server: Move all the top level files into cmd folder. (#2490)

This change brings a change which was done for the 'mc'
package to allow for clean repo and have a cleaner
github drop in experience.

cmd/erasure-createfile.go

@@ -0,0 +1,145 @@
+/*
+ * Minio Cloud Storage, (C) 2016 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package cmd
+
+import (
+	"encoding/hex"
+	"hash"
+	"io"
+	"sync"
+
+	"github.com/klauspost/reedsolomon"
+)
+
+// erasureCreateFile - writes an entire stream by erasure coding to
+// all the disks, writes also calculate individual block's checksum
+// for future bit-rot protection.
+func erasureCreateFile(disks []StorageAPI, volume, path string, reader io.Reader, blockSize int64, dataBlocks int, parityBlocks int, algo string, writeQuorum int) (bytesWritten int64, checkSums []string, err error) {
+	// Allocated blockSized buffer for reading.
+	buf := make([]byte, blockSize)
+
+	hashWriters := newHashWriters(len(disks), algo)
+
+	// Read until io.EOF, erasure codes data and writes to all disks.
+	for {
+		var blocks [][]byte
+		n, rErr := io.ReadFull(reader, buf)
+		// FIXME: this is a bug in Golang, n == 0 and err ==
+		// io.ErrUnexpectedEOF for io.ReadFull function.
+		if n == 0 && rErr == io.ErrUnexpectedEOF {
+			return 0, nil, rErr
+		}
+		if rErr == io.EOF {
+			// We have reached EOF on the first byte read, io.Reader
+			// must be 0bytes, we don't need to erasure code
+			// data. Will create a 0byte file instead.
+			if bytesWritten == 0 {
+				blocks = make([][]byte, len(disks))
+				rErr = appendFile(disks, volume, path, blocks, hashWriters, writeQuorum)
+				if rErr != nil {
+					return 0, nil, rErr
+				}
+			} // else we have reached EOF after few reads, no need to
+			// add an additional 0bytes at the end.
+			break
+		}
+		if rErr != nil && rErr != io.ErrUnexpectedEOF {
+			return 0, nil, rErr
+		}
+		if n > 0 {
+			// Returns encoded blocks.
+			var enErr error
+			blocks, enErr = encodeData(buf[0:n], dataBlocks, parityBlocks)
+			if enErr != nil {
+				return 0, nil, enErr
+			}
+
+			// Write to all disks.
+			if err = appendFile(disks, volume, path, blocks, hashWriters, writeQuorum); err != nil {
+				return 0, nil, err
+			}
+			bytesWritten += int64(n)
+		}
+	}
+
+	checkSums = make([]string, len(disks))
+	for i := range checkSums {
+		checkSums[i] = hex.EncodeToString(hashWriters[i].Sum(nil))
+	}
+	return bytesWritten, checkSums, nil
+}
+
+// encodeData - encodes incoming data buffer into
+// dataBlocks+parityBlocks returns a 2 dimensional byte array.
+func encodeData(dataBuffer []byte, dataBlocks, parityBlocks int) ([][]byte, error) {
+	rs, err := reedsolomon.New(dataBlocks, parityBlocks)
+	if err != nil {
+		return nil, err
+	}
+	// Split the input buffer into data and parity blocks.
+	var blocks [][]byte
+	blocks, err = rs.Split(dataBuffer)
+	if err != nil {
+		return nil, err
+	}
+
+	// Encode parity blocks using data blocks.
+	err = rs.Encode(blocks)
+	if err != nil {
+		return nil, err
+	}
+
+	// Return encoded blocks.
+	return blocks, nil
+}
+
+// appendFile - append data buffer at path.
+func appendFile(disks []StorageAPI, volume, path string, enBlocks [][]byte, hashWriters []hash.Hash, writeQuorum int) (err error) {
+	var wg = &sync.WaitGroup{}
+	var wErrs = make([]error, len(disks))
+	// Write encoded data to quorum disks in parallel.
+	for index, disk := range disks {
+		if disk == nil {
+			continue
+		}
+		wg.Add(1)
+		// Write encoded data in routine.
+		go func(index int, disk StorageAPI) {
+			defer wg.Done()
+			wErr := disk.AppendFile(volume, path, enBlocks[index])
+			if wErr != nil {
+				wErrs[index] = wErr
+				return
+			}
+
+			// Calculate hash for each blocks.
+			hashWriters[index].Write(enBlocks[index])
+
+			// Successfully wrote.
+			wErrs[index] = nil
+		}(index, disk)
+	}
+
+	// Wait for all the appends to finish.
+	wg.Wait()
+
+	// Do we have write quorum?.
+	if !isDiskQuorum(wErrs, writeQuorum) {
+		return errXLWriteQuorum
+	}
+	return nil
+}