Artifact [b508a447ae]

Artifact b508a447ae1af2e242fb4e425dbccc0891731b210220a913ca6e83c2935e1484:

• File simio/buggify.go — part of check-in [f5744359d3] at 2026-04-19 16:30:54 on branch trunk — Initial open source release

  libfossil is a pure-Go implementation of the Fossil SCM, reading and writing the same .fossil SQLite repository format as upstream Fossil.

  This is the first public release of code that previously lived in a private repository. The module path is github.com/danmestas/libfossil and the binary is named libfossil to avoid $PATH collisions with upstream fossil.

  Included: - Repo lifecycle (create, clone), checkout/checkin, timeline, merge, diff, annotate, shun, tag, branch, bisect, stash, undo/redo - Sync-over-HTTP protocol (client and handler) - Two SQLite drivers: modernc (pure Go, default) and ncruces (wasm-capable) - Observer interfaces (SyncObserver, CheckoutObserver) with an optional OpenTelemetry implementation in observer/otel (separate submodule) - Deterministic simulation testing harness with BUGGIFY fault injection - Kong-based embeddable CLI under cli/ and a standalone binary under cmd/libfossil/ (user: [email protected], size: 1361) [annotate] [blame] [check-ins using]

package simio

import (
	mrand "math/rand"
	"sync"
)

// buggifyState holds the global simulation fault injection state.
// Guarded by a mutex for safety, though DST is single-threaded.
var buggifyState struct {
	mu      sync.Mutex
	enabled bool
	rng     *mrand.Rand
}

// EnableBuggify activates fault injection with the given seed.
// Call this at the start of a simulation run.
func EnableBuggify(seed int64) {
	buggifyState.mu.Lock()
	defer buggifyState.mu.Unlock()
	buggifyState.enabled = true
	buggifyState.rng = mrand.New(mrand.NewSource(seed))
}

// DisableBuggify deactivates all fault injection.
// Call this at the end of a simulation run.
func DisableBuggify() {
	buggifyState.mu.Lock()
	defer buggifyState.mu.Unlock()
	buggifyState.enabled = false
	buggifyState.rng = nil
}

// Buggify returns true with the given probability, but ONLY when
// simulation mode is active. In production (not enabled), it always
// returns false with near-zero overhead (single boolean check).
func Buggify(probability float64) bool {
	if !buggifyState.enabled {
		return false
	}
	buggifyState.mu.Lock()
	defer buggifyState.mu.Unlock()
	if !buggifyState.enabled {
		return false
	}
	return buggifyState.rng.Float64() < probability
}

// BuggifyEnabled returns whether simulation fault injection is active.
func BuggifyEnabled() bool {
	return buggifyState.enabled
}