ccpaging/nxlog4go

package driver

import (
    "errors"
)

// Appender is an interface for anything that should be able to write logs
type Appender interface {
    // Open opens and creates the appender.
    Open(dsn string, args ...interface{}) (Appender, error)

    // Set sets name-value option. Checkable
    Set(name string, value interface{}) error

    // Enabled returns true if the given recorder should be encoded
    // and written bytes after.
    //
    // Enabled can write the recorder directly with owner format,
    // and then return false.
    Enabled(*Recorder) bool

    // Write will be called to write the log bytes.
    Write([]byte) (int, error)

    // Close should clean up anything lingering about the Appender, as it is called before
    // the Appender is removed.  Write should not be called after Close.
    Close()
}

type nopAppender struct{}

// NewNopAppender returns a no-op Layout.
func NewNopAppender() Appender                                     { return &nopAppender{} }
func (*nopAppender) Open(string, ...interface{}) (Appender, error) { return &nopAppender{}, nil }
func (*nopAppender) Set(string, interface{}) error                 { return nil }
func (*nopAppender) Enabled(*Recorder) bool                        { return false }
func (*nopAppender) Write([]byte) (int, error)                     { return 0, errors.New("NOP") }
func (*nopAppender) Close()                                        {}

/** Register **/

var registered = make(map[string]Appender)

// Register is called by 3rd appender's init() function
// to register the new appender interface.
func Register(name string, app Appender) {
    if name == "" {
        return
    }
    if app == nil {
        delete(registered, name)
        return
    }
    registered[name] = app
}

// Open opens and creates the named appender.
//
// Return new appender and error
func Open(name string, dsn string, args ...interface{}) (Appender, error) {
    if app, ok := registered[name]; ok {
        return app.Open(dsn, args...)
    }
    return nil, errors.New("Not register " + name)
}