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60 lines
1.7 KiB
Go
60 lines
1.7 KiB
Go
/*
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Copyright 2014 The Go4 Authors
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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// Package fault handles fault injection for testing.
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package fault // import "go4.org/fault"
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import (
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"errors"
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"math/rand"
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"os"
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"strconv"
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"strings"
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)
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var fakeErr = errors.New("fake injected error for testing")
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// An Injector reports whether fake errors should be returned.
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type Injector struct {
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failPercent int
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}
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// NewInjector returns a new fault injector with the given name. The
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// environment variable "FAULT_" + capital(name) + "_FAIL_PERCENT"
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// controls the percentage of requests that fail. If undefined or
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// zero, no requests fail.
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func NewInjector(name string) *Injector {
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var failPercent, _ = strconv.Atoi(os.Getenv("FAULT_" + strings.ToUpper(name) + "_FAIL_PERCENT"))
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return &Injector{
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failPercent: failPercent,
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}
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}
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// ShouldFail reports whether a fake error should be returned.
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func (in *Injector) ShouldFail() bool {
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return in.failPercent > 0 && in.failPercent > rand.Intn(100)
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}
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// FailErr checks ShouldFail and, if true, assigns a fake error to err
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// and returns true.
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func (in *Injector) FailErr(err *error) bool {
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if !in.ShouldFail() {
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return false
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}
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*err = fakeErr
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return true
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}
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