Enqueue mDns requests if send on socket in progress.

net/dns/mdns_client_impl.cc

Index: net/dns/mdns_client_impl.cc
diff --git a/net/dns/mdns_client_impl.cc b/net/dns/mdns_client_impl.cc
index 1745385784a8ec4ba1f6e1b420fa877f7b190d7f..941e9eec58ce4d9c959d30103ccd25dd93446b12 100644
--- a/net/dns/mdns_client_impl.cc
+++ b/net/dns/mdns_client_impl.cc
@@ -4,6 +4,8 @@
 
 #include "net/dns/mdns_client_impl.h"
 
+#include <queue>
+
 #include "base/bind.h"
 #include "base/message_loop/message_loop_proxy.h"
 #include "base/stl_util.h"
@@ -54,7 +56,8 @@ MDnsConnection::SocketHandler::SocketHandler(
     MDnsConnection* connection)
     : socket_(socket.Pass()),
       connection_(connection),
-      response_(dns_protocol::kMaxMulticastSize) {
+      response_(dns_protocol::kMaxMulticastSize),
+      send_in_progress_(false) {
 }
 
 MDnsConnection::SocketHandler::~SocketHandler() {
@@ -98,14 +101,30 @@ void MDnsConnection::SocketHandler::OnDatagramReceived(int rv) {
     connection_->OnError(this, rv);
 }
 
-int MDnsConnection::SocketHandler::Send(IOBuffer* buffer, unsigned size) {
-  return socket_->SendTo(buffer, size, multicast_addr_,
-                         base::Bind(&MDnsConnection::SocketHandler::SendDone,
-                                    base::Unretained(this) ));
+int MDnsConnection::SocketHandler::Send(
+    const scoped_refptr<IOBufferWithSize>& buffer) {
+  if (send_in_progress_) {
+    send_queue_.push(buffer);
+    return ERR_IO_PENDING;
+  }
+  int rv = socket_->SendTo(buffer.get(),
+                           buffer->size(),
+                           multicast_addr_,
+                           base::Bind(&MDnsConnection::SocketHandler::SendDone,
+                                      base::Unretained(this)));
+  if (rv != ERR_IO_PENDING)
+    return rv;
+  send_in_progress_ = true;
+  return ERR_IO_PENDING;
 }
 
 void MDnsConnection::SocketHandler::SendDone(int rv) {
-  // TODO(noamsml): Retry logic.
+  send_in_progress_ = false;

[Sergey Ulanov, 2014/09/19 20:40:19]

|rv| is ignored here. I'm not sure how important it is to return correct result
from MDnsConnection::Send(). Maybe move error check from MDnsConnection::Send()
here and make  MDnsConnection::SocketHandler::Send() return void? Or maybe call
connection_->OnError() when rv != net::OK?
I'm fine with just logging here and adding TODO to fix it later.

[Vitaly Buka (NO REVIEWS), 2014/09/19 21:01:45]

Done.

+  while (!send_in_progress_ && !send_queue_.empty()) {
+    scoped_refptr<IOBufferWithSize> buffer = send_queue_.front();
+    send_queue_.pop();
+    Send(buffer);
+  }
 }
 
 MDnsConnection::MDnsConnection(MDnsConnection::Delegate* delegate) :
@@ -141,10 +160,10 @@ bool MDnsConnection::Init(MDnsSocketFactory* socket_factory) {
   return !socket_handlers_.empty();
 }
 
-bool MDnsConnection::Send(IOBuffer* buffer, unsigned size) {
+bool MDnsConnection::Send(const scoped_refptr<IOBufferWithSize>& buffer) {
   bool success = false;
   for (size_t i = 0; i < socket_handlers_.size(); ++i) {
-    int rv = socket_handlers_[i]->Send(buffer, size);
+    int rv = socket_handlers_[i]->Send(buffer);
     if (rv >= OK || rv == ERR_IO_PENDING) {
       success = true;
     } else {
@@ -190,7 +209,7 @@ bool MDnsClientImpl::Core::SendQuery(uint16 rrtype, std::string name) {
   DnsQuery query(0, name_dns, rrtype);
   query.set_flags(0);  // Remove the RD flag from the query. It is unneeded.
 
-  return connection_->Send(query.io_buffer(), query.io_buffer()->size());
+  return connection_->Send(query.io_buffer());
 }
 
 void MDnsClientImpl::Core::HandlePacket(DnsResponse* response,