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

2 files changed, 14 insertions, 44 deletions

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);
     }
   }