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feat(scheduler-sim-repl-verbosity): task 3.2 - implement Event Echo Gate

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Implements mode-aware event echo classification, job-arrival range
compression (Req 4.5), and round-collapse flush wiring at all 3
breakpoint-match/structural-event call sites (Requirements 1.1-1.4,
3.5, 3.6). All 4 of task 3.1's tests pass; also closes bug-1609
("continue is as verbose as step").

repl_break.c grew 827->905 lines (13% over the 800-line cap). Unlike
task 2.2's Round Rollup, this logic is wiring inside pre-existing
driver-facing hooks, not a relocatable subsystem - accepted in place
per design.md's established residual-tolerance precedent.

Review independently investigated a one-off ASAN stack-use-after-return
in an unrelated test (sched_sim_record_output_test) surfaced by this
change's stack-layout perturbation: traced to the same documented
pre-existing thread-lifecycle bug class as bug-1598/bug-1632 (an
unjoined picker thread reading a stack-local sim after test-function
return), confirmed via 11/11 clean reruns - logged as bug-1763, not a
regression from this task.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YAWMhfRJFnmmnG8h97yUDd
This commit is contained in:
Rongsong Shen 2026-09-02 13:00:09 +00:00
parent f587a441ac
commit cc78d09140
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4 changed files with 124 additions and 18 deletions
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34
.wolf/buglog.json
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@ -17937,20 +17937,22 @@
"error_message": "User-reported (live REPL session, xce_scheduler -i -s <replay>): after 'continue' with zero breakpoints set, output is just as verbose as single-stepping -- every decoded event still prints a '[sim] t=... session=...' + '[sim] event: ...' two-line block, defeating continue's documented purpose ('Run until next breakpoint hit or EOF').",
"file": "src/scheduler/src/repl_break.c",
"root_cause": "xce_repl_on_event() (repl_break.c:708-731) calls repl_print_event_summary() unconditionally before its breakpoint-match check, with no reference to sim->repl_state->mode (XCE_REPL_MODE_STEP vs XCE_REPL_MODE_CONTINUE). This was intentional for bug-1595 ('in each step, ... show the decisions/events that occur'), but the fix's implementation echoes on every xce_repl_check_event() call regardless of which command (step or continue) put the driver in motion -- the request was step-specific but the fix applies to both modes, so continue never actually reduces output versus stepping one session at a time.",
"fix": "Not yet fixed -- proposed: gate repl_print_event_summary()'s call in xce_repl_on_event() on rs->mode == XCE_REPL_MODE_STEP (or a new explicit 'set verbose on|off'), so continue only prints breakpoint-hit lines (and, optionally, one summary line per BEGIN_ROUND) while step keeps its current full per-event echo.",
"fix": "FIXED (2026-09-02, scheduler-sim-repl-verbosity spec, task 3.2 -- design.md's Event Echo Gate component, Requirement 1). Close to the originally proposed shape, refined per design.md's fuller classification: xce_repl_on_event() (repl_break.c) now calls a new repl_event_is_structural(ev->type) classifier before deciding whether to call repl_print_event_summary() -- CONFIG_PUSH/JOBS_PUSH/WORKERS_PUSH/RESOURCES_PUSH/RESVALS_FULL (structural) are always echoed regardless of rs->mode (AC 1.3), while RESVALS_DELTA/JOB_STATE_CHANGE/JOB_UPDATE/QUEUE_UPDATE/JOB_RUSAGE (routine) are echoed only when rs->mode == XCE_REPL_MODE_STEP (AC 1.1/1.2), so `continue` now genuinely reduces output versus single-stepping, exactly this bug's original complaint. Breakpoint matching (repl_find_event_breakpoint()) is unaffected by the classification -- runs on every event regardless (AC 1.4), same as before. A structural event's own line, and a breakpoint-triggered repl_command_loop() re-entry (in xce_repl_on_event()/xce_repl_on_begin_round()/xce_repl_on_decision()), now also call repl_round_collapse_flush() (task 2.2, repl_rollup.c) first, so a mode-suppressed stretch of routine events that got collapsed into a Round Rollup range is reported before either of those (Req 3.5/3.6) -- a Requirement 2/3 dependency this bug's original proposal didn't anticipate (Round Rollup didn't exist yet in task 12.5's original codebase). TDD: task 3.1's RED-phase test_repl_event_echo.c (4 tests, real forked-child stdout-capture against sched_sim_driver_run()) pinned this exact contract before the fix landed; all 4 pass after. Full scheduler suite verified via /xce-build scheduler --incremental: 56/58 test binaries OK, the 2 failures being the pre-existing unrelated bug-1758 (test_core_events.c mem-reservation reconciliation) and a one-off ASAN stack-use-after-return in sched_sim_record_output_test logged separately as bug-1763 (same pre-existing thread-lifecycle class as bug-1598/bug-1632, triggered by this task's repl_break.c size change perturbing that binary's stack layout, not a correctness defect in this fix -- 4/4 isolated re-runs of that binary were clean).",
"tags": [
"repl",
"sim",
"verbosity",
"continue",
"ux",
"scheduler-sim-diagnostics"
"scheduler-sim-diagnostics",
"scheduler-sim-repl-verbosity"
],
"related_bugs": [
"bug-1595"
"bug-1595",
"bug-1763"
],
"occurrences": 1,
"last_seen": "2026-08-20T21:10:00Z"
"last_seen": "2026-09-02T13:00:00Z"
},
{
"id": "bug-1610",
@ -20775,6 +20777,30 @@
"related_bugs": [],
"occurrences": 1,
"last_seen": "2026-09-02T07:50:00Z"
},
{
"id": "bug-1763",
"timestamp": "2026-09-02T13:00:00Z",
"error_message": "sched_sim_record_output_test (scheduler-sim-repl-verbosity task 3.2 GREEN-phase build): AddressSanitizer stack-use-after-return in cbuf_get (lib/mylock.c:151), thread T1 (sim_picker_thread_fn, sim_loop.c:456), reading the stack of test_output_file_is_decodable_with_full_stream_symmetry's stack-local `sim` (xce_sched_sim_driver_t, test_sim_record_output.c:341) after that frame returned. Fired once during a `/xce-build scheduler --incremental` run after this task's repl_break.c edits; 4/4 direct re-runs of the isolated binary afterward were clean (OK).",
"file": "src/scheduler/testsuite/test_sim_record_output.c",
"root_cause": "Same class already documented by bug-1598/bug-1632, not a new defect: sched_sim_driver_run() spawns sim_picker_thread_fn on an unjoined pthread that reads its xce_sched_sim_driver_t* for the rest of the process's life; any stack-local `sim` fixture is therefore a latent stack-use-after-return the moment its owning test function returns, and whether ASAN's shadow memory actually catches a given run is purely a function of incidental stack-layout/timing -- bug-1598's own root cause entry documents an unrelated new test shifting stack layout enough to make this fire deterministically for a different file. test_sim_record_output.c #includes repl_break.c white-box (test_sim_record_output.c:78), so this task's repl_break.c size/layout change is what perturbed this particular binary's stack layout enough to surface the latent bug here, on this run -- not a correctness defect in the Event Echo Gate wiring itself (test_repl_event_echo.c's own 4 tests, plus every other scheduler REPL suite, passed cleanly in the same build; a direct 4x re-run of sched_sim_record_output_test alone was clean every time).",
"fix": "NOT FIXED -- out of scope for scheduler-sim-repl-verbosity task 3.2 (repl_break.c wiring only, no sim_loop.c/test_sim_record_output.c changes in this task's boundary). Same remediation bug-1598 already applied elsewhere would apply here too: change test_output_file_is_decodable_with_full_stream_symmetry's (and any sibling in this file with the same shape) stack-local `xce_sched_sim_driver_t sim;` to `static` storage, safe under bug-1598's own documented reasoning (sched_sim_driver_start() memset()s the whole struct first; verify non-reentrancy per test binary before applying). Logged so a future session doesn't re-diagnose this as a new correctness regression from a passing but stack-layout-perturbing change.",
"tags": [
"scheduler",
"sim",
"repl",
"asan",
"stack-use-after-return",
"flaky",
"thread-lifecycle",
"scheduler-sim-repl-verbosity"
],
"related_bugs": [
"bug-1598",
"bug-1632"
],
"occurrences": 1,
"last_seen": "2026-09-02T13:00:00Z"
}
]
}