Systems 5: the game location, item icons and index status tell through signals

companion/src/main/java/com/github/minecraft_ta/totalDebugCompanion/CompanionApplication.java

@@ -151,7 +151,9 @@ public CompanionApplication(CompanionLaunchConfiguration configuration, String t
         try {
             JDTHacks.init(configuration.paths().jdtCache());
             runtimeIndexService = new RuntimeIndexService(lifecycleLock, this::installRuntimeSnapshot);
-            runtimeIndexService.addStatusListener(this::updateRuntimeIndexUi);
+            RuntimeIndexService index = runtimeIndexService;
+            index.statusChanged().subscribe(() -> updateRuntimeIndexUi(index.status()));
+            updateRuntimeIndexUi(index.status());
             debuggerController = createDebuggerController();
             debuggerController.addListener(new DebuggerSessionController.Listener() {
                 private Throwable lastFailure;

companion/src/main/java/com/github/minecraft_ta/totalDebugCompanion/catalog/ConfigChanges.java

@@ -56,12 +56,9 @@ public ConfigChanges(GameLocation location, ChangeRecord record) {
         this.location = Objects.requireNonNull(location, "location");
         this.workspace = location.workspace();
         this.record = Objects.requireNonNull(record, "record");
-        location.addListener(change -> {
-            switch (change) {
-                case PROCESS -> gameProcess(location.process());
-                case DISCONNECTED -> gameDisconnected();
-                default -> { }
-            }
+        location.processChanged().subscribe(() -> gameProcess(location.process()));
+        location.connectionChanged().subscribe(() -> {
+            if (location.connection() == null) gameDisconnected();
         });
     }
 

companion/src/main/java/com/github/minecraft_ta/totalDebugCompanion/catalog/WorldReading.java

@@ -70,7 +70,12 @@ public WorldReading(GameLocation location, GamePacks packs) {
                 () -> Workers.later(SETTLE_MILLIS, this.strand, this::follow));
         // Companion changed the datapacks, also in the level.dat of a world the game does not hold.
         this.stopFollowingDatapacks = packs.changed(ChangeRecord.PackSide.DATA).subscribe(() -> this.strand.execute(this::follow));
-        this.stopFollowingGame = location.addListener(change -> this.strand.execute(this::follow));
+        Runnable stopConnection = location.connectionChanged().subscribe(() -> this.strand.execute(this::follow));
+        Runnable stopPlaying = location.playingChanged().subscribe(() -> this.strand.execute(this::follow));
+        this.stopFollowingGame = () -> {
+            stopConnection.run();
+            stopPlaying.run();
+        };
         // Followed after the triggers are, so none is missed in between; on the strand, as every later look.
         CompletableFuture.runAsync(this::follow, this.strand).join();
     }

companion/src/main/java/com/github/minecraft_ta/totalDebugCompanion/change/ChangePipeline.java

@@ -74,8 +74,8 @@ public ChangePipeline(GameLocation location, ChangeRecord record, Executor write
         this.record = Objects.requireNonNull(record, "record");
         this.writes = Objects.requireNonNull(writes, "writes");
         this.reloads = new Reloads(location);
-        location.addListener(change -> {
-            if (change == GameLocation.Change.DISCONNECTED) gameDisconnected();
+        location.connectionChanged().subscribe(() -> {
+            if (location.connection() == null) gameDisconnected();
         });
     }
 

companion/src/main/java/com/github/minecraft_ta/totalDebugCompanion/change/Reloads.java

@@ -119,10 +119,10 @@ void sendIfIdle() {
 
     public Reloads(GameLocation location) {
         this.location = Objects.requireNonNull(location, "location");
-        location.addListener(change -> {
-            if (change == GameLocation.Change.DISCONNECTED) gameDisconnected();
-            else if (change == GameLocation.Change.PLAYING) leftWorld();
+        location.connectionChanged().subscribe(() -> {
+            if (location.connection() == null) gameDisconnected();
         });
+        location.playingChanged().subscribe(this::leftWorld);
     }
 
     /** A write is queued whose reload the next reloads wait for, so writes in quick succession take one reload. */

companion/src/main/java/com/github/minecraft_ta/totalDebugCompanion/game/GameLocation.java

@@ -1,16 +1,14 @@
 package com.github.minecraft_ta.totalDebugCompanion.game;
 
+import com.github.minecraft_ta.totalDebugCompanion.util.Signal;
 import com.github.minecraft_ta.totalDebugCompanion.catalog.Worlds;
 import com.github.minecraft_ta.totaldebug.protocol.message.PlayingPayload;
 import com.github.minecraft_ta.totaldebug.storage.GameLock;
 import com.github.minecraft_ta.totaldebug.storage.InstancePaths;
 import com.github.tth05.scnet.message.AbstractMessage;
 
 import java.nio.file.Path;
-import java.util.List;
 import java.util.Objects;
-import java.util.concurrent.CopyOnWriteArrayList;
-import java.util.function.Consumer;
 
 /**
  * Where a project's game is, as {@code docs/GAME_LOCATION.md} describes: closed, running without a connection, or
@@ -25,9 +23,6 @@ public interface Connection {
         boolean send(AbstractMessage message);
     }
 
-    /** What changed, told to listeners on the thread that changed it. */
-    public enum Change { CONNECTED, DISCONNECTED, PROCESS, PLAYING }
-
     /** The instance's files that tell whether a game runs and whether a world is held. Blocking. */
     public interface Files {
         /** Whether a game holds the instance's game lock; a lock that cannot be checked counts as held. */
@@ -60,7 +55,9 @@ record Link(Connection connection, long process, PlayingPayload playing) {
 
     private final Path workspace;
     private final Files files;
-    private final List<Consumer<Change>> listeners = new CopyOnWriteArrayList<>();
+    private final Signal connectionChanged = new Signal();
+    private final Signal processChanged = new Signal();
+    private final Signal playingChanged = new Signal();
     private volatile Link link;
     /**
      * What the game told on the current connection, kept from its first message: Companion may take the connection as
@@ -85,8 +82,8 @@ public Path workspace() {
     }
 
     /**
-     * The game's connection is established, with what the game has told on it so far; listeners hear of that as well, as
-     * if it was told now.
+     * The game's connection is established, with what the game has told on it so far; its followers hear of that as well,
+     * as if it was told now.
      */
     public void connected(Connection connection) {
         Objects.requireNonNull(connection, "connection");
@@ -95,24 +92,24 @@ public void connected(Connection connection) {
             established = new Link(connection, this.toldProcess, this.toldPlaying);
             this.link = established;
         }
-        tell(Change.CONNECTED);
-        if (established.process() != 0) tell(Change.PROCESS);
-        if (established.playing() != null) tell(Change.PLAYING);
+        this.connectionChanged.fire();
+        if (established.process() != 0) this.processChanged.fire();
+        if (established.playing() != null) this.playingChanged.fire();
     }
 
-    /** The game's process, as it announced it on the current connection; listeners hear of it when it changed. */
+    /** The game's process, as it announced it on the current connection; followers hear of it when it changed. */
     public void process(long process) {
         synchronized (this) {
             this.toldProcess = process;
             Link current = this.link;
             if (current == null || current.process() == process) return;
             this.link = new Link(current.connection(), process, current.playing());
         }
-        tell(Change.PROCESS);
+        this.processChanged.fire();
     }
 
     /**
-     * What the game plays, as it told on the current connection; listeners hear of it when it changed. The game tells it
+     * What the game plays, as it told on the current connection; followers hear of it when it changed. The game tells it
      * again after each handshake, which may repeat what {@link #connected} already announced.
      */
     public void playing(PlayingPayload playing) {
@@ -123,7 +120,7 @@ public void playing(PlayingPayload playing) {
             if (current == null || playing.equals(current.playing())) return;
             this.link = new Link(current.connection(), current.process(), playing);
         }
-        tell(Change.PLAYING);
+        this.playingChanged.fire();
     }
 
     /** The game's connection ended; what it told on it no longer holds. */
@@ -134,7 +131,7 @@ public void disconnected() {
             if (this.link == null) return;
             this.link = null;
         }
-        tell(Change.DISCONNECTED);
+        this.connectionChanged.fire();
     }
 
     /** The connection to the game, or null without one. Not blocking. */
@@ -165,13 +162,21 @@ public GameState read() {
         return new GameState(this.workspace, this.files, new GameState.Game.Unconnected());
     }
 
-    /** Tells {@code listener} of each change, on the thread that made it; returns what removes it. */
-    public Runnable addListener(Consumer<Change> listener) {
-        this.listeners.add(Objects.requireNonNull(listener, "listener"));
-        return () -> this.listeners.remove(listener);
+    /**
+     * Fires when the game connected or disconnected, on the thread that saw it; {@link #connection()} tells which. The
+     * followers of one change hear of it before anything else changes the location.
+     */
+    public Signal connectionChanged() {
+        return this.connectionChanged;
+    }
+
+    /** Fires when the connected game's process became known or changed, on the thread that saw it. */
+    public Signal processChanged() {
+        return this.processChanged;
     }
 
-    private void tell(Change change) {
-        this.listeners.forEach(listener -> listener.accept(change));
+    /** Fires when what the connected game plays changed, also when a connection is established, on the thread that saw it. */
+    public Signal playingChanged() {
+        return this.playingChanged;
     }
 }

companion/src/main/java/com/github/minecraft_ta/totalDebugCompanion/inspection/ItemIconService.java

@@ -1,5 +1,6 @@
 package com.github.minecraft_ta.totalDebugCompanion.inspection;
 
+import com.github.minecraft_ta.totalDebugCompanion.util.Signal;
 import com.github.minecraft_ta.totalDebugCompanion.catalog.CatalogIndex;
 import com.github.minecraft_ta.totalDebugCompanion.itemrender.ItemModelId;
 import com.github.minecraft_ta.totalDebugCompanion.itemrender.ItemRenderBackend;
@@ -21,7 +22,6 @@
 import java.util.Objects;
 import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
-import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.Executor;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
@@ -54,7 +54,9 @@ private record Key(String model, Map<Integer, Integer> tints, int size) {
             .daemon()
             .name("Companion item icons")
             .unstarted(task));
-    private final List<Runnable> listeners = new CopyOnWriteArrayList<>();
+    private final Signal changed = new Signal();
+    /** Held while an adoption decides whether it is the newest. */
+    private final Object adoption = new Object();
     private final Map<Key, Optional<BufferedImage>> cache = new LinkedHashMap<>(64, 0.75f, true) {
         @Override
         protected boolean removeEldestEntry(Map.Entry<Key, Optional<BufferedImage>> eldest) {
@@ -97,20 +99,20 @@ CompletableFuture<Void> restore(Path directory, Executor reader) {
 
     /** Starts an adoption, superseding every earlier one that has not finished. */
     private long start() {
-        synchronized (this.listeners) {
+        synchronized (this.adoption) {
             return ++this.adoptions;
         }
     }
 
     /** Replaces the snapshot, unless a newer adoption started since {@code generation}. */
     private void adopt(long generation, Snapshot next) {
-        synchronized (this.listeners) {
+        synchronized (this.adoption) {
             if (this.closed || generation != this.adoptions || Objects.equals(next, this.snapshot)) {
                 return;
             }
             this.snapshot = next;
         }
-        SwingUtilities.invokeLater(() -> this.listeners.forEach(Runnable::run));
+        SwingUtilities.invokeLater(this.changed::fire);
     }
 
     static Snapshot newestSnapshot(Path directory) {
@@ -165,10 +167,9 @@ Snapshot snapshot() {
         return this.snapshot;
     }
 
-    /** Registers a listener for new snapshots and returns its removal. */
-    public Runnable addListener(Runnable listener) {
-        this.listeners.add(Objects.requireNonNull(listener, "listener"));
-        return () -> this.listeners.remove(listener);
+    /** Fires on the Swing thread after a newer snapshot was adopted, so views draw their icons again. */
+    public Signal changed() {
+        return this.changed;
     }
 
     /** Renders {@code model} (for example {@code minecraft:item/furnace}); empty when it cannot be drawn. */
@@ -312,7 +313,6 @@ public void close() {
             return;
         }
         this.closed = true;
-        this.listeners.clear();
         this.worker.execute(this::closeBackend);
         this.worker.shutdown();
     }

companion/src/main/java/com/github/minecraft_ta/totalDebugCompanion/pack/GamePacks.java

@@ -54,20 +54,20 @@ ChangeRecord.PackSide.RESOURCES, new Signal(),
     public GamePacks(GameLocation location) {
         this.location = Objects.requireNonNull(location, "location");
         this.workspace = location.workspace();
-        location.addListener(change -> {
-            if (change == GameLocation.Change.DISCONNECTED) gameDisconnected();
-            else if (change == GameLocation.Change.PLAYING) {
-                // The datapacks the server named belong to the world it played; its next world's server is asked.
-                synchronized (this) {
-                    if (!Objects.equals(this.datapacksFor, location.playing())) {
-                        this.datapacks = null;
-                        this.worldRefusal = "";
-                    }
+        location.connectionChanged().subscribe(() -> {
+            if (location.connection() == null) gameDisconnected();
+        });
+        location.playingChanged().subscribe(() -> {
+            // The datapacks the server named belong to the world it played; its next world's server is asked.
+            synchronized (this) {
+                if (!Objects.equals(this.datapacksFor, location.playing())) {
+                    this.datapacks = null;
+                    this.worldRefusal = "";
                 }
-                askForDatapacks();
-                // Without datapacks named yet, the world's own files stand for them, and they are another world's now.
-                tell(ChangeRecord.PackSide.DATA);
             }
+            askForDatapacks();
+            // Without datapacks named yet, the world's own files stand for them, and they are another world's now.
+            tell(ChangeRecord.PackSide.DATA);
         });
     }
 

companion/src/main/java/com/github/minecraft_ta/totalDebugCompanion/runtime/RuntimeIndexService.java

@@ -1,5 +1,6 @@
 package com.github.minecraft_ta.totalDebugCompanion.runtime;
 
+import com.github.minecraft_ta.totalDebugCompanion.util.Signal;
 import com.github.minecraft_ta.totaldebug.storage.RuntimeInventory;
 import com.github.minecraft_ta.totaldebug.storage.InstancePaths;
 import com.github.minecraft_ta.totaldebug.storage.AtomicFiles;
@@ -24,7 +25,6 @@
 import java.util.Objects;
 import java.util.Set;
 import java.util.zip.ZipFile;
-import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.CancellationException;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
@@ -114,7 +114,7 @@ record PreparedInput(IndexSource indexSource, RuntimeSnapshotBytecodeSource.Sour
     private final Object lifecycleLock;
     private final Consumer<ReadySnapshot> readyHandler;
     private final Function<String, ClassIndex> indexLoader;
-    private final CopyOnWriteArrayList<Consumer<Status>> listeners = new CopyOnWriteArrayList<>();
+    private final Signal statusChanged = new Signal();
     private volatile Status status = new Status(Phase.WAITING, "Waiting for runtime inventory", null);
     private String activeInventoryId;
     private Metrics activeMetrics;
@@ -166,10 +166,9 @@ public Status status() {
         return this.status;
     }
 
-    public void addStatusListener(Consumer<Status> listener) {
-        Consumer<Status> checked = Objects.requireNonNull(listener, "listener");
-        this.listeners.add(checked);
-        checked.accept(this.status);
+    /** Fires after {@link #status()} changed, on the thread that changed it, under the lifecycle lock. */
+    public Signal statusChanged() {
+        return this.statusChanged;
     }
 
     public void waiting(String detail) {
@@ -185,10 +184,6 @@ public void waiting(String detail) {
         }
     }
 
-    public void removeStatusListener(Consumer<Status> listener) {
-        this.listeners.remove(listener);
-    }
-
     public void restore(Path dataDirectory) {
         restore(dataDirectory, null);
     }
@@ -608,9 +603,10 @@ private void update(Work work, Status status) {
     }
 
     private void update(Status replacement) {
-        this.status = replacement;
-        for (Consumer<Status> listener : this.listeners) {
-            listener.accept(replacement);
+        // Under the lock, so what the followers read of the status is this one.
+        synchronized (this.lifecycleLock) {
+            this.status = replacement;
+            this.statusChanged.fire();
         }
     }
 

companion/src/main/java/com/github/minecraft_ta/totalDebugCompanion/ui/components/catalog/CatalogIcons.java

@@ -20,7 +20,7 @@ public CatalogIcons(ItemIconService service, int size) {
         this.size = size;
         this.icons = new IconLoader<>(4_096, 8, item -> service.render(item.model(), item.tints(), size)
                 .thenApply(image -> image.<Icon>map(ImageIcon::new)));
-        this.removeListener = service.addListener(this.icons::clear);
+        this.removeListener = service.changed().subscribe(this.icons::clear);
     }
 
     public int size() {

companion/src/main/java/com/github/minecraft_ta/totalDebugCompanion/ui/components/catalog/ConfigPanel.java

@@ -112,12 +112,10 @@ final class ConfigPanel extends JPanel {
                 failure -> showFailure("Could not list the worlds' copies: " + failure.getMessage()))
                 // A server configuration is shown from the world the game has open first; it follows the game to another
                 // world, unless its text has unsaved changes, which stay with the file they were made in.
-                .follow(listener -> this.location.addListener(change -> {
-                    if (change == GameLocation.Change.PLAYING) SwingUtilities.invokeLater(() -> {
-                        PackCatalog.ConfigFile file = selectedFile();
-                        if (file != null && file.type() == PackCatalog.ConfigType.SERVER && !this.textEditor.modified()) listener.run();
-                    });
-                }));
+                .follow(listener -> this.location.playingChanged().subscribe(() -> SwingUtilities.invokeLater(() -> {
+                    PackCatalog.ConfigFile file = selectedFile();
+                    if (file != null && file.type() == PackCatalog.ConfigType.SERVER && !this.textEditor.modified()) listener.run();
+                })));
         configureFiles();
         this.content.add(toolbar(), BorderLayout.NORTH);
         JPanel settings = new JPanel(new BorderLayout());

companion/src/main/java/com/github/minecraft_ta/totalDebugCompanion/ui/components/catalog/DefinitionDetails.java

@@ -108,7 +108,7 @@ public DefinitionDetails(SubjectRef.Definition subject, Services services, JComp
             this.appearance = found.appearance();
             this.appearancePreviews = found.previews();
             showExtras();
-        }, failure -> { }).waitsWhileHidden(page).follow(services.icons()::addListener);
+        }, failure -> { }).waitsWhileHidden(page).follow(services.icons().changed()::subscribe);
         this.resourceLoader = new PageLoader<>(this::prepareResources, list -> {
             this.owned = list;
             this.matched = matching(this.owned, this.subject.namespace(), resourceName());