#2975 add an optional flush flag to the xpra chunk packet header

git-svn-id: https://xpra.org/svn/Xpra/trunk@28117 3bb7dfac-3a0b-4e04-842a-767bc560f471

src/html5/js/Protocol.js

@@ -267,6 +267,11 @@ XpraProtocol.prototype.do_process_receive_queue = function() {
 		proto_flags = proto_flags & ~0x2;
 	}
 
+	if (proto_flags & 0x8) {
+		//this flag is unused client-side, so just ignore it:
+		proto_flags = proto_flags & ~0x8;
+	}
+
 	if (proto_flags > 1) {
 		this.protocol_error("we can't handle this protocol flag yet: "+proto_flags);
 		return;

src/xpra/net/common.py

@@ -14,6 +14,7 @@ class ConnectionClosedException(Exception):
     pass
 
 MAX_PACKET_SIZE = envint("XPRA_MAX_PACKET_SIZE", 16*1024*1024)
+FLUSH_HEADER = envbool("XPRA_FLUSH_HEADER", True)
 
 SOCKET_TYPES = ("tcp", "ws", "wss", "ssl", "ssh", "rfb", "vsock", "udp")
 

src/xpra/net/header.py

@@ -15,6 +15,7 @@
 FLAGS_RENCODE   = 0x1
 FLAGS_CIPHER    = 0x2
 FLAGS_YAML      = 0x4
+FLAGS_FLUSH     = 0x8
 
 #compression flags are carried in the "level" field,
 #the low bits contain the compression level, the high bits the compression algo:

src/xpra/net/net_util.py

@@ -1,6 +1,6 @@
 #!/usr/bin/env python
 # This file is part of Xpra.
-# Copyright (C) 2013-2019 Antoine Martin <[email protected]>
+# Copyright (C) 2013-2020 Antoine Martin <[email protected]>
 # Xpra is released under the terms of the GNU GPL v2, or, at your option, any
 # later version. See the file COPYING for details.
 
@@ -372,6 +372,9 @@ def get_network_caps() -> dict:
                 "compressors"           : get_enabled_compressors(),
                 "encoders"              : get_enabled_encoders(),
                }
+    from xpra.net.common import FLUSH_HEADER
+    if FLUSH_HEADER:
+        caps["flush"] = True
     caps.update(get_crypto_caps())
     caps.update(get_compression_caps())
     caps.update(get_packet_encoding_caps())

src/xpra/net/protocol.py

@@ -16,7 +16,10 @@
 from xpra.os_util import memoryview_to_bytes, strtobytes, bytestostr, hexstr, monotonic_time
 from xpra.util import repr_ellipsized, ellipsizer, csv, envint, envbool, typedict
 from xpra.make_thread import make_thread, start_thread
-from xpra.net.common import ConnectionClosedException, may_log_packet, MAX_PACKET_SIZE    #@UndefinedVariable (pydev false positive)
+from xpra.net.common import (
+    ConnectionClosedException, may_log_packet,
+    MAX_PACKET_SIZE, FLUSH_HEADER,
+    )
 from xpra.net.bytestreams import ABORT
 from xpra.net import compression
 from xpra.net.compression import (
@@ -29,7 +32,7 @@
     decode, sanity_checks as packet_encoding_sanity_checks,
     InvalidPacketEncodingException,
     )
-from xpra.net.header import unpack_header, pack_header, FLAGS_CIPHER, FLAGS_NOHEADER, HEADER_SIZE
+from xpra.net.header import unpack_header, pack_header, FLAGS_CIPHER, FLAGS_NOHEADER, FLAGS_FLUSH, HEADER_SIZE
 from xpra.net.crypto import get_encryptor, get_decryptor, pad, INITIAL_PADDING
 from xpra.log import Logger
 
@@ -165,6 +168,7 @@ def __init__(self, scheduler, conn, process_packet_cb, get_packet_cb=None):
         self.abs_max_packet_size = 256*1024*1024
         self.large_packets = [b"hello", b"window-metadata", b"sound-data", b"notify_show", b"setting-change", b"shell-reply"]
         self.send_aliases = {}
+        self.send_flush_flag = False
         self.receive_aliases = {}
         self._log_stats = None          #None here means auto-detect
         self._closed = False
@@ -264,13 +268,16 @@ def accept(self):
     def parse_remote_caps(self, caps : typedict):
         for k,v in caps.dictget("aliases", {}).items():
             self.send_aliases[bytestostr(k)] = v
+        if FLUSH_HEADER:
+            self.send_flush_flag = caps.boolget("flush", False)
 
     def get_info(self, alias_info=True) -> dict:
         info = {
             "large_packets"         : tuple(bytestostr(x) for x in self.large_packets),
             "compression_level"     : self.compression_level,
             "max_packet_size"       : self.max_packet_size,
             "aliases"               : USE_ALIASES,
+            "flush"                 : self.send_flush_flag,
             }
         c = self.compressor
         if c:
@@ -420,6 +427,9 @@ def _add_chunks_to_queue(self, packet_type, chunks, start_send_cb=None, end_send
                 log("sending %s bytes without header", payload_size)
                 items.append(data)
             else:
+                #if the other end can use this flag, expose it:
+                if self.send_flush_flag and not more and index==0:
+                    proto_flags |= FLAGS_FLUSH
                 #the xpra packet header:
                 #(WebSocketProtocol may also add a websocket header too)
                 header = self.make_chunk_header(packet_type, proto_flags, level, index, payload_size)