Only allow regular files and directories spawn outputs to be uploaded to a remote cache.

The remote cache protocol only knows about regular files and
directories. Currently, during action output upload, symlinks are
resolved into regular files. This means cached "executions" of an
action may have different output file types than the original
execution, which can be a footgun. This CL bans symlinks from cachable
spawn outputs and fixes https://github.com/bazelbuild/bazel/issues/4840.

The interface of SpawnCache.CacheHandle.store is refactored:
1. The outputs parameter is removed, since that can be retrieved from the underlying Spawn.
2. It can now throw ExecException in order to fail actions.

Closes #4902.

Change-Id: I0d1d94d48779b970bb5d0840c66a14c189ab0091
PiperOrigin-RevId: 190608852

1 files changed, 28 insertions, 34 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/exec/SpawnCache.java b/src/main/java/com/google/devtools/build/lib/exec/SpawnCache.java
index 1374b47fd8..206aa58bfc 100644
--- a/src/main/java/com/google/devtools/build/lib/exec/SpawnCache.java
+++ b/src/main/java/com/google/devtools/build/lib/exec/SpawnCache.java
@@ -19,10 +19,8 @@ import com.google.devtools.build.lib.actions.ExecutionStrategy;
 import com.google.devtools.build.lib.actions.Spawn;
 import com.google.devtools.build.lib.actions.SpawnResult;
 import com.google.devtools.build.lib.exec.SpawnRunner.SpawnExecutionPolicy;
-import com.google.devtools.build.lib.vfs.Path;
 import java.io.Closeable;
 import java.io.IOException;
-import java.util.Collection;
 import java.util.NoSuchElementException;
 
 /**
@@ -33,32 +31,31 @@ import java.util.NoSuchElementException;
  */
 public interface SpawnCache extends ActionContext {
   /** A no-op implementation that has no result, and performs no upload. */
-  public static CacheHandle NO_RESULT_NO_STORE = new CacheHandle() {
-    @Override
-    public boolean hasResult() {
-      return false;
-    }
-
-    @Override
-    public SpawnResult getResult() {
-      throw new NoSuchElementException();
-    }
-
-    @Override
-    public boolean willStore() {
-      return false;
-    }
-
-    @Override
-    public void store(SpawnResult result, Collection<Path> files)
-        throws InterruptedException, IOException {
-      // Do nothing.
-    }
-
-    @Override
-    public void close() {
-    }
-  };
+  public static CacheHandle NO_RESULT_NO_STORE =
+      new CacheHandle() {
+        @Override
+        public boolean hasResult() {
+          return false;
+        }
+
+        @Override
+        public SpawnResult getResult() {
+          throw new NoSuchElementException();
+        }
+
+        @Override
+        public boolean willStore() {
+          return false;
+        }
+
+        @Override
+        public void store(SpawnResult result) throws InterruptedException, IOException {
+          // Do nothing.
+        }
+
+        @Override
+        public void close() {}
+      };
 
   /**
    * Helper method to create a {@link CacheHandle} from a successful {@link SpawnResult} instance.
@@ -81,14 +78,12 @@ public interface SpawnCache extends ActionContext {
       }
 
       @Override
-      public void store(SpawnResult result, Collection<Path> files)
-          throws InterruptedException, IOException {
+      public void store(SpawnResult result) throws InterruptedException, IOException {
         throw new IllegalStateException();
       }
 
       @Override
-      public void close() {
-      }
+      public void close() {}
     };
   }
 
@@ -148,8 +143,7 @@ public interface SpawnCache extends ActionContext {
      * <p>If the current thread is interrupted, then this method should return as quickly as
      * possible with an {@link InterruptedException}.
      */
-    void store(SpawnResult result, Collection<Path> files)
-        throws InterruptedException, IOException;
+    void store(SpawnResult result) throws ExecException, InterruptedException, IOException;
   }
 
   /**