Remove dependency on external cache package

go.mod

@@ -15,7 +15,6 @@ require (
 	github.com/golang-migrate/migrate/v4 v4.18.3
 	github.com/google/uuid v1.6.0
 	github.com/lib/pq v1.10.9
-	github.com/patrickmn/go-cache v2.1.0+incompatible
 	github.com/prometheus/client_golang v1.14.0
 	github.com/segmentio/kafka-go v0.4.38
 	github.com/segmentio/kafka-go/sasl/aws_msk_iam_v2 v0.1.0

go.sum

@@ -192,8 +192,6 @@ github.com/opencontainers/go-digest v1.0.0 h1:apOUWs51W5PlhuyGyz9FCeeBIOUDA/6nW8
 github.com/opencontainers/go-digest v1.0.0/go.mod h1:0JzlMkj0TRzQZfJkVvzbP0HBR3IKzErnv2BNG4W4MAM=
 github.com/opencontainers/image-spec v1.1.0 h1:8SG7/vwALn54lVB/0yZ/MMwhFrPYtpEHQb2IpWsCzug=
 github.com/opencontainers/image-spec v1.1.0/go.mod h1:W4s4sFTMaBeK1BQLXbG4AdM2szdn85PY75RI83NrTrM=
-github.com/patrickmn/go-cache v2.1.0+incompatible h1:HRMgzkcYKYpi3C8ajMPV8OFXaaRUnok+kx1WdO15EQc=
-github.com/patrickmn/go-cache v2.1.0+incompatible/go.mod h1:3Qf8kWWT7OJRJbdiICTKqZju1ZixQ/KpMGzzAfe6+WQ=
 github.com/pierrec/lz4/v4 v4.1.15/go.mod h1:gZWDp/Ze/IJXGXf23ltt2EXimqmTUXEy0GFuRQyBid4=
 github.com/pierrec/lz4/v4 v4.1.17 h1:kV4Ip+/hUBC+8T6+2EgburRtkE9ef4nbY3f4dFhGjMc=
 github.com/pierrec/lz4/v4 v4.1.17/go.mod h1:gZWDp/Ze/IJXGXf23ltt2EXimqmTUXEy0GFuRQyBid4=

server/cache.go

@@ -0,0 +1,148 @@
+package server
+
+import (
+	"sync"
+	"time"
+
+	"github.com/brave-intl/challenge-bypass-server/model"
+)
+
+type CachingConfig struct {
+	Enabled       bool `json:"enabled"`
+	ExpirationSec int  `json:"expirationSec"`
+}
+
+type Cache[T any] interface {
+	Get(k string) (T, bool)
+	Delete(k string)
+	SetDefault(k string, x T)
+}
+
+// Clock interface allows us to mock time in tests
+type Clock interface {
+	Now() time.Time
+}
+
+type RealClock struct{}
+
+func (RealClock) Now() time.Time {
+	return time.Now()
+}
+
+type SimpleCache[T any] struct {
+	items             sync.Map
+	defaultExpiration time.Duration
+	cleanupInterval   time.Duration
+	stopCleanup       chan bool
+	clock             Clock
+}
+
+type cacheItem[T any] struct {
+	value      T
+	expiration int64
+}
+
+// NewSimpleCache creates a new cache with the given default expiration and cleanup interval
+func NewSimpleCache[T any](defaultExpiration, cleanupInterval time.Duration) *SimpleCache[T] {
+	return newSimpleCacheWithClock[T](defaultExpiration, cleanupInterval, RealClock{})
+}
+
+func newSimpleCacheWithClock[T any](defaultExpiration, cleanupInterval time.Duration, clock Clock) *SimpleCache[T] {
+	cache := &SimpleCache[T]{
+		defaultExpiration: defaultExpiration,
+		cleanupInterval:   cleanupInterval,
+		stopCleanup:       make(chan bool),
+		clock:             clock,
+	}
+
+	if cleanupInterval > 0 {
+		go cache.startCleanupTimer()
+	}
+
+	return cache
+}
+
+func (c *SimpleCache[T]) startCleanupTimer() {
+	ticker := time.NewTicker(c.cleanupInterval)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ticker.C:
+			c.deleteExpired()
+		case <-c.stopCleanup:
+			return
+		}
+	}
+}
+
+func (c *SimpleCache[T]) deleteExpired() {
+	now := c.clock.Now().UnixNano()
+	c.items.Range(func(key, value any) bool {
+		item, ok := value.(cacheItem[T])
+		if ok && item.expiration > 0 && item.expiration < now {
+			c.items.Delete(key)
+		}
+		return true
+	})
+}
+
+func (c *SimpleCache[T]) Get(k string) (T, bool) {
+	var zero T
+	value, found := c.items.Load(k)
+	if !found {
+		return zero, false
+	}
+
+	item, ok := value.(cacheItem[T])
+	if !ok {
+		return zero, false
+	}
+
+	if item.expiration > 0 && item.expiration < c.clock.Now().UnixNano() {
+		c.items.Delete(k)
+		return zero, false
+	}
+
+	return item.value, true
+}
+
+func (c *SimpleCache[T]) Delete(k string) {
+	c.items.Delete(k)
+}
+
+// SetDefault adds an item to the cache with the default expiration time
+func (c *SimpleCache[T]) SetDefault(k string, x T) {
+	var expiration int64 = 0
+	if c.defaultExpiration > 0 {
+		expiration = c.clock.Now().Add(c.defaultExpiration).UnixNano()
+	}
+
+	c.items.Store(k, cacheItem[T]{
+		value:      x,
+		expiration: expiration,
+	})
+}
+
+type CacheCollection struct {
+	Issuer       *SimpleCache[*model.Issuer]
+	Issuers      *SimpleCache[[]model.Issuer]
+	Redemptions  *SimpleCache[*Redemption]
+	IssuerCohort *SimpleCache[[]model.Issuer]
+}
+
+func bootstrapCache(cfg DBConfig) *CacheCollection {
+	if !cfg.CachingConfig.Enabled {
+		return nil
+	}
+
+	defaultDuration := time.Duration(cfg.CachingConfig.ExpirationSec) * time.Second
+	cleanupInterval := defaultDuration * 2
+
+	return &CacheCollection{
+		Issuer:       NewSimpleCache[*model.Issuer](defaultDuration, cleanupInterval),
+		Issuers:      NewSimpleCache[[]model.Issuer](defaultDuration, cleanupInterval),
+		Redemptions:  NewSimpleCache[*Redemption](defaultDuration, cleanupInterval),
+		IssuerCohort: NewSimpleCache[[]model.Issuer](defaultDuration, cleanupInterval),
+	}
+}