Closes #4

szextractor/lib.go

@@ -0,0 +1,32 @@
+package szextractor
+
+import (
+	"sync"
+
+	"github.com/itchio/sevenzip-go/sz"
+	"github.com/itchio/wharf/state"
+)
+
+var _libMutex sync.Mutex
+var _lib *sz.Lib
+var _libErr error
+var _loadOnce sync.Once
+
+func GetLib(consumer *state.Consumer) (*sz.Lib, error) {
+	_libMutex.Lock()
+	defer _libMutex.Unlock()
+
+	_loadOnce.Do(func() {
+		_libErr = EnsureDeps(consumer)
+		if _libErr != nil {
+			return
+		}
+
+		_lib, _libErr = sz.NewLib()
+	})
+
+	if _libErr != nil {
+		return nil, _libErr
+	}
+	return _lib, nil
+}

szextractor/szextractor.go

@@ -33,7 +33,6 @@ type szExtractor struct {
 	consumer     *state.Consumer
 	saveConsumer savior.SaveConsumer
 
-	lib     *sz.Lib
 	archive *sz.Archive
 	in      *sz.InStream
 	format  string
@@ -72,16 +71,10 @@ func New(file eos.File, consumer *state.Consumer) (SzExtractor, error) {
 		se.free()
 	})
 
-	err := EnsureDeps(consumer)
-	if err != nil {
-		return nil, errors.Wrap(err, "ensuring 7-zip deps")
-	}
-
-	lib, err := sz.NewLib()
+	lib, err := GetLib(consumer)
 	if err != nil {
 		return nil, errors.Wrap(err, "opening 7-zip library")
 	}
-	se.lib = lib
 
 	stats, err := file.Stat()
 	if err != nil {
@@ -425,11 +418,6 @@ func (se *szExtractor) free() {
 		se.in = nil
 	}
 
-	if se.lib != nil {
-		se.lib.Free()
-		se.lib = nil
-	}
-
 	se.freed = true
 }