dotcloud/docker

package jsonlog // import "github.com/docker/docker/daemon/logger/jsonfilelog/jsonlog"

import (
    "bytes"
    "encoding/json"
    "time"
    "unicode/utf8"
)

// JSONLogs marshals encoded JSONLog objects
type JSONLogs struct {
    Log     []byte    `json:"log,omitempty"`
    Stream  string    `json:"stream,omitempty"`
    Created time.Time `json:"time"`

    // json-encoded bytes
    RawAttrs json.RawMessage `json:"attrs,omitempty"`
}

// MarshalJSONBuf is an optimized JSON marshaller that avoids reflection
// and unnecessary allocation.
func (mj *JSONLogs) MarshalJSONBuf(buf *bytes.Buffer) error {
    first := true

    buf.WriteString(`{`)
    if len(mj.Log) != 0 {
        first = false
        buf.WriteString(`"log":`)
        ffjsonWriteJSONBytesAsString(buf, mj.Log)
    }
    if len(mj.Stream) != 0 {
        if first {
            first = false
        } else {
            buf.WriteString(`,`)
        }
        buf.WriteString(`"stream":`)
        ffjsonWriteJSONBytesAsString(buf, []byte(mj.Stream))
    }
    if len(mj.RawAttrs) > 0 {
        if first {
            first = false
        } else {
            buf.WriteString(`,`)
        }
        buf.WriteString(`"attrs":`)
        buf.Write(mj.RawAttrs)
    }
    if !first {
        buf.WriteString(`,`)
    }

    created, err := fastTimeMarshalJSON(mj.Created)
    if err != nil {
        return err
    }

    buf.WriteString(`"time":`)
    buf.WriteString(created)
    buf.WriteString(`}`)
    return nil
}

func ffjsonWriteJSONBytesAsString(buf *bytes.Buffer, s []byte) {
    const hex = "0123456789abcdef"

    buf.WriteByte('"')
    start := 0
    for i := 0; i < len(s); {
        if b := s[i]; b < utf8.RuneSelf {
            if 0x20 <= b && b != '\\' && b != '"' && b != '<' && b != '>' && b != '&' {
                i++
                continue
            }
            if start < i {
                buf.Write(s[start:i])
            }
            switch b {
            case '\\', '"':
                buf.WriteByte('\\')
                buf.WriteByte(b)
            case '\n':
                buf.WriteByte('\\')
                buf.WriteByte('n')
            case '\r':
                buf.WriteByte('\\')
                buf.WriteByte('r')
            default:

                buf.WriteString(`\u00`)
                buf.WriteByte(hex[b>>4])
                buf.WriteByte(hex[b&0xF])
            }
            i++
            start = i
            continue
        }
        c, size := utf8.DecodeRune(s[i:])
        if c == utf8.RuneError && size == 1 {
            if start < i {
                buf.Write(s[start:i])
            }
            buf.WriteString(`\ufffd`)
            i += size
            start = i
            continue
        }

        if c == '\u2028' || c == '\u2029' {
            if start < i {
                buf.Write(s[start:i])
            }
            buf.WriteString(`\u202`)
            buf.WriteByte(hex[c&0xF])
            i += size
            start = i
            continue
        }
        i += size
    }
    if start < len(s) {
        buf.Write(s[start:])
    }
    buf.WriteByte('"')
}