Artifact [80430d124f]

Artifact 80430d124f268efebf270d50bfda53509630fb6d3f79d7c05a51707763c0df41:

• File internal/verify/verify.go — part of check-in [0fd2a507b8] at 2026-07-24 15:27:03 on branch trunk — perf: route history-walking expansions through content.Cache (#151) (#153)

  The buffer-reuse fix in #145/#150 cut the cost of expanding one delta chain once. It did nothing for callers that expand many versions of the same artifact in a single operation: each bare content.Expand still replayed the whole O(depth) chain, so a walk over N overlapping revisions cost O(N^2) blob reads even though content.Cache already existed for exactly this pattern.

  Audited every non-test content.Expand caller. Two access patterns genuinely repeat over overlapping delta chains and are now routed through a per-operation content.Cache:

  - annotate walks every revision of one file along the parent chain. content_deltify stores each older file blob as a delta against its successor, so the per-revision expansions are all walks of the same few chains. One cache threaded through the walk (file blob + manifest listing via new manifest.ListFilesCached/GetManifestCached, both nil-passthrough so existing callers are unchanged) turns it linear. Measured on a deltified 150-revision file: 1.60s -> 0.65s (2.5x), 764k -> 308k allocs; the win grows with history depth.

  - verify.Verify and verify.Rebuild sweep every blob more than once (Rebuild: checkBlobs + rebuildManifests + rebuildTags x2). A single cache shared across the pass walks each chain once instead of once per sweep and amortizes overlap within each sweep. Measured on a 150-revision two-file repo: Rebuild 3.34s -> 0.068s (48x), 4.59M -> 98k allocs.

  Callers that only ever touch the tip or make a single pass over distinct blobs (branch create, merge-config load, R-card / delta manifest build, MergeParentFiles, crosslinkSingle, shun undelta, pairwise Diff) are left on bare Expand, each with a comment stating why a cache cannot amortize their access.

  No behavior change: expansion output is byte-identical, verified across the modernc and ncruces drivers with REQUIRE_FOSSIL_BIN=1 cross-checks and the DST suite. (user: [email protected], size: 3017) [annotate] [blame] [check-ins using]

// Package verify provides comprehensive repository verification and rebuild.
package verify

import (
	"time"

	"github.com/danmestas/go-libfossil/internal/content"
	libfossil "github.com/danmestas/go-libfossil/internal/fsltype"
	"github.com/danmestas/go-libfossil/internal/repo"
)

// verifyCacheBytes bounds the expanded content one Verify or Rebuild pass keeps
// live. Both passes sweep every blob more than once -- Verify expands each blob
// in checkBlobs and again in checkCheckins; Rebuild expands each in checkBlobs,
// rebuildManifests, and twice in rebuildTags -- so a single cache shared across
// the pass walks each blob's delta chain once instead of once per sweep, and
// amortizes overlapping chains within each sweep. A miss costs throughput, not
// correctness; blob content is immutable and neither pass rewrites it, so no
// cached entry can go stale. Matches manifest.crosslinkCacheBytes.
const verifyCacheBytes = 256 << 20

// IssueKind categorizes the type of verification issue found.
type IssueKind int

const (
	IssueHashMismatch IssueKind = iota
	IssueBlobCorrupt
	IssueDeltaDangling
	IssuePhantomOrphan
	IssueEventMissing
	IssueEventMismatch
	IssueMlinkMissing
	IssuePlinkMissing
	IssueTagxrefMissing
	IssueFilenameMissing
	IssueLeafIncorrect
	IssueMissingReference
)

// Issue represents a single verification problem found in the repository.
type Issue struct {
	Kind    IssueKind
	RID     libfossil.FslID
	UUID    string
	Table   string
	Message string
}

// Report contains the results of a repository verification pass.
type Report struct {
	Issues        []Issue
	BlobsChecked  int
	BlobsOK       int
	BlobsFailed   int
	BlobsSkipped  int
	MissingRefs   int
	TablesRebuilt []string
	Duration      time.Duration
}

// OK returns true if no issues were found during verification.
func (r *Report) OK() bool {
	return len(r.Issues) == 0
}

// addIssue appends a new issue to the report.
func (r *Report) addIssue(issue Issue) {
	r.Issues = append(r.Issues, issue)
}

// Verify performs comprehensive repository verification.
// It checks blob integrity, delta chains, phantom records, and derived tables.
// Returns a report of all issues found. Never stops early - reports all problems.
func Verify(r *repo.Repo) (*Report, error) {
	if r == nil {
		panic("verify: nil repo")
	}

	start := time.Now()
	report := &Report{}

	// One expansion cache for the whole pass; see verifyCacheBytes.
	cache := content.NewCache(verifyCacheBytes)

	// Phase 1: Blob integrity (content hash verification)
	if err := checkBlobs(r, report, cache); err != nil {
		return nil, err
	}

	// Phase 2: Structural integrity (delta chains, phantoms)
	if err := checkDeltaChains(r, report); err != nil {
		return nil, err
	}
	if err := checkPhantoms(r, report); err != nil {
		return nil, err
	}

	// Phase 3: Derived tables (event, mlink, plink, tagxref, filename, leaf)
	if err := checkDerived(r, report, cache); err != nil {
		return nil, err
	}

	report.Duration = time.Since(start)
	return report, nil
}