From b5e5d68098a2807f6b0df99c4d27a8e79411af8c Mon Sep 17 00:00:00 2001
From: tian <xiaoliang.tian@gmail.com>
Date: Thu, 5 Jul 2018 17:11:58 +0800
Subject: [PATCH 1/2] add Flush by name, support force closed options

---
 hystrix/circuit.go  | 39 ++++++++++++++++++++++++++++++++++++++-
 hystrix/settings.go |  3 +++
 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/hystrix/circuit.go b/hystrix/circuit.go
index 87d88b9..899a595 100644
--- a/hystrix/circuit.go
+++ b/hystrix/circuit.go
@@ -5,6 +5,7 @@ import (
 	"sync"
 	"sync/atomic"
 	"time"
+	"errors"
 )
 
 // CircuitBreaker is created for each ExecutorPool to track whether requests
@@ -13,6 +14,7 @@ type CircuitBreaker struct {
 	Name                   string
 	open                   bool
 	forceOpen              bool
+	forceClosed            bool
 	mutex                  *sync.RWMutex
 	openedOrLastTestedTime int64
 
@@ -20,6 +22,11 @@ type CircuitBreaker struct {
 	metrics      *metricExchange
 }
 
+var (
+	// ErrCBNotExist occurs when no CircuitBreaker exists
+	ErrCBNotExist = errors.New("circuit breaker not exist")
+)
+
 var (
 	circuitBreakersMutex *sync.RWMutex
 	circuitBreakers      map[string]*CircuitBreaker
@@ -30,6 +37,17 @@ func init() {
 	circuitBreakers = make(map[string]*CircuitBreaker)
 }
 
+// IsCircuitBreakerOpen returns whether a circuitBreaker is open for an interface
+func IsCircuitBreakerOpen(name string) (bool, error) {
+	circuitBreakersMutex.Lock()
+	defer circuitBreakersMutex.Unlock()
+	if c, ok := circuitBreakers[name]; ok {
+		return c.IsOpen(), nil
+	} else {
+		return false, ErrCBNotExist
+	}
+}
+
 // GetCircuit returns the circuit for the given command and whether this call created it.
 func GetCircuit(name string) (*CircuitBreaker, bool, error) {
 	circuitBreakersMutex.RLock()
@@ -51,6 +69,17 @@ func GetCircuit(name string) (*CircuitBreaker, bool, error) {
 
 	return circuitBreakers[name], !ok, nil
 }
+func FlushByName(name string) {
+	circuitBreakersMutex.Lock()
+	defer circuitBreakersMutex.Unlock()
+	cb, ok := circuitBreakers[name]
+	if ok {
+		cb.metrics.Reset()
+		cb.executorPool.Metrics.Reset()
+		delete(circuitBreakers, name)
+	}
+
+}
 
 // Flush purges all circuit and metric information from memory.
 func Flush() {
@@ -71,7 +100,8 @@ func newCircuitBreaker(name string) *CircuitBreaker {
 	c.metrics = newMetricExchange(name)
 	c.executorPool = newExecutorPool(name)
 	c.mutex = &sync.RWMutex{}
-
+	c.forceOpen = getSettings(name).ForceOpen
+	c.forceClosed = getSettings(name).ForceClose
 	return c
 }
 
@@ -115,6 +145,13 @@ func (circuit *CircuitBreaker) IsOpen() bool {
 // When the circuit is open, this call will occasionally return true to measure whether the external service
 // has recovered.
 func (circuit *CircuitBreaker) AllowRequest() bool {
+	//force open has highest priority
+	if circuit.forceOpen {
+		return false
+	}
+	if circuit.forceClosed {
+		return true
+	}
 	return !circuit.IsOpen() || circuit.allowSingleTest()
 }
 
diff --git a/hystrix/settings.go b/hystrix/settings.go
index 8a7d47f..cfdcb72 100644
--- a/hystrix/settings.go
+++ b/hystrix/settings.go
@@ -26,6 +26,9 @@ type Settings struct {
 	RequestVolumeThreshold uint64
 	SleepWindow            time.Duration
 	ErrorPercentThreshold  int
+	ForceFallback bool
+	ForceOpen     bool
+	ForceClose    bool
 }
 
 // CommandConfig is used to tune circuit settings at runtime

From 3fc47cdab25a67af354953725c2e2ba5e97da32b Mon Sep 17 00:00:00 2001
From: Shawn <xiaoliang.tian@gmail.com>
Date: Fri, 26 Oct 2018 17:46:56 +0800
Subject: [PATCH 2/2] fix go routine massive increase,

if there is multiple collector and high concurrency, it will cause too much GC
---
 hystrix/metrics.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hystrix/metrics.go b/hystrix/metrics.go
index d289fe6..01e6c0d 100644
--- a/hystrix/metrics.go
+++ b/hystrix/metrics.go
@@ -58,7 +58,7 @@ func (m *metricExchange) Monitor() {
 		wg := &sync.WaitGroup{}
 		for _, collector := range m.metricCollectors {
 			wg.Add(1)
-			go m.IncrementMetrics(wg, collector, update, totalDuration)
+			m.IncrementMetrics(wg, collector, update, totalDuration)
 		}
 		wg.Wait()