mtsatellite/tilemapper/client.go

package main

import (
	"fmt"
	"net"

	"bufio"

	"bitbucket.org/s_l_teichmann/mtredisalize/common"
)

type Client struct {
	conn   net.Conn
	reader *bufio.Reader
}

func NewClient(network, address string) (client *Client, err error) {
	var conn net.Conn
	if conn, err = net.Dial(network, address); err != nil {
		return
	}

	client = &Client{conn: conn, reader: bufio.NewReaderSize(conn, 8*1024)}
	return
}

func (client *Client) Close() error {
	return client.conn.Close()
}

func (client *Client) writeArray(size int) (err error) {
	_, err = client.conn.Write([]byte(fmt.Sprintf("*%d\r\n", size)))
	return
}

func (client *Client) writeBulkString(data []byte) (err error) {
	if _, err = client.conn.Write([]byte(fmt.Sprintf("$%d\r\n", len(data)))); err != nil {
		return
	}
	if _, err = client.conn.Write(data); err != nil {
		return
	}
	_, err = client.conn.Write([]byte("\r\n"))
	return
}

func (client *Client) writeHSpatial(p1, p2 int64) (err error) {
	if err = client.writeArray(4); err != nil {
		return
	}
	if err = client.writeBulkString([]byte("HSPATIAL")); err != nil {
		return
	}
	if err = client.writeBulkString([]byte("IGNORE")); err != nil {
		return
	}
	if err = client.writeBulkString(common.StringToBytes(p1)); err != nil {
		return
	}
	err = client.writeBulkString(common.StringToBytes(p2))
	return
}

func (client *Client) readLine() (data []byte, err error) {
	return client.reader.ReadBytes('\n')
}

func isError(line []byte) error {
	if len(line) > 0 && line[0] == '-' {
		return fmt.Errorf("error: %s", line[1:])
	}
	return nil
}

func (client *Client) readBulkString(data *[]byte) (size int, err error) {
	var line []byte
	if line, err = client.readLine(); err != nil {
		return
	}
	if err = isError(line); err != nil {
		return
	}
	if _, err = fmt.Sscanf(string(line), "$%d\r\n", &size); err != nil {
		return
	}
	if size <= 0 {
		return
	}
	if cap(*data) < size {
		*data = make([]byte, size)
	}
	for rest := size; rest > 0; {
		var n int
		if n, err = client.reader.Read((*data)[size-rest : size]); err != nil {
			return
		}
		rest -= n
	}
	if _, err = client.reader.ReadBytes('\n'); err != nil {
		return
	}
	return
}

func (client *Client) QueryCuboid(cuboid common.Cuboid, fn func(*common.Block)) (err error) {
	p1 := common.CoordToPlain(cuboid.P1)
	p2 := common.CoordToPlain(cuboid.P2)
	if err = client.writeHSpatial(p1, p2); err != nil {
		return
	}
	var (
		data  = make([]byte, 8*1024)
		block = common.Block{}
		size  int
		key   int64
	)

	for {
		if size, err = client.readBulkString(&data); err != nil {
			return
		}
		if size <= 0 {
			break
		}
		if key, err = common.DecodeStringFromBytes(data[0:size]); err != nil {
			return
		}
		block.Coord = common.PlainToCoord(key)
		if size, err = client.readBulkString(&data); err != nil {
			return
		}
		block.Data = data[0:size]
		fn(&block)
	}

	return
}