Bazel server, VFS: revert to using asByteSource

commit 59f17d6e0550bf63a0b6ef182e2d63474e058ede updated files to use
try-with-resources when dealing with streams.

The change also got rid of asByteSource, replacing
it with throw-away ByteSource instances wrapping a
try-with-resources-guarded InputStream. Doing so
was unnecessary though, because all ByteSource
methods (except for open[Buffered]InputStream)
close the stream. Thanks to @jbduncan to point
that out and explain in detail [1].

[1] see comment thread on https://github.com/bazelbuild/bazel/commit/59f17d6e0550bf63a0b6ef182e2d63474e058ede under `FilesetManifest.java`

RELNOTES: none
PiperOrigin-RevId: 203934830

3 files changed, 17 insertions, 53 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/exec/FilesetManifest.java b/src/main/java/com/google/devtools/build/lib/exec/FilesetManifest.java
index 2a54103fde..c48674a913 100644
--- a/src/main/java/com/google/devtools/build/lib/exec/FilesetManifest.java
+++ b/src/main/java/com/google/devtools/build/lib/exec/FilesetManifest.java
@@ -15,14 +15,13 @@ package com.google.devtools.build.lib.exec;
 
 import static java.nio.charset.StandardCharsets.UTF_8;
 
-import com.google.common.io.ByteSource;
 import com.google.common.io.LineProcessor;
 import com.google.devtools.build.lib.actions.FilesetOutputSymlink;
 import com.google.devtools.build.lib.analysis.AnalysisUtils;
+import com.google.devtools.build.lib.vfs.FileSystemUtils;
 import com.google.devtools.build.lib.vfs.Path;
 import com.google.devtools.build.lib.vfs.PathFragment;
 import java.io.IOException;
-import java.io.InputStream;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.LinkedHashMap;
@@ -60,13 +59,8 @@ public final class FilesetManifest {
       RelativeSymlinkBehavior relSymlinkBehavior)
           throws IOException {
     Path file = execRoot.getRelative(AnalysisUtils.getManifestPathFromFilesetPath(manifest));
-    try (InputStream in = file.getInputStream()) {
-      return new ByteSource() {
-        @Override
-        public InputStream openStream() throws IOException {
-          return in;
-        }
-      }.asCharSource(UTF_8)
+    try {
+      return FileSystemUtils.asByteSource(file).asCharSource(UTF_8)
           .readLines(
               new ManifestLineProcessor(workspaceName, manifest, relSymlinkBehavior));
     } catch (IllegalStateException e) {
diff --git a/src/main/java/com/google/devtools/build/lib/vfs/FileSystem.java b/src/main/java/com/google/devtools/build/lib/vfs/FileSystem.java
index 01c016905f..8258dccfc0 100644
--- a/src/main/java/com/google/devtools/build/lib/vfs/FileSystem.java
+++ b/src/main/java/com/google/devtools/build/lib/vfs/FileSystem.java
@@ -268,14 +268,12 @@ public abstract class FileSystem {
    * @throws IOException if the digest could not be computed for any reason
    */
   protected byte[] getDigest(final Path path, DigestHashFunction hashFunction) throws IOException {
-    try (InputStream in = getInputStream(path)) {
-      return new ByteSource() {
-        @Override
-        public InputStream openStream() throws IOException {
-          return in;
-        }
-      }.hash(hashFunction.getHash()).asBytes();
-    }
+    return new ByteSource() {
+      @Override
+      public InputStream openStream() throws IOException {
+        return getInputStream(path);
+      }
+    }.hash(hashFunction.getHash()).asBytes();
   }
 
   /**
diff --git a/src/main/java/com/google/devtools/build/lib/vfs/FileSystemUtils.java b/src/main/java/com/google/devtools/build/lib/vfs/FileSystemUtils.java
index 9883030cb6..4d1e9c6533 100644
--- a/src/main/java/com/google/devtools/build/lib/vfs/FileSystemUtils.java
+++ b/src/main/java/com/google/devtools/build/lib/vfs/FileSystemUtils.java
@@ -852,14 +852,7 @@ public class FileSystemUtils {
    * @throws IOException if there was an error
    */
   public static Iterable<String> readLines(Path inputFile, Charset charset) throws IOException {
-    try (InputStream in = inputFile.getInputStream()) {
-      return new ByteSource() {
-        @Override
-        public InputStream openStream() throws IOException {
-          return in;
-        }
-      }.asCharSource(charset).readLines();
-    }
+    return asByteSource(inputFile).asCharSource(charset).readLines();
   }
 
   /**
@@ -868,28 +861,14 @@ public class FileSystemUtils {
    * @throws IOException if there was an error
    */
   public static byte[] readContent(Path inputFile) throws IOException {
-    try (InputStream in = inputFile.getInputStream()) {
-      return new ByteSource() {
-        @Override
-        public InputStream openStream() throws IOException {
-          return in;
-        }
-      }.read();
-    }
+    return asByteSource(inputFile).read();
   }
 
   /**
    * Reads the entire file using the given charset and returns the contents as a string
    */
   public static String readContent(Path inputFile, Charset charset) throws IOException {
-    try (InputStream in = inputFile.getInputStream()) {
-      return new ByteSource() {
-        @Override
-        public InputStream openStream() throws IOException {
-          return in;
-        }
-      }.asCharSource(charset).read();
-    }
+    return asByteSource(inputFile).asCharSource(charset).read();
   }
 
   /**
@@ -899,18 +878,11 @@ public class FileSystemUtils {
    */
   public static byte[] readContentWithLimit(Path inputFile, int limit) throws IOException {
     Preconditions.checkArgument(limit >= 0, "limit needs to be >=0, but it is %s", limit);
-    try (InputStream in = inputFile.getInputStream()) {
-      byte[] buffer = new byte[limit];
-      try (InputStream inputStream =
-          new ByteSource() {
-            @Override
-            public InputStream openStream() throws IOException {
-              return in;
-            }
-          }.openBufferedStream()) {
-        int read = ByteStreams.read(inputStream, buffer, 0, limit);
-        return read == limit ? buffer : Arrays.copyOf(buffer, read);
-      }
+    ByteSource byteSource = asByteSource(inputFile);
+    byte[] buffer = new byte[limit];
+    try (InputStream inputStream = byteSource.openBufferedStream()) {
+      int read = ByteStreams.read(inputStream, buffer, 0, limit);
+      return read == limit ? buffer : Arrays.copyOf(buffer, read);
     }
   }