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Commit 3aedc246 authored by Kirill Smelkov's avatar Kirill Smelkov
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Move error-handling routines & co to lab.nexedi.com/kirr/go123 

error.go is completely being moved to that shared place for handy Go
utilities into several subpackages:

	lab.nexedi.com/kirr/go123/exc		-- exception-style error handling for Go
	lab.nexedi.com/kirr/go123/myname	-- easy way to determine current function's name and package
	lab.nexedi.com/kirr/go123/xerr		-- addons for error-handling
	lab.nexedi.com/kirr/go123/xruntime	-- addons to standard package runtime
parent 3ba6cf73
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Showing with 67 additions and 473 deletions
error.go deleted 100644 → 0
View file @ 3ba6cf73
// Copyright (C) 2015-2016 Nexedi SA and Contributors.
// Kirill Smelkov <kirr@nexedi.com>
//
// This program is free software: you can Use, Study, Modify and Redistribute
// it under the terms of the GNU General Public License version 3, or (at your
// option) any later version, as published by the Free Software Foundation.
//
// This program is distributed WITHOUT ANY WARRANTY; without even the implied
// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
//
// See COPYING file for full licensing terms.
// Git-backup | Exception-style errors
package main
import (
"fmt"
"runtime"
"strings"
)
// error type which is raised by raise(arg)
type Error struct {
arg interface{}
link *Error // chain of linked Error(s) - see e.g. errcontext()
}
func (e *Error) Error() string {
msgv := []string{}
msg := ""
for e != nil {
// TODO(go1.7) -> runtime.Frame (see xtraceback())
if f, ok := e.arg.(Frame); ok {
//msg = f.Function
//msg = fmt.Sprintf("%s (%s:%d)", f.Function, f.File, f.Line)
msg = strings.TrimPrefix(f.Name(), _errorpkgdot) // XXX -> better prettyfunc
} else {
msg = fmt.Sprint(e.arg)
}
msgv = append(msgv, msg)
e = e.link
}
return strings.Join(msgv, ": ")
}
// turn any value into Error
// if v is already Error - it stays the same
// otherwise new Error is created
func aserror(v interface{}) *Error {
if e, ok := v.(*Error); ok {
return e
}
return &Error{v, nil}
}
// raise error to upper level
func raise(arg interface{}) {
panic(aserror(arg))
}
// raise formatted string
func raisef(format string, a ...interface{}) {
panic(aserror(fmt.Sprintf(format, a...)))
}
// raise if err != nil
// NOTE err can be != nil even if typed obj = nil:
// var obj *T;
// err = obj
// err != nil is true
func raiseif(err error) {
//if err != nil && !reflect.ValueOf(err).IsNil() {
if err != nil {
panic(aserror(err))
}
}
// checks recovered value to be of *Error
// if there is non-Error error - repanic it
// otherwise return Error either nil (no panic), or actual value
func _errcatch(r interface{}) *Error {
e, _ := r.(*Error)
if e == nil && r != nil {
panic(r)
}
return e
}
// catch error and call f(e) if it was caught.
// must be called under defer
func errcatch(f func(e *Error)) {
e := _errcatch(recover())
if e == nil {
return
}
f(e)
}
// be notified when error unwinding is being happening.
// hook into unwinding process with f() call. Returned error is reraised.
// see also: errcontext()
// must be called under defer
func erronunwind(f func(e *Error) *Error) {
// cannot do errcatch(...)
// as recover() works only in first-level called functions
e := _errcatch(recover())
if e == nil {
return
}
e = f(e)
panic(e)
}
// provide error context to automatically add on unwinding.
// f is called if error unwinding is happening.
// call result is added to raised error as "prefix" context
// must be called under defer
func errcontext(f func() interface{}) {
e := _errcatch(recover())
if e == nil {
return
}
arg := f()
panic(erraddcontext(e, arg))
}
// add "prefix" context to error
func erraddcontext(e *Error, arg interface{}) *Error {
return &Error{arg, e}
}
func _myfuncname(nskip int) string {
pcv := [1]uintptr{}
runtime.Callers(nskip, pcv[:])
f := runtime.FuncForPC(pcv[0])
if f == nil {
return ""
}
return f.Name()
}
// get name of currently running function (caller of myfuncname())
// name is fully qualified package/name.function(.x)
func myfuncname() string {
return _myfuncname(3)
}
// get name of currently running function's package
// package is fully qualified package/name
func mypkgname() string {
myfunc := _myfuncname(3)
if myfunc == "" {
return ""
}
// NOTE dots in package name are after last slash are escaped by go as %2e
// this way the first '.' after last '/' is delimiter between package and function
//
// lab.nexedi.com/kirr/git-backup/package%2ename.Function
// lab.nexedi.com/kirr/git-backup/pkg2.qqq/name%2ezzz.Function
islash := strings.LastIndexByte(myfunc, '/')
iafterslash := islash + 1 // NOTE if '/' not found iafterslash = 0
idot := strings.IndexByte(myfunc[iafterslash:], '.')
if idot == -1 {
panic(fmt.Errorf("funcname %q is not fully qualified", myfunc))
}
return myfunc[:iafterslash+idot]
}
// TODO(go1.7) goes away in favour of runtime.Frame
type Frame struct {
*runtime.Func
pc uintptr
}
// get current calling traceback as []Frame
// nskip meaning: the same as in runtime.Callers()
// TODO(go1.7) []Frame -> []runtime.Frame
func xtraceback(nskip int) []Frame {
// all callers
var pcv = []uintptr{0}
for {
pcv = make([]uintptr, 2*len(pcv))
n := runtime.Callers(nskip+1, pcv)
if n < len(pcv) {
pcv = pcv[:n]
break
}
}
// pcv -> frames
/*
framev := make([]runtime.Frame, 0, len(pcv))
frames := runtime.CallersFrames(pcv)
for more := true; more; {
var frame runtime.Frame
frame, more = frames.Next()
framev = append(framev, frame)
}
*/
framev := make([]Frame, 0, len(pcv))
for _, pc := range pcv {
framev = append(framev, Frame{runtime.FuncForPC(pc), pc})
}
return framev
}
var (
_errorpkgname string // package name under which error.go lives
_errorpkgdot string // errorpkg.
_errorraise string // errorpkg.raise
)
func init() {
_errorpkgname = mypkgname()
_errorpkgdot = _errorpkgname + "."
_errorraise = _errorpkgname + ".raise"
}
// add calling context to error.
// Add calling function names as error context up-to topfunc not including.
// see also: erraddcontext()
func erraddcallingcontext(topfunc string, e *Error) *Error {
seenraise := false
for _, f := range xtraceback(2) {
// do not show anything after raise*()
if !seenraise && strings.HasPrefix(f.Name(), _errorraise) {
seenraise = true
continue
}
if !seenraise {
continue
}
// do not go beyond topfunc
if topfunc != "" && f.Name() == topfunc {
break
}
// skip intermediates
if strings.HasSuffix(f.Name(), "_") { // XXX -> better skipfunc
continue
}
e = &Error{f, e}
}
return e
}
// error merging multiple errors (e.g. after collecting them from several parallel workers)
type Errorv []error
func (ev Errorv) Error() string {
if len(ev) == 1 {
return ev[0].Error()
}
msg := fmt.Sprintf("%d errors:\n", len(ev))
for _, e := range ev {
msg += fmt.Sprintf("\t- %s\n", e)
}
return msg
}
error_test.go deleted 100644 → 0
View file @ 3ba6cf73
// Copyright (C) 2015-2016 Nexedi SA and Contributors.
// Kirill Smelkov <kirr@nexedi.com>
//
// This program is free software: you can Use, Study, Modify and Redistribute
// it under the terms of the GNU General Public License version 3, or (at your
// option) any later version, as published by the Free Software Foundation.
//
// This program is distributed WITHOUT ANY WARRANTY; without even the implied
// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
//
// See COPYING file for full licensing terms.
package main
import (
"errors"
"strings"
"testing"
)
func do_raise1() {
raise(1)
}
func TestErrRaiseCatch(t *testing.T) {
defer errcatch(func(e *Error) {
if !(e.arg == 1 && e.link == nil) {
t.Fatalf("error caught but unexpected: %#v ; want {1, nil}", e)
}
})
do_raise1()
t.Fatal("error not caught")
}
// verify err chain has .arg(s) as expected
func verifyErrChain(t *testing.T, e *Error, argv ...interface{}) {
i := 0
for ; e != nil; i, e = i+1, e.link {
if i >= len(argv) {
t.Fatal("too long error chain")
}
if e.arg != argv[i] {
t.Fatalf("error caught but unexpected %vth arg: %v ; want %v", i, e.arg, argv[i])
}
}
if i < len(argv) {
t.Fatal("too small error chain")
}
}
func do_onunwind1(t *testing.T) {
defer erronunwind(func(e *Error) *Error {
t.Fatal("on unwind called without raise")
return nil
})
}
func do_onunwind2() {
defer erronunwind(func(e *Error) *Error {
return &Error{2, e}
})
do_raise1()
}
func TestErrOnUnwind(t *testing.T) {
defer errcatch(func(e *Error) {
verifyErrChain(t, e, 2, 1)
})
do_onunwind1(t)
do_onunwind2()
t.Fatal("error not caught")
}
func do_context1(t *testing.T) {
defer errcontext(func() interface{} {
t.Fatal("on context called without raise")
return nil
})
}
func do_context2() {
defer errcontext(func() interface{} {
return 3
})
do_raise1()
}
func TestErrContext(t *testing.T) {
defer errcatch(func(e *Error) {
verifyErrChain(t, e, 3, 1)
})
do_context1(t)
do_context2()
t.Fatal("error not caught")
}
func TestMyFuncName(t *testing.T) {
myfunc := myfuncname()
// go test changes full package name (putting filesystem of the tree into ti)
// thus we check only for suffix
wantsuffix := ".TestMyFuncName"
if !strings.HasSuffix(myfunc, wantsuffix) {
t.Errorf("myfuncname() -> %v ; want *%v", myfunc, wantsuffix)
}
}
func do_raise11() {
do_raise1()
}
func do_raise3if() {
raiseif(errors.New("3"))
}
func do_raise3if1() {
do_raise3if()
}
func do_raise4f() {
raisef("%d", 4)
}
func do_raise4f1() {
do_raise4f()
}
func TestErrAddCallingContext(t *testing.T) {
var tests = []struct{ f func(); wanterrcontext string } {
{do_raise11, "do_raise11: do_raise1: 1"},
{do_raise3if1, "do_raise3if1: do_raise3if: 3"},
{do_raise4f1, "do_raise4f1: do_raise4f: 4"},
}
for _, tt := range tests {
func() {
myfunc := myfuncname()
defer errcatch(func(e *Error) {
e = erraddcallingcontext(myfunc, e)
msg := e.Error()
if msg != tt.wanterrcontext {
t.Fatalf("err + calling context: %q ; want %q", msg, tt.wanterrcontext)
}
})
tt.f()
t.Fatal("error not caught")
}()
}
}
git-backup.go
View file @ 3aedc246
This diff is collapsed.
git-backup_test.go
View file @ 3aedc246
......@@ -22,6 +22,10 @@ import (
"syscall"
"testing"
"lab.nexedi.com/kirr/go123/exc"
"lab.nexedi.com/kirr/go123/myname"
"lab.nexedi.com/kirr/go123/xruntime"
git "github.com/libgit2/git2go"
)
......@@ -51,16 +55,16 @@ func XSha1(s string) Sha1 {
// verify end-to-end pull-restore
func TestPullRestore(t *testing.T) {
// if something raises -> don't let testing panic - report it as proper error with context.
here := myfuncname()
defer errcatch(func(e *Error) {
e = erraddcallingcontext(here, e)
here := myname.Func()
defer exc.Catch(func(e *exc.Error) {
e = exc.Addcallingcontext(here, e)
// add file:line for failing code inside testing function - so we have exact context to debug
failedat := ""
for _, f := range xtraceback(1) {
for _, f := range xruntime.Traceback(1) {
if f.Name() == here {
// TODO(go1.7) -> f.File, f.Line (f becomes runtime.Frame)
file, line := f.FileLine(f.pc - 1)
file, line := f.FileLine(f.Pc - 1)
failedat = fmt.Sprintf("%s:%d", filepath.Base(file), line)
break
}
......@@ -251,7 +255,7 @@ func TestPullRestore(t *testing.T) {
// now try to pull corrupt repo - pull should refuse if transferred pack contains bad objects
my2 := mydir + "/testdata/2"
func() {
defer errcatch(func(e *Error) {
defer exc.Catch(func(e *exc.Error) {
// it ok - pull should raise
})
cmd_pull(gb, []string{my2+":b2"})
......
git.go
View file @ 3aedc246
......@@ -19,6 +19,8 @@ import (
"os"
"os/exec"
"strings"
"lab.nexedi.com/kirr/go123/exc"
)
// how/whether to redirect stdio of spawned process
......@@ -164,7 +166,7 @@ func ggit2(argv []string, ctx RunWith) (err *GitError, stdout, stderr string) {
e, stdout, stderr := _git(argv, ctx)
eexec, _ := e.(*exec.ExitError)
if e != nil && eexec == nil {
raisef("git %s : ", strings.Join(argv, " "), e)
exc.Raisef("git %s : ", strings.Join(argv, " "), e)
}
if eexec != nil {
err = &GitError{GitErrContext{argv, ctx.stdin, stdout, stderr}, eexec}
......@@ -181,7 +183,7 @@ func xgit(argv ...interface{}) string {
func xgit2(argv []string, ctx RunWith) string {
gerr, stdout, _ := ggit2(argv, ctx)
if gerr != nil {
raise(gerr)
exc.Raise(gerr)
}
return stdout
}
......@@ -205,11 +207,11 @@ func (e *GitSha1Error) Error() string {
func xgit2Sha1(argv []string, ctx RunWith) Sha1 {
gerr, stdout, stderr := ggit2(argv, ctx)
if gerr != nil {
raise(gerr)
exc.Raise(gerr)
}
sha1, err := Sha1Parse(stdout)
if err != nil {
raise(&GitSha1Error{GitErrContext{argv, ctx.stdin, stdout, stderr}})
exc.Raise(&GitSha1Error{GitErrContext{argv, ctx.stdin, stdout, stderr}})
}
return sha1
}
gitobjects.go
View file @ 3aedc246
......@@ -21,6 +21,8 @@ import (
"sync"
"time"
"lab.nexedi.com/kirr/go123/exc"
git "github.com/libgit2/git2go"
)
......@@ -96,11 +98,11 @@ type Tag struct {
// (libgit2 does not provide such functionality at all)
func xload_tag(g *git.Repository, tag_sha1 Sha1) (tag *Tag, tag_obj *git.OdbObject) {
tag_obj, err := ReadObject(g, tag_sha1, git.ObjectTag)
raiseif(err)
exc.Raiseif(err)
tag, err = tag_parse(String(tag_obj.Data()))
if err != nil {
raise(&TagLoadError{tag_sha1, err})
exc.Raise(&TagLoadError{tag_sha1, err})
}
return tag, tag_obj
}
......@@ -225,7 +227,7 @@ func xcommit_tree2(g *git.Repository, tree Sha1, parents []Sha1, msg string, aut
commit += fmt.Sprintf("\n%s", msg)
sha1, err := WriteObject(g, Bytes(commit), git.ObjectCommit)
raiseif(err)
exc.Raiseif(err)
return sha1
}
......
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