warden

README

Warden

Warden is a library that provides distributed leases for Go backed by Redis and PostgreSQL.

Features

• Multiple Backends: Choose between Redis or PostgreSQL based on your infrastructure
• Blocking & Non-blocking Acquisition: Lock() waits for lease availability, TryLock() returns immediately
• Automatic Expiration: Leases automatically expire after TTL to prevent deadlocks
• Lease Renewal: Extend lease lifetime while work is in progress
• Fencing Tokens: Prevent conflicts when multiple nodes compete for the same lease
• Context-aware: Full support for context cancellation and timeouts
• Thread-safe: Safe for concurrent use by multiple goroutines

Installation

go get github.com/denpeshkov/warden

Usage

Redis Backend

package main

import (
	"context"
	"log"

	warden "github.com/denpeshkov/warden/redis"
	"github.com/redis/go-redis/v9"
)

func main() {
	// Create Redis client
	rdb := redis.NewClient(&redis.Options{
		Addr: "localhost:6379",
	})
	defer func() { _ = rdb.Close() }()

	// Create lease manager
	manager := warden.NewManager(rdb)

	// Create a lease for a specific resource
	lease := manager.Lease("my-task")

	// Acquire the lease
	ctx := context.Background()
	if err := lease.Lock(ctx); err != nil {
		log.Fatal(err)
	}
	defer func() {
		if err := lease.Unlock(ctx); err != nil {
			log.Fatal(err)
		}
	}()

	// Do your work while holding the lease
	// ...
}

PostgreSQL Backend

package main

import (
	"context"
	"log"

	"github.com/denpeshkov/warden/postgres"
	"github.com/jackc/pgx/v5/pgxpool"
)

func main() {
	// Create PostgreSQL connection pool
	pool, err := pgxpool.New(context.Background(),
		"postgres://user:password@localhost:5432/mydb?sslmode=disable")
	if err != nil {
		panic(err)
	}
	defer pool.Close()

	// Create the lease table (run once)
	if _, err = pool.Exec(context.Background(), postgres.CreateLockTableSQL); err != nil {
		log.Fatal(err)
	}

	// Create lease manager
	manager := postgres.NewManager(pool)

	// Create a lease for a specific resource
	lease := manager.Lease("my-task")

	// Acquire the lease
	ctx := context.Background()
	if err := lease.Lock(ctx); err != nil {
		log.Fatal(err)
	}
	defer func() {
		if err := lease.Unlock(ctx); err != nil {
			log.Fatal(err)
		}
	}()

	// Do your work while holding the lease
	// ...
}