Update to last common bleve (#3986)

vendor/github.com/glycerine/go-unsnap-stream/snap.go

@@ -0,0 +1,100 @@
+package unsnap
+
+import (
+	"encoding/binary"
+
+	// no c lib dependency
+	snappy "github.com/golang/snappy"
+	// or, use the C wrapper for speed
+	//snappy "github.com/dgryski/go-csnappy"
+)
+
+// add Write() method for SnappyFile (see unsnap.go)
+
+// reference for snappy framing/streaming format:
+//         http://code.google.com/p/snappy/source/browse/trunk/framing_format.txt
+//             ?spec=svn68&r=71
+
+//
+// Write writes len(p) bytes from p to the underlying data stream.
+// It returns the number of bytes written from p (0 <= n <= len(p)) and
+// any error encountered that caused the write to stop early. Write
+// must return a non-nil error if it returns n < len(p).
+//
+func (sf *SnappyFile) Write(p []byte) (n int, err error) {
+
+	if sf.SnappyEncodeDecodeOff {
+		return sf.Writer.Write(p)
+	}
+
+	if !sf.Writing {
+		panic("Writing on a read-only SnappyFile")
+	}
+
+	// encoding in snappy can apparently go beyond the original size, beware.
+	// so our buffers must be sized 2*max snappy chunk => 2 * CHUNK_MAX(65536)
+
+	sf.DecBuf.Reset()
+	sf.EncBuf.Reset()
+
+	if !sf.HeaderChunkWritten {
+		sf.HeaderChunkWritten = true
+		_, err = sf.Writer.Write(SnappyStreamHeaderMagic)
+		if err != nil {
+			return
+		}
+	}
+	var chunk []byte
+	var chunk_type byte
+	var crc uint32
+
+	for len(p) > 0 {
+
+		// chunk points to input p by default, unencoded input.
+		chunk = p[:IntMin(len(p), CHUNK_MAX)]
+		crc = masked_crc32c(chunk)
+
+		writeme := chunk[:]
+
+		// first write to EncBuf, as a temp, in case we want
+		// to discard and send uncompressed instead.
+		compressed_chunk := snappy.Encode(sf.EncBuf.GetEndmostWritableSlice(), chunk)
+
+		if len(compressed_chunk) <= int((1-_COMPRESSION_THRESHOLD)*float64(len(chunk))) {
+			writeme = compressed_chunk
+			chunk_type = _COMPRESSED_CHUNK
+		} else {
+			// keep writeme pointing at original chunk (uncompressed)
+			chunk_type = _UNCOMPRESSED_CHUNK
+		}
+
+		const crc32Sz = 4
+		var tag32 uint32 = uint32(chunk_type) + (uint32(len(writeme)+crc32Sz) << 8)
+
+		err = binary.Write(sf.Writer, binary.LittleEndian, tag32)
+		if err != nil {
+			return
+		}
+
+		err = binary.Write(sf.Writer, binary.LittleEndian, crc)
+		if err != nil {
+			return
+		}
+
+		_, err = sf.Writer.Write(writeme)
+		if err != nil {
+			return
+		}
+
+		n += len(chunk)
+		p = p[len(chunk):]
+	}
+	return n, nil
+}
+
+func IntMin(a int, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}