issue octolab#8: extend Interface, add Err()

.travis.yml

@@ -16,30 +16,31 @@ go:
   - 1.11.x
   - 1.12.x
   - 1.13.x
+  - 1.14.x
 
 jobs:
   allow_failures:
     - go: master
 
 before_script:
   - |
-    if [[ $TRAVIS_GO_VERSION == 1.13* ]]; then
+    if [[ $TRAVIS_GO_VERSION == 1.14* ]]; then
       curl -L $CODECLIMATE > /home/travis/gopath/bin/cc-test-reporter
       chmod +x /home/travis/gopath/bin/cc-test-reporter
       cc-test-reporter before-build
     fi
 
 script:
   - |
-    if [[ $TRAVIS_GO_VERSION == 1.13* ]]; then
+    if [[ $TRAVIS_GO_VERSION == 1.14* ]]; then
       make test-with-coverage-profile
     else
       make test
     fi
 
 after_script:
   - |
-    if [[ $TRAVIS_GO_VERSION == 1.13* ]]; then
+    if [[ $TRAVIS_GO_VERSION == 1.14* ]]; then
       cc-test-reporter after-build -t gocov -p $(basename $(go list -m)) --exit-code $TRAVIS_TEST_RESULT
     fi
 

breaker.go

@@ -50,11 +50,6 @@ type breaker struct {
 	released int32
 }
 
-// Done returns a channel that's closed when a cancellation signal occurred.
-func (br *breaker) Done() <-chan struct{} {
-	return br.signal
-}
-
 // Close closes the Done channel and releases resources associated with it.
 func (br *breaker) Close() {
 	br.closer.Do(func() {
@@ -63,6 +58,20 @@ func (br *breaker) Close() {
 	})
 }
 
+// Done returns a channel that's closed when a cancellation signal occurred.
+func (br *breaker) Done() <-chan struct{} {
+	return br.signal
+}
+
+// Err returns a non-nil error if Done is closed and nil otherwise.
+// After Err returns a non-nil error, successive calls to Err return the same error.
+func (br *breaker) Err() error {
+	if atomic.LoadInt32(&br.released) == 1 {
+		return Interrupted
+	}
+	return nil
+}
+
 // Released returns true if resources associated with the Breaker were released.
 func (br *breaker) Released() bool {
 	return atomic.LoadInt32(&br.released) == 1

context.go

@@ -7,36 +7,42 @@ import (
 
 // BreakByContext returns a new Breaker based on the Context.
 func BreakByContext(ctx context.Context, cancel context.CancelFunc) Interface {
-	return (&contextBreaker{newBreaker(), cancel, ctx.Done()}).trigger()
+	return (&contextBreaker{newBreaker(), cancel, ctx}).trigger()
 }
 
 // WithContext returns a new Breaker and an associated Context derived from ctx.
 // Deprecated: use BreakByContext instead.
 // TODO:v2 will be removed
 func WithContext(ctx context.Context) (Interface, context.Context) {
 	ctx, cancel := context.WithCancel(ctx)
-	return (&contextBreaker{newBreaker(), cancel, ctx.Done()}).trigger(), ctx
+	return (&contextBreaker{newBreaker(), cancel, ctx}).trigger(), ctx
 }
 
 type contextBreaker struct {
 	*breaker
 	cancel context.CancelFunc
-	signal <-chan struct{}
+	ctx    context.Context
+}
+
+// Close closes the Done channel and releases resources associated with it.
+func (br *contextBreaker) Close() {
+	br.cancel()
 }
 
 // Done returns a channel that's closed when a cancellation signal occurred.
 func (br *contextBreaker) Done() <-chan struct{} {
-	return br.signal
+	return br.ctx.Done()
 }
 
-// Close closes the Done channel and releases resources associated with it.
-func (br *contextBreaker) Close() {
-	br.cancel()
+// Err returns a non-nil error if Done is closed and nil otherwise.
+// After Err returns a non-nil error, successive calls to Err return the same error.
+func (br *contextBreaker) Err() error {
+	return br.ctx.Err()
 }
 
 func (br *contextBreaker) trigger() Interface {
 	go func() {
-		<-br.signal
+		<-br.ctx.Done()
 		atomic.StoreInt32(&br.released, 1)
 	}()
 	return br

interface.go

@@ -15,10 +15,13 @@ package breaker
 //  }
 //
 type Interface interface {
-	// Done returns a channel that's closed when a cancellation signal occurred.
-	Done() <-chan struct{}
 	// Close closes the Done channel and releases resources associated with it.
 	Close()
+	// Done returns a channel that's closed when a cancellation signal occurred.
+	Done() <-chan struct{}
+	// Err returns a non-nil error if Done is closed and nil otherwise.
+	// After Err returns a non-nil error, successive calls to Err return the same error.
+	Err() error
 	// trigger is a private method to guarantee that the Breakers come from
 	// this package and all of them return a valid Done channel.
 	trigger() Interface