chore: add temporary WriteCtx constructor that allows specifying the initial crc32c value

The desired default will be `Crc32cValue.zero()`, but not all tests or uploads are ready to handle this. Stick with the existing null as default, and provide the overload to selectively opt into things incrementally.

Author: BenWhitehead

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

@@ -31,13 +31,22 @@ final class WriteCtx<RequestFactoryT extends WriteObjectRequestBuilderFactory> {
 
   private final AtomicLong totalSentBytes;
   private final AtomicLong confirmedBytes;
-  private final AtomicReference<Crc32cLengthKnown> cumulativeCrc32c;
+  private final AtomicReference<@Nullable Crc32cLengthKnown> cumulativeCrc32c;
 
   WriteCtx(RequestFactoryT requestFactory) {
+    this(requestFactory, null);
+  }
+
+  /**
+   * TODO: Remove initialValue and replace with Crc32cValue.zero() once all uploads have been
+   * updated to do e2e checksumming by default.
+   */
+  @Deprecated
+  WriteCtx(RequestFactoryT requestFactory, @Nullable Crc32cLengthKnown initialValue) {
     this.requestFactory = requestFactory;
     this.totalSentBytes = new AtomicLong(0);
     this.confirmedBytes = new AtomicLong(0);
-    this.cumulativeCrc32c = new AtomicReference<>(null);
+    this.cumulativeCrc32c = new AtomicReference<>(initialValue);
   }
 
   public RequestFactoryT getRequestFactory() {
@@ -56,7 +65,7 @@ public AtomicLong getConfirmedBytes() {
     return confirmedBytes;
   }
 
-  public AtomicReference<Crc32cLengthKnown> getCumulativeCrc32c() {
+  public AtomicReference<@Nullable Crc32cLengthKnown> getCumulativeCrc32c() {
     return cumulativeCrc32c;
   }
 

google-cloud-storage/src/test/java/com/google/cloud/storage/ITGapicUnbufferedWritableByteChannelTest.java

@@ -159,7 +159,10 @@ public void directUpload() throws IOException, InterruptedException, ExecutionEx
       SettableApiFuture<WriteObjectResponse> result = SettableApiFuture.create();
       try (GapicUnbufferedDirectWritableByteChannel c =
           new GapicUnbufferedDirectWritableByteChannel(
-              result, segmenter, sc.writeObjectCallable(), new WriteCtx<>(reqFactory))) {
+              result,
+              segmenter,
+              sc.writeObjectCallable(),
+              new WriteCtx<>(reqFactory, Crc32cValue.zero()))) {
         c.write(ByteBuffer.wrap(bytes));
       }
       assertThat(result.get()).isEqualTo(resp);
@@ -185,7 +188,7 @@ public void resumableUpload() throws IOException, InterruptedException, Executio
               result,
               segmenter,
               sc.writeObjectCallable(),
-              new WriteCtx<>(reqFactory),
+              new WriteCtx<>(reqFactory, Crc32cValue.zero()),
               RetrierWithAlg.attemptOnce(),
               Retrying::newCallContext);
       ArrayList<String> debugMessages = new ArrayList<>();
@@ -267,7 +270,7 @@ public void resumableUpload_chunkAutomaticRetry()
               result,
               segmenter,
               sc.writeObjectCallable(),
-              new WriteCtx<>(reqFactory),
+              new WriteCtx<>(reqFactory, Crc32cValue.zero()),
               TestUtils.retrierFromStorageOptions(fake.getGrpcStorageOptions())
                   .withAlg(Retrying.alwaysRetry()),
               Retrying::newCallContext)) {
@@ -319,7 +322,7 @@ public void resumableUpload_finalizeWhenWriteAndCloseCalledEvenWhenQuantumAligne
               result,
               segmenter,
               sc.writeObjectCallable(),
-              new WriteCtx<>(reqFactory),
+              new WriteCtx<>(reqFactory, Crc32cValue.zero()),
               RetrierWithAlg.attemptOnce(),
               Retrying::newCallContext);
       try {