doodle/lib/debugging/debugging.go

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// Package debugging contains useful methods for debugging the app, safely
// isolated from the rest of the app's packages.
package debugging
import (
"fmt"
"runtime"
"strings"
)
// Configurable variables for the stack tracer functions.
var (
// StackDepth is the depth that Callers() will crawl up the call stack. This
// variable is configurable.
StackDepth = 20
// StopAt is the function name to stop the tracebacks at. Set to a blank
// string to not stop and trace all the way up to `runtime.goexit` or
// wherever.
StopAt = "main.main"
)
// Minimum depth given to runtime.Caller() so that the call stacks will exclude
// the call to debugging.Caller() itself -- so this debug module won't debug its
// own function calls in the tracebacks.
const minDepth = 2
// Caller returns the filename and line number that called the calling
// function.
func Caller() string {
if pc, file, no, ok := runtime.Caller(minDepth); ok {
frames := runtime.CallersFrames([]uintptr{pc})
frame, _ := frames.Next()
if frame.Function != "" {
return fmt.Sprintf("%s#%d: %s()",
frame.File,
frame.Line,
frame.Function,
)
}
return fmt.Sprintf("%s#%d",
file,
no,
)
}
return "[no caller information]"
}
// Callers returns an array of all the callers of the current function.
func Callers() []string {
var (
callers []string
pc = make([]uintptr, StackDepth)
count = runtime.Callers(minDepth, pc)
)
pc = pc[:count] // only pass valid program counters to CallersFrames
var frames = runtime.CallersFrames(pc)
_ = frames
// Loop to get frames of the call stack.
for {
frame, more := frames.Next()
callers = append(callers, fmt.Sprintf("%s#%d: %s()",
frame.File,
frame.Line,
frame.Function,
))
if StopAt != "" && frame.Function == StopAt {
break
}
if !more {
break
}
}
return callers
}
// StringifyCallers pretty-prints the Callers as a single string with newlines.
func StringifyCallers() string {
callers := Callers()
var result []string
for i, caller := range callers {
if i == 0 {
continue // StringifyCallers() would be the first row, skip it.
}
result = append(result, fmt.Sprintf("%d: %s", i, caller))
}
return strings.Join(result, "\n")
}
// PrintCallers prints the stringified callers directly to STDOUT.
func PrintCallers() {
fmt.Println("Call stack (most recent/current function first):")
for i, caller := range Callers() {
if i == 0 {
continue // PrintCallers() would be the first row, skip it.
}
fmt.Printf("%d: %s\n", i, caller)
}
}
// Pause until the user hits enter in the console.
func Pause() {
var x string
fmt.Print("Press enter to continue . . .")
fmt.Scanf("%s", &x)
}