nacl_io: Requeue UDP packets if send buffer is full

The Pepper resource (see kPluginSendBufferSlots in
udp_socket_resource_base.cc) will return PP_ERROR_INPROGRESS if the
send buffer is full. In that case, we should requeue packets for
sending rather than discarding them.

R=sbc@chromium.org

Review URL: https://codereview.chromium.org/946913002

Cr-Commit-Position: refs/heads/master@{#318479}

1 files changed, 13 insertions, 3 deletions

diff --git a/native_client_sdk/src/libraries/nacl_io/socket/udp_node.cc b/native_client_sdk/src/libraries/nacl_io/socket/udp_node.cc
index c84d212..7b8bc1e 100644
--- a/native_client_sdk/src/libraries/nacl_io/socket/udp_node.cc
+++ b/native_client_sdk/src/libraries/nacl_io/socket/udp_node.cc
@@ -57,9 +57,13 @@ class UdpSendWork : public UdpWork {
     if (node_->TestStreamFlags(SSF_SENDING))
       return false;
 
-    packet_ = emitter_->ReadTXPacket_Locked();
-    if (NULL == packet_)
-      return false;
+    // If this is a retry packet, packet_ will be already set
+    // and we don't need to dequeue from emitter_.
+    if (NULL == packet_) {
+      packet_ = emitter_->ReadTXPacket_Locked();
+      if (NULL == packet_)
+        return false;
+    }
 
     int err = UDPInterface()->SendTo(node_->socket_resource(),
                                      packet_->buffer(),
@@ -80,6 +84,12 @@ class UdpSendWork : public UdpWork {
     AUTO_LOCK(emitter_->GetLock());
 
     if (length_error < 0) {
+      if (length_error == PP_ERROR_INPROGRESS) {
+        // We need to retry this packet later.
+        node_->ClearStreamFlags(SSF_SENDING);
+        node_->stream()->EnqueueWork(this);
+        return;
+      }
       node_->SetError_Locked(length_error);
       return;
     }