Compression improvements

- Remove unnecessary error return from compressNoContextTakeover.
- Simplify use of sync.Pool.
- Fix formatting in compression documentation.

Author: garyburd

compression.go

@@ -13,8 +13,13 @@ import (
 )
 
 var (
-	flateWriterPool = sync.Pool{}
-	flateReaderPool = sync.Pool{}
+	flateWriterPool = sync.Pool{New: func() interface{} {
+		fw, _ := flate.NewWriter(nil, 3)
+		return fw
+	}}
+	flateReaderPool = sync.Pool{New: func() interface{} {
+		return flate.NewReader(nil)
+	}}
 )
 
 func decompressNoContextTakeover(r io.Reader) io.ReadCloser {
@@ -24,26 +29,16 @@ func decompressNoContextTakeover(r io.Reader) io.ReadCloser {
 		// Add final block to squelch unexpected EOF error from flate reader.
 		"\x01\x00\x00\xff\xff"
 
-	i := flateReaderPool.Get()
-	if i == nil {
-		i = flate.NewReader(nil)
-	}
-	i.(flate.Resetter).Reset(io.MultiReader(r, strings.NewReader(tail)), nil)
-	return &flateReadWrapper{i.(io.ReadCloser)}
+	fr, _ := flateReaderPool.Get().(io.ReadCloser)
+	fr.(flate.Resetter).Reset(io.MultiReader(r, strings.NewReader(tail)), nil)
+	return &flateReadWrapper{fr}
 }
 
-func compressNoContextTakeover(w io.WriteCloser) (io.WriteCloser, error) {
+func compressNoContextTakeover(w io.WriteCloser) io.WriteCloser {
 	tw := &truncWriter{w: w}
-	i := flateWriterPool.Get()
-	var fw *flate.Writer
-	var err error
-	if i == nil {
-		fw, err = flate.NewWriter(tw, 3)
-	} else {
-		fw = i.(*flate.Writer)
-		fw.Reset(tw)
-	}
-	return &flateWriteWrapper{fw: fw, tw: tw}, err
+	fw, _ := flateWriterPool.Get().(*flate.Writer)
+	fw.Reset(tw)
+	return &flateWriteWrapper{fw: fw, tw: tw}
 }
 
 // truncWriter is an io.Writer that writes all but the last four bytes of the

conn.go

@@ -235,7 +235,7 @@ type Conn struct {
 	writeErr   error
 
 	enableWriteCompression bool
-	newCompressionWriter   func(io.WriteCloser) (io.WriteCloser, error)
+	newCompressionWriter   func(io.WriteCloser) io.WriteCloser
 
 	// Read fields
 	reader        io.ReadCloser // the current reader returned to the application
@@ -444,11 +444,7 @@ func (c *Conn) NextWriter(messageType int) (io.WriteCloser, error) {
 	}
 	c.writer = mw
 	if c.newCompressionWriter != nil && c.enableWriteCompression && isData(messageType) {
-		w, err := c.newCompressionWriter(c.writer)
-		if err != nil {
-			c.writer = nil
-			return nil, err
-		}
+		w := c.newCompressionWriter(c.writer)
 		mw.compress = true
 		c.writer = w
 	}

doc.go

@@ -150,7 +150,7 @@
 // application's responsibility to check the Origin header before calling
 // Upgrade.
 //
-// Compression [Experimental]
+// Compression
 //
 // Per message compression extensions (RFC 7692) are experimentally supported
 // by this package in a limited capacity. Setting the EnableCompression option
@@ -162,7 +162,7 @@
 // Per message compression of messages written to a connection can be enabled
 // or disabled by calling the corresponding Conn method:
 //
-// conn.EnableWriteCompression(true)
+//  conn.EnableWriteCompression(true)
 //
 // Currently this package does not support compression with "context takeover".
 // This means that messages must be compressed and decompressed in isolation,