Cache static files in memory

.gitignore

@@ -6,8 +6,7 @@
 *.test
 *.out
 go.work
-
 *.local
 .env
 dist/
-/book
+/book

go.mod

@@ -70,13 +70,16 @@ require (
 	github.com/aws/aws-sdk-go-v2/service/ssooidc v1.15.1 // indirect
 	github.com/aws/aws-sdk-go-v2/service/sts v1.21.1 // indirect
 	github.com/aws/smithy-go v1.14.0 // indirect
+	github.com/cespare/xxhash/v2 v2.2.0 // indirect
 	github.com/chzyer/readline v1.5.0 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/dgraph-io/ristretto v0.1.1 // indirect
 	github.com/foxcpp/go-mockdns v1.0.0 // indirect
 	github.com/gabriel-vasile/mimetype v1.4.2 // indirect
 	github.com/go-playground/locales v0.14.1 // indirect
 	github.com/go-playground/universal-translator v0.18.1 // indirect
 	github.com/golang-jwt/jwt/v4 v4.5.0 // indirect
+	github.com/golang/glog v1.1.0 // indirect
 	github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da // indirect
 	github.com/golang/protobuf v1.5.3 // indirect
 	github.com/google/go-cmp v0.5.9 // indirect
@@ -111,6 +114,7 @@ require (
 	github.com/miekg/dns v1.1.50 // indirect
 	github.com/mitchellh/colorstring v0.0.0-20190213212951-d06e56a500db // indirect
 	github.com/pkg/browser v0.0.0-20210911075715-681adbf594b8 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
 	github.com/rivo/uniseg v0.2.0 // indirect

go.sum

@@ -256,9 +256,12 @@ github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA
 github.com/census-instrumentation/opencensus-proto v0.3.0/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
 github.com/certifi/gocertifi v0.0.0-20191021191039-0944d244cd40/go.mod h1:sGbDF6GwGcLpkNXPUTkMRoywsNa/ol15pxFe6ERfguA=
 github.com/certifi/gocertifi v0.0.0-20200922220541-2c3bb06c6054/go.mod h1:sGbDF6GwGcLpkNXPUTkMRoywsNa/ol15pxFe6ERfguA=
+github.com/cespare/xxhash v1.1.0 h1:a6HrQnmkObjyL+Gs60czilIUGqrzKutQD6XZog3p+ko=
 github.com/cespare/xxhash v1.1.0/go.mod h1:XrSqR1VqqWfGrhpAt58auRo0WTKS1nRRg3ghfAqPWnc=
 github.com/cespare/xxhash/v2 v2.1.1/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/cespare/xxhash/v2 v2.1.2/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
+github.com/cespare/xxhash/v2 v2.2.0 h1:DC2CZ1Ep5Y4k3ZQ899DldepgrayRUGE6BBZ/cd9Cj44=
+github.com/cespare/xxhash/v2 v2.2.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/checkpoint-restore/go-criu/v4 v4.1.0/go.mod h1:xUQBLp4RLc5zJtWY++yjOoMoB5lihDt7fai+75m+rGw=
 github.com/checkpoint-restore/go-criu/v5 v5.0.0/go.mod h1:cfwC0EG7HMUenopBsUf9d89JlCLQIfgVcNsNN0t6T2M=
 github.com/checkpoint-restore/go-criu/v5 v5.3.0/go.mod h1:E/eQpaFtUKGOOSEBZgmKAcn+zUUwWxqcaKZlF54wK8E=
@@ -429,8 +432,11 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/denisenkom/go-mssqldb v0.10.0/go.mod h1:xbL0rPBG9cCiLr28tMa8zpbdarY27NDyej4t/EjAShU=
 github.com/denverdino/aliyungo v0.0.0-20190125010748-a747050bb1ba/go.mod h1:dV8lFg6daOBZbT6/BDGIz6Y3WFGn8juu6G+CQ6LHtl0=
+github.com/dgraph-io/ristretto v0.1.1 h1:6CWw5tJNgpegArSHpNHJKldNeq03FQCwYvfMVWajOK8=
+github.com/dgraph-io/ristretto v0.1.1/go.mod h1:S1GPSBCYCIhmVNfcth17y2zZtQT6wzkzgwUve0VDWWA=
 github.com/dgrijalva/jwt-go v0.0.0-20170104182250-a601269ab70c/go.mod h1:E3ru+11k8xSBh+hMPgOLZmtrrCbhqsmaPHjLKYnJCaQ=
 github.com/dgrijalva/jwt-go v3.2.0+incompatible/go.mod h1:E3ru+11k8xSBh+hMPgOLZmtrrCbhqsmaPHjLKYnJCaQ=
+github.com/dgryski/go-farm v0.0.0-20190423205320-6a90982ecee2/go.mod h1:SqUrOPUnsFjfmXRMNPybcSiG0BgUW2AuFH8PAnS2iTw=
 github.com/dgryski/go-sip13 v0.0.0-20181026042036-e10d5fee7954/go.mod h1:vAd38F8PWV+bWy6jNmig1y/TA+kYO4g3RSRF0IAv0no=
 github.com/dhui/dktest v0.3.10 h1:0frpeeoM9pHouHjhLeZDuDTJ0PqjDTrycaHaMmkJAo8=
 github.com/dhui/dktest v0.3.10/go.mod h1:h5Enh0nG3Qbo9WjNFRrwmKUaePEBhXMOygbz3Ww7Sz0=
@@ -612,6 +618,8 @@ github.com/golang-migrate/migrate/v4 v4.15.2/go.mod h1:f2toGLkYqD3JH+Todi4aZ2Zdb
 github.com/golang-sql/civil v0.0.0-20190719163853-cb61b32ac6fe/go.mod h1:8vg3r2VgvsThLBIFL93Qb5yWzgyZWhEmBwUJWevAkK0=
 github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0/go.mod h1:E/TSTwGwJL78qG/PmXZO1EjYhfJinVAhrmmHX6Z8B9k=
 github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b/go.mod h1:SBH7ygxi8pfUlaOkMMuAQtPIUF8ecWP5IEl/CR7VP2Q=
+github.com/golang/glog v1.1.0 h1:/d3pCKDPWNnvIWe0vVUpNP32qc8U3PDVxySP/y360qE=
+github.com/golang/glog v1.1.0/go.mod h1:pfYeQZ3JWZoXTV5sFc986z3HTpwQs9At6P4ImfuP3NQ=
 github.com/golang/groupcache v0.0.0-20160516000752-02826c3e7903/go.mod h1:cIg4eruTrX1D+g88fzRXU5OdNfaM+9IcxsU14FzY7Hc=
 github.com/golang/groupcache v0.0.0-20190129154638-5b532d6fd5ef/go.mod h1:cIg4eruTrX1D+g88fzRXU5OdNfaM+9IcxsU14FzY7Hc=
 github.com/golang/groupcache v0.0.0-20190702054246-869f871628b6/go.mod h1:cIg4eruTrX1D+g88fzRXU5OdNfaM+9IcxsU14FzY7Hc=
@@ -1697,6 +1705,7 @@ golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220811171246-fbc7d0a398ab/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220908164124-27713097b956/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20221010170243-090e33056c14/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.1.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.15.0 h1:h48lPFYpsTvQJZF4EKyI4aLHaev3CxivZmv7yZig9pc=

internal/cache/contentcache.go

@@ -0,0 +1,158 @@
+package cache
+
+import (
+	"fmt"
+	"sync"
+
+	"github.com/dgraph-io/ristretto"
+)
+
+type ContentCache[K any, V any, R any] struct {
+	m     *mm
+	size  int64
+	cache *ristretto.Cache
+	load  func(r R) (V, int64, error)
+}
+
+func NewContentCache[K any, V any, R any](contentCacheSize int64, metrics bool, load func(r R) (V, int64, error)) (*ContentCache[K, V, R], error) {
+	m := New()
+	size := contentCacheSize
+	nc := size / 1000
+	if (nc < 100) { //mainly for testing
+		nc = 100
+	}
+	cache, err := ristretto.NewCache(&ristretto.Config{
+		//NumCounters is 10 times estimated max number of items in cache, as suggested in https://pkg.go.dev/github.com/dgraph-io/ristretto@v0.1.1#Config
+		NumCounters: nc, //limit / 10 KB small files * 10
+		MaxCost:     size,
+		BufferItems: 64,
+		Metrics:     metrics,
+		IgnoreInternalCost: true,
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	return &ContentCache[K, V, R]{m: m, size: size, cache: cache, load: load}, nil
+}
+
+func (c *ContentCache[K, V, R]) keyToString(key K) string {
+	return fmt.Sprintf("%v", key)
+}
+
+func (c *ContentCache[K, V, R]) GetContent(key K) (V, bool) {
+	l := c.m.RLock(key)
+	defer l.RUnlock()
+
+	v, b := c.cache.Get(c.keyToString(key))
+	if v == nil {
+		var nv V
+		return nv, b
+	}
+	return v.(V), b
+}
+
+func (c *ContentCache[K, V, R]) SetContent(key K, r R) (V, error) {
+	l := c.m.Lock(key)
+	defer l.Unlock()
+
+	b, n, err := c.load(r)
+	if err != nil {
+		return b, err
+	}
+
+	c.cache.Set(c.keyToString(key), b, n)
+	return b, nil
+}
+
+//modified from https://stackoverflow.com/questions/40931373/how-to-gc-a-map-of-mutexes-in-go
+type mm struct {
+    ml sync.Mutex              
+    ma map[interface{}]*mentry 
+}
+
+type mentry struct {
+    m   *mm         
+    el  sync.RWMutex 
+    cnt int        
+    key interface{}
+}
+
+type Unlocker interface {
+    Unlock()
+}
+
+type RUnlocker interface {
+    RUnlock()
+}
+
+func New() *mm {
+    return &mm{ma: make(map[interface{}]*mentry)}
+}
+
+func (m *mm) Lock(key interface{}) Unlocker {
+    m.ml.Lock()
+    e, ok := m.ma[key]
+    if !ok {
+        e = &mentry{m: m, key: key}
+        m.ma[key] = e
+    }
+    e.cnt++
+    m.ml.Unlock()
+
+    e.el.Lock()
+
+    return e
+}
+
+func (me *mentry) Unlock() {
+    m := me.m
+
+    m.ml.Lock()
+    e, ok := m.ma[me.key]
+    if !ok {
+        m.ml.Unlock()
+        panic(fmt.Errorf("Unlock requested for key=%v but no entry found", me.key))
+    }
+    e.cnt--        
+    if e.cnt < 1 { 
+        delete(m.ma, me.key)
+    }
+    m.ml.Unlock()
+
+    e.el.Unlock()
+}
+
+
+func (m *mm) RLock(key interface{}) RUnlocker {
+    m.ml.Lock()
+    e, ok := m.ma[key]
+    if !ok {
+        e = &mentry{m: m, key: key}
+        m.ma[key] = e
+    }
+    e.cnt++
+    m.ml.Unlock()
+
+    e.el.RLock()
+
+    return e
+}
+
+func (me *mentry) RUnlock() {
+    m := me.m
+
+    m.ml.Lock()
+    e, ok := m.ma[me.key]
+    if !ok {
+        m.ml.Unlock()
+        panic(fmt.Errorf("Unlock requested for key=%v but no entry found", me.key))
+    }
+    e.cnt--        
+    if e.cnt < 1 { 
+        delete(m.ma, me.key)
+    }
+    m.ml.Unlock()
+
+    e.el.RUnlock()
+}

internal/cache/contentcache_test.go

@@ -0,0 +1,153 @@
+package cache //white box testing
+
+import (
+	"bytes"
+	"testing"
+	"sync"
+	"time"
+	"fmt"
+	"io"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type CacheKeyMock string
+
+func TestGetContent(t *testing.T) {
+	fmt.Println("testing GetContent...")
+	load := func(r io.ReadSeeker) (*bytes.Buffer, int64, error) {
+		b, err := io.ReadAll(r)
+		nb := bytes.NewBuffer(b)
+		if err != nil {
+			return nb, 0, err
+		}
+		return nb, int64(nb.Len()), nil 
+	}
+	cc, err := NewContentCache[CacheKeyMock](8, true, load)
+	assert.Empty(t, err)
+
+	k1 := CacheKeyMock("id1")
+	k2 := CacheKeyMock("id2")
+	k3 := CacheKeyMock("id3")
+
+	ccc, found := cc.GetContent(k1)
+	assert.Equal(t, false, found)
+	assert.Equal(t, "hit: 0 miss: 1 keys-added: 0 keys-updated: 0 keys-evicted: 0 cost-added: 0 cost-evicted: 0 sets-dropped: 0 sets-rejected: 0 gets-dropped: 0 gets-kept: 0 gets-total: 1 hit-ratio: 0.00", cc.cache.Metrics.String())
+
+	ccc, err = cc.SetContent(k1, bytes.NewReader([]byte("a")))
+	time.Sleep(100 * time.Millisecond) //https://github.com/dgraph-io/ristretto/issues/161
+	assert.Empty(t, err)
+	assert.Equal(t, bytes.NewBuffer([]byte("a")), ccc)
+	assert.Equal(t, "hit: 0 miss: 1 keys-added: 1 keys-updated: 0 keys-evicted: 0 cost-added: 1 cost-evicted: 0 sets-dropped: 0 sets-rejected: 0 gets-dropped: 0 gets-kept: 0 gets-total: 1 hit-ratio: 0.00", cc.cache.Metrics.String())
+
+	ccc, found = cc.GetContent(k1)
+	assert.Equal(t, true, found)
+	assert.Equal(t, bytes.NewBuffer([]byte("a")), ccc)
+	assert.Equal(t, "hit: 1 miss: 1 keys-added: 1 keys-updated: 0 keys-evicted: 0 cost-added: 1 cost-evicted: 0 sets-dropped: 0 sets-rejected: 0 gets-dropped: 0 gets-kept: 0 gets-total: 2 hit-ratio: 0.50", cc.cache.Metrics.String())
+
+	ccc, err = cc.SetContent(k1, bytes.NewReader([]byte("test")))
+	time.Sleep(100 * time.Millisecond)
+	assert.Empty(t, err)
+	assert.Equal(t, bytes.NewBuffer([]byte("test")), ccc)
+	assert.Equal(t, "hit: 1 miss: 1 keys-added: 1 keys-updated: 1 keys-evicted: 0 cost-added: 4 cost-evicted: 0 sets-dropped: 0 sets-rejected: 0 gets-dropped: 0 gets-kept: 0 gets-total: 2 hit-ratio: 0.50", cc.cache.Metrics.String())
+
+	ccc, found = cc.GetContent(k1)
+	assert.Equal(t, true, found)
+	assert.Equal(t, bytes.NewBuffer([]byte("test")), ccc)
+	assert.Equal(t, "hit: 2 miss: 1 keys-added: 1 keys-updated: 1 keys-evicted: 0 cost-added: 4 cost-evicted: 0 sets-dropped: 0 sets-rejected: 0 gets-dropped: 0 gets-kept: 0 gets-total: 3 hit-ratio: 0.67", cc.cache.Metrics.String())
+
+	ccc, err = cc.SetContent(k2, bytes.NewReader([]byte("overflow")))
+	time.Sleep(100 * time.Millisecond)
+	assert.Empty(t, err)
+	assert.Equal(t, bytes.NewBuffer([]byte("overflow")), ccc)
+	assert.Equal(t, "hit: 2 miss: 1 keys-added: 2 keys-updated: 1 keys-evicted: 1 cost-added: 12 cost-evicted: 4 sets-dropped: 0 sets-rejected: 0 gets-dropped: 0 gets-kept: 0 gets-total: 3 hit-ratio: 0.67", cc.cache.Metrics.String())
+
+	ccc, found = cc.GetContent(k2)
+	assert.Equal(t, true, found)
+	assert.Equal(t, bytes.NewBuffer([]byte("overflow")), ccc)
+	assert.Equal(t, "hit: 3 miss: 1 keys-added: 2 keys-updated: 1 keys-evicted: 1 cost-added: 12 cost-evicted: 4 sets-dropped: 0 sets-rejected: 0 gets-dropped: 0 gets-kept: 0 gets-total: 4 hit-ratio: 0.75", cc.cache.Metrics.String())
+
+	ccc, err = cc.SetContent(k3, bytes.NewReader([]byte("content too big")))
+	time.Sleep(100 * time.Millisecond)
+	assert.Empty(t, err)
+	assert.Equal(t, bytes.NewBuffer([]byte("content too big")), ccc)
+	assert.Equal(t, "hit: 3 miss: 1 keys-added: 2 keys-updated: 1 keys-evicted: 1 cost-added: 12 cost-evicted: 4 sets-dropped: 0 sets-rejected: 0 gets-dropped: 0 gets-kept: 0 gets-total: 4 hit-ratio: 0.75", cc.cache.Metrics.String())
+
+	ccc, found = cc.GetContent(k3)
+	assert.Equal(t, false, found)
+	assert.Equal(t, "hit: 3 miss: 2 keys-added: 2 keys-updated: 1 keys-evicted: 1 cost-added: 12 cost-evicted: 4 sets-dropped: 0 sets-rejected: 0 gets-dropped: 0 gets-kept: 0 gets-total: 5 hit-ratio: 0.60", cc.cache.Metrics.String())
+}
+
+func TestDataRace(t *testing.T) {
+	fmt.Println("testing data race...")
+	var wg sync.WaitGroup
+	load := func(r io.ReadSeeker) (*bytes.Buffer, int64, error) {
+		b, err := io.ReadAll(r)
+		nb := bytes.NewBuffer(b)
+		if err != nil {
+			return nb, 0, err
+		}
+		return nb, int64(nb.Len()), nil 
+	}
+	cc, err := NewContentCache[CacheKeyMock](16, true, load)
+	assert.Empty(t, err)
+	k1 := CacheKeyMock("id1")
+	k2 := CacheKeyMock("id2")
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		_, err := cc.SetContent(k1, bytes.NewReader([]byte("data")))
+		time.Sleep(100 * time.Millisecond) 
+		assert.Empty(t, err)
+		_, err = cc.SetContent(k2, bytes.NewReader([]byte("race")))
+		time.Sleep(100 * time.Millisecond) 
+		assert.Empty(t, err)
+		_, found := cc.GetContent(k1)
+		assert.Equal(t, true, found)
+		_, found = cc.GetContent(k2)
+		assert.Equal(t, true, found)
+	}()
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		_, err := cc.SetContent(k1, bytes.NewReader([]byte("race")))
+		time.Sleep(100 * time.Millisecond) 
+		assert.Empty(t, err)
+		_, err = cc.SetContent(k2, bytes.NewReader([]byte("data")))
+		time.Sleep(100 * time.Millisecond) 
+		assert.Empty(t, err)
+		_, found := cc.GetContent(k1)
+		assert.Equal(t, true, found)
+		_, found = cc.GetContent(k2)
+		assert.Equal(t, true, found)
+	}()
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		_, err := cc.SetContent(k2, bytes.NewReader([]byte("data")))
+		time.Sleep(100 * time.Millisecond) 
+		assert.Empty(t, err)
+		_, err = cc.SetContent(k1, bytes.NewReader([]byte("race")))
+		time.Sleep(100 * time.Millisecond) 
+		assert.Empty(t, err)
+		_, found := cc.GetContent(k1)
+		assert.Equal(t, true, found)
+		_, found = cc.GetContent(k2)
+		assert.Equal(t, true, found)
+	}()
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		_, err := cc.SetContent(k2, bytes.NewReader([]byte("race")))
+		time.Sleep(100 * time.Millisecond) 
+		assert.Empty(t, err)
+		_, err = cc.SetContent(k1, bytes.NewReader([]byte("data")))
+		time.Sleep(100 * time.Millisecond) 
+		assert.Empty(t, err)
+		_, found := cc.GetContent(k1)
+		assert.Equal(t, true, found)
+		_, found = cc.GetContent(k2)
+		assert.Equal(t, true, found)
+	}()
+	wg.Wait()
+}