Change iproto and box.session.push re out-of-band

Author: pgulutzan

doc/dev_guide/internals/box_protocol.rst

@@ -67,6 +67,9 @@ Index
     | :ref:`Responses if no error and no                 | Responses for no SQL   |
     | SQL <box_protocol-responses>`                      |                        |
     +----------------------------------------------------+------------------------+
+    | :ref:`Responses if no error and out-of-band        | Responses for          |
+    | <box_protocol-responses_out_of_band>`              | out-of-band            |
+    +----------------------------------------------------+------------------------+
     | :ref:`Responses for errors                         | Responses for errors   |
     | <box_protocol-responses_error>`                    |                        |
     +----------------------------------------------------+------------------------+
@@ -197,6 +200,7 @@ The IPROTO constants that appear within requests or responses that we will descr
     IPROTO_FIELD_IS_NULLABLE=0x03
     IPROTO_FIELD_IS_AUTOINCREMENT=0x04
     IPROTO_FIELD_SPAN=0x05
+    IPROTO_CHUNK=0x80
 
 To denote message descriptions we will say ``msgpack(...)`` and within it we will use modified
 `YAML <https://en.wikipedia.org/wiki/YAML>`_ so: |br|
@@ -924,6 +928,14 @@ so if we were using net_box we could decode with
 or we could convert to a string with :samp:`ffi.string({pointer},{length})`.
 The :ref:`pickle.unpack() <pickle-unpack>` function might also be helpful.
 
+..  _box_protocol-responses_out_of_band:
+
+Responses for no error and out-of-band
+--------------------------------------
+
+If the response is out-of-band, due to use of
+:ref:`box.session.push() <box_session-push>`,
+then the header Response-Code-indicator will be IPROTO_CHUNK instead of IPROTO_OK.
 
 ..  _box_protocol-responses_error:
 

doc/reference/reference_lua/box_session/push.rst

@@ -37,7 +37,8 @@ box.session.push()
             * If the result is not an error, then the return is the boolean value ``true``.
             * When the return is ``true``, the message has gone to the network
               buffer as a :ref:`packet <box_protocol-iproto_protocol>`
-              with the code IPROTO_CHUNK (0x80).
+              with a different :ref:`header code <box_protocol-responses_out_of_band>`
+              so the client can distinguish from an ordinary Okay response.
 
     The server's sole job is to call ``box.session.push()``, there is no
     automatic mechanism for showing that the message was received.
@@ -139,4 +140,4 @@ box.session.push()
         --   - *0
         -- ...
         -- Good. That shows that the message was asynchronous, and
-        -- that box.session.push() did its job.
+        -- that box.session.push() did its job.