Added a net::BidirectionalStream to expose a bidirectional streaming interface

net/spdy/bidirectional_stream_spdy_job.cc

+// Copyright 2015 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.
+
+#include "net/spdy/bidirectional_stream_spdy_job.h"
+
+#include "base/bind.h"
+#include "base/memory/scoped_ptr.h"

[mmenke, 2015/12/11 22:19:58]

Nit:  This should be in the header.

[xunjieli, 2015/12/11 23:48:40]

Done.

+#include "base/time/time.h"
+#include "base/timer/timer.h"
+#include "net/base/request_priority.h"
+#include "net/spdy/spdy_buffer.h"
+#include "net/spdy/spdy_header_block.h"
+#include "net/spdy/spdy_http_utils.h"
+#include "net/spdy/spdy_stream.h"
+
+namespace net {
+
+const base::TimeDelta kBufferTime = base::TimeDelta::FromMilliseconds(1);

[mmenke, 2015/12/11 22:19:59]

global must be POD types.  Standard way to do this is kBufferTimeMs = 1, and to
use TimeDelta::FromMilliseconds(kBufferTimeMs) where you're currently using
kBufferTime

[xunjieli, 2015/12/11 23:48:40]

Done.

+
+BidirectionalStreamSpdyJob::BidirectionalStreamSpdyJob(
+    const base::WeakPtr<SpdySession>& spdy_session,
+    scoped_ptr<base::Timer> timer)
+    : spdy_session_(spdy_session),
+      timer_(timer.release()),

[mmenke, 2015/12/11 22:19:58]

std::move(timer)

[xunjieli, 2015/12/11 23:48:40]

Done.

+      stream_closed_(false),
+      closed_stream_status_(ERR_FAILED),
+      more_read_data_pending_(false),
+      negotiated_protocol_(kProtoUnknown),
+      closed_stream_received_bytes_(0),
+      closed_stream_sent_bytes_(0),
+      weak_factory_(this) {}
+
+BidirectionalStreamSpdyJob::BidirectionalStreamSpdyJob(

[mmenke, 2015/12/11 22:19:59]

definition order should match delcaration order.

[xunjieli, 2015/12/11 23:48:40]

Done.

+    const base::WeakPtr<SpdySession>& spdy_session)
+    : BidirectionalStreamSpdyJob(
+          spdy_session,
+          make_scoped_ptr(new base::Timer(false, false))) {}
+
+BidirectionalStreamSpdyJob::~BidirectionalStreamSpdyJob() {
+  if (stream_.get()) {

[mmenke, 2015/12/11 22:19:59]

nit:  .get() not needed.

[xunjieli, 2015/12/11 23:48:40]

Done.

+    stream_->DetachDelegate();
+    DCHECK(!stream_.get());

[mmenke, 2015/12/11 22:19:58]

Am I missing something, or can this not currently be safely done while in
OnDataSent() / OnRequestHeadersSent()?  Seems worth documenting in the parent
class, and the exported class as well.

[mmenke, 2015/12/11 22:19:58]

nit:  .get() not needed.

[xunjieli, 2015/12/11 23:48:40]

Why is it unsafe? The delegate can't delete the job in OnDataSent callback?

[xunjieli, 2015/12/11 23:48:40]

Done.

[mmenke, 2015/12/14 19:48:37]

Sorry, I wasn't remotely clear there.

See:
https://code.google.com/p/chromium/codesearch#chromium/src/net/spdy/spdy_stre...

[mmenke, 2015/12/14 19:52:34]

And I think we should have tests for destruction during callbacks, if we intend
to support it.

[xunjieli, 2015/12/14 21:03:05]

Done. Thanks for pointing me to the code. I have documented on this requirement.

+  }
+}
+
+void BidirectionalStreamSpdyJob::Start(
+    const HttpRequestInfo& request_info,
+    RequestPriority priority,
+    const BoundNetLog& net_log,
+    BidirectionalStreamJob::Delegate* delegate) {
+  delegate_ = delegate;
+  DCHECK(!stream_);
+  if (!spdy_session_) {
+    delegate_->OnFailed(ERR_CONNECTION_CLOSED);
+    return;
+  }
+
+  request_info_ = request_info;
+
+  int rv = stream_request_.StartRequest(
+      SPDY_BIDIRECTIONAL_STREAM, spdy_session_, request_info_.url, priority,
+      net_log, base::Bind(&BidirectionalStreamSpdyJob::OnStreamInitialized,
+                          weak_factory_.GetWeakPtr()));
+  if (rv != ERR_IO_PENDING)
+    OnStreamInitialized(rv);
+}
+
+int BidirectionalStreamSpdyJob::ReadData(IOBuffer* buf, int buf_len) {
+  if (stream_.get())
+    CHECK(!stream_->IsIdle());
+
+  CHECK(buf);
+  CHECK(buf_len);
+  CHECK(!timer_->IsRunning()) << "There should be only one ReadData in flight";
+
+  if (!stream_closed_)
+    CHECK(stream_);

[mmenke, 2015/12/11 22:19:58]

All these CHECKs should be DCHECKs.

[xunjieli, 2015/12/11 23:48:40]

Done.

+
+  // If there is data buffered, complete the IO immediately.
+  if (!data_queue_.IsEmpty()) {
+    return data_queue_.Dequeue(buf->data(), buf_len);
+  } else if (stream_closed_) {
+    return closed_stream_status_;
+  }
+  // Read will complete asynchronously and Delegate::OnReadCompleted will be
+  // called upon completion.
+  user_buffer_ = buf;
+  user_buffer_len_ = buf_len;
+  return ERR_IO_PENDING;
+}
+
+void BidirectionalStreamSpdyJob::SendData(IOBuffer* data,
+                                          int length,
+                                          bool end_stream) {
+  CHECK(!stream_closed_);
+  CHECK(stream_);
+
+  stream_->SendData(data, length,
+                    end_stream ? NO_MORE_DATA_TO_SEND : MORE_DATA_TO_SEND);
+}
+
+void BidirectionalStreamSpdyJob::Cancel() {
+  if (!stream_)
+    return;
+  // Cancels the stream and detaches the delegate so it doesn't get called back.
+  stream_->DetachDelegate();
+  DCHECK(!stream_);
+}
+
+NextProto BidirectionalStreamSpdyJob::GetProtocol() const {
+  return negotiated_protocol_;
+}
+
+int64_t BidirectionalStreamSpdyJob::GetTotalReceivedBytes() const {
+  if (stream_closed_)
+    return closed_stream_received_bytes_;
+
+  if (!stream_)
+    return 0;
+
+  return stream_->raw_received_bytes();
+}
+
+int64_t BidirectionalStreamSpdyJob::GetTotalSentBytes() const {
+  if (stream_closed_)
+    return closed_stream_sent_bytes_;
+
+  if (!stream_)
+    return 0;
+
+  return stream_->raw_sent_bytes();
+}
+
+void BidirectionalStreamSpdyJob::OnRequestHeadersSent() {
+  DCHECK(stream_);
+
+  delegate_->OnHeadersSent();
+}
+
+SpdyResponseHeadersStatus BidirectionalStreamSpdyJob::OnResponseHeadersUpdated(
+    const SpdyHeaderBlock& response_headers) {
+  DCHECK(stream_);
+
+  negotiated_protocol_ = stream_->GetProtocol();
+  delegate_->OnHeadersReceived(response_headers);
+  return RESPONSE_HEADERS_ARE_COMPLETE;
+}
+
+void BidirectionalStreamSpdyJob::OnDataReceived(scoped_ptr<SpdyBuffer> buffer) {
+  DCHECK(stream_);
+  DCHECK(!stream_closed_);
+
+  if (buffer) {

[mmenke, 2015/12/11 22:19:58]

Maybe early return if NULL?

[xunjieli, 2015/12/11 23:48:40]

Done.

+    data_queue_.Enqueue(buffer.Pass());

[mmenke, 2015/12/11 22:19:59]

std::move

[mmenke, 2015/12/11 22:19:59]

What about flow control?

I'm not familiar with the SPDY code, but what's to either pevent this buffer
from getting so large we OOM or die?  Or if flow control is enabled, do we need
to tell the stream when we actually consume data from the queue?

[xunjieli, 2015/12/11 23:48:40]

Done.

[xunjieli, 2015/12/11 23:48:40]

Good question. I added comment. I believe that SpdyBuffer that we received has a
ConsumeCallback hooked up that it would adjust recv window flow: 

   buffer->AddConsumeCallback(
        base::Bind(&SpdyStream::OnReadBufferConsumed, GetWeakPtr()));

[mmenke, 2015/12/14 19:48:37]

I'll dig into this a bit before responding.

[xunjieli, 2015/12/14 21:03:05]

Acknowledged.

+    if (user_buffer_) {
+      // Handing small chunks of data to the caller creates measurable overhead.
+      // So buffer data in short time-spans and send a single read notification.
+      ScheduleBufferedRead();

[mmenke, 2015/12/11 22:19:58]

Can we just not make this call if data_queue_ was non-empty when this call was
made, and then remove ScheduleBufferedRead's logic to check if the timer is
already scheduled?

[xunjieli, 2015/12/11 23:48:40]

There is one case where we still need to invoke OnDataReceived even though the
data_queue is empty.

If client calls ReadData, but there is no data buffered, the call will return
IO_PENDING.
If the server sends us END_STREAM with empty buffer after this, we won't enqueue
anything to the data_queue_, but we still should invoke the completion callback
here.

[mmenke, 2015/12/14 19:48:37]

Think it would actually be simpler to just have OnClose directly call into the
delegate in that case.

[xunjieli, 2015/12/14 21:03:05]

We are having OnClose calling into Delegate via Delegate::OnDataRead(0) here
though. We don't have a Delegate::OnClose method, which was removed for
simplicity. 

+    }
+  }
+  // If |buffer| is null, BidirectionalStreamSpdyJob::OnClose will be invoked by
+  // SpdyStream to indicate the end of stream.
+}
+
+void BidirectionalStreamSpdyJob::OnDataSent() {
+  DCHECK(stream_);
+  DCHECK(!stream_closed_);
+
+  delegate_->OnDataSent();
+}
+
+void BidirectionalStreamSpdyJob::OnTrailers(const SpdyHeaderBlock& trailers) {
+  DCHECK(stream_);
+  DCHECK(!stream_closed_);
+
+  delegate_->OnTrailersReceived(trailers);
+}
+
+void BidirectionalStreamSpdyJob::OnClose(int status) {
+  DCHECK(stream_);
+
+  stream_closed_ = true;
+  closed_stream_status_ = status;
+  closed_stream_received_bytes_ = stream_->raw_received_bytes();
+  closed_stream_sent_bytes_ = stream_->raw_sent_bytes();
+  stream_.reset();
+
+  if (status != OK) {
+    delegate_->OnFailed(status);
+    return;
+  }
+  // Complete any remaining read, as all data has been buffered.
+  // If user has not called ReadData (i.e |user_buffer_| is nullptr), this will
+  // do nothing.
+  DCHECK_EQ(OK, status);
+  timer_->Stop();
+  DoBufferedRead();
+}
+
+void BidirectionalStreamSpdyJob::SendRequestHeaders() {
+  scoped_ptr<SpdyHeaderBlock> headers(new SpdyHeaderBlock);
+  CreateSpdyHeadersFromHttpRequest(request_info_, request_info_.extra_headers,
+                                   stream_->GetProtocolVersion(), true,
+                                   headers.get());
+  stream_->SendRequestHeaders(headers.Pass(), MORE_DATA_TO_SEND);

[mmenke, 2015/12/11 22:19:58]

std::move

[xunjieli, 2015/12/11 23:48:40]

Done.

+}
+
+void BidirectionalStreamSpdyJob::OnStreamInitialized(int rv) {
+  DCHECK_NE(ERR_IO_PENDING, rv);

[mmenke, 2015/12/11 22:19:58]

nit:  include base/logging.h

[xunjieli, 2015/12/11 23:48:40]

Done.

+  if (rv == OK) {
+    stream_ = stream_request_.ReleaseStream();
+    stream_->SetDelegate(this);
+    SendRequestHeaders();
+    return;
+  }
+  delegate_->OnFailed(static_cast<Error>(rv));
+}
+
+void BidirectionalStreamSpdyJob::ScheduleBufferedRead() {
+  // If there is already a scheduled DoBufferedRead, don't issue
+  // another one. Mark that we have received more data and return.
+  if (timer_->IsRunning()) {
+    more_read_data_pending_ = true;
+    return;
+  }
+
+  more_read_data_pending_ = false;
+  timer_->Start(FROM_HERE, kBufferTime,

[mmenke, 2015/12/11 22:19:58]

nit:  Include base/location.h for FROM_HERE.

[xunjieli, 2015/12/11 23:48:40]

Done.

+                base::Bind(&BidirectionalStreamSpdyJob::DoBufferedRead,
+                           weak_factory_.GetWeakPtr()));
+}
+
+void BidirectionalStreamSpdyJob::DoBufferedRead() {
+  DCHECK(!timer_->IsRunning());
+  // If the stream errored out, do not complete the read.

[mmenke, 2015/12/11 22:19:59]

Should we just DCHECK on this, and not allow it, instead?  We generally don't
let clients do things they should know ill fail, in net/.

[xunjieli, 2015/12/11 23:48:40]

Done.

+  if (!stream_ && !stream_closed_)
+    return;
+  if (stream_closed_ && closed_stream_status_ != OK)
+    return;
+
+  // When |more_read_data_pending_| is true, it means that more data has arrived
+  // since started waiting. Wait a little longer and continue to buffer.
+  if (more_read_data_pending_ && ShouldWaitForMoreBufferedData()) {

[mmenke, 2015/12/11 22:19:58]

Why do we need more_read_data_pending_?  Can't we just check the state of
data_queue_?

[xunjieli, 2015/12/11 23:48:41]

I was copying SpdyHttpStream's logic. The ShouldWaitForMoreBufferedData does
check the state of data_queue, not sure what else we can check so we can
substitue this more_read_data_pending_.

[mmenke, 2015/12/14 19:48:37]

Hrm...I think the extra variable here makes this code more confusing than
strictly necessary.  The more variables you have whose states can be derived
from other variables, the easier it is to end up in an inconsistent state where
something isn't being updated correctly.

[xunjieli, 2015/12/14 21:03:05]

I don't think ShouldWaitForMoreBufferedData is enough.
If the ReadData is called with a large |user_buffer|, with
|more_read_data_pending_| removed, we would wait until OnClose is called or
|user_buffer_| is completely filled before invoking OnDataRead callback. However
this is not the right behavior. Because the send data and received data can
interleave. (The client can expect to receive a small amount of data, send some
data, then receive some data, ... and finally to have both sides close)

If we only depend on the state of the |data_queue_|, we might be postponing the
read completion callback forever.

+    ScheduleBufferedRead();
+    return;
+  }
+
+  int rv = 0;
+  if (user_buffer_) {
+    rv = ReadData(user_buffer_.get(), user_buffer_len_);
+    DCHECK_NE(ERR_IO_PENDING, rv);
+    user_buffer_ = nullptr;
+    user_buffer_len_ = 0;
+    delegate_->OnDataRead(rv);
+  }
+}
+
+bool BidirectionalStreamSpdyJob::ShouldWaitForMoreBufferedData() const {
+  if (stream_closed_)
+    return false;
+  DCHECK_GT(user_buffer_len_, 0);
+  return data_queue_.GetTotalSize() < static_cast<size_t>(user_buffer_len_);
+}
+
+}  // namespace net