Fix time processing, more docs
Evan Huus
9 years ago
| 25 | 25 | lock sync.RWMutex |
| 26 | 26 | state state |
| 27 | 27 | errors, successes int |
| 28 | lastError time.Time | |
| 28 | 29 | } |
| 29 | 30 | |
| 30 | // New constructs a new circuit-breaker. | |
| 31 | // New constructs a new circuit-breaker that starts closed. | |
| 32 | // From closed, the breaker opens if "errorThreshold" errors are seen | |
| 33 | // without an error-free period of at least "timeout". From open, the | |
| 34 | // breaker half-closes after "timeout". From half-open, the breaker closes | |
| 35 | // after "successThreshold" consecutive successes, or opens on a single error. | |
| 31 | 36 | func New(errorThreshold, successThreshold int, timeout time.Duration) *Breaker { |
| 32 | 37 | return &Breaker{ |
| 33 | 38 | errorThreshold: errorThreshold, |
| 38 | 43 | |
| 39 | 44 | // Run will either return BreakerOpen immediately if the circuit-breaker is |
| 40 | 45 | // already open, or it will run the given function and pass along its return |
| 41 | // value. | |
| 46 | // value. It is safe to call Run concurrently on the same Breaker. | |
| 42 | 47 | func (b *Breaker) Run(x func() error) error { |
| 43 | 48 | b.lock.RLock() |
| 44 | 49 | state := b.state |
| 57 | 62 | return x() |
| 58 | 63 | }() |
| 59 | 64 | |
| 65 | b.processResult(result, panicValue) | |
| 66 | ||
| 67 | if panicValue != nil { | |
| 68 | // as close as Go lets us come to a "rethrow" although unfortunately | |
| 69 | // we lose the original panicing location | |
| 70 | panic(panicValue) | |
| 71 | } | |
| 72 | ||
| 73 | return result | |
| 74 | } | |
| 75 | ||
| 76 | func (b *Breaker) processResult(result error, panicValue interface{}) { | |
| 60 | 77 | b.lock.Lock() |
| 61 | 78 | defer b.lock.Unlock() |
| 62 | 79 | |
| 68 | 85 | } |
| 69 | 86 | } |
| 70 | 87 | } else { |
| 88 | if b.errors > 0 { | |
| 89 | expiry := b.lastError //time.Add mutates, so take a copy | |
| 90 | expiry.Add(b.timeout) | |
| 91 | if time.Now().After(expiry) { | |
| 92 | b.errors = 0 | |
| 93 | } | |
| 94 | } | |
| 95 | ||
| 71 | 96 | switch b.state { |
| 72 | 97 | case closed: |
| 73 | 98 | b.errors++ |
| 74 | 99 | if b.errors == b.errorThreshold { |
| 75 | 100 | b.openBreaker() |
| 101 | } else { | |
| 102 | b.lastError = time.Now() | |
| 76 | 103 | } |
| 77 | 104 | case halfOpen: |
| 78 | 105 | b.openBreaker() |
| 79 | 106 | } |
| 80 | 107 | } |
| 81 | ||
| 82 | if panicValue != nil { | |
| 83 | // as close as Go lets us come to a "rethrow" although unfortunately | |
| 84 | // we lose the original panicing location | |
| 85 | panic(panicValue) | |
| 86 | } | |
| 87 | ||
| 88 | return result | |
| 89 | 108 | } |
| 90 | 109 | |
| 91 | 110 | func (b *Breaker) openBreaker() { |