Replace path implementation.

Path and PathFragment have been replaced with String-based implementations. They are pretty similar, but each method is dissimilar enough that I did not feel sharing code was appropriate.

A summary of changes:

PATH
====

* Subsumes LocalPath (deleted, its tests repurposed)
* Use a simple string to back Path
* Path instances are no longer interned; Reference equality will no longer work
* Always normalized (same as before)
* Some operations will now be slower, like instance compares (which were previously just a reference check)
* Multiple identical paths will now consume more memory since they are not interned

PATH FRAGMENT
=============

* Use a simple string to back PathFragment
* No more segment arrays with interned strings
* Always normalized
* Remove isNormalized
* Replace some isNormalizied uses with containsUpLevelReferences() to check if path fragments try to escape their scope
* To check if user input is normalized, supply static methods on PathFragment to validate the string before constructing a PathFragment
* Because PathFragments are always normalized, we have to replace checks for literal "." from PathFragment#getPathString to PathFragment#getSafePathString. The latter returns "." for the empty string.
* The previous implementation supported efficient segment semantics (segment count, iterating over segments). This is now expensive since we do longer have a segment array.

ARTIFACT
========

* Remove Path instance. It is instead dynamically constructed on request. This is necessary to avoid this CL becoming a memory regression.

RELNOTES: None
PiperOrigin-RevId: 185062932

1 files changed, 14 insertions, 2 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/PackageFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/PackageFunction.java
index 6da94fd90b..6114f1d933 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/PackageFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/PackageFunction.java
@@ -814,7 +814,13 @@ public class PackageFunction implements SkyFunction {
     Set<SkyKey> containingPkgLookupKeys = Sets.newHashSet();
     Map<Target, SkyKey> targetToKey = new HashMap<>();
     for (Target target : pkgBuilder.getTargets()) {
-      PathFragment dir = target.getLabel().toPathFragment().getParentDirectory();
+      PathFragment dir = getContainingDirectory(target.getLabel());
+      if (dir == null) {
+        throw new IllegalStateException(
+            String.format(
+                "Null pkg for label %s as path fragment %s in pkg %s",
+                target.getLabel(), target.getLabel().getPackageFragment(), pkgId));
+      }
       PackageIdentifier dirId = PackageIdentifier.create(pkgId.getRepository(), dir);
       if (dir.equals(pkgId.getPackageFragment())) {
         continue;
@@ -825,7 +831,7 @@ public class PackageFunction implements SkyFunction {
     }
     Map<Label, SkyKey> subincludeToKey = new HashMap<>();
     for (Label subincludeLabel : pkgBuilder.getSubincludeLabels()) {
-      PathFragment dir = subincludeLabel.toPathFragment().getParentDirectory();
+      PathFragment dir = getContainingDirectory(subincludeLabel);
       PackageIdentifier dirId = PackageIdentifier.create(pkgId.getRepository(), dir);
       if (dir.equals(pkgId.getPackageFragment())) {
         continue;
@@ -870,6 +876,12 @@ public class PackageFunction implements SkyFunction {
     }
   }
 
+  private static PathFragment getContainingDirectory(Label label) {
+    PathFragment pkg = label.getPackageFragment();
+    String name = label.getName();
+    return name.equals(".") ? pkg : pkg.getRelative(name).getParentDirectory();
+  }
+
   @Nullable
   private static ContainingPackageLookupValue
   getContainingPkgLookupValueAndPropagateInconsistentFilesystemExceptions(