log.go

// mgo - MongoDB driver for Go
//
// Copyright (c) 2010-2012 - Gustavo Niemeyer <gustavo@niemeyer.net>
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this
//    list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright notice,
//    this list of conditions and the following disclaimer in the documentation
//    and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
// ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

package mgo

import (
	"fmt"
	"sync"
)

// ---------------------------------------------------------------------------
// Logging integration.

// LogLogger avoid importing the log type information unnecessarily.  There's a small cost
// associated with using an interface rather than the type.  Depending on how
// often the logger is plugged in, it would be worth using the type instead.
type logLogger interface {
	Output(calldepth int, s string) error
}

var (
	globalLogger logLogger
	globalDebug  bool
	globalMutex  sync.Mutex
)

// RACE WARNING: There are known data races when logging, which are manually
// silenced when the race detector is in use. These data races won't be
// observed in typical use, because logging is supposed to be set up once when
// the application starts. Having raceDetector as a constant, the compiler
// should elide the locks altogether in actual use.

// SetLogger specify the *log.Logger object where log messages should be sent to.
func SetLogger(logger logLogger) {
	if raceDetector {
		globalMutex.Lock()
		defer globalMutex.Unlock()
	}
	globalLogger = logger
}

// SetDebug enable the delivery of debug messages to the logger.  Only meaningful
// if a logger is also set.
func SetDebug(debug bool) {
	if raceDetector {
		globalMutex.Lock()
		defer globalMutex.Unlock()
	}
	globalDebug = debug
}

func log(v ...interface{}) {
	if raceDetector {
		globalMutex.Lock()
		defer globalMutex.Unlock()
	}
	if globalLogger != nil {
		globalLogger.Output(2, fmt.Sprint(v...))
	}
}

func logln(v ...interface{}) {
	if raceDetector {
		globalMutex.Lock()
		defer globalMutex.Unlock()
	}
	if globalLogger != nil {
		globalLogger.Output(2, fmt.Sprintln(v...))
	}
}

func logf(format string, v ...interface{}) {
	if raceDetector {
		globalMutex.Lock()
		defer globalMutex.Unlock()
	}
	if globalLogger != nil {
		globalLogger.Output(2, fmt.Sprintf(format, v...))
	}
}

func debug(v ...interface{}) {
	if raceDetector {
		globalMutex.Lock()
		defer globalMutex.Unlock()
	}
	if globalDebug && globalLogger != nil {
		globalLogger.Output(2, fmt.Sprint(v...))
	}
}

func debugln(v ...interface{}) {
	if raceDetector {
		globalMutex.Lock()
		defer globalMutex.Unlock()
	}
	if globalDebug && globalLogger != nil {
		globalLogger.Output(2, fmt.Sprintln(v...))
	}
}

func debugf(format string, v ...interface{}) {
	if raceDetector {
		globalMutex.Lock()
		defer globalMutex.Unlock()
	}
	if globalDebug && globalLogger != nil {
		globalLogger.Output(2, fmt.Sprintf(format, v...))
	}
}