[pgpool-committers: 3689] pgpool: Fix packet kind does not match error in extended protocol per b

[Tatsuo Ishii]

Fix packet kind does not match error in extended protocol per bug 231.

According to the bug231, the bug seem to bite you if all of following
conditions are met:

  - Streaming replication mode
  - Load balance node is not node 0
  - Extended protocol is used
  - SELECT is executed, the statement is closed, then a transaction
    command is executed

The sequence of how the problem bites is:

  1) SELECT executes on statement S1 on the load balance node 1
  2) Frontend send Close statement
  3) Pgool-II forward it to backend 1
  4) Frontend sends Parse, Bind, Execute of COMMIT
  5) Pgool-II forward it to backend 0 & 1
  6) Frontend sends sync message
  7) Pgool-II forward it to backend 0 & 1
  8) Backend 0 replies back Parse complete ("1"), while backend 1
     replies back close complete ("3") because of #3.
  9) Kind mismatch occurs

The solution is, in #3, let Pgpool-II wait for response from backend
1, but do not read the response message. Later on Pgpool-II's state
machine will read the response from it before the sync message is sent
in #6. With this, backend 1 will reply back "1" in #8, and the kind
mismatch error does not occur.

Also, fix not calling pool_set_doing_extended_query_message() when
receives Close message.  (I don't know why it was missed).

New regression test "067.bug231" was added.

Branch
------
V3_6_STABLE

Details
-------
http://git.postgresql.org/gitweb?p=pgpool2.git;a=commitdiff;h=9274f827ea28e12968158e1c56f6d7a7b1227570

Modified Files
--------------
src/context/pool_query_context.c                   |  5 ++-
src/protocol/pool_proto_modules.c                  |  5 +--
.../regression/tests/067.bug231/TestReplGap.java   | 29 +++++++++++++++
src/test/regression/tests/067.bug231/test.sh       | 41 ++++++++++++++++++++++
4 files changed, 77 insertions(+), 3 deletions(-)