diff options
Diffstat (limited to 'net')
| -rw-r--r-- | net/http/http_stream_parser.cc | 29 |
1 files changed, 26 insertions, 3 deletions
diff --git a/net/http/http_stream_parser.cc b/net/http/http_stream_parser.cc index 53c57f1..334e770 100644 --- a/net/http/http_stream_parser.cc +++ b/net/http/http_stream_parser.cc @@ -5,6 +5,7 @@ #include "net/http/http_stream_parser.h" #include "base/compiler_specific.h" +#include "base/field_trial.h" #include "base/trace_event.h" #include "net/base/io_buffer.h" #include "net/http/http_request_info.h" @@ -186,17 +187,39 @@ int HttpStreamParser::DoLoop(int result) { int HttpStreamParser::DoSendHeaders(int result) { request_headers_->DidConsume(result); - if (request_headers_->BytesRemaining() > 0) { + // Set up a field trial to see if splitting the first packet helps with + // latency (loss of the first packet may otherwise cause an RTO of 3 seconds + // at least on Windows... but with two packets, the probability of loss + // without any ack to alert us should be lower, and receipt of a first ack + // will lower the RTO dramatically, so recovery will be fast.). + static const FieldTrial* kTrial = FieldTrialList::Find("PacketSplit"); + static const bool kForceSecondPacket(kTrial && (kTrial->group() == 0)); + if (kForceSecondPacket) + DCHECK_EQ(kTrial->group_name(), "_first_packet_split"); + + int bytes_remaining = request_headers_->BytesRemaining(); + if (bytes_remaining > 0) { // Record our best estimate of the 'request time' as the time when we send // out the first bytes of the request headers. - if (request_headers_->BytesRemaining() == request_headers_->size()) { + if (bytes_remaining == request_headers_->size()) { response_->request_time = base::Time::Now(); + + // Note that we ONLY ensure second packet when this is a fresh connection, + // as a reused connection (re: reuse_type()) already had traffic, and + // hence has an RTO which will provide for a fast packet-loss recovery. + // We also avoid splitting out a second packet if we have a request_body_ + // to send, as it will provide the desired second packet (see bug 38703). + if (kForceSecondPacket && + connection_->reuse_type() != ClientSocketHandle::REUSED_IDLE && + (request_body_ == NULL || !request_body_->size()) && + bytes_remaining > 1) + --bytes_remaining; // Leave one byte for next packet. } // TODO(vandebo) remove when bug 31096 is resolved CHECK(connection_); CHECK(connection_->socket()); result = connection_->socket()->Write(request_headers_, - request_headers_->BytesRemaining(), + bytes_remaining, &io_callback_); } else if (request_body_ != NULL && request_body_->size()) { io_state_ = STATE_SENDING_BODY; |