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Comment:Use 0dev.org/ioutil.SizedWriter as an output buffer for pdc in both compress and decompress modes.
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SHA1: 1717bfae3bf0f8bd5a8f8df29b883a569f24de1f
User & Date: spaskalev on 2014-12-24 22:32:42
Other Links: manifest | tags
Context
2014-12-24
23:33
Made SizedReader faster by keeping explicit buffer indices. check-in: 701ac713de user: spaskalev tags: trunk
22:32
Use 0dev.org/ioutil.SizedWriter as an output buffer for pdc in both compress and decompress modes. check-in: 1717bfae3b user: spaskalev tags: trunk
21:40
Fixed SizedWriter behavior so that it follows io.Writer's Write(...) contract. Added more tests for 100% CC on the ioutil package. Predictor's compressor now uses SizedWriter and no longer has to do any internal buffering. check-in: e1778aba98 user: spaskalev tags: trunk
Changes
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Modified src/0dev.org/commands/pdc/main.go from [c6f8b3fe28] to [1dda5424c0]. 

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package main

import (
	iou "0dev.org/ioutil"
	predictor "0dev.org/predictor"
	"bufio"
	"fmt"
	"io"
	"os"
)
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}

// Compress the data from the given io.Reader and write it to the given io.Writer
// I/O is buffered for better performance
func compress(output io.Writer, input io.Reader) int {
	var (
		err        error
		buffer     *bufio.Writer = bufio.NewWriter(output)
		compressor io.Writer     = predictor.Compressor(buffer)
		buffer     io.Writer = iou.SizedWriter(output, 4096)
		compressor io.Writer = predictor.Compressor(buffer)
	)

	_, err = io.Copy(compressor, bufio.NewReader(input))
	_, err = io.Copy(compressor, input)
	if err != nil {
		fmt.Fprintln(os.Stderr, "Error while compressing.\n", err)
		return 1
	}

	// Flush the compressor
	_, err = compressor.Write(nil)
	if err != nil {
		fmt.Fprintln(os.Stderr, "Error while flushing compresssor buffer.\n", err)
		return 1
	}

	// Flush the buffer
	err = buffer.Flush()
	_, err = buffer.Write(nil)
	if err != nil {
		fmt.Fprintln(os.Stderr, "Error while flushing output buffer.\n", err)
		return 1
	}

	return 0
}

// Decompress the data from the given io.Reader and write it to the given io.Writer
// I/O is buffered for better performance
func decompress(output io.Writer, input io.Reader) int {
	var (
		err          error
		buffer       *bufio.Writer = bufio.NewWriter(output)
		decompressor io.Reader     = predictor.Decompressor(bufio.NewReader(input))
		buffer       io.Writer = iou.SizedWriter(output, 4096)
		decompressor io.Reader = predictor.Decompressor(bufio.NewReader(input))
	)

	_, err = io.Copy(buffer, decompressor)
	if err != nil {
		fmt.Fprintln(os.Stderr, "Error while decompressing.\n", err)
		return 1
	}

	// Flush
	err = buffer.Flush()
	// Flush the buffer
	_, err = buffer.Write(nil)
	if err != nil {
		fmt.Fprintln(os.Stderr, "Error while flushing output buffer.\n", err)
		return 1
	}

	return 0
}

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