org.postgresql.adba.communication.ProtocolV3States Maven / Gradle / Ivy

Go to download
package org.postgresql.adba.communication;

import java.util.HashMap;
import java.util.Map;

public class ProtocolV3States {
  public enum States {
    NOT_CONNECTED,
    STARTUP_PACKET_SENT,
    AUTHENTICATION_REQUESTED,
    AUTHENTICATION_SENT,
    CONNECTED,
    CLOSED
  }

  public enum Events {
    CONNECTION,
    AUTHENTICATION_REQUEST,
    PASSWORD_SENT,
    AUTHENTICATION_SUCCESS,
    PARAMETER_STATUS,
    BACKEND_KEY_DATA,
    READY_FOR_QUERY,
    PARSE_COMPLETE,
    BIND_COMPLETE,
    COMMAND_COMPLETE;
  }

  private static final Map> transitions = new HashMap<>();

  static {
    addTransition(States.NOT_CONNECTED, Events.CONNECTION, States.STARTUP_PACKET_SENT);
    addTransition(States.STARTUP_PACKET_SENT, Events.AUTHENTICATION_REQUEST, States.AUTHENTICATION_REQUESTED);
    addTransition(States.AUTHENTICATION_REQUESTED, Events.PASSWORD_SENT, States.AUTHENTICATION_REQUESTED);
    addTransition(States.AUTHENTICATION_REQUESTED, Events.AUTHENTICATION_SUCCESS, States.AUTHENTICATION_REQUESTED);
    addTransition(States.AUTHENTICATION_REQUESTED, Events.PARAMETER_STATUS, States.AUTHENTICATION_REQUESTED);
    addTransition(States.AUTHENTICATION_REQUESTED, Events.BACKEND_KEY_DATA, States.AUTHENTICATION_REQUESTED);
    addTransition(States.AUTHENTICATION_REQUESTED, Events.READY_FOR_QUERY, States.CONNECTED);
    addTransition(States.CONNECTED, Events.PARAMETER_STATUS, States.CONNECTED);
    addTransition(States.CONNECTED, Events.READY_FOR_QUERY, States.CONNECTED);
    
    // States suggest only one query at a time, but NIO should be capable of pipelining
    addTransition(States.CONNECTED, Events.PARSE_COMPLETE, States.CONNECTED);
    addTransition(States.CONNECTED, Events.BIND_COMPLETE, States.CONNECTED);
    addTransition(States.CONNECTED, Events.BIND_COMPLETE, States.CONNECTED);
    addTransition(States.CONNECTED, Events.COMMAND_COMPLETE, States.CONNECTED);
    addTransition(States.CONNECTED, Events.READY_FOR_QUERY, States.CONNECTED);
  }

  private static void addTransition(States start, Events event, States end) {
    if (!transitions.containsKey(start)) {
      transitions.put(start, new HashMap<>());
    }

    transitions.get(start).put(event, end);
  }

  /**
   * Used to transition the state from an initial state using an event, returns the new state according to the
   * transition rules.
   * @param state current state
   * @param event the event that happened
   * @return the new state that we are in after the event
   */
  public static States lookup(States state, Events event) {
    States targetState = transitions.get(state).get(event);

    if (targetState == null) {
      System.out.println("target state missing for start state: " + state + " and event: " + event);
    }

    return targetState;
  }
}