package common
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import (
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"fmt"
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"runtime"
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)
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//----------------------------------------
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// Convenience methods
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// ErrorWrap will just call .TraceFrom(), or create a new *cmnError.
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func ErrorWrap(cause interface{}, format string, args ...interface{}) Error {
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msg := Fmt(format, args...)
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if causeCmnError, ok := cause.(*cmnError); ok {
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return causeCmnError.TraceFrom(1, msg)
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}
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// NOTE: cause may be nil.
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// NOTE: do not use causeCmnError here, not the same as nil.
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return newError(msg, cause, cause).Stacktrace()
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}
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//----------------------------------------
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// Error & cmnError
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/*
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Usage:
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```go
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// Error construction
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var someT = errors.New("Some err type")
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var err1 error = NewErrorWithT(someT, "my message")
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...
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// Wrapping
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var err2 error = ErrorWrap(err1, "another message")
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if (err1 != err2) { panic("should be the same")
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...
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// Error handling
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switch err2.T() {
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case someT: ...
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default: ...
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}
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```
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*/
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type Error interface {
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Error() string
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Message() string
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Stacktrace() Error
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Trace(format string, args ...interface{}) Error
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TraceFrom(offset int, format string, args ...interface{}) Error
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Cause() interface{}
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WithT(t interface{}) Error
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T() interface{}
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Format(s fmt.State, verb rune)
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}
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// New Error with no cause where the type is the format string of the message..
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func NewError(format string, args ...interface{}) Error {
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msg := Fmt(format, args...)
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return newError(msg, nil, format)
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}
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// New Error with specified type and message.
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func NewErrorWithT(t interface{}, format string, args ...interface{}) Error {
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msg := Fmt(format, args...)
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return newError(msg, nil, t)
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}
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// NOTE: The name of a function "NewErrorWithCause()" implies that you are
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// creating a new Error, yet, if the cause is an Error, creating a new Error to
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// hold a ref to the old Error is probably *not* what you want to do.
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// So, use ErrorWrap(cause, format, a...) instead, which returns the same error
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// if cause is an Error.
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// IF you must set an Error as the cause of an Error,
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// then you can use the WithCauser interface to do so manually.
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// e.g. (error).(tmlibs.WithCauser).WithCause(causeError)
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type WithCauser interface {
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WithCause(cause interface{}) Error
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}
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type cmnError struct {
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msg string // first msg which also appears in msg
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cause interface{} // underlying cause (or panic object)
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t interface{} // for switching on error
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msgtraces []msgtraceItem // all messages traced
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stacktrace []uintptr // first stack trace
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}
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var _ WithCauser = &cmnError{}
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var _ Error = &cmnError{}
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// NOTE: do not expose.
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func newError(msg string, cause interface{}, t interface{}) *cmnError {
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return &cmnError{
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msg: msg,
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cause: cause,
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t: t,
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msgtraces: nil,
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stacktrace: nil,
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}
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}
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func (err *cmnError) Message() string {
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return err.msg
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}
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func (err *cmnError) Error() string {
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return fmt.Sprintf("%v", err)
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}
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// Captures a stacktrace if one was not already captured.
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func (err *cmnError) Stacktrace() Error {
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if err.stacktrace == nil {
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var offset = 3
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var depth = 32
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err.stacktrace = captureStacktrace(offset, depth)
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}
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return err
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}
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// Add tracing information with msg.
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func (err *cmnError) Trace(format string, args ...interface{}) Error {
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msg := Fmt(format, args...)
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return err.doTrace(msg, 0)
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}
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// Same as Trace, but traces the line `offset` calls out.
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// If n == 0, the behavior is identical to Trace().
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func (err *cmnError) TraceFrom(offset int, format string, args ...interface{}) Error {
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msg := Fmt(format, args...)
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return err.doTrace(msg, offset)
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}
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// Return last known cause.
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// NOTE: The meaning of "cause" is left for the caller to define.
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// There exists no "canonical" definition of "cause".
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// Instead of blaming, try to handle it, or organize it.
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func (err *cmnError) Cause() interface{} {
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return err.cause
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}
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// Overwrites the Error's cause.
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func (err *cmnError) WithCause(cause interface{}) Error {
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err.cause = cause
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return err
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}
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// Overwrites the Error's type.
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func (err *cmnError) WithT(t interface{}) Error {
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err.t = t
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return err
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}
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// Return the "type" of this message, primarily for switching
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// to handle this Error.
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func (err *cmnError) T() interface{} {
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return err.t
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}
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func (err *cmnError) doTrace(msg string, n int) Error {
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pc, _, _, _ := runtime.Caller(n + 2) // +1 for doTrace(). +1 for the caller.
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// Include file & line number & msg.
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// Do not include the whole stack trace.
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err.msgtraces = append(err.msgtraces, msgtraceItem{
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pc: pc,
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msg: msg,
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})
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return err
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}
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func (err *cmnError) Format(s fmt.State, verb rune) {
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switch verb {
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case 'p':
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s.Write([]byte(fmt.Sprintf("%p", &err)))
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default:
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if s.Flag('#') {
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s.Write([]byte("--= Error =--\n"))
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// Write msg.
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s.Write([]byte(fmt.Sprintf("Message: %#s\n", err.msg)))
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// Write cause.
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s.Write([]byte(fmt.Sprintf("Cause: %#v\n", err.cause)))
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// Write type.
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s.Write([]byte(fmt.Sprintf("T: %#v\n", err.t)))
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// Write msg trace items.
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s.Write([]byte(fmt.Sprintf("Msg Traces:\n")))
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for i, msgtrace := range err.msgtraces {
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s.Write([]byte(fmt.Sprintf(" %4d %s\n", i, msgtrace.String())))
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}
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// Write stack trace.
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if err.stacktrace != nil {
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s.Write([]byte(fmt.Sprintf("Stack Trace:\n")))
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for i, pc := range err.stacktrace {
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fnc := runtime.FuncForPC(pc)
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file, line := fnc.FileLine(pc)
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s.Write([]byte(fmt.Sprintf(" %4d %s:%d\n", i, file, line)))
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}
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}
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s.Write([]byte("--= /Error =--\n"))
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} else {
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// Write msg.
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if err.cause != nil {
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s.Write([]byte(fmt.Sprintf("Error{`%s` (cause: %v)}", err.msg, err.cause))) // TODO tick-esc?
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} else {
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s.Write([]byte(fmt.Sprintf("Error{`%s`}", err.msg))) // TODO tick-esc?
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}
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}
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}
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}
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//----------------------------------------
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// stacktrace & msgtraceItem
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func captureStacktrace(offset int, depth int) []uintptr {
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var pcs = make([]uintptr, depth)
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n := runtime.Callers(offset, pcs)
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return pcs[0:n]
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}
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type msgtraceItem struct {
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pc uintptr
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msg string
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}
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func (mti msgtraceItem) String() string {
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fnc := runtime.FuncForPC(mti.pc)
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file, line := fnc.FileLine(mti.pc)
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return fmt.Sprintf("%s:%d - %s",
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file, line,
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mti.msg,
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)
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}
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//----------------------------------------
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// Panic wrappers
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// XXX DEPRECATED
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// A panic resulting from a sanity check means there is a programmer error
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// and some guarantee is not satisfied.
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// XXX DEPRECATED
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func PanicSanity(v interface{}) {
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panic(Fmt("Panicked on a Sanity Check: %v", v))
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}
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// A panic here means something has gone horribly wrong, in the form of data corruption or
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// failure of the operating system. In a correct/healthy system, these should never fire.
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// If they do, it's indicative of a much more serious problem.
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// XXX DEPRECATED
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func PanicCrisis(v interface{}) {
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panic(Fmt("Panicked on a Crisis: %v", v))
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}
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// Indicates a failure of consensus. Someone was malicious or something has
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// gone horribly wrong. These should really boot us into an "emergency-recover" mode
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// XXX DEPRECATED
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func PanicConsensus(v interface{}) {
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panic(Fmt("Panicked on a Consensus Failure: %v", v))
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}
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// For those times when we're not sure if we should panic
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// XXX DEPRECATED
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func PanicQ(v interface{}) {
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panic(Fmt("Panicked questionably: %v", v))
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}
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