auto close functionality for compressors

v2/autoclose.go

@@ -0,0 +1,16 @@
+package libdeflate
+
+import "runtime"
+
+// panicFreeCloser is a type that can be closed without panicking if it is already closed. This is used for AutoClose functionality.
+type panicFreeCloser interface {
+	PanicFreeClose()
+}
+
+// attachAutoClose attaches a finalizer to the given panicFreeCloser that calls PanicFreeClose() when the object is garbage collected.
+// Used for AutoClose functionality. Do not call this function directly.
+func attachAutoClose(c panicFreeCloser) {
+	runtime.SetFinalizer(c, func(finalized panicFreeCloser) {
+		finalized.PanicFreeClose()
+	})
+}

v2/compressor.go

@@ -1,19 +1,43 @@
 package libdeflate
 
-import "github.com/4kills/go-libdeflate/v2/native"
+import (
+	"github.com/4kills/go-libdeflate/v2/native"
+)
 
 // Compressor compresses data at the specified compression level.
 //
 // A single compressor must not not be used across multiple threads concurrently.
 // If you want to compress concurrently, create a compressor for each thread.
 //
-// Always Close() the decompressor to free c memory.
+// Always Close() the decompressor to free c memory or use the AutoClose constructors, which will automatically close the Compressor at garabage collection time of the underlying natvie equivalent.
 // One Compressor allocates at least 32 KiB.
 type Compressor struct {
 	c   *native.Compressor
 	lvl int
 }
 
+// NewCompressorAutoClose returns a Compressor used to compress data with compression level DefaultCompressionLevel and AutoClose functionality.
+// This will close the Compressor automatically, when it is no longer used.
+// Errors if out of memory. Allocates 32KiB.
+// See NewCompressorLevelPointer for custom compression level
+func NewCompressorAutoClose() (Compressor, error) {
+	compressor, err := NewCompressorLevelAutoClose(DefaultCompressionLevel)
+	return compressor, err
+}
+
+// NewCompressorLevelAutoClose returns a new pointer to a Compressor used to compress data and AutoClose functionality.
+// This will close the Compressor automatically, when it is no longer used.
+// Errors if out of memory or if an invalid compression level was passed.
+// Allocates 32KiB.
+//
+// The compression level is legal if and only if:
+// MinCompressionLevel <= level <= MaxCompressionLevel
+func NewCompressorLevelAutoClose(level int) (Compressor, error) {
+	compressor, err := NewCompressorLevel(level)
+	attachAutoClose(compressor.c)
+	return compressor, err
+}
+
 // NewCompressor returns a new Compressor used to compress data with compression level DefaultCompressionLevel.
 // Errors if out of memory. Allocates 32KiB.
 // See NewCompressorLevel for custom compression level

v2/compressor_test.go

@@ -101,6 +101,22 @@ func TestCompressZlib(t *testing.T) {
 	slicesEqual([]byte(shortString), decomp, t)
 }
 
+func TestCompressZlib_AutoClose(t *testing.T) {
+	c, _ := NewCompressorAutoClose()
+	defer c.Close()
+	_, comp, err := c.CompressZlib(shortString, nil)
+	if err != nil {
+		t.Error(err)
+	}
+
+	r, _ := zlib.NewReader(bytes.NewBuffer(comp))
+	defer r.Close()
+	decomp := make([]byte, len(shortString))
+	r.Read(decomp)
+
+	slicesEqual([]byte(shortString), decomp, t)
+}
+
 // this test doesn't really say as much as TestCompress
 func TestCompressMeta(t *testing.T) {
 	c, _ := NewCompressor()
@@ -141,7 +157,7 @@ func TestCompressDecompress(t *testing.T) {
 	out := make([]byte, len(shortString))
 	dc, _ := NewDecompressor()
 	defer dc.Close()
-	if c, _, err := dc.DecompressZlib(comp, out); err != nil || c != len(comp){
+	if c, _, err := dc.DecompressZlib(comp, out); err != nil || c != len(comp) {
 		t.Error(err)
 	}
 	slicesEqual(shortString, out, t)

v2/decompressor.go

@@ -7,12 +7,32 @@ import "github.com/4kills/go-libdeflate/v2/native"
 // A single decompressor must not not be used across multiple threads concurrently.
 // If you want to decompress concurrently, create a decompressor for each thread.
 //
-// Always Close() the decompressor to free c memory.
+// Always Close() the decompressor to free c memory or use the AutoClose constructors, which will automatically close the Compressor at garabage collection time of the underlying natvie equivalent.
 // One Decompressor allocates at least 32KiB.
 type Decompressor struct {
 	dc *native.Decompressor
 }
 
+// NewDecompressor returns a new Decompressor used to decompress data at any compression level and with any Mode. It has AutoClose functionality.
+// This will close the Decompressor automatically, when it is no longer used.
+// Errors if out of memory. Allocates 32KiB.
+func NewDecompressorAutoClose() (Decompressor, error) {
+	decompressor, err := NewDecompressor()
+	attachAutoClose(decompressor.dc)
+	return decompressor, err
+}
+
+// NewDecompressorWithExtendedDecompression returns a new Decompressor used to decompress data at any compression level and with any Mode.
+// It has AutoClose functionality, which will close the Decompressor automatically, when it is no longer used.
+// maxDecompressionFactor customizes how much larger your output than your input may be. This is set to a sensible default,
+// however, it might need some tweaking if you have a huge compression factor. Usually, NewDecompressor should suffice.
+// Errors if out of memory. Allocates 32KiB.
+func NewDecompressorAutoCloseWithExtendedDecompression(maxDecompressionFactor int) (Decompressor, error) {
+	decompressor, err := NewDecompressorWithExtendedDecompression(maxDecompressionFactor)
+	attachAutoClose(decompressor.dc)
+	return decompressor, err
+}
+
 // NewDecompressor returns a new Decompressor used to decompress data at any compression level and with any Mode.
 // Errors if out of memory. Allocates 32KiB.
 func NewDecompressor() (Decompressor, error) {

v2/decompressor_test.go

@@ -89,6 +89,31 @@ func TestDecompressZlib(t *testing.T) {
 	slicesEqual(shortString, out, t)
 }
 
+func TestDecompressZlib_AutoClose(t *testing.T) {
+	// compress with go standard lib
+	buf := &bytes.Buffer{}
+	w := zlib.NewWriter(buf)
+	w.Write(shortString)
+	w.Close()
+	in := buf.Bytes()
+
+	// decompress with this lib
+
+	out := make([]byte, len(shortString))
+	dc, _ := NewDecompressorAutoClose()
+	defer dc.Close()
+	if c, _, err := dc.DecompressZlib(in, out); err != nil || c != len(in) {
+		t.Error(err)
+	}
+	slicesEqual(shortString, out, t)
+
+	c, out, err := dc.DecompressZlib(in, nil)
+	if err != nil || c != len(in) {
+		t.Error(err)
+	}
+	slicesEqual(shortString, out, t)
+}
+
 var (
 	deadlyCode = "789c7d90316f83301085f7fc0ac45cac3b1b63cc0685542c55a4264b1784825bd1024686284851fe7b8104c454c" +
 		"b8bdff7de9def6e3b6b3cf6db298dedc0b26f02384014858efb2af78ecb1573c224e24e92301e4919d158c0dd7e7" +

v2/native/compressor.go

@@ -91,3 +91,11 @@ func (c *Compressor) Close() {
 	C.libdeflate_free_compressor(c.c)
 	c.isClosed = true
 }
+
+// PanicFreeClose is like Close but doesn't panic if the compressor is already closed. This is useful for the higher-level autoclose functionality.
+func (c *Compressor) PanicFreeClose() {
+	if c.isClosed {
+		return
+	}
+	c.Close()
+}

v2/native/decompressor.go

@@ -14,8 +14,8 @@ import "unsafe"
 
 // Decompressor decompresses any DEFLATE, zlib or gzip compressed data at any level
 type Decompressor struct {
-	dc *C.decomp
-	isClosed bool
+	dc                     *C.decomp
+	isClosed               bool
 	maxDecompressionFactor int
 }
 
@@ -80,7 +80,7 @@ func (dc *Decompressor) decompress(in, out []byte, fit bool, f decompress) (int,
 
 	var (
 		cons int
-		n int
+		n    int
 	)
 
 	consPtr := uintptr(unsafe.Pointer(&cons))
@@ -106,3 +106,11 @@ func (dc *Decompressor) Close() {
 	C.libdeflate_free_decompressor(dc.dc)
 	dc.isClosed = true
 }
+
+// PanicFreeClose is like Close but doesn't panic if the decompressor is already closed. This is useful for the higher-level autoclose functionality.
+func (c *Decompressor) PanicFreeClose() {
+	if c.isClosed {
+		return
+	}
+	c.Close()
+}