expose the force dynamic size

Author: TingDaoK

src/main/java/software/amazon/awssdk/crt/s3/S3Client.java

@@ -220,7 +220,8 @@ public S3MetaRequest makeMetaRequest(S3MetaRequestOptions options) {
                 fioOptionsSet,
                 shouldStream,
                 diskThroughputGbps,
-                directIo);
+                directIo,
+                options.getForceDynamicPartSize());
 
         metaRequest.setMetaRequestNativeHandle(metaRequestNativeHandle);
 
@@ -299,5 +300,6 @@ private static native long s3ClientMakeMetaRequest(long clientId, S3MetaRequest
             boolean fioOptionsSet,
             boolean shouldStream,
             double diskThroughputGbps,
-            boolean directIo);
+            boolean directIo,
+            boolean forceDynamicPartSize);
 }

src/main/java/software/amazon/awssdk/crt/s3/S3MetaRequestOptions.java

@@ -96,6 +96,7 @@ private static Map<Integer, MetaRequestType> buildEnumMapping() {
     private ResumeToken resumeToken;
     private Long objectSizeHint;
     private FileIoOptions fileIoOptions;
+    private boolean forceDynamicPartSize = false;
 
     public S3MetaRequestOptions withMetaRequestType(MetaRequestType metaRequestType) {
         this.metaRequestType = metaRequestType;
@@ -472,4 +473,20 @@ public S3MetaRequestOptions withFileIoOptions(FileIoOptions fileIoOptions) {
     public FileIoOptions getFileIoOptions() {
         return fileIoOptions;
     }
+
+    /**
+     * WARNING: experimental/unstable.
+     * Set this to force the dynamic default part_size regardless the part size set from client or meta request.
+     * Set this to get the best performance under the memory constrain, especially for getting large objects.
+     *
+     * @param forceDynamicPartSize True to force the dynamic part size, False to use the part size set from client or meta request.
+     * @return this
+     */
+    public S3MetaRequestOptions withForceDynamicPartSize(boolean forceDynamicPartSize) {
+        this.forceDynamicPartSize = forceDynamicPartSize;
+        return this;
+    }
+    public boolean getForceDynamicPartSize() {
+        return forceDynamicPartSize;
+    }
 }

src/native/s3_client.c

@@ -1001,7 +1001,8 @@ JNIEXPORT jlong JNICALL Java_software_amazon_awssdk_crt_s3_S3Client_s3ClientMake
     jboolean fio_options_set,
     jboolean should_stream,
     jdouble disk_throughput_gbps,
-    jboolean direct_io) {
+    jboolean direct_io,
+    jboolean force_dynamic_part_size) {
     (void)jni_class;
     aws_cache_jni_ids(env);
 
@@ -1147,6 +1148,7 @@ JNIEXPORT jlong JNICALL Java_software_amazon_awssdk_crt_s3_S3Client_s3ClientMake
         .recv_file_delete_on_failure = jni_response_file_delete_on_failure,
         /* If fio options not set, let native code to decide the default instead */
         .fio_opts = fio_options_set ? &fio_opts : NULL,
+        .force_dynamic_part_size = force_dynamic_part_size,
     };
 
     meta_request = aws_s3_client_make_meta_request(client, &meta_request_options);