Cronet Java wrappers to fallback to HttpUrlConnection if Cronet is not available.

net/cronet/android/java/src/org/chromium/net/ChromiumUrlRequest.java

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.net;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.WritableByteChannel;
+import java.util.Map;
+
+/**
+ * Network request using the native http stack implementation.
+ */
+class ChromiumUrlRequest extends UrlRequest implements HttpUrlRequest {
+
+  private final HttpUrlRequestListener mListener;
+  private boolean mBufferFullResponse;
+  private long mOffset;

[dplotnikov, 2014/03/07 20:01:12]

Do you believe we should keep this resumable download functionality here or
break it out into something done by the clients who need it?  I would be in
favor of the latter approach.

[mef, 2014/03/07 20:54:12]

Good question. At this point my primary goal was to upstream existing
functionality and use it as a starting point.
I'm totally fine with keeping resumable downloads out of cronet.
I think it is worth deciding on API that Cronet will initially support, and your
wrappers seemed like a good start.
Opinions?

+  private long mContentLength;
+  private long mContentLengthLimit;
+  private boolean mCancelIfContentLengthOverLimit;
+  private boolean mContentLengthOverLimit;
+  private boolean mSkippingToOffset;
+  private long mSize;

[mmenke, 2014/03/07 17:02:39]

Entire file should be using 4-space indent (Goes for a bunch of these files).

[mef, 2014/03/07 20:54:12]

Yeah, is there some tool for that? 'git cl format' doesn't seem to format java.

[mef, 2014/03/14 20:03:24]

Done.

+
+  public ChromiumUrlRequest(ChromiumUrlRequestContext requestContext, String url,

[mmenke, 2014/03/07 17:02:39]

Line too long (Goes for a bunch of lines in these files).

[mef, 2014/03/07 20:54:12]

Roger that.

+      int priority, Map<String, String> headers, HttpUrlRequestListener listener) {

[mmenke, 2014/03/07 17:02:39]

All lines with arguments should be lined up.First argument should

+    this(requestContext, url, priority, headers, new ChunkedWritableByteChannel(), listener);
+    mBufferFullResponse = true;
+  }
+
+  public ChromiumUrlRequest(ChromiumUrlRequestContext requestContext, String url,
+      int priority, Map<String, String> headers, WritableByteChannel sink,
+      HttpUrlRequestListener listener) {
+    super(requestContext, url, convertRequestPriority(priority), headers, sink);
+    if (requestContext == null) {
+      throw new NullPointerException("Context is required");
+    }
+    if (url == null) {
+      throw new NullPointerException("URL is required");
+    }
+    mListener = listener;
+  }
+
+  private static int convertRequestPriority(int priority) {
+    switch (priority) {
+      case HttpUrlRequest.REQUEST_PRIORITY_IDLE:
+        return UrlRequest.REQUEST_PRIORITY_IDLE;
+      case HttpUrlRequest.REQUEST_PRIORITY_LOWEST:
+        return UrlRequest.REQUEST_PRIORITY_LOWEST;
+      case HttpUrlRequest.REQUEST_PRIORITY_LOW:
+        return UrlRequest.REQUEST_PRIORITY_LOW;
+      case HttpUrlRequest.REQUEST_PRIORITY_MEDIUM:
+        return UrlRequest.REQUEST_PRIORITY_MEDIUM;
+      case HttpUrlRequest.REQUEST_PRIORITY_HIGHEST:
+        return UrlRequest.REQUEST_PRIORITY_HIGHEST;
+      default:
+        return UrlRequest.REQUEST_PRIORITY_MEDIUM;
+    }
+  }
+
+  @Override
+  public void setOffset(long offset) {
+    mOffset = offset;
+    if (offset != 0) {
+      addHeader("Range", "bytes=" + offset + "-");
+    }
+  }
+
+  @Override
+  public long getContentLength() {
+    return mContentLength;
+  }
+
+  @Override
+  public void setContentLengthLimit(long limit, boolean cancelEarly) {
+    mContentLengthLimit = limit;
+    mCancelIfContentLengthOverLimit = cancelEarly;
+  }
+
+  @Override
+  protected void onResponseStarted() {
+    super.onResponseStarted();
+
+    mContentLength = super.getContentLength();
+    if (mContentLengthLimit > 0 && mContentLength > mContentLengthLimit
+        && mCancelIfContentLengthOverLimit) {
+      onContentLengthOverLimit();
+      return;
+    }
+
+    if (mBufferFullResponse && mContentLength != -1 && !mContentLengthOverLimit) {
+      ((ChunkedWritableByteChannel) getSink()).setCapacity((int) mContentLength);
+    }
+
+    if (mOffset != 0) {
+      // The server may ignore the request for a byte range

[mmenke, 2014/03/07 17:02:39]

Suggestion adding a period.  Android style guide doesn't require it, but my
opinion is that where the android style guide doesn't prohibit it, we should
follow Google style.

[mef, 2014/03/07 20:54:12]

Done. Agreed.

+      if (super.getHttpStatusCode() == 200) {
+        if (mContentLength != -1) {
+          mContentLength -= mOffset;
+        }
+        mSkippingToOffset = true;
+      } else {
+        mSize = mOffset;
+      }
+    }
+  }
+
+  @Override
+  protected void onBytesRead(ByteBuffer buffer) {
+    if (mContentLengthOverLimit) {
+      return;
+    }
+
+    int size = buffer.remaining();
+    mSize += size;
+    if (mSkippingToOffset) {
+      if (mSize <= mOffset) {
+        return;
+      } else {
+        mSkippingToOffset = false;
+        buffer.position((int) (mOffset - (mSize - size)));
+      }
+    }
+
+    if (mContentLengthLimit != 0 && mSize > mContentLengthLimit) {
+      buffer.limit(size - (int) (mSize - mContentLengthLimit));
+      super.onBytesRead(buffer);
+      onContentLengthOverLimit();
+      return;
+    }
+
+    super.onBytesRead(buffer);
+  }
+
+  private void onContentLengthOverLimit() {
+    mContentLengthOverLimit = true;
+    cancel();
+  }
+
+  @Override
+  protected void onRequestComplete() {
+    mListener.onRequestComplete(this);
+  }
+
+  @Override
+  public int getHttpStatusCode() {
+    int httpStatusCode = super.getHttpStatusCode();
+
+    // If we have been able to successfully resume a previously interrupted download,
+    // the status code will be 206, not 200. Since the rest of the application is
+    // expecting 200 to indicate success, we need to fake it.

[mmenke, 2014/03/07 17:02:39]

Add a TODO about investigating this - I'm not sure if our network stack does
this.  If it does, it's done at that cache layer...And we're thinking about
getting rid of that for the library.

[mef, 2014/03/07 20:54:12]

Done.

+    if (httpStatusCode == 206) {
+      httpStatusCode = 200;
+    }
+    return httpStatusCode;
+  }
+
+  @Override
+  public IOException getException() {
+    IOException ex = super.getException();
+    if (ex == null && mContentLengthOverLimit) {
+      ex = new ResponseTooLargeException();
+    }
+    return ex;
+  }
+
+  @Override
+  public ByteBuffer getByteBuffer() {
+    return ((ChunkedWritableByteChannel) getSink()).getByteBuffer();
+  }
+
+  @Override
+  public byte[] getResponseAsBytes() {
+    return ((ChunkedWritableByteChannel) getSink()).getBytes();
+  }
+}