From 3999f6eca2d982b5cfdcdc8196ccf396bc0be56d Mon Sep 17 00:00:00 2001
From: Mark Vieira <portugee@gmail.com>
Date: Fri, 13 Dec 2024 15:07:29 -0800
Subject: [PATCH] Improve efficiency of incremental builds when building bwc
 distributions

---
 .../InternalDistributionBwcSetupPlugin.java   | 45 +++++++++++++++----
 1 file changed, 36 insertions(+), 9 deletions(-)

diff --git a/build-tools-internal/src/main/java/org/elasticsearch/gradle/internal/InternalDistributionBwcSetupPlugin.java b/build-tools-internal/src/main/java/org/elasticsearch/gradle/internal/InternalDistributionBwcSetupPlugin.java
index da26cb66122ad..41d91574e8c02 100644
--- a/build-tools-internal/src/main/java/org/elasticsearch/gradle/internal/InternalDistributionBwcSetupPlugin.java
+++ b/build-tools-internal/src/main/java/org/elasticsearch/gradle/internal/InternalDistributionBwcSetupPlugin.java
@@ -17,12 +17,12 @@
 import org.gradle.api.Plugin;
 import org.gradle.api.Project;
 import org.gradle.api.Task;
+import org.gradle.api.file.FileSystemOperations;
 import org.gradle.api.file.ProjectLayout;
 import org.gradle.api.model.ObjectFactory;
 import org.gradle.api.plugins.JvmToolchainsPlugin;
 import org.gradle.api.provider.Provider;
 import org.gradle.api.provider.ProviderFactory;
-import org.gradle.api.tasks.Copy;
 import org.gradle.api.tasks.PathSensitivity;
 import org.gradle.api.tasks.TaskProvider;
 import org.gradle.jvm.toolchain.JavaToolchainService;
@@ -54,11 +54,17 @@ public class InternalDistributionBwcSetupPlugin implements Plugin<Project> {
     private final ObjectFactory objectFactory;
     private ProviderFactory providerFactory;
     private JavaToolchainService toolChainService;
+    private FileSystemOperations fileSystemOperations;
 
     @Inject
-    public InternalDistributionBwcSetupPlugin(ObjectFactory objectFactory, ProviderFactory providerFactory) {
+    public InternalDistributionBwcSetupPlugin(
+        ObjectFactory objectFactory,
+        ProviderFactory providerFactory,
+        FileSystemOperations fileSystemOperations
+    ) {
         this.objectFactory = objectFactory;
         this.providerFactory = providerFactory;
+        this.fileSystemOperations = fileSystemOperations;
     }
 
     @Override
@@ -76,7 +82,8 @@ public void apply(Project project) {
                 providerFactory,
                 objectFactory,
                 toolChainService,
-                isCi
+                isCi,
+                fileSystemOperations
             );
         });
     }
@@ -88,7 +95,8 @@ private static void configureBwcProject(
         ProviderFactory providerFactory,
         ObjectFactory objectFactory,
         JavaToolchainService toolChainService,
-        Boolean isCi
+        Boolean isCi,
+        FileSystemOperations fileSystemOperations
     ) {
         ProjectLayout layout = project.getLayout();
         Provider<BwcVersions.UnreleasedVersionInfo> versionInfoProvider = providerFactory.provider(() -> versionInfo);
@@ -120,11 +128,30 @@ private static void configureBwcProject(
         List<DistributionProject> distributionProjects = resolveArchiveProjects(checkoutDir.get(), bwcVersion.get());
 
         // Setup gradle user home directory
-        project.getTasks().register("setupGradleUserHome", Copy.class, copy -> {
-            copy.into(project.getGradle().getGradleUserHomeDir().getAbsolutePath() + "-" + project.getName());
-            copy.from(project.getGradle().getGradleUserHomeDir().getAbsolutePath(), copySpec -> {
-                copySpec.include("gradle.properties");
-                copySpec.include("init.d/*");
+        // We manually setup input/outputs here to avoid having the entire gradle user home directory as an output directory, as that
+        // makes task output snapshotting very expensive
+        project.getTasks().register("setupGradleUserHome", task -> {
+            task.getInputs()
+                .file(new File(project.getGradle().getGradleUserHomeDir().getAbsolutePath(), "gradle.properties"))
+                .withPathSensitivity(PathSensitivity.NONE);
+            task.getInputs()
+                .dir(new File(project.getGradle().getGradleUserHomeDir().getAbsolutePath(), "init.d"))
+                .withPathSensitivity(PathSensitivity.NONE);
+            task.getOutputs()
+                .file(
+                    new File(project.getGradle().getGradleUserHomeDir().getAbsolutePath() + "-" + project.getName(), "gradle.properties")
+                );
+            task.getOutputs()
+                .dir(new File(project.getGradle().getGradleUserHomeDir().getAbsolutePath() + "-" + project.getName(), "init.d"));
+
+            task.doLast(t -> {
+                fileSystemOperations.copy(copy -> {
+                    copy.into(project.getGradle().getGradleUserHomeDir().getAbsolutePath() + "-" + project.getName());
+                    copy.from(project.getGradle().getGradleUserHomeDir().getAbsolutePath(), copySpec -> {
+                        copySpec.include("gradle.properties");
+                        copySpec.include("init.d/*");
+                    });
+                });
             });
         });