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fix(scheduler): cache hits keep the full pend reason; sim uses the cache (bug-1932)

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The session-level unsatisfiable-resreq cache stored only the exhausted
attempt's main reason (an int). The allocators record shortfalls as
per-host/per-resource entries and leave main_reason at 0, so every cache
hit in the live scheduler pended its job with an empty reason. The
simulator registered no cache at all (its table lived on xce_scheduler_t),
so it searched every identical pending job again and its traces differed
from production.

- The cache table moves to xce_sched_core_t; cache_lookup/insert/clear and
  the hook adapters take the core, with no cast to a driver struct.
  sched_init() builds it, cache_clear() rebuilds it per session,
  xce_sched_core_fini() destroys it.
- A cache entry is a deep copy of the attempt's full xce_job_preason_t
  plus the job that proved the request unsatisfiable (core->alloc_jobid,
  set by sched_allocator()). A hit moves a copy into ctx->reason; a miss
  leaves ctx->reason untouched.
- main.c passes the same three adapters to the simulator through new
  sched_sim_args_t fields; sched_sim_driver_start() sets them on the sim
  core (plain field writes: white-box tests include sim.c alone).
- Decision trace: a hit renders "no plan generated: skipped, same request
  as <job> proved unsatisfiable earlier this session" (new
  XCE_TRACE_NOPLAN_KNOWN_UNSAT via sched_trace_known_unsat()); the outcome
  shows the restored reasons.
- sim_verify keeps its main-only PEND compare (old recordings carry
  main-only hits); comments and the scheduler-sim-live-allocation design
  note updated.

Tests: full-reason assertions in the cache dispatch tests (RED before:
"a cache hit must restore the original attempt's FULL pend reason"),
test_alloc_cache.c ported to the new API (deep copy, clear frees, -EEXIST
frees), a sim-registered clear test, a renderer test, and a sim e2e
scenario with two identical unsatisfiable jobs (204, 205) where 205 is
skipped with 204's full reasons (RED before: no skip line).

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
This commit is contained in:
Rongsong Shen 2026-10-09 08:02:18 +00:00
parent cff3304f5d
commit 0317c7af98
Signed by untrusted user: rshen
GPG key ID: 80533536B0EB651C
27 changed files with 982 additions and 737 deletions
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6
src/include/preason.h
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@ -62,9 +62,9 @@ extern void erase_preason_index(xce_preason_index_t*);
*
* The scheduler simulator (--sim-verify, sim_verify.c) deliberately does NOT
* use this function for its PEND outcome check: it compares main_reason only
* (bug-1845), because a recorded alloc-cache-hit PEND carries only the main
* reason while the simulator (which has no alloc cache) always builds the
* full detail lists. That loosening is a replay property, not object
* (bug-1845), because a recorded PEND and its replay can legitimately carry
* different detail (an alloc-cache hit recorded before bug-1932 carries only
* the main reason). That loosening is a replay property, not object
* identity, so it stays simulator-local.
*
* NULL handling: identical pointers (including two NULLs) are equal; exactly