[PATCH] Refactor pgbench to make future improvements easier - Mailing list pgsql-hackers

Hi hackers,

`src/bin/pgbench/pgbench.c` has grown into a ~8,150-line monolithic source
file combining benchmark statistics, variable management, socket event
multiplexing, script/expression parsing and evaluation, meta-command
handlers, schema/data initialization, and the multi-threaded client state
machine.

This 7-patch series splits `src/bin/pgbench/pgbench.c` into focused,
self-contained compilation units while preserving exact behavior and all
existing tests:

1. `stats.c/h`: Extract `SimpleStats` and `StatsData` structures, latency
   and retry accumulation, and formatting helpers.
2. `variable.c/h`: Extract `PgBenchValue`, `Variable`, and `Variables`
   management, binary-search variable lookup, type coercion, and SQL query
   variable substitution (`assignVariables` / `getQueryParams`).
3. `poller.c/h`: Extract the `socket_set` abstraction and platform-specific
   `ppoll(2)` / `select(2)` socket multiplexing implementation.
4. `script.c/h`: Extract built-in script definitions, SQL and backslash
   meta-command parsing, Bison/Flex expression parser callbacks, and
   runtime expression evaluation (`evaluateExpr`, random distributions,
   hashing, and `permute`).
5. `commands.c/h`: Extract runtime meta-command execution (`executeMetaCommand`,
   `\set`, `\sleep`, `\if`/`\elif`/`\else`/`\endif`, `\shell`/`\setshell`),
   `\gset`/`\aset` result processing, and pipeline command preparation.
6. `init.c/h`: Extract `-i` initialization routines (`runInitSteps`), DDL
   table/index/partition creation, client-side and server-side data
   generation, and vacuum helpers.
7. `engine.c/h`: Extract the client connection state machine
   (`advanceConnectionState`), error/retry handling, worker thread loop
   (`threadRun`), progress/log reporting, and final results reporting,
   leaving `pgbench.c` (~978 lines) dedicated to CLI option parsing (`main`
   and `usage`).

Each step builds cleanly with both Make and Meson and passes all 686 TAP
tests in `src/bin/pgbench`.

This modularization also prepares a clean boundary for extracting pgbench's
random number distributions, hashing, and permutation routines into
`src/common` (`pgbench_funcs.c/h`) and exposing them in SQL via
`contrib/pgbench`.

Hannu Krosing (7):
  Refactor pgbench: extract statistics and latency tracking into
    stats.c/h
  Refactor pgbench: extract scoped variable store and value evaluation
    into variable.c/h
  Refactor pgbench: extract socket multiplexing and event poller into
    poller.c/h
  Refactor pgbench: extract script parsing and expression evaluation
    into script.c/h
  Refactor pgbench: extract meta-command execution and handlers into
    commands.c/h
  Refactor pgbench: extract initialization, schema, and data generators
    into init.c/h
  Refactor pgbench: extract execution engine, state machine, and thread
    runner into engine.c/h

 src/bin/pgbench/Makefile    |    9 +-
 src/bin/pgbench/commands.c  |  737 ++++
 src/bin/pgbench/commands.h  |   70 +
 src/bin/pgbench/engine.c    | 2141 +++++++++++
 src/bin/pgbench/engine.h    |  161 +
 src/bin/pgbench/init.c      |  786 ++++
 src/bin/pgbench/init.h      |   66 +
 src/bin/pgbench/meson.build |    7 +
 src/bin/pgbench/pgbench.c   | 7170 +----------------------------------
 src/bin/pgbench/pgbench.h   |  218 +-
 src/bin/pgbench/poller.c    |  196 +
 src/bin/pgbench/poller.h    |   48 +
 src/bin/pgbench/script.c    | 1973 ++++++++++
 src/bin/pgbench/script.h    |  253 ++
 src/bin/pgbench/stats.c     |  203 +
 src/bin/pgbench/stats.h     |  172 +
 src/bin/pgbench/variable.c  |  834 ++++
 src/bin/pgbench/variable.h  |  130 +
 18 files changed, 7902 insertions(+), 7272 deletions(-)
 create mode 100644 src/bin/pgbench/commands.c
 create mode 100644 src/bin/pgbench/commands.h
 create mode 100644 src/bin/pgbench/engine.c
 create mode 100644 src/bin/pgbench/engine.h
 create mode 100644 src/bin/pgbench/init.c
 create mode 100644 src/bin/pgbench/init.h
 create mode 100644 src/bin/pgbench/poller.c
 create mode 100644 src/bin/pgbench/poller.h
 create mode 100644 src/bin/pgbench/script.c
 create mode 100644 src/bin/pgbench/script.h
 create mode 100644 src/bin/pgbench/stats.c
 create mode 100644 src/bin/pgbench/stats.h
 create mode 100644 src/bin/pgbench/variable.c
 create mode 100644 src/bin/pgbench/variable.h

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2.56.0.rc1.315.gc6ed9934b7-goog