Optional interruption support#1039
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Adds an optional :resource-check function to SCI contexts. When provided, it is called on every loop/recur iteration and every fn-call dispatch. The function can throw to abort execution. This enables: - Iteration limits (prevent infinite loops) - Memory limits (via JVM getThreadAllocatedBytes in the callback) - External timeout (via Thread.interrupted check in the callback) - Per-context bounds (different sandboxes get different limits) The check is cached at function creation time (not looked up per call). When nil (default), zero overhead — the `when` branch is never taken. Overhead with amortized check (every 10K iterations): ~2.5x on tight loops. With every 100K: ~10%. For real workloads: negligible. Changes: - opts.cljc: add :resource-check field to Ctx record, wire through init - fns.cljc: call resource-check on each recur in gen-fn macro - evaluator.cljc: call resource-check on fn-call dispatch
- Rename the option to :interrupt-fn throughout (opts, fns, evaluator) - Move the check to the top of gen-fn's loop: fires on every function entry (initial call) AND every recur, covering direct recursion, mutual recursion, dotimes, while, and loop/recur uniformly - Remove the check from fn-call: it was only reachable for 20+ arg calls (gen-return-call generates direct (f ...) calls for 0-19 args), so the original placement was both insufficient and added overhead for existing users — now fn-call is truly zero-cost for nil :interrupt-fn - Add rc# capture to arity-many (20+ arg) fallback in gen-fn - Fix merge-opts to preserve :interrupt-fn when not overridden - Add interrupt_fn_test.cljc covering recur, dotimes, direct recursion, mutual recursion, nil default, fork, and merge-opts propagation
…ll/dorun/count/into/reduce When :interrupt-fn is provided, opts/init installs interruptible versions of nine clojure.core functions that would otherwise bypass the interrupt mechanism by running entirely host-side: Producers: range, repeat, cycle, iterate Materializers: doall, dorun, count, into, reduce Each wrapper calls store/get-ctx at invocation time to read :interrupt-fn, so fork and merge-opts work correctly. When :interrupt-fn is absent the original host functions are used unchanged — zero overhead for existing users. counted? collections (vectors, maps, sets) take the fast O(1) path in count. reduce supports reduced for early termination.
borkdude
reviewed
Apr 17, 2026
borkdude
reviewed
Apr 17, 2026
- Restore unrelated TODO and prn debug comments in fn-call macro that were accidentally removed when the resource-check block was removed. - Use (when (some? interrupt-fn#) ...) instead of (when interrupt-fn# ...) in gen-fn hot paths — faster on CLJS, semantically equivalent since interrupt-fn# is always either a fn or nil.
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Adds
:interrupt-fncallback for per-context execution bounding (fixes #1038).An optional
:interrupt-fnin the SCI context options is called on every function entry. The function can throw to abort execution, enabling iteration limits, memory limits, and external timeout checks — independently per context.The check is captured as a closed-over local at function-creation time, so it is a free nil test when not configured: zero overhead for existing users.
Coverage:
loop/recur,dotimes,while, direct self-calls, mutual recursion.merge-optsandforkpreserve the callback.I have read the developer documentation.
This PR corresponds to an issue with a clear problem statement.
This PR contains a test to prevent against future regressions.