feat(storage): log additional bytes received from GCS in read path

Fixes bug 475824752. Tracks the number of bytes received from the transport layer and emits a warning log if GCS sends more bytes than requested by the user during explicit range requests.

[Generated-by: AI]

Author: nidhiii-27

java-storage/google-cloud-storage/src/main/java/com/google/cloud/storage/ApiaryUnbufferedReadableByteChannel.java

@@ -73,6 +73,7 @@ class ApiaryUnbufferedReadableByteChannel implements UnbufferedReadableByteChann
   private ScatteringByteChannel sbc;
   private boolean open;
   private boolean returnEOF;
+  private long totalBytesReadFromNetwork;
 
   // returned X-Goog-Generation header value
   private Long xGoogGeneration;
@@ -128,6 +129,7 @@ public long read(ByteBuffer[] dsts, int offset, int length) throws IOException {
           returnEOF = true;
         } else {
           totalRead += read;
+          totalBytesReadFromNetwork += read;
         }
         return totalRead;
       } catch (Exception t) {
@@ -163,6 +165,18 @@ public boolean isOpen() {
 
   @Override
   public void close() throws IOException {
+    long requestedLength = apiaryReadRequest.getByteRangeSpec().length();
+    if (requestedLength >= 0
+        && requestedLength < ByteRangeSpec.EFFECTIVE_INFINITY
+        && totalBytesReadFromNetwork > requestedLength) {
+      java.util.logging.Logger.getLogger(ApiaryUnbufferedReadableByteChannel.class.getName())
+          .warning(
+              String.format(
+                  "storage: received %d more bytes than requested from GCS for bucket '%s', object '%s'",
+                  totalBytesReadFromNetwork - requestedLength,
+                  apiaryReadRequest.getObject().getBucket(),
+                  apiaryReadRequest.getObject().getName()));
+    }
     open = false;
     if (sbc != null) {
       sbc.close();

java-storage/google-cloud-storage/src/main/java/com/google/cloud/storage/GapicUnbufferedReadableByteChannel.java

@@ -199,6 +199,17 @@ public boolean isOpen() {
 
   @Override
   public void close() throws IOException {
+    long readLimit = req.getReadLimit();
+    long receivedBytes = fetchOffset.get() - req.getReadOffset();
+    if (readLimit > 0 && receivedBytes > readLimit) {
+      java.util.logging.Logger.getLogger(GapicUnbufferedReadableByteChannel.class.getName())
+          .warning(
+              String.format(
+                  "storage: received %d more bytes than requested from GCS for bucket '%s', object '%s'",
+                  receivedBytes - readLimit,
+                  req.getBucket(),
+                  req.getObject()));
+    }
     open = false;
     try {
       if (leftovers != null) {