mtbf/log.go

package main

import (
	"fmt"
	"os"
	"strings"
)

func shouldLog(facility string, level, maxLevel int) bool {
	moduleMap := CfgGet("log-module-map").(map[string]bool)

	logModule, ok := moduleMap[strings.ToLower(facility)]
	if ok {
		return logModule
	}

	if maxLevel < 0 {
		return true // log everything if log-level is -1
	}

	return maxLevel >= level
}

func log(facility string, level int, s string, params ...interface{}) {
	maxLevel := CfgGetInt("log-level")
	if !shouldLog(facility, level, maxLevel) {
		return
	}

	var prefix = ""
	if level > 0 {
		prefix = strings.Repeat("-", level) + "> "
	}
	if (maxLevel >= 2 || maxLevel < 0) && facility != "" {
		prefix = prefix + "[" + strings.ToUpper(facility) + "]: "
	}

	if len(params) == 0 {
		fmt.Printf(prefix + s + "\n")
	} else {
		fmt.Printf(prefix+s+"\n", params...)
	}
}

func fail(s string, params ...interface{}) {
	if len(params) == 0 {
		fmt.Fprintf(os.Stderr, "ERROR: "+s+"\n")
	} else {
		fmt.Fprintf(os.Stderr, "ERROR: "+s+"\n", params...)
	}
	os.Exit(1)
}

func logIf(condition bool, facility string, level int, s string, params ...interface{}) {
	if condition {
		log(facility, level, s, params...)
	}
}

func failIf(condition bool, s string, params ...interface{}) {
	if condition {
		fail(s, params...)
	}
}

func updateModuleMap() {
	logModules := CfgGet("log-modules").([]string)
	noLogModules := CfgGet("no-log-modules").([]string)

	newMap := map[string]bool{}

	for _, module := range logModules {
		module = strings.ToLower(module)
		newMap[module] = true
	}

	for _, module := range noLogModules {
		module = strings.ToLower(module)
		failIf(newMap[module] == true, "log module \"%v\" is defined both in log-modules and no-log-modules", module)
		newMap[module] = false
	}

	CfgSet("log-module-map", newMap)
}

func init() {
	CfgRegister("log-level", 0, "max log level, useful for debugging. -1 logs everything")
	CfgRegisterCallback("log-modules", []string{}, "always log output from these modules", updateModuleMap)
	CfgRegisterCallback("no-log-modules", []string{}, "never log output from these modules", updateModuleMap)
	CfgRegisterHidden("log-module-map", map[string]bool{})
}