chore: update GrpcBlobReadChannel to configure lazy buffer allocation (…

…#1719)
googleapis · Oct 19, 2022 · 5ff8be1 · 5ff8be1
1 parent e78e3d2
commit 5ff8be1
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Showing 2 changed files with 18 additions and 11 deletions.
diff --git a/google-cloud-storage/src/main/java/com/google/cloud/storage/GapicDownloadSessionBuilder.java b/google-cloud-storage/src/main/java/com/google/cloud/storage/GapicDownloadSessionBuilder.java
@@ -28,13 +28,18 @@
 import com.google.storage.v2.ReadObjectResponse;
 import java.nio.ByteBuffer;
 import java.util.function.BiFunction;
+import javax.annotation.concurrent.Immutable;
 
+@Immutable
 final class GapicDownloadSessionBuilder {
+  private static final GapicDownloadSessionBuilder INSTANCE = new GapicDownloadSessionBuilder();
+
+  private static final int DEFAULT_BUFFER_CAPACITY = ByteSizeConstants._16MiB;
 
   private GapicDownloadSessionBuilder() {}
 
   public static GapicDownloadSessionBuilder create() {
-    return new GapicDownloadSessionBuilder();
+    return INSTANCE;
   }
 
   /**
@@ -60,7 +65,7 @@ private ReadableByteChannelSessionBuilder(
     }
 
     public BufferedReadableByteChannelSessionBuilder buffered() {
-      return buffered(Buffers.allocate(16 * 1024 * 1024));
+      return buffered(BufferHandle.allocate(DEFAULT_BUFFER_CAPACITY));
     }
 
     public ReadableByteChannelSessionBuilder setHasher(Hasher hasher) {
@@ -74,20 +79,20 @@ public ReadableByteChannelSessionBuilder setAutoGzipDecompression(
       return this;
     }
 
-    public BufferedReadableByteChannelSessionBuilder buffered(int capacity) {
-      return new BufferedReadableByteChannelSessionBuilder(BufferHandle.allocate(capacity), getF());
+    public BufferedReadableByteChannelSessionBuilder buffered(BufferHandle bufferHandle) {
+      return new BufferedReadableByteChannelSessionBuilder(bufferHandle, bindFunction());
     }
 
     public BufferedReadableByteChannelSessionBuilder buffered(ByteBuffer buffer) {
-      return new BufferedReadableByteChannelSessionBuilder(BufferHandle.handleOf(buffer), getF());
+      return buffered(BufferHandle.handleOf(buffer));
     }
 
     public UnbufferedReadableByteChannelSessionBuilder unbuffered() {
-      return new UnbufferedReadableByteChannelSessionBuilder(getF());
+      return new UnbufferedReadableByteChannelSessionBuilder(bindFunction());
     }
 
     private BiFunction<ReadObjectRequest, SettableApiFuture<Object>, UnbufferedReadableByteChannel>
-        getF() {
+        bindFunction() {
       // for any non-final value, create a reference to the value at this point in time
       Hasher hasher = this.hasher;
       boolean autoGzipDecompression = this.autoGzipDecompression;
@@ -103,7 +108,8 @@ public UnbufferedReadableByteChannelSessionBuilder unbuffered() {
 
     public static final class BufferedReadableByteChannelSessionBuilder {
 
-      private BiFunction<ReadObjectRequest, SettableApiFuture<Object>, BufferedReadableByteChannel>
+      private final BiFunction<
+              ReadObjectRequest, SettableApiFuture<Object>, BufferedReadableByteChannel>
           f;
       private ReadObjectRequest request;
 
@@ -129,7 +135,7 @@ public BufferedReadableByteChannelSession<Object> build() {
 
     public static final class UnbufferedReadableByteChannelSessionBuilder {
 
-      private BiFunction<
+      private final BiFunction<
               ReadObjectRequest, SettableApiFuture<Object>, UnbufferedReadableByteChannel>
           f;
       private ReadObjectRequest request;

diff --git a/google-cloud-storage/src/main/java/com/google/cloud/storage/GrpcBlobReadChannel.java b/google-cloud-storage/src/main/java/com/google/cloud/storage/GrpcBlobReadChannel.java
@@ -16,6 +16,7 @@
 
 package com.google.cloud.storage;
 
+import static com.google.cloud.storage.ByteSizeConstants._16MiB;
 import static com.google.cloud.storage.StorageV2ProtoUtils.seekReadObjectRequest;
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkState;
@@ -40,7 +41,7 @@ final class GrpcBlobReadChannel implements ReadChannel {
 
   private Long position;
   private Long limit;
-  private int chunkSize = 16 * 1024 * 1024;
+  private int chunkSize = _16MiB;
 
   GrpcBlobReadChannel(
       ServerStreamingCallable<ReadObjectRequest, ReadObjectResponse> read,
@@ -57,7 +58,7 @@ final class GrpcBlobReadChannel implements ReadChannel {
                       .byteChannel(read)
                       .setHasher(Hasher.noop())
                       .setAutoGzipDecompression(autoGzipDecompression)
-                      .buffered(Buffers.allocate(chunkSize))
+                      .buffered(BufferHandle.allocate(chunkSize))
                       .setReadObjectRequest(req)
                       .build();
                 }));