
      return prepare_to_die(contp);
    }
    txn_sm->q_client_response_buffer_reader = TSIOBufferReaderAlloc(txn_sm->q_client_response_buffer);
    if (!txn_sm->q_client_response_buffer_reader) {
      return prepare_to_die(contp);
    }
    txn_sm->q_cache_read_buffer = TSIOBufferCreate();
    if (!txn_sm->q_cache_read_buffer) {
      return prepare_to_die(contp);
    }
    txn_sm->q_cache_read_buffer_reader = TSIOBufferReaderAlloc(txn_sm->q_cache_read_buffer);
    if (!txn_sm->q_cache_read_buffer_reader) {
      return prepare_to_die(contp);
    }

    /* Read doc from the cache. */
    set_handler(txn_sm->q_current_handler, (TxnSMHandler)&state_handle_cache_read_response);
    txn_sm->q_cache_read_vio = TSVConnRead(txn_sm->q_cache_vc, contp, txn_sm->q_cache_read_buffer, response_size);

    break;

  case TS_EVENT_CACHE_OPEN_READ_FAILED:
    /* Cache miss or error, open cache write_vc. */
    Dbg(dbg_ctl, "cache miss or error!!!");
    /* Write log */
    ret_val = TSTextLogObjectWrite(protocol_plugin_log, "%s %s %d \n", txn_sm->q_file_name, txn_sm->q_server_name, 0);

    if (ret_val != TS_SUCCESS) {
      TSError("[%s] Fail to write into log", PLUGIN_NAME);