Allow for metadata lookup alongside the existing #prepareAndGet() graph construction.

--
MOS_MIGRATED_REVID=100709648

4 files changed, 55 insertions, 7 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/pkgcache/PathPackageLocator.java b/src/main/java/com/google/devtools/build/lib/pkgcache/PathPackageLocator.java
index 0c8b174802..e250eba121 100644
--- a/src/main/java/com/google/devtools/build/lib/pkgcache/PathPackageLocator.java
+++ b/src/main/java/com/google/devtools/build/lib/pkgcache/PathPackageLocator.java
@@ -151,13 +151,15 @@ public class PathPackageLocator implements Serializable {
    * @param eventHandler The eventHandler.
    * @param workspace The nearest enclosing package root directory.
    * @param clientWorkingDirectory The client's working directory.
+   * @param checkExistence If true, verify that the element exists before adding it to the locator.
    * @return a list of {@link Path}s.
    */
   public static PathPackageLocator create(Path outputBase,
                                           List<String> pathElements,
                                           EventHandler eventHandler,
                                           Path workspace,
-                                          Path clientWorkingDirectory) {
+                                          Path clientWorkingDirectory,
+                                          boolean checkExistence) {
     List<Path> resolvedPaths = new ArrayList<>();
     final String workspaceWildcard = "%workspace%";
 
@@ -179,13 +181,36 @@ public class PathPackageLocator implements Serializable {
                 + "If so, please use the '" + workspaceWildcard + "' wildcard."));
       }
 
-      if (rootPath.exists()) {
+      if (!checkExistence || rootPath.exists()) {
         resolvedPaths.add(rootPath);
       }
     }
     return new PathPackageLocator(outputBase, resolvedPaths);
   }
 
+    /**
+     * A factory of PathPackageLocators from a list of path elements.  Elements
+     * may contain "%workspace%", indicating the workspace.
+     *
+     * @param outputBase the output base. Can be null if remote repositories are not in use.
+     * @param pathElements Each element must be an absolute path, relative path,
+     *                     or some string "%workspace%" + relative, where relative is itself a
+     *                     relative path.  The special symbol "%workspace%" means to interpret
+     *                     the path relative to the nearest enclosing workspace.  Relative
+     *                     paths are interpreted relative to the client's working directory,
+     *                     which may be below the workspace.
+     * @param eventHandler The eventHandler.
+     * @param workspace The nearest enclosing package root directory.
+     * @param clientWorkingDirectory The client's working directory.
+     * @return a list of {@link Path}s.
+     */
+    public static PathPackageLocator create(Path outputBase,
+            List<String> pathElements, EventHandler eventHandler, Path workspace,
+            Path clientWorkingDirectory) {
+        return create(outputBase, pathElements, eventHandler, workspace, clientWorkingDirectory,
+                /*checkExistence=*/true);
+    }
+
   /**
    * Returns the path to the WORKSPACE file for this build.
    *
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeExecutor.java b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeExecutor.java
index 93c0ce898f..8b482e5aa2 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeExecutor.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeExecutor.java
@@ -1255,10 +1255,7 @@ public abstract class SkyframeExecutor implements WalkableGraphFactory {
   @Override
   public EvaluationResult<SkyValue> prepareAndGet(Collection<String> patterns,
       int numThreads, EventHandler eventHandler) throws InterruptedException {
-    SkyframeTargetPatternEvaluator patternEvaluator =
-        (SkyframeTargetPatternEvaluator) packageManager.getTargetPatternEvaluator();
-    String offset = patternEvaluator.getOffset();
-    SkyKey skyKey = PrepareDepsOfPatternsValue.key(ImmutableList.copyOf(patterns), offset);
+    SkyKey skyKey = getPrepareDepsKey(patterns);
     EvaluationResult<SkyValue> evaluationResult =
         buildDriver.evaluate(ImmutableList.of(skyKey), true, numThreads, eventHandler);
     Preconditions.checkNotNull(evaluationResult.getWalkableGraph(), patterns);
@@ -1266,6 +1263,21 @@ public abstract class SkyframeExecutor implements WalkableGraphFactory {
   }
 
   /**
+   * Get metadata related to the prepareAndGet() lookup. Resulting data is specific to the
+   * underlying evaluation implementation.
+   */
+  public String prepareAndGetMetadata(Collection<String> patterns) {
+    return buildDriver.meta(ImmutableList.of(getPrepareDepsKey(patterns)));
+  }
+
+  private SkyKey getPrepareDepsKey(Collection<String> patterns) {
+    SkyframeTargetPatternEvaluator patternEvaluator =
+        (SkyframeTargetPatternEvaluator) packageManager.getTargetPatternEvaluator();
+    String offset = patternEvaluator.getOffset();
+    return PrepareDepsOfPatternsValue.key(ImmutableList.copyOf(patterns), offset);
+  }
+
+  /**
    * Returns the generating {@link Action} of the given {@link Artifact}.
    *
    * <p>For use for legacy support from {@code BuildView} only.
diff --git a/src/main/java/com/google/devtools/build/skyframe/BuildDriver.java b/src/main/java/com/google/devtools/build/skyframe/BuildDriver.java
index 938735be94..16c2d9dd26 100644
--- a/src/main/java/com/google/devtools/build/skyframe/BuildDriver.java
+++ b/src/main/java/com/google/devtools/build/skyframe/BuildDriver.java
@@ -28,5 +28,11 @@ public interface BuildDriver {
       Iterable<SkyKey> roots, boolean keepGoing, int numThreads, EventHandler reporter)
       throws InterruptedException;
 
+  /**
+   * Retrieve metadata about the computation over the given roots. Data returned is specific to the
+   * underlying evaluator implementation.
+   */
+  String meta(Iterable<SkyKey> roots);
+
   MemoizingEvaluator getGraphForTesting();
 }
diff --git a/src/main/java/com/google/devtools/build/skyframe/SequentialBuildDriver.java b/src/main/java/com/google/devtools/build/skyframe/SequentialBuildDriver.java
index 9b7f0366d2..5eee3a38a4 100644
--- a/src/main/java/com/google/devtools/build/skyframe/SequentialBuildDriver.java
+++ b/src/main/java/com/google/devtools/build/skyframe/SequentialBuildDriver.java
@@ -39,7 +39,12 @@ public class SequentialBuildDriver implements BuildDriver {
     }
   }
 
-  @Override
+ @Override
+ public String meta(Iterable<SkyKey> of) {
+   return "";
+ }
+
+ @Override
   public MemoizingEvaluator getGraphForTesting() {
     return memoizingEvaluator;
   }