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tessl/golang-github-com-go-co-op-gocron-v2

A Golang job scheduling library that lets you run Go functions at pre-determined intervals using cron expressions, fixed durations, daily, weekly, monthly, or one-time schedules with support for distributed deployments.

Overview
Eval results
Files

web-app-tasks.mddocs/examples/by-scenario/

Web Application Task Examples

Common scheduled tasks for web applications: cache refresh, session cleanup, metrics collection.

Cache Refresh Patterns

Simple Cache Refresh

// Refresh cache every 5 minutes
j, _ := s.NewJob(
    gocron.DurationJob(5*time.Minute),
    gocron.NewTask(func() {
        fmt.Println("Refreshing cache...")
        data := fetchDataFromDatabase()
        cache.Set("app:data", data, 10*time.Minute)
        fmt.Println("Cache refreshed")
    }),
    gocron.WithName("cache-refresh"),
    gocron.WithSingletonMode(gocron.LimitModeReschedule),
)

Stale-While-Revalidate Cache

// Refresh cache before expiry
j, _ := s.NewJob(
    gocron.DurationJob(4*time.Minute),
    gocron.NewTask(func() {
        // Cache TTL is 5 minutes, refresh at 4 minutes
        data := fetchDataFromDatabase()
        cache.Set("app:data", data, 5*time.Minute)
    }),
    gocron.WithName("swr-cache"),
    gocron.WithIntervalFromCompletion(),
)

Multi-Tier Cache Warming

// Warm L1 and L2 caches
j, _ := s.NewJob(
    gocron.DurationJob(10*time.Minute),
    gocron.NewTask(func() error {
        // Warm L2 cache (Redis)
        data, err := fetchFromDatabase()
        if err != nil {
            return fmt.Errorf("database fetch failed: %w", err)
        }
        cache.L2.Set("data", data, 15*time.Minute)

        // Warm L1 cache (in-memory)
        cache.L1.Set("data", data, 5*time.Minute)

        log.Println("Multi-tier cache warmed")
        return nil
    }),
    gocron.WithName("multi-tier-cache-warm"),
    gocron.WithSingletonMode(gocron.LimitModeReschedule),
    gocron.WithEventListeners(
        gocron.AfterJobRunsWithError(func(jobID uuid.UUID, jobName string, err error) {
            log.Printf("Cache warming failed: %v", err)
            alertOps("cache-warming-failure", err)
        }),
    ),
)

Conditional Cache Refresh

// Only refresh if cache is stale
j, _ := s.NewJob(
    gocron.DurationJob(2*time.Minute),
    gocron.NewTask(func() {
        if cache.IsFresh("app:data") {
            log.Println("Cache still fresh, skipping refresh")
            return
        }

        log.Println("Cache stale, refreshing...")
        data := fetchDataFromDatabase()
        cache.Set("app:data", data, 10*time.Minute)
    }),
    gocron.WithName("conditional-cache-refresh"),
)

Session Cleanup

Expired Session Cleanup

// Clean up expired sessions every hour
j, _ := s.NewJob(
    gocron.DurationJob(time.Hour),
    gocron.NewTask(func() {
        count := 0
        expiredSessions := db.Query("SELECT id FROM sessions WHERE expires_at < NOW()")

        for _, session := range expiredSessions {
            db.Delete("sessions", session.ID)
            cache.Delete("session:" + session.ID)
            count++
        }

        log.Printf("Cleaned up %d expired sessions", count)
        metrics.RecordSessionCleanup(count)
    }),
    gocron.WithName("session-cleanup"),
    gocron.WithSingletonMode(gocron.LimitModeReschedule),
)

Session Activity Pruning

// Remove inactive sessions daily at 3 AM
j, _ := s.NewJob(
    gocron.DailyJob(1, gocron.NewAtTimes(gocron.NewAtTime(3, 0, 0))),
    gocron.NewTask(func() {
        inactiveThreshold := time.Now().Add(-30 * 24 * time.Hour) // 30 days

        result := db.Exec(`
            DELETE FROM sessions
            WHERE last_activity < ?
            AND expires_at > NOW()
        `, inactiveThreshold)

        count := result.RowsAffected
        log.Printf("Pruned %d inactive sessions", count)

        // Alert if too many inactive sessions
        if count > 10000 {
            alertOps("high-inactive-sessions", fmt.Sprintf("%d sessions pruned", count))
        }
    }),
    gocron.WithName("session-prune"),
)

Session Store Compaction

// Compact session store weekly
j, _ := s.NewJob(
    gocron.WeeklyJob(
        1,
        gocron.NewWeekdays(time.Sunday),
        gocron.NewAtTimes(gocron.NewAtTime(4, 0, 0)),
    ),
    gocron.NewTask(func() {
        log.Println("Starting session store compaction")

        // Remove orphaned session data
        db.Exec("DELETE FROM session_data WHERE session_id NOT IN (SELECT id FROM sessions)")

        // Vacuum session tables
        db.Exec("VACUUM ANALYZE sessions")
        db.Exec("VACUUM ANALYZE session_data")

        log.Println("Session store compaction complete")
    }),
    gocron.WithName("session-compaction"),
)

Metrics Collection

Application Metrics Aggregation

// Aggregate and flush metrics every minute
j, _ := s.NewJob(
    gocron.DurationJob(time.Minute),
    gocron.NewTask(func() {
        metrics := collectApplicationMetrics()

        // Send to metrics backend
        prometheus.RecordMetrics(metrics)

        // Also store in database for historical analysis
        db.Insert("metrics", map[string]interface{}{
            "timestamp":      time.Now(),
            "active_users":   metrics.ActiveUsers,
            "requests_total": metrics.RequestsTotal,
            "error_rate":     metrics.ErrorRate,
        })
    }),
    gocron.WithName("metrics-aggregation"),
    gocron.WithSingletonMode(gocron.LimitModeReschedule),
)

User Analytics Rollup

// Roll up hourly analytics every hour
j, _ := s.NewJob(
    gocron.CronJob("0 * * * *", false), // Every hour at minute 0
    gocron.NewTask(func() {
        startTime := time.Now().Add(-time.Hour).Truncate(time.Hour)
        endTime := startTime.Add(time.Hour)

        analytics := db.Query(`
            SELECT
                COUNT(DISTINCT user_id) as unique_users,
                COUNT(*) as total_events,
                event_type
            FROM events
            WHERE created_at >= ? AND created_at < ?
            GROUP BY event_type
        `, startTime, endTime)

        for _, row := range analytics {
            db.Insert("analytics_hourly", map[string]interface{}{
                "hour":         startTime,
                "event_type":   row.EventType,
                "unique_users": row.UniqueUsers,
                "total_events": row.TotalEvents,
            })
        }

        log.Printf("Rolled up analytics for %v", startTime)
    }),
    gocron.WithName("analytics-rollup"),
)

Performance Metrics Snapshot

// Take performance snapshot every 5 minutes
j, _ := s.NewJob(
    gocron.DurationJob(5*time.Minute),
    gocron.NewTask(func() {
        snapshot := PerformanceSnapshot{
            Timestamp:       time.Now(),
            ResponseTimeP50: metrics.GetPercentile("response_time", 0.50),
            ResponseTimeP95: metrics.GetPercentile("response_time", 0.95),
            ResponseTimeP99: metrics.GetPercentile("response_time", 0.99),
            ErrorRate:       metrics.GetRate("errors"),
            RequestRate:     metrics.GetRate("requests"),
            CPUUsage:        system.GetCPUUsage(),
            MemoryUsage:     system.GetMemoryUsage(),
        }

        db.Insert("performance_snapshots", snapshot)

        // Alert on degraded performance
        if snapshot.ResponseTimeP95 > 1000 { // > 1s
            alertOps("slow-response-time", fmt.Sprintf("P95: %.2fms", snapshot.ResponseTimeP95))
        }
    }),
    gocron.WithName("performance-snapshot"),
)

API Rate Limit Reset

Rate Limit Window Reset

// Reset rate limit counters every minute
j, _ := s.NewJob(
    gocron.DurationJob(time.Minute),
    gocron.NewTask(func() {
        // Reset sliding window counters
        currentMinute := time.Now().Truncate(time.Minute)
        previousMinute := currentMinute.Add(-time.Minute)

        cache.Delete("rate_limit:" + previousMinute.Format("2006-01-02T15:04"))

        // Clean up old rate limit data
        cutoff := time.Now().Add(-10 * time.Minute)
        pattern := "rate_limit:*"
        keys := cache.Keys(pattern)

        for _, key := range keys {
            if isOlderThan(key, cutoff) {
                cache.Delete(key)
            }
        }
    }),
    gocron.WithName("rate-limit-reset"),
)

Daily API Quota Reset

// Reset daily API quotas at midnight
j, _ := s.NewJob(
    gocron.DailyJob(1, gocron.NewAtTimes(gocron.NewAtTime(0, 0, 0))),
    gocron.NewTask(func() {
        log.Println("Resetting daily API quotas")

        // Reset all user quotas
        db.Exec("UPDATE api_keys SET daily_usage = 0")

        // Clear cache
        cache.DeletePattern("api_quota:*")

        // Log quota usage
        stats := db.QueryOne(`
            SELECT
                COUNT(*) as total_keys,
                SUM(daily_usage) as total_requests,
                AVG(daily_usage) as avg_requests
            FROM api_keys
        `)

        log.Printf("Daily API stats: %d keys, %d total requests, %.0f avg requests",
            stats.TotalKeys, stats.TotalRequests, stats.AvgRequests)
    }),
    gocron.WithName("daily-quota-reset"),
)

Email Queue Processing

Process Email Queue

// Process email queue every 30 seconds
j, _ := s.NewJob(
    gocron.DurationJob(30*time.Second),
    gocron.NewTask(func() {
        batchSize := 50
        emails := db.Query(`
            SELECT * FROM email_queue
            WHERE status = 'pending'
            ORDER BY priority DESC, created_at ASC
            LIMIT ?
        `, batchSize)

        for _, email := range emails {
            err := sendEmail(email)
            if err != nil {
                // Mark as failed, will retry later
                db.Exec(`
                    UPDATE email_queue
                    SET status = 'failed', attempts = attempts + 1, error = ?
                    WHERE id = ?
                `, err.Error(), email.ID)
            } else {
                // Mark as sent
                db.Exec(`
                    UPDATE email_queue
                    SET status = 'sent', sent_at = NOW()
                    WHERE id = ?
                `, email.ID)
            }
        }

        log.Printf("Processed %d emails", len(emails))
    }),
    gocron.WithName("email-queue"),
    gocron.WithSingletonMode(gocron.LimitModeReschedule),
    gocron.WithIntervalFromCompletion(),
)

Retry Failed Emails

// Retry failed emails every 5 minutes
j, _ := s.NewJob(
    gocron.DurationJob(5*time.Minute),
    gocron.NewTask(func() {
        emails := db.Query(`
            SELECT * FROM email_queue
            WHERE status = 'failed'
            AND attempts < 3
            AND created_at > NOW() - INTERVAL '1 day'
        `)

        for _, email := range emails {
            err := sendEmail(email)
            if err == nil {
                db.Exec("UPDATE email_queue SET status = 'sent', sent_at = NOW() WHERE id = ?", email.ID)
            } else {
                db.Exec("UPDATE email_queue SET attempts = attempts + 1 WHERE id = ?", email.ID)
            }
        }
    }),
    gocron.WithName("email-retry"),
)

Complete Web App Example

package main

import (
    "fmt"
    "log"
    "time"

    "github.com/go-co-op/gocron/v2"
)

func main() {
    s, _ := gocron.NewScheduler()
    defer s.Shutdown()

    // Cache refresh every 5 minutes
    s.NewJob(
        gocron.DurationJob(5*time.Minute),
        gocron.NewTask(func() {
            data := fetchFromDatabase()
            cache.Set("app:data", data, 10*time.Minute)
            log.Println("Cache refreshed")
        }),
        gocron.WithName("cache-refresh"),
        gocron.WithSingletonMode(gocron.LimitModeReschedule),
    )

    // Session cleanup hourly
    s.NewJob(
        gocron.DurationJob(time.Hour),
        gocron.NewTask(func() {
            count := cleanupExpiredSessions()
            log.Printf("Cleaned up %d sessions", count)
        }),
        gocron.WithName("session-cleanup"),
    )

    // Metrics every minute
    s.NewJob(
        gocron.DurationJob(time.Minute),
        gocron.NewTask(func() {
            metrics := collectMetrics()
            sendToPrometheus(metrics)
        }),
        gocron.WithName("metrics-collection"),
    )

    // Email queue every 30 seconds
    s.NewJob(
        gocron.DurationJob(30*time.Second),
        gocron.NewTask(func() {
            processEmailQueue()
        }),
        gocron.WithName("email-queue"),
        gocron.WithIntervalFromCompletion(),
    )

    // Daily analytics rollup at 1 AM
    s.NewJob(
        gocron.DailyJob(1, gocron.NewAtTimes(gocron.NewAtTime(1, 0, 0))),
        gocron.NewTask(func() {
            rollupDailyAnalytics()
        }),
        gocron.WithName("daily-analytics"),
    )

    s.Start()
    log.Println("Web app scheduler started")
    select {}
}

Related Documentation

  • Examples: Cache Patterns
  • Examples: Maintenance Jobs
  • Examples: Initialization
  • Guide: Concurrency Control

Install with Tessl CLI

npx tessl i tessl/golang-github-com-go-co-op-gocron-v2@2.19.1

docs

examples

by-scenario

data-processing.md

initialization.md

maintenance-jobs.md

web-app-tasks.md

index.md

tile.json