Timeline

A docs page for sparse cones and horizons: concepts, the library API, the CLI, interop with zit and fossil 2.28, and the limits as they stand. check-in: 441604df52 user: [email protected] tags: feat/horizon-cones, trunk

The page described the leaves rule as each childless check-in's ancestry back to its meeting point with C, the rule before zit#265. The rule at the pinned draft holds every descendant of each meeting point, which is why it holds nearly all of fossil-scm.org's history: old unmerged branches fork near the root. check-in: 097153487d user: [email protected] tags: feat/horizon-cones, trunk

The structural horizon's seed (draft-fossil-horizon-00 §5.2): an origin mints a control artifact carrying the tags in force at every entry of the held set, a clone holds it outside the artifact store where no sync, clone or rebuild can reach it, and the derivation applies it so every check-in in K derives as it does densely. Byte-identical to zit's seed when the latest summarized event is on a whole second. Conflicts in the horizon suite and table kept both sides; the seed's zit test now probes for a horizon-capable zit like the other horizon interop tests. check-in: 12dcbdeed6 user: [email protected] tags: feat/horizon-cones, trunk

deck.Marshal writes D to the millisecond, so a go-libfossil seed could never match zit's bytes or name even over identical state. Mint now writes D as YYYY-MM-DDTHH:MM:SS, keeping the round-up to the next whole second that Section 5.2.2's "no earlier than the latest tag event" needs, and recomputes Z over the body. Over whole-second tag events the seed is now byte-identical to zit's, which the interop test asserts for the full seed and its name. check-in: 038e50befb user: [email protected] tags: feat/horizon-cones, trunk

The cursor slice keeps a client's horizon cursor per origin, named by the internal SyncOpts.Origin, but the public Repo.Sync never set it, so a library or CLI sync kept no cursor and every request announced in full. The HTTP transport now names its peer by its URL with any password removed, as last-sync-url keeps it, and Sync passes that through. Other transports name no origin and keep announcing in full, which §6.2.6 allows. The test pulls with a credential-bearing URL and finds the cursor under the password-free one, and no config row holding the password. check-in: 331b540f1c user: [email protected] tags: feat/horizon-cones, trunk

The horizon cursor (draft-fossil-horizon-00 §6.2.6): an origin that classified a request answers pragma horizon-cursor with its position, a converged client records it per origin and cone and sends it back, and neither side announces again what the other already has. Interoperates with zit both ways. check-in: f704c6d58b user: [email protected] tags: feat/horizon-cones, trunk

A horizon pull announced the client's whole holding with igot on every request, and the origin answered with its whole kept inventory: one card per artifact, both ways, on every pull. draft-fossil-horizon-00 §6.2.6 replaces both with a position.

The origin values pragma horizon-cursor right after horizon-served in every reply to a horizon pull, as zit places it. Its position is rid order (the clone SEQNO sense), stopped short of the lowest phantom: a filled phantom keeps its old rid, so a cursor covering it would hide the arrival. Receiving a cursor, any reply that pulls announces nothing at or below it. A filled phantom that a check-in from an earlier receipt already named as parent is recorded as the reclassification position; a cursor below it is answered as if absent. A cursor beyond the origin's own position is ignored.

The client keeps, per origin and cone, the last reply's cursor and the rid count the origin holds through, sends the cursor on every request, announces nothing on a pull-only request and only what it appended on one that sends. Sessions name their origin with SyncOpts.Origin; without it nothing is kept and every request announces in full. check-in: b61bd3475c user: [email protected] tags: feat/horizon-cones, trunk

TestZitHorizonInterop took whatever zit was on PATH. A zit release from trunk reports the same version as the horizon-rfc build but has no --horizon flag, so the test failed in zit's argument parser. The new zitHorizonBinary probes the binary for horizon support, as zitBinary already probes for send-submanifests, and skips it, or fails the run under REQUIRE_ZIT_BIN=1, with the reason. check-in: 27b85364f2 user: [email protected] tags: feat/horizon-cones, trunk

The public horizon API in the shape approved: a horizon is part of Cone (NewHorizonCone, Cone.Horizon, Cone.WithHorizon), store cones carry it through SetStoreCone and SetStoreConeContext and the new CloneOpts.StoreCone, checkout cones refuse it with ErrHorizonCheckout, and the CLI takes --horizon and --leaves on repo clone and repo cone store and --no-horizon on repo cone store. check-in: 964b91f682 user: [email protected] tags: feat/horizon-cones, trunk

A store cone could carry a horizon only through internal/cone, so library users and the CLI had no way to clone into or edit a content-horizon store. Add Horizon, HorizonRule, NewHorizonCone, Cone.Horizon and Cone.WithHorizon over the internal cone (always the content cut), carry it through SetStoreCone/SetStoreConeContext (deepening fetches what the older check-in keeps) and CloneOpts.StoreCone, and add --horizon, --leaves, --no-horizon and --cone to repo clone and repo cone store.

A horizon is a property of the store, not of a checkout (draft-fossil-horizon-00 3.2), so checkout cones carrying one are refused with ErrHorizonCheckout, and widening the store from a checkout cone keeps the store's horizon. check-in: e5904fc85b user: [email protected] tags: feat/horizon-cones, trunk

Appendix A step 3 without the cursor: the client sends pragma horizon, the origin computes the held set over its dense graph, sends only the blobs above the horizon, inflates crossing deltas, sends no cluster, answers horizon-served content and refuses what it cannot cover (§6.4). Against a horizon-ignorant origin the client requests what its clusters name, as transit (§4.5 after zit#266). Interoperates with zit both ways. check-in: 84be5ad824 user: [email protected] tags: feat/horizon-cones, trunk

A structural-horizon clone lacks C's ancestry, so tag propagation has nowhere to start: every check-in in K would derive no branch, and closed markers and names set below C would vanish. The seed of draft-fossil-horizon-00 Section 5.2 restates the dense tag state at each entry of K so the unmodified derivation comes out exact.

internal/horizon/seed mints it at an origin (T cards per row in force at C and each check-in of K whose primary parent is outside K; D the latest summarized event rounded up to a whole second; U the origin's login), and holds it at a clone in a table of its own, outside the artifact store, so nothing that enumerates or serves artifacts can send it. It is applied when held, by Rebuild, and by seed.Apply, which the sync layer calls after each round. Replacing or discarding a seed re-derives the store, since only a re-derivation separates the old seed's rows from those real artifacts wrote. A Verifier hook carries the Section 5.2.4 provenance policy; no signing is implemented.

The crosslink-table clearing moves from verify into manifest.Rederive so Rebuild and the seed share one owner of re-derivation. The cards match zit's seed byte for byte in T and U, and each implementation derives from the other's seed what it derives from its own. check-in: 45fb2c7ed4 user: [email protected] tags: feat/horizon-cones, trunk

The Appendix A step 4 measurement: an opt-in corpus test reporting what a structural horizon saves over a content horizon at several depths. check-in: 5430186930 user: [email protected] tags: feat/horizon-cones, trunk

Opt-in corpus test (LIBFOSSIL_CORPUS) for draft-fossil-horizon-00 Appendix A step 4: for C at 10, 100 and 1000 check-ins back along trunk's primary-parent chain and at the check-in nearest a year before the tip, compare a content horizon's transfer with a structural horizon's under both held-set rules. It works on a copy of the repository. The seed is estimated as one control artifact with one T card per tag in force at each entry of K, uncompressed.

fossil-scm.org clone: 67894 artifacts, 37.2 MiB stored, 8425.2 MiB expanded (21008 manifests, 8.9 MiB stored, 1099.8 MiB expanded; no sub-manifest nodes; 6263 other structure, 691 clusters). Runtime 58s, peak heap 161 MiB. Share = (content - structural) / content.

descendants rule K below (n / MiB exp) content MiB exp structural MiB exp share exp share stored 10 back 12 20996 / 1098.9 1136.5 37.6 96.7% 49.0% 100 back 121 20887 / 1089.9 1262.0 172.1 86.4% 48.5% 1000 back 1746 19262 / 962.2 2341.0 1379.0 41.1% 40.0% 1 year (426 back) 796 20212 / 1036.1 1846.3 810.3 56.1% 44.5%

leaves rule: K = 20907 of 21008 at every depth; share 0.0% expanded, -7.7% stored (the seed outweighs the 101 manifests below). check-in: c6ef4af29f user: [email protected] tags: feat/horizon-cones, trunk

The re-pinned §4.5 (zit#266) splits the cluster rule by origin. An origin that says horizon-served announces what it keeps directly, so a horizon store must not request a name only a cluster gives it. A horizon-ignorant origin, fossil(1) among them, folds 100 or more unclustered artifacts into a cluster as it answers a pull and announces only the cluster, so a new check-in may be named nowhere else: the store must request what the cluster names, as transit, and classify what arrives. A horizon store acted on no cluster from either, and so never received such a check-in from fossil.

CrosslinkCluster now mints member phantoms in every store, as fossil does; the received-file filter already drops the cluster and the blobs below the horizon at the end of the transfer. Whether to act on a cluster is decided where the origin is known: once a reply of the session says horizon-served content, the sync client asks for no cluster catalog and the sync and clone clients store no cluster file card, so no cluster-only phantom is minted from such an origin.

A real fossil(1) case pulls a leaf announced only through the cluster fossil makes, and holds it and its blob without holding the cluster. check-in: 588d5b264e user: [email protected] tags: feat/horizon-cones, trunk

A horizon store asked every peer for the whole history and threw away what fell below C on arrival, so a horizon clone cost a dense clone's bandwidth. draft-fossil-horizon-00 §6 lets the request carry the horizon and the origin restrict what it sends.

The client sends `pragma horizon HASH RULE` after its path-cone pragmas on every clone and pull, never horizon-structural, and counts the replies that say `pragma horizon-served content` (HorizonServed on the clone and sync results, internal and public). It still classifies every reply locally, so a horizon-ignorant peer stays correct (§6.3).

The handler reads the pragma into the request's cone and serves it through the existing keep machinery rather than a parallel path: the pull inventory's keep set drops the blobs below the horizon (via ConeReferences.HorizonBelow) and every cluster; the clone walk walks the tree of a held-set check-in only, counts a parent as sent only inside the held set, and sends every sub-manifest node at its row while sending no cluster. A crossing delta is inflated through the same sourceKept test the path cone uses, charged to the round's batch. req-clusters under a horizon answers nothing, and every reply says horizon-served content.

A horizon store refuses, through refuseClone, a dense clone and a horizon whose held set is not inside its own, both computed over the store with horizon.Place. That is the spec's subset test; zit refuses any other C or rule. A path-only store now also refuses a horizon-only request, which keeps every path.

Interop with zit at horizon-rfc bbd1435674 holds both ways: zit clones and pulls at a horizon from the handler, the client from `zit serve`, and each side's horizon store refuses the other's dense clone. check-in: 352a0d9e0b user: [email protected] tags: feat/horizon-cones, trunk

zit#266 reported that a horizon clone pulling from stock Fossil never learns a check-in Fossil announced only inside a cluster: xfer.c clusters 100 or more unclustered artifacts and then announces only the cluster. §4.5 at 9bf7ebfe0f binds the cluster prohibition to an origin whose replies carry horizon-served, and has the clone request a horizon-ignorant origin's cluster members as transit and classify what arrives. HZ-4.5-1 is restated; implementing it waits for horizon-served, which the horizon pragmas bring. The sync draft on that branch differs from the trunk copy pinned here only by §9's editorial list of extension pragma names. check-in: d5926b325c user: [email protected] tags: feat/horizon-cones, trunk

A content-horizon store against any peer: below-horizon blobs it is sent are recorded as elided rather than stored, it holds and requests no cluster, and a below-horizon blob an operation needs is fetched on demand. check-in: 27b8439777 user: [email protected] tags: feat/horizon-cones, trunk

No peer speaks the horizon pragmas yet, so a content-horizon store receives whatever a dense peer sends (draft-fossil-horizon-00 §6.3). The received-content filter now applies the horizon's classification, read from internal/content rather than re-derived: blobs below the horizon become elided phantoms and are counted in the result's Elided. Blobs no held manifest names yet stay as unreferenced holdings, and retained delta bases stay transit (§4.2).

A horizon store also acts on no cluster (§4.5). Crosslinking a cluster applies its tag but makes no member phantoms. The filter drops the cluster's content, and classification elides any phantom that carries the cluster tag. The client stops sending req-clusters. Path-cone-only stores keep today's cluster behaviour.

Conformance cases run against go-libfossil's handler and fossil(1): clone and pull, deepen, demand fetch through UpdateContext, transit deltas, and cluster rules. check-in: f1f4240f40 user: [email protected] tags: feat/horizon-cones, trunk

Sparse-store classification sized to what it proves rather than to the store: file content is never read, completely linked check-ins answer from the crosslink tables, and a content horizon reads only its held set's trees. A path-cone store of fossil-scm.org classifies in about 2 s at a 65 MiB peak, where v0.14.0 failed with a byte-budget error. check-in: cd1b25e114 user: [email protected] tags: feat/horizon-cones, trunk

Sparse classification read, inflated and delta-expanded every held blob, file content included, under a whole-store byte budget. On a clone of the Fossil SCM repository (67,894 blobs, 8.4 GB expanded) LoadAbsences failed at once with "byte budget exceeded", so no path-cone or content-horizon store of a real repository could classify its phantoms, and pull, verify and compaction failed with it.

Reference facts now come from the tables wherever they provably stand in for raw cards. A blob the crosslinker recorded as no artifact and mlink names as a file version is never read. A completely linked check-in (event row, no orphan row, a primary parent edge) whose primary parent and baseline trees are themselves reproduced contributes its mlink rows as F cards and its plink, cherrypick and tagxref rows as references; by induction over the primary chain those rows give the same (name, file) pairs as its raw cards. Everything else is still read raw: unlinked and orphaned check-ins, roots, check-ins whose parent never arrived, other artifacts, and every check-in once the store has seen a sub-manifest, since trees are not crosslinked. Budgets are charged per round for the selected blobs and their delta ancestors only, and a base's bytes are released once its last delta is applied.

A content horizon now reads only its held set's manifests and the baselines and nodes they reach, on demand, with one visited set and a byte budget scaled to the held set.

On the Fossil SCM clone, cone {src} classifies in about 2 s at a 65 MiB peak heap, reading 8,655 of 67,894 blobs; the inside/outside sets equal the all-raw result, and Outside/Required agree on every artifact. check-in: b28c06506b user: [email protected] tags: feat/horizon-cones, trunk

The content horizon's store classification: a blob is elided when no check-in in the held set names it through its full tree, a kept blob is in both keep sets under a path cone, structure is never elided under a horizon, and a horizon the store cannot place elides nothing, as zit does. check-in: bc54a61b2c user: [email protected] tags: feat/horizon-cones, trunk

# Conflicts: # conformance/horizon_test.go # conformance/requirements/horizon.tsv check-in: 80c8df6a74 user: [email protected] tags: feat/horizon-cones, trunk

A store cone may now carry a content horizon (draft-fossil-horizon-00 §3.2, §4.1-§4.3). Classification computes the held set K from the store's own check-in graph and walks K's full trees -- F cards directly, through B baselines and through S sub-manifest nodes, with one visited set over structural names -- because mlink records a file version only where it changed, and a blob introduced below C and unchanged through C is named by C's tree alone. Nothing about K is stored: every classification recomputes it, so moving C or losing the cone is a reload, never a migration.

Blobs no K check-in names are elided; with path members as well a blob is kept only when it is in both keep sets. Under a horizon nothing structural is elided, by the horizon or by path members, and delta bases of held artifacts and shunned names keep their classes. A C the store does not hold elides nothing, as zit's classification does: eliding everything would leave the pull that brings a deepened C nothing to ask for. A structural horizon is refused by SetStoreCone until it is implemented.

internal/content now imports internal/horizon, so the held-set tests, which commit through internal/manifest, move to an external test package to avoid an import cycle. check-in: 2ea6479ba9 user: [email protected] tags: feat/horizon-cones, trunk

zit's author called horizon-rfc bbd1435674 ready to implement against, and zit#265 settled the leaves rule there against fossil's leaf: a childless check-in is one no P card names, open or closed, and K under the leaves rule is C's descendants plus every descendant of each check-in where a childless check-in's ancestry meets C's. Both rules now yield a set closed under descendants, so leaves and branch tips derive exactly.

HeldSet follows zit's computation at that check-in (src/sparse.zig, ClassifyState.extend): meeting points are the members of C's ancestry a childless check-in's parent walk reaches without passing one, and a childless check-in is skipped only when it descends from C. The tests that encoded the old rule are restated: a merged-but-open branch tip adds nothing, a closed branch's tip does, the fork's descendants on C's side are held, and an unrelated root adds nothing.

The draft copy, the README pin and the table follow: HZ-3.1-1, HZ-5.2-1 (the seed applies to every entry of K) and HZ-6.2-11 (announce only in reply to a request that pulls) are restated, and HZ-3.1-4 (closure under descendants) is new, with a case checking that no child of a held check-in falls outside K under either rule. check-in: a68f89e414 user: [email protected] tags: feat/horizon-cones, trunk

Both slices defined the descendants/leaves rule: cone.HorizonRule for the serialized member and horizon.Rule for the walk. One concept gets one type; the walk now takes the value the cone carries. check-in: 6d8ccec5da user: [email protected] tags: feat/horizon-cones, trunk

The held set K of draft-fossil-horizon-00 §3.1 under both rules, bounded and computed from the check-in graph the repository holds. Conflicts in the horizon suite and table resolved by keeping both slices' cases and rows. check-in: 7a5ae7cee7 user: [email protected] tags: feat/horizon-cones, trunk

draft-fossil-horizon-00 Section 3.1 defines K as a function of C, the rule and the check-in graph, recomputed by whoever needs it and stored by no one. internal/horizon.HeldSet computes it from the plink and leaf tables: one bounded plink load, then iterative breadth-first walks.

Merge parents are followed both ways, as zit's walk does (src/sparse.zig, ClassifyState.extend and walkParents). Under the leaves rule each open leaf's ancestry is held up to where it meets C's ancestry, inclusive, so every equally near common ancestor the walk reaches is held. "Open leaf" is fossil's leaf table minus active closed tags rather than zit's "no held child", which keeps a below-C branch merged into a descendant held back to its fork, so any two open leaves keep their merge base in K. C that is not a held check-in is ErrNotHeld; phantom parents are never entered.

Section 8 requires the walk to carry visited-node bounds: the load and every walk share the 1<<20 bound of the other graph walks and fail with ErrBound, and cancellation is honoured. The conformance suite gains cases for HZ-3.1-1 and HZ-3.1-3, both PARTIAL until the horizon member and the content horizon exist. check-in: 75ded1b0e0 user: [email protected] tags: feat/horizon-cones, trunk

The horizon member of a cone and its version-3 serialization, byte-identical to zit's (draft-fossil-horizon-00 §3.3). check-in: 6da46813f9 user: [email protected] tags: feat/horizon-cones, trunk

A horizon names one check-in by full hash, a held-set rule and a depth. Version 3 carries it between the count and the flagged members, a distinct version so a reader predating horizons refuses the cone instead of reading the lead-in as path members. Forms without a horizon are unchanged, so their digests hold. A horizon-only cone has no path members and is path-dense. Parse re-serializes and compares, so an upper-case hash or any other non-canonical input is refused.

HZ-3.3-1 and HZ-3.3-2 are now covered. check-in: 5f637a3b62 user: [email protected] tags: feat/horizon-cones, trunk

Moves the horizon copy from 86d4b67372 to e6ee276c89, the check-in the sparse-cone copy is already pinned at. Every change between the two is in §6: §6.1 lets any request carry pragma horizon-cursor, §6.2 adds the SHOULDs to keep the classification and the structural graph per store prefix, and §6.2.6 defines the cursor. Five new rows read them into the table (HZ-6.2-9 to HZ-6.2-13) and HZ-6.1-1 names the cursor; the table is now 50 requirements, none implemented. check-in: be103fe35a user: [email protected] tags: feat/horizon-cones, trunk

chore(release): v0.14.0 changelog leaf check-in: 6d5357235a user: [email protected] tags: main, trunk, v0.14.0

feat: sub-manifest trees and sparse cones (draft-fossil-submanifests-00, draft-fossil-sparse-cone-00) check-in: 7244496a09 user: [email protected] tags: main, trunk

StartServer kills the server's process group and reaps the leader, but fossil server forks a child per connection, and SIGKILL reaches that child asynchronously. On a loaded machine the child could still finish a write after Wait returned, and t.TempDir's RemoveAll failed with "directory not empty" (TestCloneFromRealFossilUncompressedReply, load average ~20). This is the race #352 narrowed; cleanup now also waits, for at most five seconds, until the group has no member left. leaf check-in: f1b6155c8f user: [email protected] tags: feat/submanifest-reader, main, trunk

Five fixes the three-tool round trip and the fossil-scm.org comparison surfaced: an uncovered clone is refused with the push card first, repo status reports the checkout's changes, repo clone remembers last-sync-url, repo verify reports damage, transit phantoms and elision, and adding a directory adds the files beneath it. check-in: b3c5ad7bca user: [email protected] tags: feat/submanifest-reader, main, trunk

TestScenarioClusterConvergence calls content.GenerateClusters once the simulation is over, to check the API on a repository of 500 blobs. Buggify was still armed, so at hostile seeds 11 and 23 a write-path site corrupted a cluster artifact, blob.Store's round-trip check refused it, and the test failed on the refusal. That refusal is the safeguard working. The call now runs with injection suspended, as the invariant checks and fixtures do. check-in: 0be3dddeae user: [email protected] tags: feat/submanifest-reader, main, trunk