add BuildChain, for associating two errors together #6
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@lysu PTAL |
errors.go
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| func (err *chain) Cause() error { | ||
| return err.prevErr |
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should we recursively find the root cause?
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No: this is the causer interface that goes just one level deeper.
errors.go
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| func (err *chain) Error() string { | ||
| return err.currentErr.Error() + "\n" + err.prevErr.Error() |
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Error should not got preErr.
e.g. TruncateErr, error info should only contain a column, b row value be truncate for end-user
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Okay, that makes sense since this is joining two separate errors. The previous will show up in the formatter.
| @@ -335,3 +335,29 @@ func Find(origErr error, test func(error) bool) error { | |||
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| return foundErr | |||
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| // Chain ties together two errors, giving them a Causer interface and a concatenated Error message. | |||
| type chain struct { | |||
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need override ErrorStack or %+v to print errors info before wrap recursively.
e.g.
func main() {
_, err := time.ParseDuration("dfasdf")
err = resetErrDataTooLong("c", 1, err)
err = resetErrDataTooLong("b", 2, err)
fmt.Println(errors.ErrorStack(err))
}
func resetErrDataTooLong(colName string, rowIdx int, err error) error {
newErr := types.ErrDataTooLong.Gen("Data too long for column '%v' at row %v", colName, rowIdx)
return errors.Wrap(err, newErr)
}should output:
time: invalid duration dfasdf
/home/robi/Code/go/src/github.com/pingcap/tidb/executor/test/zz.go:24: [types:1406]Data too long for column 'c' at row 1
/home/robi/Code/go/src/github.com/pingcap/tidb/executor/test/zz.go:24: [types:1406]Data too long for column 'b' at row 2
I think time: invalid duration dfasdf is what we need for this method
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IMHO, I still think do |
gregwebs
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| func (err *chain) Cause() error { | ||
| return err.prevErr |
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hi @gregwebs , I check juju's impl again. It seem will return .error in Cause(), and Error() will go preErr when error == nil...should we follow them ~?
expect this two question, others are look good to me
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The implementation for vertical composition of distinct errors is turning out to be complex and fragile. I think it is better to just do annotations vertically. For combining errors, we can use ErrorGroup and combine horizontally. You could use uber-go/multierr. |
The nee for this came up in pingcap/tidb#7151 (comment)