Revision history for Shared::Arena

0.14	2026-10-05
        - FIXES a map write dropped under contention: a store, incr or delete
          whose stripe was held burned 100k test-and-sets and gave up. A
          FreeBSD smoker counted 38 of 40 and an Alpine one 999 of 1000, in a
          table of 64 slots holding six keys.
        - The write path's wait escalates, 50us to 2ms over ~10ms, as the carve
          path's has since 0.13. Shorter than the carve path's two seconds on
          purpose: a store is on a per-request path.
        - A write refused for a held stripe answers SA_MAP_STORE_BUSY (-3) and
          counts `busy`. It answered SA_MAP_STORE_FULL before, and incremented
          no statistic at all, so `stats` showed a clean map while writes went
          missing: full means stop, busy means try again.
        - Map->delete returns undef for a refused stripe, 0 for a key that was
          not there. Both false, so a speculative delete is unaffected.
        - FIXES t/32-map-ttl.t asserting a count from an unmeasured window: the
          burst after the deadline has to fit inside the ttl it counts inside.

0.13	2026-09-22
        - FIXES two carves refused in four thousand on a loaded FreeBSD 15
          smoker, with room in the arena for all of them. 
        - A carve refused for a held stripe answers SA_E_BUSY, not SA_E_FULL:
          one means try again, the other means stop.
        - Add Shared::Arena::_last_err: why the last ->region returned empty.
        - FIXES t/32-map-ttl.t counting three hits where it asked for two.

0.12	2026-09-20
        - FIXES a waker slot outliving its owner. Nothing released a slot when
          a process was killed or _exits, so `live` stayed set for a process
          that was gone and the next taker of that index was refused 

0.11	2026-09-19
        - Add wake_init, wake_take, wake_fd and wake_drained to the C ABI (4).
        - Add map_incr_ttl to the C ABI and ttl => to Map->incr: a fixed window in one call.
        - Add rate_counts to the C ABI.
        - Add map_incr_at to the C ABI (5): map_incr_ttl on the caller's clock.
        - A counter under the stripe lock is a load and a store, not an atomic add.
        - Publish SA_READ_*, SA_MAP_STORE_*, SA_CACHE_*, SA_ERR_* and SA_TYPE_* in sa_abi.h.
        - Add Shared::Arena::_region_ptr.
        - A drain or claim at a hole never sleeps; Cursor->drain takes wait => 0.
        - A publish walks only the wakers that have pipes, and no registry when there are none.
        - The peer row is written with stores on publish, not read-modify-writes.
        - Deadlines read CLOCK_REALTIME_COARSE where it exists.
        - FIXES a region with a lease refusing wakers: the registry compared
          reserved names only up to their leading NUL.

0.10	2026-09-19
        - FIXES six files failing at once on the FreeBSD 5.14 and 5.16 smokers:
          Makefile.PL's pthread_atfork probe only linked, and FreeBSD's libc
          stub links and never runs without libthr, so a child kept its
          parent's cached pid. The probe now forks and requires the child
          handler to have run, linking -lpthread where that is what it takes.
          t/06-fork.t asserts it first, through a _pid probe.
        - FIXES the ABI selftest (step 25) on 32-bit Linux: the HyperLogLog
          estimates compared unequal under x87 excess precision. Now volatile.
        - FIXES t/32-map-ttl.t on a perl without 64-bit integers: pack 'Q'.

0.09	2026-09-17
        - FIXES a panic on every DEBUGGING perl: Map's stats reserved ten
          stack slots with EXTEND(SP, 10) and pushed twelve (six pairs), so
          t/14 and t/32 aborted after their assertions passed. A non-DEBUGGING
          perl overran the stack silently. Now reserves twelve.

0.08	2026-09-16
        - Add serialise => 1 to Cache and Map: a value can now be any Perl structure
          and comes back as the same structure, through Struct::Codec, which is
          now a prerequisite. 

0.07	2026-09-16
        - FIXES a smoker FAIL in t/08-mpsc.t. It asserted that two children's
          sequence ranges overlapped, which is the host's scheduling and not
          the ring's promise: where the storm is shorter than a timeslice the
          children run one after another. It now asserts what the sequence
          counter guarantees - every child published and was handed a range at
          least as wide as its records - and reports the overlap. The children
          give the processor up a few times mid-loop so that they interleave
          on a host that cannot run them at once.
        - t/08-mpsc.t no longer requires the reader to have been lapped, which
          is the same kind of guess; it requires that nothing went missing
          quietly.

0.05	2026-09-15
        - FIXES the build on a C89 compiler, gcc 4.2.1 on the FreeBSD 9 smoker,
          which refused 0.03 and 0.04 with "redefinition of typedef": four
          tenants typedef-named their struct where the ABI header forward
          declares it.i

0.04	2026-09-11
        - Add Shared::Arena::HyperLogLog, how many distinct keys in a few
          kilobytes: an add is a lock-free max, so a pool shares one sketch
          with nothing to contend on, and two sketches merge into their union.
        - ABI version 3.
        - FIXES two smoker FAILs on a two-processor box. t/22-cache.t let
          children churn while a sibling was still reading; they now wait
          until every read is reported. t/08-mpsc.t asserted the READER saw
          several children, which needs the parent scheduled mid-storm; it
          now asserts the children's sequence ranges overlapped.

0.03	2026-09-11
        - Add Shared::Arena::Cuckoo, a shared filter that can remove a key.
        - Add Shared::Arena::Scoreboard, one row per worker published live:
          each worker writes its own row with no lock, a supervisor reads the
          whole board in one pass
        - Add Shared::Arena::Lease, leader election: one holder at a time and
          a successor when the holder dies, with a fencing token.
        - Shared::Arena::Map store takes ttl / ttl_ms, a per-key deadline after
          which the key reads as absent everywhere; expiry is lazy and counted
          in the new `expired` stat, and an expired counter resets on incr.
        - Cache reads scale across processes. A hit wrote a counter every
          process shares; counts are now published every 64. Eight processes
          reading one key: 530ns a get before, 87ns now.
        - A cache get reads the clock only for an entry with a ttl, and a get
          or fetch no longer allocates on a miss. A cache miss: 51ns to 29ns.
        - FIXES a double free under ithreads: a new thread cloned every handle
          and freed it on exit, unmapping the arena under its creator. Handles
          are no longer cloned; a thread attaches by name.

0.02    2026-09-11
        - FIXES the Windows FAIL in 0.01. Three test files forked without
          skipping on MSWin32, where fork is emulated with threads: a child
          calling exit ends the whole file, so every assertion passed, no plan
          was printed, and the harness called it a FAIL.
        - FIXES a test that failed 9 runs in 12 on a two-processor container
          and 0 in 12 here. It had four children write 2000 churn keys into a
          512-entry cache to force eviction, then asserted an entry written
          before that churn had survived it. The children report through a
          pipe now; eviction is still asserted, where it belongs.
        - FIXES carving a region being refused under contention. The stripe
          lock is a pure spin, so with more carvers than cores the budget
          burned while the holder was not scheduled
        - FIXES a test using pack('Q<'), which is a fatal "Invalid type" on a
          perl built with ivsize=4.


0.01    2026-09-10
        - First version.