Layered structure and some improvements.

Makefile

@@ -1,15 +1,18 @@
-.PHONY: build lint test vendor
+.PHONY: build lint test vendor run
 
 default: build
 
 build:
-	go build -mod=vendor -o build/probe -ldflags "-s -w" cmd/main.go
+	@go build -mod=vendor -o build/cached -ldflags "-s -w" cmd/main.go
 
 lint:
-	golangci-lint run
+	@golangci-lint run
 
 test:
-	go test ./...
+	@go test ./...
 
 vendor:
-	go mod tidy && go mod vendor
+	@go mod tidy && go mod vendor
+
+run:
+	@go run cmd/main.go

README.md

@@ -1,14 +1,15 @@
-## Probe
-Is in-memory cache server with simple text-based protocol.
+## Cached
+Is an in-memory cache server with a simple text-based protocol.
 
 ### Features
-* TTL per key
+* TTL per key (based on BTree index)
 * Dump and Restore from disk
 * Thread-safety
 * Commands:
     * `set <key> <value> <ttl>`
     * `get <key>`
     * `del <key>`
+    * `stats`
     * `quit`
 
 ### Why?
@@ -39,10 +40,14 @@ del mykey
 OK
 ```
 
+Show stats:
+```bash
+stats
+Hit: 865, Miss: 24, Size: 853
+```
+
 ### ToDo
 * Tests and benchmarks
 * Metrics
 * Dump and restore without reflection
 * Build in GitHub Actions
-
-

cmd/main.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"flag"
+	"io"
 	"log"
 	"os"
 	"os/signal"
@@ -12,8 +13,9 @@ import (
 
 	"golang.org/x/sync/errgroup"
 
-	"probe/internal/cache"
-	"probe/internal/server"
+	"github.com/i-sevostyanov/chached/internal/cache"
+	"github.com/i-sevostyanov/chached/internal/protocol"
+	"github.com/i-sevostyanov/chached/internal/server"
 )
 
 var errCanceled = errors.New("canceled")
@@ -30,13 +32,9 @@ func main() {
 	if err != nil {
 		logger.Fatalf("Failed to open file: %v", err)
 	}
-	defer func() {
-		if err = file.Close(); err != nil {
-			logger.Printf("Failed to close file: %v", err)
-		}
-	}()
 
 	inMemCache := cache.New()
+	cacheProtocol := protocol.New(inMemCache)
 
 	if err = inMemCache.Restore(file); err != nil {
 		logger.Printf("Warning. Failed to restore cache: %v", err)
@@ -45,7 +43,7 @@ func main() {
 	gr, ctx := errgroup.WithContext(context.Background())
 
 	gr.Go(func() error {
-		return server.New(*address, inMemCache, logger).Listen(ctx)
+		return server.New(*address, cacheProtocol, logger).Listen(ctx)
 	})
 
 	gr.Go(func() error {
@@ -56,6 +54,8 @@ func main() {
 	gr.Go(func() error {
 		signals := make(chan os.Signal, 1)
 		signal.Notify(signals, syscall.SIGINT, syscall.SIGTERM)
+		defer signal.Stop(signals)
+
 		for {
 			select {
 			case <-ctx.Done():
@@ -67,15 +67,23 @@ func main() {
 		}
 	})
 
-	if err = gr.Wait(); err != nil && err != errCanceled {
+	if err = gr.Wait(); err != nil && !errors.Is(err, errCanceled) {
 		logger.Fatalf("Failed to start: %v", err)
 	}
 
-	if err := file.Truncate(0); err != nil {
+	if _, err = file.Seek(0, io.SeekStart); err != nil {
+		logger.Fatalf("Failed to set offset: %v", err)
+	}
+
+	if err = file.Truncate(0); err != nil {
 		logger.Fatalf("Failed to truncate file: %v", err)
 	}
 
-	if err := inMemCache.Dump(file); err != nil {
+	if err = inMemCache.Dump(file); err != nil {
 		logger.Fatalf("Failed to dump cache: %v", err)
 	}
+
+	if err = file.Close(); err != nil {
+		logger.Fatalf("Failed to close file: %v", err)
+	}
 }

go.mod

@@ -1,5 +1,5 @@
-module probe
+module github.com/i-sevostyanov/chached
 
-go 1.13
+go 1.15
 
-require golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e
+require golang.org/x/sync v0.0.0-20200625203802-6e8e738ad208

go.sum

@@ -1,2 +1,2 @@
-golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e h1:vcxGaoTs7kV8m5Np9uUNQin4BrLOthgV7252N8V+FwY=
-golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20200625203802-6e8e738ad208 h1:qwRHBd0NqMbJxfbotnDhm2ByMI1Shq4Y6oRJo21SGJA=
+golang.org/x/sync v0.0.0-20200625203802-6e8e738ad208/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=

internal/cache/btree.go

@@ -33,7 +33,7 @@ func (b *btree) removeNodesLessThan(k int64) map[string]struct{} {
 	}
 
 	fakeParent := &node{Right: b.Root}
-	rm := b.Root.removeNodesOlderThan(k, fakeParent)
+	rm := b.Root.removeNodesLessThan(k, fakeParent)
 	b.Root = fakeParent.Right
 
 	var nodes []*node
@@ -51,6 +51,7 @@ func (b *btree) traverse(n *node, f func(*node)) {
 	if n == nil {
 		return
 	}
+
 	b.traverse(n.Left, f)
 	f(n)
 	b.traverse(n.Right, f)
@@ -79,6 +80,7 @@ func (n *node) insert(newNode *node) {
 			n.Left = newNode
 			return
 		}
+
 		n.Left.insert(newNode)
 		return
 	}
@@ -88,6 +90,7 @@ func (n *node) insert(newNode *node) {
 			n.Right = newNode
 			return
 		}
+
 		n.Right.insert(newNode)
 		return
 	}
@@ -99,29 +102,29 @@ func (n *node) insert(newNode *node) {
 	}
 }
 
-func (n *node) removeNodesOlderThan(k int64, parent *node) map[string]struct{} {
+func (n *node) removeNodesLessThan(k int64, parent *node) map[string]struct{} {
 	if n == nil {
 		return nil
 	}
 
 	if k < n.Key {
-		return n.Left.removeNodesOlderThan(k, n)
+		return n.Left.removeNodesLessThan(k, n)
 	}
 
 	keys := make(map[string]struct{})
-	for k := range n.Values {
-		keys[k] = struct{}{}
+	for key := range n.Values {
+		keys[key] = struct{}{}
 	}
 
 	if n.Left != nil {
-		for k := range n.Left.removeNodesOlderThan(k, n) {
-			keys[k] = struct{}{}
+		for key := range n.Left.removeNodesLessThan(k, n) {
+			keys[key] = struct{}{}
 		}
 	}
 
 	if n.Right != nil {
-		for k := range n.Right.removeNodesOlderThan(k, n) {
-			keys[k] = struct{}{}
+		for key := range n.Right.removeNodesLessThan(k, n) {
+			keys[key] = struct{}{}
 		}
 	}
 

internal/cache/inmem.go → internal/cache/cache.go

@@ -6,6 +6,7 @@ import (
 	"errors"
 	"io"
 	"sync"
+	"sync/atomic"
 	"time"
 )
 
@@ -14,23 +15,33 @@ var ErrNotFound = errors.New("key not found")
 
 // InMem in-memory cache
 type InMem struct {
-	mu   *sync.RWMutex
-	data *data
+	mu    sync.RWMutex
+	data  data
+	stats stats
 }
 
 type data struct {
-	Index *btree
+	Index btree
 	KV    map[string]string
 }
 
+type stats struct {
+	miss int64
+	hit  int64
+}
+
 // New returns new in-memory cache
 func New() *InMem {
 	return &InMem{
-		mu: new(sync.RWMutex),
-		data: &data{
-			Index: new(btree),
+		mu: sync.RWMutex{},
+		data: data{
+			Index: btree{},
 			KV:    make(map[string]string),
 		},
+		stats: stats{
+			miss: 0,
+			hit:  0,
+		},
 	}
 }
 
@@ -40,9 +51,11 @@ func (m *InMem) Get(key string) (string, error) {
 	defer m.mu.RUnlock()
 
 	if v, ok := m.data.KV[key]; ok {
+		atomic.AddInt64(&m.stats.hit, 1)
 		return v, nil
 	}
 
+	atomic.AddInt64(&m.stats.miss, 1)
 	return "", ErrNotFound
 }
 
@@ -64,6 +77,17 @@ func (m *InMem) Delete(key string) {
 	m.delete(key)
 }
 
+// Stats returns hits, misses and cache size
+func (m *InMem) Stats() (int64, int64, int64) {
+	m.mu.RLock()
+	hit := m.stats.hit
+	miss := m.stats.miss
+	size := int64(len(m.data.KV))
+	m.mu.RUnlock()
+
+	return hit, miss, size
+}
+
 // Eviction starts the process of removing keys whose life has come to an end
 func (m *InMem) Eviction(ctx context.Context, interval time.Duration) {
 	ticker := time.NewTicker(interval)
@@ -98,7 +122,7 @@ func (m *InMem) Restore(r io.Reader) error {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
-	return gob.NewDecoder(r).Decode(m.data)
+	return gob.NewDecoder(r).Decode(&m.data)
 }
 
 func (m *InMem) delete(key string) {