| // Copyright 2015 The LUCI Authors. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| package errors |
| |
| import ( |
| "sync" |
| ) |
| |
| // LazyMultiError is a lazily-constructed MultiError. |
| // |
| // LazyMultiError is like MultiError, except that you know the ultimate size up |
| // front, and then you call Assign for each error encountered, and it's |
| // potential index. The underlying MultiError will only be allocated if one of |
| // the Assign'd errors is non-nil. Similarly, Get will retrieve either the |
| // allocated MultiError, or nil if no error was encountered. |
| // Build one with NewLazyMultiError. |
| type LazyMultiError interface { |
| // Assign semantically assigns the error to the given index in the MultiError. |
| // If the error is nil, no action is taken. Otherwise the MultiError is |
| // allocated to its full size (if not already), and the error assigned into |
| // it. |
| // |
| // Returns true iff err != nil (i.e. "was it assigned?"), so you can use this |
| // like: |
| // if !lme.Assign(i, err) { |
| // // stuff requiring err == nil |
| // } |
| Assign(int, error) bool |
| |
| // GetOne returns the error at the given index (which may be nil) |
| GetOne(int) error |
| |
| // Get returns the MultiError, or nil, if no non-nil error was Assign'd. |
| Get() error |
| } |
| |
| type lazyMultiError struct { |
| sync.Mutex |
| |
| size int |
| me MultiError |
| } |
| |
| // NewLazyMultiError makes a new LazyMultiError of the provided size. |
| func NewLazyMultiError(size int) LazyMultiError { |
| return &lazyMultiError{size: size} |
| } |
| |
| func (e *lazyMultiError) Assign(i int, err error) bool { |
| if err == nil { |
| return false |
| } |
| e.Lock() |
| defer e.Unlock() |
| if e.me == nil { |
| e.me = make(MultiError, e.size) |
| } |
| e.me[i] = err |
| return true |
| } |
| |
| func (e *lazyMultiError) GetOne(i int) error { |
| e.Lock() |
| defer e.Unlock() |
| if e.me == nil { |
| return nil |
| } |
| return e.me[i] |
| } |
| |
| func (e *lazyMultiError) Get() error { |
| e.Lock() |
| defer e.Unlock() |
| if e.me == nil { |
| return nil |
| } |
| return e.me |
| } |