refactor(backfill): Backfill Plugin Major Refactor And Improvements

block-node/app/src/testFixtures/java/org/hiero/block/node/app/fixtures/server/TestBlockNodeServer.java

@@ -54,6 +54,10 @@ public void stop() {
         }
     }
 
+    /**
+     * Test implementation of BlockStreamSubscribeService that serves blocks from the historical facility.
+     * Simulates a real block node's streaming behavior for backfill integration tests.
+     */
     private static final class TestBlockStreamSubscribeService implements BlockStreamSubscribeServiceInterface {
         private final HistoricalBlockFacility historicalBlockFacility;
 
@@ -66,14 +70,17 @@ public void subscribeBlockStream(
                 @NonNull final SubscribeStreamRequest request,
                 @NonNull final Pipeline<? super SubscribeStreamResponse> replies) {
             boolean blocksAvailable = true;
+
             for (long i = request.startBlockNumber(); i <= request.endBlockNumber(); i++) {
                 if (!historicalBlockFacility.availableBlocks().contains(i)) {
+                    // Path 1: Requested block not available - send NOT_AVAILABLE and abort
                     replies.onNext(SubscribeStreamResponse.newBuilder()
                             .status(SubscribeStreamResponse.Code.NOT_AVAILABLE)
                             .build());
                     blocksAvailable = false;
                     break;
                 } else {
+                    // Path 2: Block available - send block items followed by end-of-block marker
                     replies.onNext(SubscribeStreamResponse.newBuilder()
                             .blockItems(BlockItemSet.newBuilder()
                                     .blockItems(historicalBlockFacility
@@ -88,6 +95,7 @@ public void subscribeBlockStream(
                 }
             }
 
+            // Path 3: All requested blocks sent successfully - send SUCCESS status
             if (blocksAvailable) {
                 replies.onNext(SubscribeStreamResponse.newBuilder()
                         .status(Code.SUCCESS)
@@ -97,7 +105,11 @@ public void subscribeBlockStream(
         }
     }
 
-    private class TrivialBlockNodeServerInterface implements BlockNodeServiceInterface {
+    /**
+     * Test implementation of BlockNodeService that returns server status from the historical facility.
+     * Reports the available block range for backfill source discovery.
+     */
+    private static class TrivialBlockNodeServerInterface implements BlockNodeServiceInterface {
         private final HistoricalBlockFacility historicalBlockFacility;
 
         public TrivialBlockNodeServerInterface(final HistoricalBlockFacility historicalFacility) {
@@ -107,6 +119,7 @@ public TrivialBlockNodeServerInterface(final HistoricalBlockFacility historicalF
         @Override
         @NonNull
         public ServerStatusResponse serverStatus(@NonNull final ServerStatusRequest request) {
+            // Returns the available block range from the historical facility
             return ServerStatusResponse.newBuilder()
                     .firstAvailableBlock(
                             historicalBlockFacility.availableBlocks().min())

block-node/backfill/build.gradle.kts

@@ -34,15 +34,3 @@ testModuleInfo {
     requires("org.hiero.block.node.app.test.fixtures")
     requires("org.mockito")
 }
-
-sourceSets {
-    main {
-        pbj {
-            srcDir(
-                layout.projectDirectory.dir(
-                    "src/main/java/org/hiero/block/node/backfill/client/proto"
-                )
-            )
-        }
-    }
-}

block-node/backfill/src/main/java/module-info.java

@@ -21,10 +21,13 @@
     requires transitive org.hiero.block.node.spi;
     requires transitive org.hiero.block.protobuf.pbj;
     requires com.hedera.pbj.grpc.client.helidon;
+    requires org.hiero.block.node.app.config;
     requires org.hiero.block.node.base;
     requires io.helidon.common.tls;
     requires io.helidon.webclient.api;
     requires io.helidon.webclient.grpc;
+    requires io.helidon.webclient.http2;
+    requires java.logging;
     requires org.antlr.antlr4.runtime;
     requires static transitive com.github.spotbugs.annotations;
 

block-node/backfill/src/main/java/org/hiero/block/node/backfill/BackfillConfiguration.java

@@ -7,6 +7,13 @@
 import com.swirlds.config.api.validation.annotation.Min;
 import org.hiero.block.node.base.Loggable;
 
+// It is known that spotless does not format this file well
+// We use the https://github.com/palantir/palantir-java-format formatter.
+// @ConfigProperty(defaultValue = "10") – force a line break after the annotation.
+// It is a non-configurable format without complete documentation
+// we might consider switching to another formatter in the future.
+// spotless:off
+
 /**
  * Configuration for the Backfill module.
  *
@@ -39,4 +46,13 @@ public record BackfillConfiguration(
         @Loggable @ConfigProperty(defaultValue = "1000") @Min(500) int perBlockProcessingTimeout,
         @Loggable @ConfigProperty(defaultValue = "60000") @Min(10000) int grpcOverallTimeout,
         @Loggable @ConfigProperty(defaultValue = "false") boolean enableTLS,
-        @Loggable @ConfigProperty(defaultValue = "false") boolean greedy) {}
+        @Loggable @ConfigProperty(defaultValue = "false") boolean greedy,
+        // Queue capacity settings for bounded queues
+        @Loggable @ConfigProperty(defaultValue = "20") @Min(1) @Max(1000) int historicalQueueCapacity,
+        @Loggable @ConfigProperty(defaultValue = "10") @Min(1) @Max(100) int liveTailQueueCapacity,
+        // Health scoring constants
+        @Loggable @ConfigProperty(defaultValue = "1000.0") double healthPenaltyPerFailure,
+        @Loggable @ConfigProperty(defaultValue = "300000") @Min(30000) long maxBackoffMs) {}
+
+// restore spotless formatting
+// spotless:on