[PATCH v2 00/10] session: introduce box.session.push

[Vladislav Shpilevoy <v.shpilevoy@tarantool.org>]

Branch: http://github.com/tarantool/tarantool/tree/gh-2677-box-session-push
Issue: https://github.com/tarantool/tarantool/issues/2677

Sometimes it is needed to send some intermediate results from long poll request.
Or to create a watcher on a server side, which listens for some events and sends
notifications to a client. Or split a big response into multiple ones, as it is
described in Tarantool Wire Protocol RFC.

IPROTO_CHUNK protocol command solves all of the problems. IPROTO_CHUNK is a
non-final response, and a single request can produce multiple response chunks.
Box.session.push is API to send a chunk. It takes a Lua object and sends it to
a client using the way depending of a session type: console or binary.

Console session pushes are YAML documents tagged with using YAML %TAG feature -
push message is tagged with !push! tag. For example:
tarantool> box.session.push({a = 100, b = 200})
%TAG !push! tag:tarantool.io/push,2018
---       <--------- Here pushed message starts.
a: 100
b: 200
...
---       <--------- Here push() call result starts.
- true
...
It is not the same as future console.print() pushes - they are not linked with
chunks.

Binary push is an IProto response with IPROTO_CHUNK key in the REQUEST_TYPE
header field. In the rest it has the same structure as any another response.

The most of the patchset work is preparative.
First patches introduces YAML tags for Tarantool YAML codec library - they were
implemented already in libyaml, but was not used in Tarantool.

Next patches refactor session - virtual table and session meta depending on
session type are added. Session meta is used by IProto sessions to store latest
sync and connection, console session stores file descriptor of remote client,
other sessions store nothing. Session meta is accessed via session vtable.

IPROTO_CHUNK response must have the same sync as a request, and to avoid
specifying it in the box.session.push() API, that is ugly, the request sync is
stored in the local storage of the fiber that executes the request. Sync key
does not extend the storage size - instead it shares one of storage cells with
another fiber local variable, that is never used in IProto sessions.

Vladislav Shpilevoy (10):
  yaml: don't throw OOM on any error in yaml encoding
  yaml: introduce yaml.encode_tagged
  yaml: introduce yaml.decode_tag
  console: use Lua C API to do formatting for console
  session: move salt into iproto connection
  session: introduce session vtab and meta
  port: rename dump() into dump_msgpack()
  session: introduce text box.session.push
  session: enable box.session.push in local console
  session: introduce binary box.session.push

 src/box/authentication.cc                |   4 +-
 src/box/authentication.h                 |   3 +-
 src/box/box.cc                           |   4 +-
 src/box/box.h                            |   2 +-
 src/box/iproto.cc                        | 268 ++++++++++++++++++++++++------
 src/box/iproto_constants.h               |   3 +
 src/box/lua/call.c                       |   4 +-
 src/box/lua/console.c                    | 105 ++++++++++++
 src/box/lua/console.h                    |  10 ++
 src/box/lua/console.lua                  |  63 ++++---
 src/box/lua/net_box.lua                  |  50 ++++--
 src/box/lua/session.c                    | 116 ++++++++++++-
 src/box/port.c                           |  24 ++-
 src/box/port.h                           |  29 +++-
 src/box/session.cc                       |  50 +++++-
 src/box/session.h                        | 111 ++++++++++---
 src/box/xrow.c                           |  13 ++
 src/box/xrow.h                           |  12 ++
 src/fiber.h                              |  14 +-
 src/fio.c                                |   2 +-
 src/fio.h                                |   2 +-
 test/app-tap/console.test.lua            |  10 +-
 test/app-tap/yaml.test.lua               |  51 +++++-
 test/box/net.box.result                  |   4 +-
 test/box/net.box.test.lua                |   4 +-
 test/box/push.result                     | 275 +++++++++++++++++++++++++++++++
 test/box/push.test.lua                   | 147 +++++++++++++++++
 test/replication/before_replace.result   |  14 ++
 test/replication/before_replace.test.lua |  11 ++
 third_party/lua-yaml/lyaml.cc            | 185 +++++++++++++++++----
 third_party/lua-yaml/lyaml.h             |  29 ++++
 31 files changed, 1426 insertions(+), 193 deletions(-)
 create mode 100644 test/box/push.result
 create mode 100644 test/box/push.test.lua

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