Allow access to the list of created resources.

Author: caduandrade

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.3.0
+
+* Access the list of created resources.
+
 ## 0.2.0
 
 * Setting to determine how often `Future.delayed` is used instead of `Future.microtask` during event execution to allow GUI refresh.
@@ -8,8 +12,8 @@
 ## 0.1.0
 
 * Initial release
-  * Discrete event processing
-  * Event scheduling, execution, waiting, and repetition
-  * Intervals management
+  * Discrete event processing.
+  * Event scheduling, execution, waiting, and repetition.
+  * Intervals management.
   * Resources
     * Capacity limit

lib/simdart.dart

@@ -1,7 +1,7 @@
 export 'src/event.dart';
 export 'src/interval.dart';
 export 'src/observable.dart';
-export 'src/resources.dart' hide ResourcesFactory;
+export 'src/resources.dart' hide ResourcesFactory, ResourceStore;
 export 'src/simdart.dart' hide SimDartHelper;
 export 'src/simulation_track.dart';
 export 'src/start_time_handling.dart';

lib/src/internal/resource.dart

@@ -1,36 +1,126 @@
+import 'dart:collection';
+
 import 'package:meta/meta.dart';
 import 'package:simdart/src/internal/completer_action.dart';
 import 'package:simdart/src/internal/event_action.dart';
-import 'package:simdart/src/internal/resource.dart';
 import 'package:simdart/src/simdart.dart';
 import 'package:simdart/src/simulation_track.dart';
 
+@internal
+class ResourceStore {
+  /// Holds the resources in the simulator.
+  final Map<String, _ResourceImpl> _map = {};
+  final List<_ResourceImpl> _list = [];
+  late final UnmodifiableListView<_ResourceImpl> _unmodifiableList =
+      UnmodifiableListView(_list);
+
+  Map<String, int> usage() {
+    Map<String, int> result = {};
+    for (_ResourceImpl resource in _map.values) {
+      result[resource.name] = resource._queue.length;
+    }
+    return result;
+  }
+}
+
+abstract interface class Resource {
+  String get name;
+  int get capacity;
+  bool isAvailable();
+}
+
+abstract interface class LimitedResource extends Resource {}
+
+abstract class _ResourceImpl implements Resource {
+  _ResourceImpl(
+      {required this.name,
+      required this.capacity,
+      required this.acquisitionRule});
+
+  @override
+  final String name;
+
+  @override
+  final int capacity;
+
+  final List<EventAction> _queue = [];
+  final bool Function(EventAction event)? acquisitionRule;
+
+  /// A queue that holds completer to resume events waiting for a resource to become available.
+  final List<EventAction> _waiting = [];
+
+  bool acquire(EventAction event);
+
+  bool release(SimDart sim, EventAction event);
+}
+
+class _LimitedResourceImpl extends _ResourceImpl implements LimitedResource {
+  _LimitedResourceImpl(
+      {required super.name,
+      required super.capacity,
+      required super.acquisitionRule});
+
+  @override
+  bool acquire(EventAction event) {
+    if (acquisitionRule != null && !acquisitionRule!(event)) {
+      return false;
+    }
+    if (isAvailable()) {
+      _queue.add(event);
+      return true;
+    }
+
+    return false;
+  }
+
+  @override
+  bool release(SimDart sim, EventAction event) {
+    return _queue.remove(event);
+  }
+
+  @override
+  bool isAvailable() {
+    return _queue.length < capacity;
+  }
+}
+
 class Resources {
-  Resources._(SimDart sim) : _sim = sim;
+  Resources._(SimDart sim)
+      : _sim = sim,
+        _store = SimDartHelper.resourceStore(sim: sim);
 
   final SimDart _sim;
+  final ResourceStore _store;
+
+  List<Resource> get all => _store._unmodifiableList;
+
+  int get length => _store._map.length;
 
   /// Creates a resource with limited capacity.
   ///
   /// This method adds a resource with the specified capacity.
   /// The resource will be configured as limited, meaning it will have a maximum
   /// capacity defined by the [capacity] parameter.
   ///
-  /// - [id]: The unique identifier of the resource (required).
+  /// - [name]: The unique name of the resource (required).
   /// - [capacity]: The maximum capacity of the resource. The default value is 1.
-  void limited({required String id, int capacity = 1}) {
-    SimDartHelper.addResource(
-        sim: _sim,
-        resourceId: id,
-        create: () => LimitedResource(id: id, capacity: capacity));
+  Resource limited({required String name, int capacity = 1}) {
+    _ResourceImpl? resource = _store._map[name];
+    if (resource == null) {
+      resource = _LimitedResourceImpl(
+          name: name, capacity: capacity, acquisitionRule: null);
+      _store._map[name] = resource;
+      _store._list.add(resource);
+    }
+    return resource;
   }
 
   /// Checks if a resource is available.
   ///
-  /// - [id]: The id of the resource to check.
+  /// - [name]: The name of the resource to check.
   /// - Returns: `true` if the resource is available, `false` otherwise.
-  bool isAvailable(String id) {
-    Resource? resource = SimDartHelper.getResource(sim: _sim, resourceId: id);
+  bool isAvailable(String name) {
+    _ResourceImpl? resource = _store._map[name];
     if (resource != null) {
       return resource.isAvailable();
     }
@@ -47,10 +137,10 @@ class ResourcesContext extends Resources {
 
   /// Tries to acquire a resource immediately.
   ///
-  /// - [id]: The id of the resource to acquire.
+  /// - [name]: The name of the resource to acquire.
   /// - Returns: `true` if the resource was acquired, `false` otherwise.
-  bool tryAcquire(String id) {
-    Resource? resource = SimDartHelper.getResource(sim: _sim, resourceId: id);
+  bool tryAcquire(String name) {
+    _ResourceImpl? resource = _store._map[name];
     if (resource != null) {
       return resource.acquire(_event);
     }
@@ -59,17 +149,17 @@ class ResourcesContext extends Resources {
 
   /// Acquires a resource, waiting if necessary until it becomes available.
   ///
-  /// - [id]: The id of the resource to acquire.
+  /// - [name]: The name of the resource to acquire.
   /// - Returns: A [Future] that completes when the resource is acquired.
-  Future<void> acquire(String id) async {
+  Future<void> acquire(String name) async {
     if (_event.eventCompleter != null) {
       SimDartHelper.error(
           sim: _sim,
           msg:
               "This event should be waiting for the resource to be released. Did you forget to use 'await'?");
       return;
     }
-    Resource? resource = SimDartHelper.getResource(sim: _sim, resourceId: id);
+    _ResourceImpl? resource = _store._map[name];
     if (resource != null) {
       bool acquired = resource.acquire(_event);
       if (!acquired) {
@@ -78,23 +168,23 @@ class ResourcesContext extends Resources {
               sim: _sim, eventName: _event.eventName, status: Status.yielded);
         }
         _event.buildCompleter();
-        resource.waiting.add(_event);
+        resource._waiting.add(_event);
         SimDartHelper.scheduleNextAction(sim: _sim);
         await _event.eventCompleter!.future;
-        return await acquire(id);
+        return await acquire(name);
       }
     }
   }
 
   /// Releases a previously acquired resource.
   ///
-  /// - [id]: The id of the resource to release.
-  void release(String id) {
-    Resource? resource = SimDartHelper.getResource(sim: _sim, resourceId: id);
+  /// - [name]: The name of the resource to release.
+  void release(String name) {
+    _ResourceImpl? resource = _store._map[name];
     if (resource != null) {
       if (resource.release(_sim, _event)) {
-        if (resource.waiting.isNotEmpty) {
-          EventAction other = resource.waiting.removeAt(0);
+        if (resource._waiting.isNotEmpty) {
+          EventAction other = resource._waiting.removeAt(0);
           // Schedule a complete to resume this event in the future.
           SimDartHelper.addAction(
               sim: _sim,

lib/src/resources.dart

@@ -6,7 +6,6 @@ import 'package:meta/meta.dart';
 import 'package:simdart/src/event.dart';
 import 'package:simdart/src/internal/event_action.dart';
 import 'package:simdart/src/internal/repeat_event_action.dart';
-import 'package:simdart/src/internal/resource.dart';
 import 'package:simdart/src/internal/simdart_interface.dart';
 import 'package:simdart/src/internal/time_action.dart';
 import 'package:simdart/src/interval.dart';
@@ -51,9 +50,7 @@ class SimDart implements SimDartInterface {
   final Map<String, SimNum> _numProperties = {};
   final Map<String, SimCounter> _counterProperties = {};
 
-  /// Holds the resources in the simulator.
-  final Map<String, Resource> _resources = {};
-
+  final ResourceStore _resourceStore = ResourceStore();
   late final Resources resources = ResourcesFactory.sim(this);
 
   /// The instance of the random number generator used across the simulation.
@@ -242,16 +239,12 @@ class SimDart implements SimDartInterface {
   }
 
   void _addTrack({required String eventName, required Status status}) {
-    Map<String, int> resourceUsage = {};
-    for (Resource resource in _resources.values) {
-      resourceUsage[resource.id] = resource.queue.length;
-    }
     _tracks ??= [];
     _tracks!.add(SimulationTrack(
         status: status,
         name: eventName,
         time: now,
-        resourceUsage: resourceUsage));
+        resourceUsage: _resourceStore.usage()));
   }
 
   Future<void> _consumeNextAction() async {
@@ -296,17 +289,8 @@ class SimDartHelper {
     sim._addAction(action);
   }
 
-  static Resource? getResource(
-      {required SimDart sim, required String? resourceId}) {
-    return sim._resources[resourceId];
-  }
-
-  static void addResource(
-      {required SimDart sim,
-      required String resourceId,
-      required Resource Function() create}) {
-    sim._resources.putIfAbsent(resourceId, create);
-  }
+  static ResourceStore resourceStore({required SimDart sim}) =>
+      sim._resourceStore;
 
   static void addSimulationTrack(
       {required SimDart sim,

lib/src/simdart.dart

@@ -47,7 +47,7 @@ void main() {
     test('Resource - acquire and wait', () async {
       SimDart sim = SimDart(includeTracks: true);
 
-      sim.resources.limited(id: 'r');
+      sim.resources.limited(name: 'r');
 
       sim.process(
           event: (context) async {
@@ -79,7 +79,7 @@ void main() {
     test('Resource', () async {
       SimDart sim = SimDart(includeTracks: true);
 
-      sim.resources.limited(id: 'r');
+      sim.resources.limited(name: 'r');
 
       sim.repeatProcess(
           event: (context) async {
@@ -113,7 +113,7 @@ void main() {
     test('Resource - stop', () async {
       SimDart sim = SimDart(includeTracks: true);
 
-      sim.resources.limited(id: 'r');
+      sim.resources.limited(name: 'r');
 
       sim.repeatProcess(
           event: (context) async {