Moving host coordinator into vilya.
git-svn-id: svn+ssh://src.earth.threerings.net/vilya/trunk@198 c613c5cb-e716-0410-b11b-feb51c14d237
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package com.threerings.ezgame {
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import flash.events.EventDispatcher;
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/**
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HostCoordinator provides methods for determining whether the current
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client should consider itself the authority in dealing with game state
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(for example, when dealing out cards, or setting up the game board).
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Current hosting state can be retrieved from the /status/ property.
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Please note that hosting authority can be transferred between clients
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at any moment, so all clients should be prepared to suddenly take
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over host responsibilities.
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Additionally, the client can register itself for notifications
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about changes to the /status/ property - see HostEvent.
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Usage example:
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<pre>
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_coord = new HostCoordinator (_gameCtrl);
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_coord.addEventListener (HostEvent.CLAIMED, firstHostHandler);
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_coord.addEventListener (HostEvent.CHANGED, hostChangeHandler);
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...
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function firstHostHandler (event : HostEvent)
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{
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if (_coord.status == HostCoordinator.STATUS_HOST)
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{
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// I'm the first host in the game - I should set up the initial board, etc.
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}
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}
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function hostChangeHandler (event : HostEvent)
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{
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if (_coord.status == HostCoordinator.STATUS_HOST)
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{
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// I just became the host - do whatever is needed.
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}
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}
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</pre>
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*/
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public class HostCoordinator
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extends EventDispatcher
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implements OccupantChangedListener, PropertyChangedListener
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{
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// CONSTANTS
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/** Status constant, means that the current status is unknown, either because
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the data had not yet arrived from the server, or because nobody claims
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to be host for this game. */
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public static const STATUS_UNKNOWN : String = "STATUS_UNKNOWN";
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/** Status constant, means that this client is the current host. */
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public static const STATUS_HOST : String = "STATUS_HOST";
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/** Status constant, means that some other client is the current host. */
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public static const STATUS_NOT_HOST : String = "STATUS_NOT_HOST";
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// PUBLIC INTERFACE
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/**
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Constructor, expects an initialized instance of EZGameControl.
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If the optional showDebug flag is set, it will display host info
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as chat messages (only useful for debugging).
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*/
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public function HostCoordinator (control : EZGameControl, showDebug : Boolean = false)
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{
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_control = control;
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_control.registerListener (this);
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_showDebug = showDebug;
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// Try set host role if it's not already claimed (i.e. null)
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debugLog ("Trying to claim host role.");
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debugLog ("Current status: " + status);
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tryReplaceHost (null);
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}
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/**
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Retrieves current host coordination status, as one of the STATUS_*
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constants.
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Note: do not save the value of this property. Hosting status
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can change at any moment: when the current host quits the game,
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any client can suddenly become the new host.
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l */
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public function get status () : String
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{
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var hostId : Number = getHostId ();
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if (hostId == _control.getMyId ()) { return STATUS_HOST; }
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if (hostId > 0) { return STATUS_NOT_HOST; }
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return STATUS_UNKNOWN;
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}
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// EVENT HANDLERS
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/** From OccupantChangedListener: keep track of people coming in */
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public function occupantEntered (event : OccupantChangedEvent) : void
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{
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debugHostStatus ();
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}
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/** From OccupantChangedListener: keep track of people leaving */
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public function occupantLeft (event : OccupantChangedEvent) : void
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{
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// If the occupant who just left was the host, every client will
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// get a shot at trying to claim their role.
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debugLog ("My ID: " + _control.getMyId ());
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debugLog ("Occupant left: " + event.occupantId);
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debugLog ("Current host: " + getHostId());
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if (getHostId () == event.occupantId) // Elvis has left the building
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{
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debugLog ("Removing the old host...");
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// Clear the old host value, and put myself in their place.
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// Only the first client will succeed in doing this.
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tryReplaceHost (event.occupantId);
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}
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}
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/** From PropertyChangedListener: keep track of changing host values */
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public function propertyChanged (event : PropertyChangedEvent) : void
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{
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if (event.name == HOST_NAME)
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{
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debugLog ("Host variable changed to: " + event.newValue);
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// if the host was not known before, dispatch the claimed event
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if (event.oldValue == null &&
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event.newValue != null)
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{
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var claimed : HostEvent = new HostEvent (HostEvent.CLAIMED, _control);
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this.dispatchEvent (claimed);
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}
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// always dispatch the changed event
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var changed : HostEvent = new HostEvent (HostEvent.CHANGED, _control);
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this.dispatchEvent (changed);
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}
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}
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// PRIVATE FUNCTIONS
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/** Get the current host ID (will be 0 if there is no authoritative host) */
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private function getHostId () : Number
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{
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var hostvalue : Object = _control.get (HOST_NAME);
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if (hostvalue != null && hostvalue is Number)
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{
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return hostvalue as Number;
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}
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return 0;
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}
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/** Helper function: tries to set the host variable to the client's id,
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if the current value is equal to /hostId/. If the value of null for
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hostId has the meaning of "set me as host only if the role has not
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been claimed yet". */
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private function tryReplaceHost (hostId : Object) : void
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{
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_control.testAndSet (HOST_NAME, _control.getMyId (), hostId);
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debugHostStatus ();
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}
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/** Debug only */
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private function debugLog (message : String) : void
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{
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if (_showDebug) { _control.localChat (message); }
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}
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/** Debug only */
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private function debugHostStatus () : void
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{
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debugLog (
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(status == STATUS_HOST ? "I am" : "I'm not") +
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" the host (id " + getHostId() + ", mine is " + _control.getMyId() + ")");
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}
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// PRIVATE VALUES
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/** Magic key that stores current authoritative host */
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private var HOST_NAME : String = "HOST_COORDINATOR_AUTHORITATIVE_HOST";
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/** Controller storage */
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private var _control : EZGameControl = null;
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/** Debug flag */
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private var _showDebug : Boolean;
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}
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}
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@@ -0,0 +1,33 @@
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package com.threerings.ezgame {
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import flash.events.Event;
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/**
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* Dispatched by the host coordinator, to signal a change
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* in host status.
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*/
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public class HostEvent extends EZEvent
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{
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/** Indicates that the current host changed. */
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public static const CHANGED :String = "Host Changed";
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/** Indicates that the host used to be unknown, but it became claimed
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by one of the clients. */
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public static const CLAIMED :String = "Host Claimed";
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public function HostEvent (type :String, ezgame :EZGameControl)
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{
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super (type, ezgame);
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}
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override public function toString () :String
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{
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return "[HostEvent type=" + type + "]";
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}
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override public function clone () :Event
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{
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return new HostEvent (type, _ezgame);
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}
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}
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}
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