[Skymeld] Don't plant the symlinks to the paths specified in `.bazeli…

…gnore`.

Bazel in skymeld mode eagerly plants the symlinks from the execroot to every entries under the source tree. This leads to some pain points for certain groups of users (#19581).

This CL offers a workaround for that issue. The users can now list the paths that they don't want Bazel to symlink to in the `.bazelignore` file in their project.

PiperOrigin-RevId: 581919915
Change-Id: I329365b0655fc0bcb2db1eeea91ef74c775c72ae

src/main/java/com/google/devtools/build/lib/buildtool/ExecutionTool.java

@@ -275,6 +275,7 @@ public void prepareForExecution(Stopwatch executionTimer)
               singleSourceRoot,
               env.getEventBus(),
               env.getDirectories().getProductName() + "-",
+              skyframeExecutor.getIgnoredPaths(),
               request.getOptions(BuildLanguageOptions.class).experimentalSiblingRepositoryLayout,
               runtime.getWorkspace().doesAllowExternalRepositories());
       if (shouldSymlinksBePlanted) {

src/main/java/com/google/devtools/build/lib/buildtool/SymlinkForest.java

@@ -140,7 +140,7 @@ private void plantSymlinkForestWithFullMainRepository(
     for (Path target : mainRepoRoot.getDirectoryEntries()) {
       String baseName = target.getBaseName();
       Path execPath = execroot.getRelative(baseName);
-      if (symlinkShouldBePlanted(prefix, siblingRepositoryLayout, baseName)) {
+      if (symlinkShouldBePlanted(prefix, siblingRepositoryLayout, baseName, target)) {
         execPath.createSymbolicLink(target);
         plantedSymlinks.add(execPath);
         // TODO(jingwen-external): is this creating execroot/io_bazel/external?
@@ -384,7 +384,11 @@ private static void deleteSiblingRepositorySymlinks(
    * @return a set of potentially conflicting baseNames, all in lowercase.
    */
   public static ImmutableSet<String> eagerlyPlantSymlinkForestSinglePackagePath(
-      Path execroot, Path sourceRoot, String prefix, boolean siblingRepositoryLayout)
+      Path execroot,
+      Path sourceRoot,
+      String prefix,
+      ImmutableSet<Path> ignoredPaths,
+      boolean siblingRepositoryLayout)
       throws IOException {
     deleteTreesBelowNotPrefixed(execroot, prefix);
     deleteSiblingRepositorySymlinks(siblingRepositoryLayout, execroot);
@@ -406,7 +410,8 @@ public static ImmutableSet<String> eagerlyPlantSymlinkForestSinglePackagePath(
         Path target = Iterables.getOnlyElement(targets);
         String originalBaseName = target.getBaseName();
         Path link = execroot.getRelative(originalBaseName);
-        if (symlinkShouldBePlanted(prefix, siblingRepositoryLayout, originalBaseName)) {
+        if (symlinkShouldBePlanted(
+            prefix, ignoredPaths, siblingRepositoryLayout, originalBaseName, target)) {
           link.createSymbolicLink(target);
         }
       } else {
@@ -416,11 +421,22 @@ public static ImmutableSet<String> eagerlyPlantSymlinkForestSinglePackagePath(
     return ImmutableSet.copyOf(potentiallyConflictingBaseNamesLowercase);
   }
 
+  static boolean symlinkShouldBePlanted(
+      String prefix, boolean siblingRepositoryLayout, String baseName, Path target) {
+    return symlinkShouldBePlanted(
+        prefix, ImmutableSet.of(), siblingRepositoryLayout, baseName, target);
+  }
+
   public static boolean symlinkShouldBePlanted(
-      String prefix, boolean siblingRepositoryLayout, String baseName) {
+      String prefix,
+      ImmutableSet<Path> ignoredPaths,
+      boolean siblingRepositoryLayout,
+      String baseName,
+      Path target) {
     // Create any links that don't start with bazel-, and ignore external/ directory if
     // user has it in the source tree because it conflicts with external repository location.
     return !baseName.startsWith(prefix)
+        && !ignoredPaths.contains(target)
         && (siblingRepositoryLayout
             || !baseName.equals(LabelConstants.EXTERNAL_PATH_PREFIX.getBaseName()));
   }

src/main/java/com/google/devtools/build/lib/skyframe/IncrementalPackageRoots.java

@@ -67,6 +67,8 @@ public class IncrementalPackageRoots implements PackageRoots {
   private final Path execroot;
   private final Root singleSourceRoot;
   private final String prefix;
+
+  private final ImmutableSet<Path> ignoredPaths;
   private final boolean useSiblingRepositoryLayout;
 
   private final boolean allowExternalRepositories;
@@ -80,12 +82,14 @@ private IncrementalPackageRoots(
       Root singleSourceRoot,
       EventBus eventBus,
       String prefix,
+      ImmutableSet<Path> ignoredPaths,
       boolean useSiblingRepositoryLayout,
       boolean allowExternalRepositories) {
     this.threadSafeExternalRepoPackageRootsMap = Maps.newConcurrentMap();
     this.execroot = execroot;
     this.singleSourceRoot = singleSourceRoot;
     this.prefix = prefix;
+    this.ignoredPaths = ignoredPaths;
     this.eventBus = eventBus;
     this.useSiblingRepositoryLayout = useSiblingRepositoryLayout;
     this.allowExternalRepositories = allowExternalRepositories;
@@ -96,6 +100,7 @@ public static IncrementalPackageRoots createAndRegisterToEventBus(
       Root singleSourceRoot,
       EventBus eventBus,
       String prefix,
+      ImmutableSet<Path> ignoredPaths,
       boolean useSiblingRepositoryLayout,
       boolean allowExternalRepositories) {
     IncrementalPackageRoots incrementalPackageRoots =
@@ -104,6 +109,7 @@ public static IncrementalPackageRoots createAndRegisterToEventBus(
             singleSourceRoot,
             eventBus,
             prefix,
+            ignoredPaths,
             useSiblingRepositoryLayout,
             allowExternalRepositories);
     eventBus.register(incrementalPackageRoots);
@@ -140,7 +146,11 @@ public void eagerlyPlantSymlinksToSingleSourceRoot() throws AbruptExitException
     try {
       maybeConflictingBaseNamesLowercase =
           SymlinkForest.eagerlyPlantSymlinkForestSinglePackagePath(
-              execroot, singleSourceRoot.asPath(), prefix, useSiblingRepositoryLayout);
+              execroot,
+              singleSourceRoot.asPath(),
+              prefix,
+              ignoredPaths,
+              useSiblingRepositoryLayout);
     } catch (IOException e) {
       throwAbruptExitException(e);
     }
@@ -212,19 +222,19 @@ private void registerAndPlantMissingSymlinks(NestedSet<Package> packages)
           String originalBaseName = pkgId.getTopLevelDir();
           String baseNameLowercase = Ascii.toLowerCase(originalBaseName);
 
+          // As Skymeld only supports single package path at the moment, we only seek to symlink to
+          // the top-level dir i.e. what's directly under the source root.
+          Path link = execroot.getRelative(originalBaseName);
+          Path target = singleSourceRoot.getRelative(originalBaseName);
+
           if (originalBaseName.isEmpty()
               || !maybeConflictingBaseNamesLowercase.contains(baseNameLowercase)
               || !SymlinkForest.symlinkShouldBePlanted(
-                  prefix, useSiblingRepositoryLayout, originalBaseName)) {
+                  prefix, ignoredPaths, useSiblingRepositoryLayout, originalBaseName, target)) {
             // We should have already eagerly planted a symlink for this, or there's nothing to do.
             continue;
           }
 
-          // As Skymeld only supports single package path at the moment, we only seek to symlink to
-          // the top-level dir i.e. what's directly under the source root.
-          Path link = execroot.getRelative(originalBaseName);
-          Path target = singleSourceRoot.getRelative(originalBaseName);
-
           if (lazilyPlantedSymlinksLocalRef.add(link)) {
             try {
               link.createSymbolicLink(target);

src/main/java/com/google/devtools/build/lib/skyframe/SkyframeExecutor.java

@@ -446,6 +446,9 @@ public abstract class SkyframeExecutor implements WalkableGraphFactory {
   @Nullable private final WorkspaceInfoFromDiffReceiver workspaceInfoFromDiffReceiver;
   private Set<String> previousClientEnvironment = ImmutableSet.of();
 
+  // Contain the paths in the .bazelignore file.
+  private ImmutableSet<Path> ignoredPaths = ImmutableSet.of();
+
   Duration sourceDiffCheckingDuration = Duration.ofSeconds(-1L);
 
   final class PathResolverFactoryImpl implements PathResolverFactory {
@@ -1302,6 +1305,10 @@ public AtomicReference<PathPackageLocator> getPackageLocator() {
     return pkgLocator;
   }
 
+  public ImmutableSet<Path> getIgnoredPaths() {
+    return ignoredPaths;
+  }
+
   protected Differencer.Diff getDiff(
       TimestampGranularityMonitor tsgm,
       ModifiedFileSet modifiedFileSet,
@@ -3144,7 +3151,6 @@ protected WorkspaceInfoFromDiff handleDiffs(
         // Ignored package prefixes are specified relative to the workspace root
         // by definition of .bazelignore. So, we only use ignored paths when the
         // package root is equal to the workspace path.
-        ImmutableSet<Path> ignoredPaths = ImmutableSet.of();
         if (workspacePath != null && workspacePath.equals(pathEntry.asPath())) {
           ignoredPaths =
               ignoredPackagePrefixesValue.getPatterns().stream()

src/test/java/com/google/devtools/build/lib/buildtool/SkymeldBuildIntegrationTest.java

@@ -366,6 +366,36 @@ public void symlinksPlanted() throws Exception {
     assertThat(execroot.getRelative("unused").resolveSymbolicLinks()).isEqualTo(unusedDir);
   }
 
+  @Test
+  public void symlinksPlantedExceptProductNamePrefixAndIgnoredPaths() throws Exception {
+    String productName = getRuntime().getProductName();
+    Path execroot = directories.getExecRoot(directories.getWorkspace().getBaseName());
+    writeMyRuleBzl();
+    Path fooDir =
+        write(
+                "foo/BUILD",
+                "load('//foo:my_rule.bzl', 'my_rule')",
+                "my_rule(name = 'foo', srcs = ['foo.in'])")
+            .getParentDirectory();
+    write("foo/foo.in");
+    Path unusedDir = write("unused/dummy").getParentDirectory();
+    write(".bazelignore", "ignored");
+    write("ignored/dummy");
+    write(productName + "-dir/dummy");
+
+    // Before the build: no symlink.
+    assertThat(execroot.getRelative("foo").exists()).isFalse();
+
+    buildTarget("//foo:foo");
+
+    // After the build: symlinks to the source directory, even unused packages, except for those
+    // in the .bazelignore file and those with the bazel- prefix.
+    assertThat(execroot.getRelative("foo").resolveSymbolicLinks()).isEqualTo(fooDir);
+    assertThat(execroot.getRelative("unused").resolveSymbolicLinks()).isEqualTo(unusedDir);
+    assertThat(execroot.getRelative("ignored").exists()).isFalse();
+    assertThat(execroot.getRelative(productName + "-dir").exists()).isFalse();
+  }
+
   @Test
   public void symlinksReplantedEachBuild() throws Exception {
     Path execroot = directories.getExecRoot(directories.getWorkspace().getBaseName());