Exemplo n.º 1
0
  private Integer transferResource(ResourceStock buyer, Resource outResource) {
    while (true) {
      int wanted = buying.count(buyer);
      int available = externalRepository.count(outResource);
      int transfer = Math.min(available, wanted);

      if (transfer == 0) {
        return 0;
      }

      boolean procured = externalRepository.setCount(outResource, available, available - transfer);
      if (procured) {
        boolean sent = buying.setCount(buyer, wanted, wanted - transfer);
        if (sent) {
          try {
            buyer.add(transfer);
          } catch (RuntimeException e) {
            buying.remove(buyer, transfer);
            continue;
          }
          myLogTransfer(buyer, transfer, outResource);
          return transfer;
        } else {

          externalRepository.add(outResource, transfer);
        }
      }
    }
  }
Exemplo n.º 2
0
  /**
   * Transfer resources between two stocks. This method uses compensation to recover from race
   * conditions instead of locking to avoid them altogether. Arguably, this scheme provides better
   * concurrency performance.
   *
   * @param buyer
   * @param seller
   * @return the amount transfered
   */
  @Override
  protected int transfer(ResourceStock buyer, ResourceStock seller) {
    while (true) {
      int wanted = buying.count(buyer);
      int available = selling.count(seller);
      int transfer = Math.min(available, wanted);

      if (transfer == 0) {
        return 0;
      }

      boolean procured = selling.setCount(seller, available, available - transfer);
      if (procured) {
        boolean sent = buying.setCount(buyer, wanted, wanted - transfer);
        if (sent) {
          try {
            seller.remove(transfer);
          } catch (RuntimeException e) {
            selling.add(seller, transfer);
            buying.remove(buyer, transfer);
            continue;
          }
          try {
            buyer.add(transfer);
          } catch (RuntimeException e) {
            // market takes care of what was sold.
            // To fully solve this case, 2PCommit or 3PC is
            // required. Is it worth?
            buying.remove(buyer, transfer);
            continue;
          }
          logTransfer(seller, buyer, transfer);

          return transfer;
        } else {
          // Compensation. restore what we took from the order!
          selling.add(seller, transfer);
        }
      }
      // Reaching here mean we hit a race condition. Try again.
    }
  }
Exemplo n.º 3
0
  /**
   * Attempts to match buyer and sellers. This implementations uses a very simple approach: For each
   * buyer, all sellers of the resource are searched, and each of them either sells everything it
   * has, or up to the amount needed. No attempt is done to match the best buyer and seller and
   * reduce the number of operations.
   */
  @Override
  protected void matchBothEnds() {
    LOGGER.info("ACA ENTRO UNO");
    for (ResourceStock buyer : buying) {
      LOGGER.info("ACA ENTRO DOS");
      for (ResourceStock seller : selling) {
        if (buyer.resource().equals(seller.resource())) {
          // LOGGER.info("Se buscan:"+buying.count(buyer)+"Tengo en seller:"+selling.count(seller));
          LOGGER.info(buyer.name() + " Encontre algo en la cola interna");
          Integer resp = transfer(buyer, seller);
          if (resp != 0) {
            LOGGER.info(
                "ENCONTRADO EN SELLING, SE TRANSFIRIERON:"
                    + buyer.name()
                    + "<=="
                    + resp
                    + " de "
                    + buyer.resource()
                    + "<=="
                    + seller.name());
          }
        }
      }
      if (buying.count(buyer) != 0) {
        /* Me fijo si lo tenia de una transaccion anterior */
        for (Resource outResource : externalRepository) {
          if (buyer.resource().equals(outResource)) {
            LOGGER.info(buyer.name() + "ENCONTRADO EN LA COLA EXTERNA.");
            Integer resp = transferResource(buyer, outResource);
            if (resp != 0) {
              LOGGER.info(
                  "SE TRANSFIRIERON:" + buyer.name() + "<====" + resp + " de " + buyer.resource());
            }
          }
        }

        /*
         * Debo pedir afuera mi recurso, el handler de la respuesta es
         * el encargado de cargarmelo
         */

        if (buying.count(buyer) != 0) {
          LOGGER.info(
              buyer.name()
                  + " SOLICITUD RECURSOS:"
                  + buying.count(buyer)
                  + " DE "
                  + buyer.resource());
          this.myMarketManager.requestResources(buying.count(buyer), buyer.resource());
        }
      }
    }
  }