Use byte[] rather than ByteString for file digests.

ActionInputFileCache:
Change getDigest() to return the underlying byte[16] owned by each
FileArtifactValue.
Remove throws clause from getInputFromDigest(); this should be an
in-memory operation, and no implementation actually throws.

PerActionFileCache:
Invert mapping from artifact to digest only if needed.  Remove interner,
as it was used only for the reverse map keys, not the returned values.
This should be a significant cpu savings as eagerly constructing the
reverse maps was a noticeable hotspot.

--
MOS_MIGRATED_REVID=127972359

1 files changed, 3 insertions, 3 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeActionExecutor.java b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeActionExecutor.java
index a9cf5833f1..b5c0863d98 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeActionExecutor.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeActionExecutor.java
@@ -1105,8 +1105,8 @@ public final class SkyframeActionExecutor implements ActionExecutionContextFacto
     }
 
     @Override
-    public ByteString getDigest(ActionInput actionInput) throws IOException {
-      ByteString digest = perActionCache.getDigest(actionInput);
+    public byte[] getDigest(ActionInput actionInput) throws IOException {
+      byte[] digest = perActionCache.getDigest(actionInput);
       return digest != null ? digest : perBuildFileCache.getDigest(actionInput);
     }
 
@@ -1130,7 +1130,7 @@ public final class SkyframeActionExecutor implements ActionExecutionContextFacto
 
     @Nullable
     @Override
-    public ActionInput getInputFromDigest(ByteString digest) throws IOException {
+    public ActionInput getInputFromDigest(ByteString digest) {
       ActionInput file = perActionCache.getInputFromDigest(digest);
       return file != null ? file : perBuildFileCache.getInputFromDigest(digest);
     }