Enable Blaze profiling for the VFS_READ on InputStream#read(), since some helper classes do call that method to see if the stream has more data.

This is part of a series of changes with the net result being that we open, read, and parse each BUILD file exactly once.

--
MOS_MIGRATED_REVID=105253425

1 files changed, 11 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/vfs/AbstractFileSystem.java b/src/main/java/com/google/devtools/build/lib/vfs/AbstractFileSystem.java
index 2a99d7c8ad..de67af85cf 100644
--- a/src/main/java/com/google/devtools/build/lib/vfs/AbstractFileSystem.java
+++ b/src/main/java/com/google/devtools/build/lib/vfs/AbstractFileSystem.java
@@ -64,6 +64,17 @@ abstract class AbstractFileSystem extends FileSystem {
       try {
         // Replace default FileInputStream instance with the custom one that does profiling.
         return new FileInputStream(name) {
+          @Override public int read() throws IOException {
+            long startTime = Profiler.nanoTimeMaybe();
+            try {
+              // Note that FileInputStream#read() does *not* call any of our overriden methods,
+              // so there's no concern with double counting here.
+              return super.read();
+            } finally {
+              profiler.logSimpleTask(startTime, ProfilerTask.VFS_READ, name);
+            }
+          }
+
           @Override public int read(byte b[]) throws IOException {
             return read(b, 0, b.length);
           }