Add cache purge (#7)

Reviewed-on: #7
Co-authored-by: jolheiser <john.olheiser@gmail.com>
Co-committed-by: jolheiser <john.olheiser@gmail.com>

.woodpecker.yml

@@ -0,0 +1,8 @@
+pipeline:
+  compliance:
+    image: golang:1.17
+    commands:
+      - go test -race ./...
+      - go vet ./...
+    when:
+      event: [ pull_request ]

Makefile

@@ -1,17 +0,0 @@
-GO ?= go
-
-.PHONY: vet
-vet:
-	$(GO) vet ./...
-
-.PHONY: fmt
-fmt:
-	$(GO) fmt ./...
-
-.PHONY: test
-test:
-	$(GO) test -race ./...
-
-.PHONY: bench
-bench:
-	$(GO) test -benchmem -bench=.

README.md

@@ -1,4 +1,7 @@
 # Overlay
+
+[![Go Reference](https://pkg.go.dev/badge/go.jolheiser.com/overlay.svg)](https://pkg.go.dev/go.jolheiser.com/overlay)
+
 Overlay File System
 
 Overlay is an easy way to implement a file system in such a way that

bench.txt

@@ -1,9 +0,0 @@
-go test -benchmem -bench=.
-goos: linux
-goarch: amd64
-pkg: go.jolheiser.com/overlay
-cpu: Intel(R) Core(TM) i7-4700MQ CPU @ 2.40GHz
-BenchmarkCache-8     	134959974	         9.003 ns/op	       0 B/op	       0 allocs/op
-BenchmarkNoCache-8   	  897212	      1369 ns/op	     280 B/op	       4 allocs/op
-PASS
-ok  	go.jolheiser.com/overlay	3.360s

overlay.go

@@ -6,6 +6,10 @@ import (
 	"path"
 )
 
+// Interface guard
+// fs.ReadFileFS also fulfills fs.FS
+var _ fs.ReadFileFS = (*FS)(nil)
+
 // FS is an overlay File System
 type FS struct {
 	fs      fs.FS
@@ -14,12 +18,17 @@ type FS struct {
 	cache   map[string]bool
 }
 
+// PurgeCache purges the cache
+func (f *FS) PurgeCache() {
+	f.cache = make(map[string]bool)
+}
+
 func (f *FS) apn(name string) string {
 	return path.Join(f.root, name)
 }
 
 func (f *FS) exists(name string) bool {
-	if has, ok := f.cache[name]; ok && f.doCache {
+	if has, ok := f.cache[name]; ok {
 		return has
 	}
 	_, err := os.Stat(f.apn(name))
@@ -39,6 +48,14 @@ func (f *FS) Open(name string) (fs.File, error) {
 	return f.fs.Open(name)
 }
 
+// ReadFile reads a file, preferring disk
+func (f *FS) ReadFile(name string) ([]byte, error) {
+	if f.exists(name) {
+		return os.ReadFile(f.apn(name))
+	}
+	return fs.ReadFile(f.fs, name)
+}
+
 // ReadDir reads []fs.DirEntry
 // This method will prefer EMBEDDED, because that is the "real" FS for overlay
 func (f *FS) ReadDir(name string) ([]fs.DirEntry, error) {
@@ -51,10 +68,9 @@ type Option func(*FS) error
 // New returns a new FS
 func New(root string, fs fs.FS, opts ...Option) (*FS, error) {
 	x := &FS{
-		fs:      fs,
-		root:    root,
-		doCache: true,
-		cache:   make(map[string]bool),
+		fs:    fs,
+		root:  root,
+		cache: make(map[string]bool),
 	}
 
 	for _, opt := range opts {
@@ -66,6 +82,15 @@ func New(root string, fs fs.FS, opts ...Option) (*FS, error) {
 	return x, nil
 }
 
+// MustNew returns New and panics on error
+func MustNew(root string, fs fs.FS, opts ...Option) *FS {
+	f, err := New(root, fs, opts...)
+	if err != nil {
+		panic(err)
+	}
+	return f
+}
+
 // WithSub sets a fs.Sub for an FS
 func WithSub(sub string) Option {
 	return func(x *FS) (err error) {

overlay_test.go

@@ -2,7 +2,6 @@ package overlay
 
 import (
 	"embed"
-	"io"
 	"io/fs"
 	"os"
 	"strings"
@@ -49,7 +48,7 @@ func TestOverlay(t *testing.T) {
 			}
 			defer fi.Close()
 
-			contents, err := io.ReadAll(fi)
+			contents, err := x.ReadFile(tc.File)
 			if err != nil {
 				t.Log(err)
 				t.FailNow()