Implement reset methods for XXHash checksum algorithms (#6762)

Author: zoewangg

.changes/next-release/bugfix-AWSSDKforJavav2-4f9de50.json

@@ -0,0 +1,6 @@
+{
+    "type": "bugfix",
+    "category": "AWS SDK for Java v2",
+    "contributor": "",
+    "description": "Implement reset() for XxHashChecksum to allow checksum reuse."
+}

core/checksums/src/main/java/software/amazon/awssdk/checksums/internal/XxHashChecksum.java

@@ -25,9 +25,16 @@
 @SdkInternalApi
 public final class XxHashChecksum implements SdkChecksum {
 
-    private final XXHash xxHash;
+    private XXHash xxHash;
+    private final ChecksumAlgorithm algorithm;
 
     public XxHashChecksum(ChecksumAlgorithm algorithm) {
+        this.algorithm = algorithm;
+        xxHash = initializeXxHash(algorithm);
+    }
+
+    private XXHash initializeXxHash(ChecksumAlgorithm algorithm) {
+        XXHash xxHash;
         if (algorithm == DefaultChecksumAlgorithm.XXHASH64) {
             xxHash = XXHash.newXXHash64();
         } else if (algorithm == DefaultChecksumAlgorithm.XXHASH3) {
@@ -37,6 +44,7 @@ public XxHashChecksum(ChecksumAlgorithm algorithm) {
         } else {
             throw new UnsupportedOperationException("Unsupported algorithm: " + algorithm.algorithmId());
         }
+        return xxHash;
     }
 
     @Override
@@ -65,7 +73,8 @@ public void update(byte[] b, int off, int len) {
 
     @Override
     public void reset() {
-        throw new UnsupportedOperationException("mark and reset is not supported");
+        IoUtils.closeQuietlyV2(xxHash, null);
+        xxHash = initializeXxHash(algorithm);
     }
 
     @Override

core/checksums/src/test/java/software/amazon/awssdk/checksums/internal/XxHashChecksumTest.java

@@ -57,9 +57,12 @@ void mark_throwsUnsupportedOperationException(ChecksumAlgorithm algorithm, Strin
 
     @ParameterizedTest
     @MethodSource("xxHashAlgorithms")
-    void reset_throwsUnsupportedOperationException(ChecksumAlgorithm algorithm, String expectedBase64) {
+    void reset_allowsReuseOfChecksum(ChecksumAlgorithm algorithm, String expectedBase64) {
         SdkChecksum checksum = ChecksumProvider.crtXxHash(algorithm);
-        assertThrows(UnsupportedOperationException.class, () -> checksum.reset());
+        checksum.update("some other data".getBytes(StandardCharsets.UTF_8));
+        checksum.reset();
+        checksum.update("Hello world".getBytes(StandardCharsets.UTF_8));
+        assertEquals(expectedBase64, BinaryUtils.toBase64(checksum.getChecksumBytes()));
     }
 
     @ParameterizedTest

test/codegen-generated-classes-test/src/test/java/software/amazon/awssdk/services/AsyncRequestCompressionTest.java

@@ -120,7 +120,6 @@ public void asyncNonStreamingOperation_payloadSizeLessThanCompressionThreshold_d
     public void asyncStreamingOperation_compressionEnabled_compressesCorrectly() {
         mockAsyncHttpClient.stubNextResponse(mockResponse(), Duration.ofMillis(500));
 
-        mockAsyncHttpClient.setAsyncRequestBodyLength(compressedBody.length());
         PutOperationWithStreamingRequestCompressionRequest request =
             PutOperationWithStreamingRequestCompressionRequest.builder().build();
         asyncClient.putOperationWithStreamingRequestCompression(request, customAsyncRequestBodyWithoutContentLength(),
@@ -166,7 +165,6 @@ public void asyncStreamingOperation_compressionEnabledWithRetry_compressesCorrec
         mockAsyncHttpClient.stubNextResponse(mockResponse(), Duration.ofMillis(500));
         mockAsyncHttpClient.stubNextResponse(mockResponse(), Duration.ofMillis(500));
 
-        mockAsyncHttpClient.setAsyncRequestBodyLength(compressedBody.length());
         PutOperationWithStreamingRequestCompressionRequest request =
             PutOperationWithStreamingRequestCompressionRequest.builder().build();
         asyncClient.putOperationWithStreamingRequestCompression(request, customAsyncRequestBodyWithoutContentLength(),