[pgpool-committers: 8329] pgpool: Implement flush tracking feature.

[Tatsuo Ishii]

Implement flush tracking feature.

When a flush message arrives from frontend, any pending message from
backend should be flushed and sent to frontend. In order to do that,
this commit implements "flush tracking" feature. i.e. when a flush
message arrives, pgpool sets "flush pending" flag in each pending
messages. If the response message from backend corresponds to the
pending message with the flush pending flag being set, the message is
immediately flushed to frontend, rather than buffered.

Discussion: https://www.pgpool.net/pipermail/pgpool-general/2022-January/008026.html

Branch
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master

Details
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https://git.postgresql.org/gitweb?p=pgpool2.git;a=commitdiff;h=f9521fe49131a0bd7c7d63d6c050c2edfca5155c

Modified Files
--------------
src/context/pool_session_context.c         | 21 ++++++++++++++++++-
src/include/context/pool_session_context.h | 13 +++++++++++-
src/protocol/pool_process_query.c          | 33 ++++++++++++++++++++++++------
src/protocol/pool_proto_modules.c          |  4 ++++
4 files changed, 63 insertions(+), 8 deletions(-)