feat: add support for context.Context in Retry

Existing function `Retry` is maintained with the same API to preserve
backwards compatibility.

New function `RetryWithContext` accepts a context and delivers it to the
retryable function. Each retry attempt can be limited by timeout (via
context, `WithAttemptTimeout`).

Garbage-collected channel `C` which wasn't used.

Replaced stop channel delivery with `close(ch)` to avoid having a
channel with a single entry.

Removed `time.After()` as it leaks the object until timer fires.

Fixes #2

Signed-off-by: Andrey Smirnov <[email protected]>

.drone.yml

@@ -1,7 +1,7 @@
 ---
 # THIS FILE WAS AUTOMATICALLY GENERATED, PLEASE DO NOT EDIT.
 #
-# Generated on 2020-09-01T21:14:08Z by kres ee90a80-dirty.
+# Generated on 2021-01-18T14:11:16Z by kres latest.
 
 kind: pipeline
 type: kubernetes
@@ -132,7 +132,6 @@ services:
   - --dns=8.8.4.4
   - --mtu=1500
   - --log-level=error
-  - --insecure-registry=http://registry.ci.svc:5000
   privileged: true
   volumes:
   - name: outer-docker-socket

.golangci.yml

@@ -1,6 +1,6 @@
 # THIS FILE WAS AUTOMATICALLY GENERATED, PLEASE DO NOT EDIT.
 #
-# Generated on 2020-09-01T21:14:08Z by kres ee90a80-dirty.
+# Generated on 2021-01-18T14:11:16Z by kres latest.
 
 
 # options for analysis running
@@ -125,6 +125,9 @@ linters:
     - gomnd
     - goerr113
     - nestif
+    - wrapcheck
+    - paralleltest
+    - exhaustivestruct
   disable-all: false
   fast: false
 

Dockerfile

@@ -1,8 +1,8 @@
-# syntax = docker/dockerfile-upstream:1.1.7-experimental
+# syntax = docker/dockerfile-upstream:1.2.0-labs
 
 # THIS FILE WAS AUTOMATICALLY GENERATED, PLEASE DO NOT EDIT.
 #
-# Generated on 2020-09-01T21:14:08Z by kres ee90a80-dirty.
+# Generated on 2021-01-18T14:11:16Z by kres latest.
 
 ARG TOOLCHAIN
 
@@ -24,7 +24,7 @@ FROM toolchain AS tools
 ENV GO111MODULE on
 ENV CGO_ENABLED 0
 ENV GOPATH /go
-RUN curl -sfL https://install.goreleaser.com/github.com/golangci/golangci-lint.sh | bash -s -- -b /bin v1.30.0
+RUN curl -sfL https://install.goreleaser.com/github.com/golangci/golangci-lint.sh | bash -s -- -b /bin v1.33.0
 ARG GOFUMPT_VERSION
 RUN cd $(mktemp -d) \
 	&& go mod init tmp \

Makefile

@@ -1,20 +1,20 @@
 # THIS FILE WAS AUTOMATICALLY GENERATED, PLEASE DO NOT EDIT.
 #
-# Generated on 2020-09-21T13:20:49Z by kres 7e146df-dirty.
+# Generated on 2021-01-18T14:11:16Z by kres latest.
 
 # common variables
 
 SHA := $(shell git describe --match=none --always --abbrev=8 --dirty)
 TAG := $(shell git describe --tag --always --dirty)
 BRANCH := $(shell git rev-parse --abbrev-ref HEAD)
 ARTIFACTS := _out
-REGISTRY ?= docker.io
-USERNAME ?= autonomy
+REGISTRY ?= ghcr.io
+USERNAME ?= talos-systems
 REGISTRY_AND_USERNAME ?= $(REGISTRY)/$(USERNAME)
 GOFUMPT_VERSION ?= abc0db2c416aca0f60ea33c23c76665f6e7ba0b6
 GO_VERSION ?= 1.14
 TESTPKGS ?= ./...
-KRES_IMAGE ?= autonomy/kres:latest
+KRES_IMAGE ?= ghcr.io/talos-systems/kres:latest
 
 # docker build settings
 

retry/constant.go

@@ -5,6 +5,7 @@
 package retry
 
 import (
+	"context"
 	"time"
 )
 
@@ -34,9 +35,8 @@ func Constant(duration time.Duration, setters ...Option) Retryer {
 func NewConstantTicker(opts *Options) *ConstantTicker {
 	l := &ConstantTicker{
 		ticker: ticker{
-			C:       make(chan time.Time, 1),
 			options: opts,
-			s:       make(chan struct{}, 1),
+			s:       make(chan struct{}),
 		},
 	}
 
@@ -45,10 +45,15 @@ func NewConstantTicker(opts *Options) *ConstantTicker {
 
 // Retry implements the Retryer interface.
 func (c constantRetryer) Retry(f RetryableFunc) error {
+	return c.RetryWithContext(context.Background(), removeContext(f))
+}
+
+// RetryWithContext implements the Retryer interface.
+func (c constantRetryer) RetryWithContext(ctx context.Context, f RetryableFuncWithContext) error {
 	tick := NewConstantTicker(c.options)
 	defer tick.Stop()
 
-	return retry(f, c.duration, tick, c.options)
+	return retry(ctx, f, c.duration, tick, c.options)
 }
 
 // Tick implements the Ticker interface.

retry/exponential.go

@@ -5,6 +5,7 @@
 package retry
 
 import (
+	"context"
 	"math"
 	"time"
 )
@@ -39,9 +40,8 @@ func Exponential(duration time.Duration, setters ...Option) Retryer {
 func NewExponentialTicker(opts *Options) *ExponentialTicker {
 	e := &ExponentialTicker{
 		ticker: ticker{
-			C:       make(chan time.Time, 1),
 			options: opts,
-			s:       make(chan struct{}, 1),
+			s:       make(chan struct{}),
 		},
 		c: 1.0,
 	}
@@ -51,10 +51,15 @@ func NewExponentialTicker(opts *Options) *ExponentialTicker {
 
 // Retry implements the Retryer interface.
 func (e exponentialRetryer) Retry(f RetryableFunc) error {
+	return e.RetryWithContext(context.Background(), removeContext(f))
+}
+
+// RetryWithContext implements the Retryer interface.
+func (e exponentialRetryer) RetryWithContext(ctx context.Context, f RetryableFuncWithContext) error {
 	tick := NewExponentialTicker(e.options)
 	defer tick.Stop()
 
-	return retry(f, e.duration, tick, e.options)
+	return retry(ctx, f, e.duration, tick, e.options)
 }
 
 // Tick implements the Ticker interface.

retry/linear.go

@@ -5,6 +5,7 @@
 package retry
 
 import (
+	"context"
 	"time"
 )
 
@@ -36,9 +37,8 @@ func Linear(duration time.Duration, setters ...Option) Retryer {
 func NewLinearTicker(opts *Options) *LinearTicker {
 	l := &LinearTicker{
 		ticker: ticker{
-			C:       make(chan time.Time, 1),
 			options: opts,
-			s:       make(chan struct{}, 1),
+			s:       make(chan struct{}),
 		},
 		c: 1,
 	}
@@ -48,10 +48,15 @@ func NewLinearTicker(opts *Options) *LinearTicker {
 
 // Retry implements the Retryer interface.
 func (l linearRetryer) Retry(f RetryableFunc) error {
+	return l.RetryWithContext(context.Background(), removeContext(f))
+}
+
+// RetryWithContext implements the Retryer interface.
+func (l linearRetryer) RetryWithContext(ctx context.Context, f RetryableFuncWithContext) error {
 	tick := NewLinearTicker(l.options)
 	defer tick.Stop()
 
-	return retry(f, l.duration, tick, l.options)
+	return retry(ctx, f, l.duration, tick, l.options)
 }
 
 // Tick implements the Ticker interface.

retry/options.go

@@ -10,9 +10,10 @@ import (
 
 // Options is the functional options struct.
 type Options struct {
-	Units     time.Duration
-	Jitter    time.Duration
-	LogErrors bool
+	Units          time.Duration
+	Jitter         time.Duration
+	AttemptTimeout time.Duration
+	LogErrors      bool
 }
 
 // Option is the functional option func.
@@ -39,6 +40,13 @@ func WithErrorLogging(enable bool) Option {
 	}
 }
 
+// WithAttemptTimeout sets timeout for each retry attempt.
+func WithAttemptTimeout(o time.Duration) Option {
+	return func(args *Options) {
+		args.AttemptTimeout = o
+	}
+}
+
 // NewDefaultOptions initializes a Options struct with default values.
 func NewDefaultOptions(setters ...Option) *Options {
 	opts := &Options{

retry/retry.go

@@ -6,6 +6,7 @@
 package retry
 
 import (
+	"context"
 	"errors"
 	"fmt"
 	"log"
@@ -17,9 +18,19 @@ import (
 // RetryableFunc represents a function that can be retried.
 type RetryableFunc func() error
 
+// RetryableFuncWithContext represents a function that can be retried.
+type RetryableFuncWithContext func(context.Context) error
+
+func removeContext(f RetryableFunc) RetryableFuncWithContext {
+	return func(context.Context) error {
+		return f()
+	}
+}
+
 // Retryer defines the requirements for retrying a function.
 type Retryer interface {
 	Retry(RetryableFunc) error
+	RetryWithContext(context.Context, RetryableFuncWithContext) error
 }
 
 // Ticker defines the requirements for providing a clock to the retry logic.
@@ -92,9 +103,7 @@ func (TimeoutError) Error() string {
 
 // IsTimeout reutrns if the provided error is a timeout error.
 func IsTimeout(err error) bool {
-	_, ok := err.(TimeoutError)
-
-	return ok
+	return errors.Is(err, TimeoutError{})
 }
 
 type expectedError struct{ error }
@@ -115,7 +124,6 @@ type retryer struct {
 }
 
 type ticker struct {
-	C       chan time.Time
 	options *Options
 	rand    *rand.Rand
 	s       chan struct{}
@@ -138,7 +146,7 @@ func (t ticker) StopChan() <-chan struct{} {
 }
 
 func (t ticker) Stop() {
-	t.s <- struct{}{}
+	close(t.s)
 }
 
 // ExpectedError error represents an error that is expected by the retrying
@@ -161,37 +169,77 @@ func UnexpectedError(err error) error {
 	return unexpectedError{err}
 }
 
-func retry(f RetryableFunc, d time.Duration, t Ticker, o *Options) error {
-	timer := time.NewTimer(d)
-	defer timer.Stop()
+func retry(ctx context.Context, f RetryableFuncWithContext, d time.Duration, t Ticker, o *Options) error {
+	ctx, cancel := context.WithTimeout(ctx, d)
+	defer cancel()
 
 	errs := &ErrorSet{}
 
+	var timer *time.Timer
+
+	defer func() {
+		if timer != nil {
+			timer.Stop()
+		}
+	}()
+
 	for {
-		if err := f(); err != nil {
-			exists := errs.Append(err)
-
-			switch err.(type) {
-			case expectedError:
-				// retry expected errors
-				if !exists && o.LogErrors {
-					log.Printf("retrying error: %s", err)
-				}
+		err := func() error {
+			var attemptCtxCancel context.CancelFunc
+
+			attemptCtx := ctx
+
+			if o.AttemptTimeout != 0 {
+				attemptCtx, attemptCtxCancel = context.WithTimeout(attemptCtx, o.AttemptTimeout)
+				defer attemptCtxCancel()
+			}
+
+			return f(attemptCtx)
+		}()
+
+		if err == nil {
+			return nil
+		}
+
+		if errors.Is(err, context.DeadlineExceeded) {
+			err = TimeoutError{}
+
+			select {
+			case <-ctx.Done():
 			default:
-				return errs
+				// main context not canceled, continue retrying
+				err = ExpectedError(err)
+			}
+		}
+
+		exists := errs.Append(err)
+
+		var expError expectedError
+
+		if errors.As(err, &expError) {
+			// retry expected errors
+			if !exists && o.LogErrors {
+				log.Printf("retrying error: %s", err)
 			}
 		} else {
-			return nil
+			return errs
 		}
 
+		timer = time.NewTimer(t.Tick())
+
 		select {
-		case <-timer.C:
-			errs.Append(TimeoutError{})
+		case <-ctx.Done():
+			err := ctx.Err()
+			if errors.Is(err, context.DeadlineExceeded) {
+				err = TimeoutError{}
+			}
+
+			errs.Append(err)
 
 			return errs
 		case <-t.StopChan():
 			return nil
-		case <-time.After(t.Tick()):
+		case <-timer.C:
 		}
 	}
 }