feat: balanced download provider. Closes #959.

HMCLCore/src/main/java/org/jackhuang/hmcl/download/BalancedDownloadProvider.java

@@ -17,6 +17,9 @@
  */
 package org.jackhuang.hmcl.download;
 
+import java.util.List;
+import java.util.stream.Collectors;
+
 /**
  * Official Download Provider fetches version list from Mojang and
  * download files from mcbbs.
@@ -24,29 +27,70 @@ package org.jackhuang.hmcl.download;
  * @author huangyuhui
  */
 public class BalancedDownloadProvider implements DownloadProvider {
+    List<DownloadProvider> candidates;
+
+    VersionList<?> game, fabric, forge, liteLoader, optifine;
+
+    public BalancedDownloadProvider(List<DownloadProvider> candidates) {
+        this.candidates = candidates;
+
+        this.game = new MultipleSourceVersionList(
+                candidates.stream()
+                        .map(downloadProvider -> downloadProvider.getVersionListById("game"))
+                        .collect(Collectors.toList()));
+        this.fabric = new MultipleSourceVersionList(
+                candidates.stream()
+                        .map(downloadProvider -> downloadProvider.getVersionListById("fabric"))
+                        .collect(Collectors.toList()));
+        this.forge = new MultipleSourceVersionList(
+                candidates.stream()
+                        .map(downloadProvider -> downloadProvider.getVersionListById("forge"))
+                        .collect(Collectors.toList()));
+        this.liteLoader = new MultipleSourceVersionList(
+                candidates.stream()
+                        .map(downloadProvider -> downloadProvider.getVersionListById("liteloader"))
+                        .collect(Collectors.toList()));
+        this.optifine = new MultipleSourceVersionList(
+                candidates.stream()
+                        .map(downloadProvider -> downloadProvider.getVersionListById("optifine"))
+                        .collect(Collectors.toList()));
+    }
 
     @Override
     public String getVersionListURL() {
-        return null;
+        throw new UnsupportedOperationException();
     }
 
     @Override
     public String getAssetBaseURL() {
-        return null;
+        throw new UnsupportedOperationException();
     }
 
     @Override
     public String injectURL(String baseURL) {
-        return null;
+        throw new UnsupportedOperationException();
     }
 
     @Override
     public VersionList<?> getVersionListById(String id) {
-        return null;
+        switch (id) {
+            case "game":
+                return game;
+            case "fabric":
+                return fabric;
+            case "forge":
+                return forge;
+            case "liteloader":
+                return liteLoader;
+            case "optifine":
+                return optifine;
+            default:
+                throw new IllegalArgumentException("Unrecognized version list id: " + id);
+        }
     }
 
     @Override
     public int getConcurrency() {
-        return 0;
+        throw new UnsupportedOperationException();
     }
 }

HMCLCore/src/main/java/org/jackhuang/hmcl/download/MultipleSourceVersionList.java

@@ -17,5 +17,50 @@
  */
 package org.jackhuang.hmcl.download;
 
-public class MultipleSourceVersionList {
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+
+public class MultipleSourceVersionList extends VersionList<RemoteVersion> {
+
+    private final List<VersionList<?>> backends;
+
+    MultipleSourceVersionList(List<VersionList<?>> backends) {
+        this.backends = backends;
+
+        assert(backends.size() >= 1);
+    }
+
+    @Override
+    public boolean hasType() {
+        boolean hasType = backends.get(0).hasType();
+        assert(backends.stream().allMatch(versionList -> versionList.hasType() == hasType));
+        return hasType;
+    }
+
+    @Override
+    public CompletableFuture<?> loadAsync() {
+        throw new UnsupportedOperationException("ForgeBMCLVersionList does not support loading the entire Forge remote version list.");
+    }
+
+    @Override
+    public CompletableFuture<?> refreshAsync() {
+        throw new UnsupportedOperationException("ForgeBMCLVersionList does not support loading the entire Forge remote version list.");
+    }
+
+    @Override
+    public CompletableFuture<?> refreshAsync(String gameVersion) {
+        versions.clear(gameVersion);
+        return CompletableFuture.anyOf(backends.stream()
+                .map(versionList -> versionList.refreshAsync(gameVersion)
+                .thenRunAsync(() -> {
+                    lock.writeLock().lock();
+
+                    try {
+                        versions.putAll(gameVersion, versionList.getVersions(gameVersion));
+                    } finally {
+                        lock.writeLock().unlock();
+                    }
+                }))
+                .toArray(CompletableFuture[]::new));
+    }
 }

settings.gradle

@@ -1,5 +1,5 @@
 rootProject.name = 'HMCL3'
-include 'HMCL'
-include 'HMCLCore'
-include 'HMCLTransformerDiscoveryService'
+include ':HMCL'
+include ':HMCLCore'
+include ':HMCLTransformerDiscoveryService'