SPI touch-ups (#71)

 - Get encoders/decoders across AdapterCodec & Encoder/Decoder.installed() from one place.
 - Correct behavior for overriding default providers.
 - Refactorings.

methanol/src/main/java/com/github/mizosoft/methanol/AdapterCodec.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2023 Moataz Abdelnasser
+ * Copyright (c) 2024 Moataz Abdelnasser
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -26,7 +26,7 @@
 
 import com.github.mizosoft.methanol.BodyAdapter.Decoder;
 import com.github.mizosoft.methanol.BodyAdapter.Encoder;
-import com.github.mizosoft.methanol.internal.spi.ServiceCache;
+import com.github.mizosoft.methanol.internal.spi.BodyAdapterProviders;
 import java.net.http.HttpHeaders;
 import java.net.http.HttpRequest.BodyPublisher;
 import java.net.http.HttpResponse.BodyHandler;
@@ -44,11 +44,6 @@
  * and a {@link MediaType} specifying the desired format.
  */
 public final class AdapterCodec {
-  private static final ServiceCache<Encoder> encodersServiceCache =
-      new ServiceCache<>(Encoder.class);
-  private static final ServiceCache<Decoder> decodersServiceCache =
-      new ServiceCache<>(Decoder.class);
-
   /**
    * Codec for the installed encoders & decoders. This is lazily created in a racy manner, which is
    * OK since ServiceCache makes sure we see a constant snapshot of the services.
@@ -181,8 +176,7 @@ public static AdapterCodec installed() {
     var installedCodec = lazyInstalledCodec;
     if (installedCodec == null) {
       installedCodec =
-          new AdapterCodec(
-              encodersServiceCache.getProviders(), decodersServiceCache.getProviders());
+          new AdapterCodec(BodyAdapterProviders.encoders(), BodyAdapterProviders.decoders());
       lazyInstalledCodec = installedCodec;
     }
     return installedCodec;

methanol/src/main/java/com/github/mizosoft/methanol/BodyAdapter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2020 Moataz Abdelnasser
+ * Copyright (c) 2024 Moataz Abdelnasser
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -22,7 +22,7 @@
 
 package com.github.mizosoft.methanol;
 
-import com.github.mizosoft.methanol.internal.spi.BodyAdapterFinder;
+import com.github.mizosoft.methanol.internal.spi.BodyAdapterProviders;
 import java.net.http.HttpRequest.BodyPublisher;
 import java.net.http.HttpResponse.BodySubscriber;
 import java.util.List;
@@ -74,7 +74,7 @@ interface Encoder extends BodyAdapter {
 
     /** Returns an immutable list containing the installed encoders. */
     static List<Encoder> installed() {
-      return BodyAdapterFinder.findInstalledEncoders();
+      return BodyAdapterProviders.encoders();
     }
 
     /**
@@ -119,7 +119,7 @@ default <T> BodySubscriber<Supplier<T>> toDeferredObject(
 
     /** Returns an immutable list containing the installed decoders. */
     static List<Decoder> installed() {
-      return BodyAdapterFinder.findInstalledDecoders();
+      return BodyAdapterProviders.decoders();
     }
 
     /**

methanol/src/main/java/com/github/mizosoft/methanol/BodyDecoder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2020 Moataz Abdelnasser
+ * Copyright (c) 2024 Moataz Abdelnasser
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -24,7 +24,7 @@
 
 import static java.util.Objects.requireNonNull;
 
-import com.github.mizosoft.methanol.internal.spi.DecoderFactoryFinder;
+import com.github.mizosoft.methanol.internal.spi.BodyDecoderFactoryProviders;
 import java.net.http.HttpResponse.BodySubscriber;
 import java.util.List;
 import java.util.Map;
@@ -114,7 +114,7 @@ interface Factory {
      *     factories
      */
     static List<Factory> installedFactories() {
-      return DecoderFactoryFinder.findInstalledFactories();
+      return BodyDecoderFactoryProviders.factories();
     }
 
     /**
@@ -124,7 +124,7 @@ static List<Factory> installedFactories() {
      * overridable.
      */
     static Map<String, Factory> installedBindings() {
-      return DecoderFactoryFinder.getInstalledBindings();
+      return BodyDecoderFactoryProviders.bindings();
     }
 
     /**

methanol/src/main/java/com/github/mizosoft/methanol/internal/spi/BodyAdapterFinder.java → methanol/src/main/java/com/github/mizosoft/methanol/internal/spi/BodyAdapterProviders.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2020 Moataz Abdelnasser
+ * Copyright (c) 2024 Moataz Abdelnasser
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -27,18 +27,17 @@
 import java.util.List;
 
 /** Utility class for loading/caching {@code Encoder/Decoder} providers. */
-public class BodyAdapterFinder {
+public class BodyAdapterProviders {
+  private static final ServiceProviders<Encoder> encoders = new ServiceProviders<>(Encoder.class);
+  private static final ServiceProviders<Decoder> decoders = new ServiceProviders<>(Decoder.class);
 
-  private static final ServiceCache<Encoder> encodersServiceCache = new ServiceCache<>(Encoder.class);
-  private static final ServiceCache<Decoder> decodersServiceCache = new ServiceCache<>(Decoder.class);
+  private BodyAdapterProviders() {}
 
-  private BodyAdapterFinder() {} // non-instantiable
-
-  public static List<Encoder> findInstalledEncoders() {
-    return encodersServiceCache.getProviders();
+  public static List<Encoder> encoders() {
+    return encoders.get();
   }
 
-  public static List<Decoder> findInstalledDecoders() {
-    return decodersServiceCache.getProviders();
+  public static List<Decoder> decoders() {
+    return decoders.get();
   }
 }

methanol/src/main/java/com/github/mizosoft/methanol/internal/spi/DecoderFactoryFinder.java → methanol/src/main/java/com/github/mizosoft/methanol/internal/spi/BodyDecoderFactoryProviders.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2020 Moataz Abdelnasser
+ * Copyright (c) 2024 Moataz Abdelnasser
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -24,44 +24,50 @@
 
 import com.github.mizosoft.methanol.BodyDecoder;
 import com.github.mizosoft.methanol.internal.annotations.DefaultProvider;
-import java.util.Collections;
 import java.util.List;
 import java.util.Map;
-import java.util.TreeMap;
+import java.util.function.Function;
+import java.util.stream.Collectors;
 import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 
 /** Utility class for finding decoder factories. */
-public class DecoderFactoryFinder {
+public class BodyDecoderFactoryProviders {
+  private static final ServiceProviders<BodyDecoder.Factory> factories =
+      new ServiceProviders<>(BodyDecoder.Factory.class);
 
-  private static final ServiceCache<BodyDecoder.Factory> CACHE =
-      new ServiceCache<>(BodyDecoder.Factory.class);
+  private static volatile @MonotonicNonNull Map<String, BodyDecoder.Factory> lazyBindings;
 
-  private static volatile @MonotonicNonNull Map<String, BodyDecoder.Factory> bindings;
+  private BodyDecoderFactoryProviders() {}
 
-  private DecoderFactoryFinder() {} // non-instantiable
-
-  public static List<BodyDecoder.Factory> findInstalledFactories() {
-    return CACHE.getProviders();
+  public static List<BodyDecoder.Factory> factories() {
+    return factories.get();
   }
 
-  public static Map<String, BodyDecoder.Factory> getInstalledBindings() {
-    // Locking is not necessary as CACHE itself is locked so the result never changes
-    Map<String, BodyDecoder.Factory> cached = bindings;
-    if (cached == null) {
-      cached = createBindings();
-      bindings = cached;
+  public static Map<String, BodyDecoder.Factory> bindings() {
+    // Locking is not necessary as the cache itself is locked so the result never changes.
+    var bindings = lazyBindings;
+    if (bindings == null) {
+      bindings = createBindings();
+      lazyBindings = bindings;
     }
-    return cached;
+    return bindings;
   }
 
   private static Map<String, BodyDecoder.Factory> createBindings() {
-    Map<String, BodyDecoder.Factory> bindings = new TreeMap<>(String.CASE_INSENSITIVE_ORDER);
-    for (BodyDecoder.Factory f : findInstalledFactories()) {
-      String enc = f.encoding();
-      // Only override if default
-      bindings.merge(
-          enc, f, (f1, f2) -> f1.getClass().isAnnotationPresent(DefaultProvider.class) ? f2 : f1);
-    }
-    return Collections.unmodifiableMap(bindings);
+    return factories().stream()
+        .collect(
+            Collectors.toMap(
+                BodyDecoder.Factory::encoding,
+                Function.identity(),
+                (f1, f2) -> {
+                  // Allow overriding default providers.
+                  if (f1.getClass().isAnnotationPresent(DefaultProvider.class)) {
+                    return f2;
+                  } else if (f2.getClass().isAnnotationPresent(DefaultProvider.class)) {
+                    return f1;
+                  } else {
+                    return f2;
+                  }
+                }));
   }
 }

methanol/src/main/java/com/github/mizosoft/methanol/internal/spi/ServiceCache.java → methanol/src/main/java/com/github/mizosoft/methanol/internal/spi/ServiceProviders.java

@@ -32,23 +32,23 @@
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** An object that loads {@literal &} caches service providers. */
-public final class ServiceCache<S> {
-  private static final Logger logger = System.getLogger(ServiceCache.class.getName());
+public final class ServiceProviders<S> {
+  private static final Logger logger = System.getLogger(ServiceProviders.class.getName());
 
   private final Lazy<List<S>> providers;
 
-  public ServiceCache(Class<S> service) {
+  public ServiceProviders(Class<S> service) {
     requireNonNull(service);
     this.providers = Lazy.of(() -> loadProviders(service));
   }
 
-  public List<S> getProviders() {
+  public List<S> get() {
     return providers.get();
   }
 
   private static <U> List<U> loadProviders(Class<U> service) {
     return ServiceLoader.load(service, service.getClassLoader()).stream()
-        .map(ServiceCache::tryGet)
+        .map(ServiceProviders::tryGet)
         .filter(Objects::nonNull)
         .collect(Collectors.toUnmodifiableList());
   }
@@ -59,7 +59,7 @@ private static <U> List<U> loadProviders(Class<U> service) {
     } catch (ServiceConfigurationError error) {
       logger.log(
           Level.WARNING,
-          "provider <" + provider.type() + "> will be ignored as it couldn't be instantiated",
+          "Provider <" + provider.type() + "> will be ignored as it couldn't be instantiated",
           error);
       return null;
     }