add events package (#2341)

* add events package

* update go version

.github/workflows/pr.yml

@@ -8,10 +8,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
 
-    - name: Set up Go 1.16
+    - name: Set up Go 1.17
       uses: actions/setup-go@v1
       with:
-        go-version: 1.16
+        go-version: 1.17
       id: go
 
     - name: Check out code into the Go module directory

.github/workflows/tests.yml

@@ -8,10 +8,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
 
-    - name: Set up Go 1.16
+    - name: Set up Go 1.17
       uses: actions/setup-go@v1
       with:
-        go-version: 1.16
+        go-version: 1.17
       id: go
 
     - name: Check out code into the Go module directory

api/handler/api/util.go

@@ -7,10 +7,10 @@ import (
 	"net/http"
 	"strings"
 
+	"github.com/oxtoacart/bpool"
 	api "go-micro.dev/v4/api/proto"
 	"go-micro.dev/v4/registry"
 	"go-micro.dev/v4/selector"
-	"github.com/oxtoacart/bpool"
 )
 
 var (

api/handler/event/event.go

@@ -10,11 +10,11 @@ import (
 	"strings"
 	"time"
 
+	"github.com/google/uuid"
+	"github.com/oxtoacart/bpool"
 	"go-micro.dev/v4/api/handler"
 	proto "go-micro.dev/v4/api/proto"
 	"go-micro.dev/v4/util/ctx"
-	"github.com/google/uuid"
-	"github.com/oxtoacart/bpool"
 )
 
 var (

api/handler/rpc/rpc.go

@@ -9,6 +9,8 @@ import (
 	"strconv"
 	"strings"
 
+	jsonpatch "github.com/evanphx/json-patch/v5"
+	"github.com/oxtoacart/bpool"
 	"go-micro.dev/v4/api"
 	"go-micro.dev/v4/api/handler"
 	"go-micro.dev/v4/api/internal/proto"
@@ -23,8 +25,6 @@ import (
 	"go-micro.dev/v4/selector"
 	"go-micro.dev/v4/util/ctx"
 	"go-micro.dev/v4/util/qson"
-	jsonpatch "github.com/evanphx/json-patch/v5"
-	"github.com/oxtoacart/bpool"
 )
 
 const (

api/handler/rpc/rpc_test.go

@@ -7,8 +7,8 @@ import (
 	"reflect"
 	"testing"
 
-	go_api "go-micro.dev/v4/api/proto"
 	"github.com/golang/protobuf/proto"
+	go_api "go-micro.dev/v4/api/proto"
 )
 
 func TestRequestPayloadFromRequest(t *testing.T) {

api/handler/rpc/stream.go

@@ -9,14 +9,14 @@ import (
 	"strings"
 	"time"
 
+	"github.com/gobwas/httphead"
+	"github.com/gobwas/ws"
+	"github.com/gobwas/ws/wsutil"
 	"go-micro.dev/v4/api"
 	"go-micro.dev/v4/client"
 	raw "go-micro.dev/v4/codec/bytes"
 	"go-micro.dev/v4/logger"
 	"go-micro.dev/v4/selector"
-	"github.com/gobwas/httphead"
-	"github.com/gobwas/ws"
-	"github.com/gobwas/ws/wsutil"
 )
 
 // serveWebsocket will stream rpc back over websockets assuming json

api/router/registry/registry_test.go

@@ -3,8 +3,8 @@ package registry
 import (
 	"testing"
 
-	"go-micro.dev/v4/registry"
 	"github.com/stretchr/testify/assert"
+	"go-micro.dev/v4/registry"
 )
 
 func TestStoreRegex(t *testing.T) {

api/server/http/http.go

@@ -8,10 +8,10 @@ import (
 	"os"
 	"sync"
 
+	"github.com/gorilla/handlers"
 	"go-micro.dev/v4/api/server"
 	"go-micro.dev/v4/api/server/cors"
 	"go-micro.dev/v4/logger"
-	"github.com/gorilla/handlers"
 )
 
 type httpServer struct {

broker/http.go

@@ -16,6 +16,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/google/uuid"
 	"go-micro.dev/v4/codec/json"
 	merr "go-micro.dev/v4/errors"
 	"go-micro.dev/v4/registry"
@@ -23,7 +24,6 @@ import (
 	maddr "go-micro.dev/v4/util/addr"
 	mnet "go-micro.dev/v4/util/net"
 	mls "go-micro.dev/v4/util/tls"
-	"github.com/google/uuid"
 	"golang.org/x/net/http2"
 )
 

broker/http_test.go

@@ -5,9 +5,9 @@ import (
 	"testing"
 	"time"
 
+	"github.com/google/uuid"
 	"go-micro.dev/v4/broker"
 	"go-micro.dev/v4/registry"
-	"github.com/google/uuid"
 )
 
 var (

client/cache.go

@@ -7,8 +7,8 @@ import (
 	"hash/fnv"
 	"time"
 
-	"go-micro.dev/v4/metadata"
 	cache "github.com/patrickmn/go-cache"
+	"go-micro.dev/v4/metadata"
 )
 
 // NewCache returns an initialised cache.

cmd/cmd.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/urfave/cli/v2"
 	"go-micro.dev/v4/auth"
 	"go-micro.dev/v4/broker"
 	"go-micro.dev/v4/cache"
@@ -23,7 +24,6 @@ import (
 	"go-micro.dev/v4/server"
 	"go-micro.dev/v4/store"
 	"go-micro.dev/v4/transport"
-	"github.com/urfave/cli/v2"
 )
 
 type Cmd interface {

codec/grpc/grpc.go

@@ -8,8 +8,8 @@ import (
 	"io"
 	"strings"
 
-	"go-micro.dev/v4/codec"
 	"github.com/golang/protobuf/proto"
+	"go-micro.dev/v4/codec"
 )
 
 type Codec struct {

codec/json/json.go

@@ -5,9 +5,9 @@ import (
 	"encoding/json"
 	"io"
 
-	"go-micro.dev/v4/codec"
 	"github.com/golang/protobuf/jsonpb"
 	"github.com/golang/protobuf/proto"
+	"go-micro.dev/v4/codec"
 )
 
 type Codec struct {

codec/proto/marshaler.go

@@ -3,9 +3,9 @@ package proto
 import (
 	"bytes"
 
-	"go-micro.dev/v4/codec"
 	"github.com/golang/protobuf/proto"
 	"github.com/oxtoacart/bpool"
+	"go-micro.dev/v4/codec"
 )
 
 // create buffer pool with 16 instances each preallocated with 256 bytes

codec/proto/proto.go

@@ -4,8 +4,8 @@ package proto
 import (
 	"io"
 
-	"go-micro.dev/v4/codec"
 	"github.com/golang/protobuf/proto"
+	"go-micro.dev/v4/codec"
 )
 
 type Codec struct {

codec/protorpc/protorpc.go

@@ -8,8 +8,8 @@ import (
 	"strconv"
 	"sync"
 
-	"go-micro.dev/v4/codec"
 	"github.com/golang/protobuf/proto"
+	"go-micro.dev/v4/codec"
 )
 
 type flusher interface {

config/reader/json/json.go

@@ -4,11 +4,11 @@ import (
 	"errors"
 	"time"
 
+	"github.com/imdario/mergo"
 	"go-micro.dev/v4/config/encoder"
 	"go-micro.dev/v4/config/encoder/json"
 	"go-micro.dev/v4/config/reader"
 	"go-micro.dev/v4/config/source"
-	"github.com/imdario/mergo"
 )
 
 type jsonReader struct {

config/secrets/box/box.go

@@ -2,8 +2,8 @@
 package box
 
 import (
-	"go-micro.dev/v4/config/secrets"
 	"github.com/pkg/errors"
+	"go-micro.dev/v4/config/secrets"
 	naclbox "golang.org/x/crypto/nacl/box"
 
 	"crypto/rand"

config/secrets/secretbox/secretbox.go

@@ -3,8 +3,8 @@
 package secretbox
 
 import (
-	"go-micro.dev/v4/config/secrets"
 	"github.com/pkg/errors"
+	"go-micro.dev/v4/config/secrets"
 	"golang.org/x/crypto/nacl/secretbox"
 
 	"crypto/rand"

config/source/cli/cli.go

@@ -7,10 +7,10 @@ import (
 	"strings"
 	"time"
 
-	"go-micro.dev/v4/cmd"
-	"go-micro.dev/v4/config/source"
 	"github.com/imdario/mergo"
 	"github.com/urfave/cli/v2"
+	"go-micro.dev/v4/cmd"
+	"go-micro.dev/v4/config/source"
 )
 
 type cliSource struct {

config/source/cli/cli_test.go

@@ -5,11 +5,11 @@ import (
 	"os"
 	"testing"
 
+	"github.com/urfave/cli/v2"
 	"go-micro.dev/v4"
 	"go-micro.dev/v4/cmd"
 	"go-micro.dev/v4/config"
 	"go-micro.dev/v4/config/source"
-	"github.com/urfave/cli/v2"
 )
 
 func TestCliSourceDefault(t *testing.T) {

config/source/cli/options.go

@@ -3,8 +3,8 @@ package cli
 import (
 	"context"
 
-	"go-micro.dev/v4/config/source"
 	"github.com/urfave/cli/v2"
+	"go-micro.dev/v4/config/source"
 )
 
 type contextKey struct{}

config/source/env/env.go

@@ -6,8 +6,8 @@ import (
 	"strings"
 	"time"
 
-	"go-micro.dev/v4/config/source"
 	"github.com/imdario/mergo"
+	"go-micro.dev/v4/config/source"
 )
 
 var (

config/source/file/watcher.go

@@ -1,3 +1,4 @@
+//go:build !linux
 // +build !linux
 
 package file
@@ -5,8 +6,8 @@ package file
 import (
 	"os"
 
-	"go-micro.dev/v4/config/source"
 	"github.com/fsnotify/fsnotify"
+	"go-micro.dev/v4/config/source"
 )
 
 type watcher struct {

config/source/file/watcher_linux.go

@@ -1,3 +1,4 @@
+//go:build linux
 // +build linux
 
 package file
@@ -5,8 +6,8 @@ package file
 import (
 	"os"
 
-	"go-micro.dev/v4/config/source"
 	"github.com/fsnotify/fsnotify"
+	"go-micro.dev/v4/config/source"
 )
 
 type watcher struct {

config/source/flag/flag.go

@@ -3,8 +3,8 @@ package flag
 import (
 	"errors"
 	"flag"
-	"go-micro.dev/v4/config/source"
 	"github.com/imdario/mergo"
+	"go-micro.dev/v4/config/source"
 	"strings"
 	"time"
 )

config/source/memory/memory.go

@@ -5,8 +5,8 @@ import (
 	"sync"
 	"time"
 
-	"go-micro.dev/v4/config/source"
 	"github.com/google/uuid"
+	"go-micro.dev/v4/config/source"
 )
 
 type memory struct {

debug/log/os.go

@@ -3,8 +3,8 @@ package log
 import (
 	"sync"
 
-	"go-micro.dev/v4/util/ring"
 	"github.com/google/uuid"
+	"go-micro.dev/v4/util/ring"
 )
 
 // Should stream from OS

debug/trace/default.go

@@ -4,8 +4,8 @@ import (
 	"context"
 	"time"
 
-	"go-micro.dev/v4/util/ring"
 	"github.com/google/uuid"
+	"go-micro.dev/v4/util/ring"
 )
 
 type memTracer struct {

events/events.go

@@ -0,0 +1,92 @@
+// Package events is for event streaming and storage
+package events
+
+import (
+	"encoding/json"
+	"errors"
+	"time"
+)
+
+var (
+	// DefaultStream is the default events stream implementation
+	DefaultStream Stream
+	// DefaultStore is the default events store implementation
+	DefaultStore Store
+)
+
+var (
+	// ErrMissingTopic is returned if a blank topic was provided to publish
+	ErrMissingTopic = errors.New("Missing topic")
+	// ErrEncodingMessage is returned from publish if there was an error encoding the message option
+	ErrEncodingMessage = errors.New("Error encoding message")
+)
+
+// Stream is an event streaming interface
+type Stream interface {
+	Publish(topic string, msg interface{}, opts ...PublishOption) error
+	Consume(topic string, opts ...ConsumeOption) (<-chan Event, error)
+}
+
+// Store is an event store interface
+type Store interface {
+	Read(topic string, opts ...ReadOption) ([]*Event, error)
+	Write(event *Event, opts ...WriteOption) error
+}
+
+type AckFunc func() error
+type NackFunc func() error
+
+// Event is the object returned by the broker when you subscribe to a topic
+type Event struct {
+	// ID to uniquely identify the event
+	ID string
+	// Topic of event, e.g. "registry.service.created"
+	Topic string
+	// Timestamp of the event
+	Timestamp time.Time
+	// Metadata contains the values the event was indexed by
+	Metadata map[string]string
+	// Payload contains the encoded message
+	Payload []byte
+
+	ackFunc  AckFunc
+	nackFunc NackFunc
+}
+
+// Unmarshal the events message into an object
+func (e *Event) Unmarshal(v interface{}) error {
+	return json.Unmarshal(e.Payload, v)
+}
+
+// Ack acknowledges successful processing of the event in ManualAck mode
+func (e *Event) Ack() error {
+	return e.ackFunc()
+}
+
+func (e *Event) SetAckFunc(f AckFunc) {
+	e.ackFunc = f
+}
+
+// Nack negatively acknowledges processing of the event (i.e. failure) in ManualAck mode
+func (e *Event) Nack() error {
+	return e.nackFunc()
+}
+
+func (e *Event) SetNackFunc(f NackFunc) {
+	e.nackFunc = f
+}
+
+// Publish an event to a topic
+func Publish(topic string, msg interface{}, opts ...PublishOption) error {
+	return DefaultStream.Publish(topic, msg, opts...)
+}
+
+// Consume to events
+func Consume(topic string, opts ...ConsumeOption) (<-chan Event, error) {
+	return DefaultStream.Consume(topic, opts...)
+}
+
+// Read events for a topic
+func Read(topic string, opts ...ReadOption) ([]*Event, error) {
+	return DefaultStore.Read(topic, opts...)
+}

events/memory.go

@@ -0,0 +1,244 @@
+package events
+
+import (
+	"encoding/json"
+	"fmt"
+	"sync"
+	"time"
+
+	"github.com/google/uuid"
+	"github.com/pkg/errors"
+	"go-micro.dev/v4/logger"
+	"go-micro.dev/v4/store"
+)
+
+// NewStream returns an initialized memory stream
+func NewStream(opts ...Option) (Stream, error) {
+	// parse the options
+	var options Options
+	for _, o := range opts {
+		o(&options)
+	}
+	return &mem{store: store.NewMemoryStore()}, nil
+}
+
+type subscriber struct {
+	Group   string
+	Topic   string
+	Channel chan Event
+
+	sync.RWMutex
+	retryMap   map[string]int
+	retryLimit int
+	autoAck    bool
+	ackWait    time.Duration
+}
+
+type mem struct {
+	store store.Store
+
+	subs []*subscriber
+	sync.RWMutex
+}
+
+func (m *mem) Publish(topic string, msg interface{}, opts ...PublishOption) error {
+	// validate the topic
+	if len(topic) == 0 {
+		return ErrMissingTopic
+	}
+
+	// parse the options
+	options := PublishOptions{
+		Timestamp: time.Now(),
+	}
+	for _, o := range opts {
+		o(&options)
+	}
+
+	// encode the message if it's not already encoded
+	var payload []byte
+	if p, ok := msg.([]byte); ok {
+		payload = p
+	} else {
+		p, err := json.Marshal(msg)
+		if err != nil {
+			return ErrEncodingMessage
+		}
+		payload = p
+	}
+
+	// construct the event
+	event := &Event{
+		ID:        uuid.New().String(),
+		Topic:     topic,
+		Timestamp: options.Timestamp,
+		Metadata:  options.Metadata,
+		Payload:   payload,
+	}
+
+	// serialize the event to bytes
+	bytes, err := json.Marshal(event)
+	if err != nil {
+		return errors.Wrap(err, "Error encoding event")
+	}
+
+	// write to the store
+	key := fmt.Sprintf("%v/%v", event.Topic, event.ID)
+	if err := m.store.Write(&store.Record{Key: key, Value: bytes}); err != nil {
+		return errors.Wrap(err, "Error writing event to store")
+	}
+
+	// send to the subscribers async
+	go m.handleEvent(event)
+
+	return nil
+}
+
+func (m *mem) Consume(topic string, opts ...ConsumeOption) (<-chan Event, error) {
+	// validate the topic
+	if len(topic) == 0 {
+		return nil, ErrMissingTopic
+	}
+
+	// parse the options
+	options := ConsumeOptions{
+		Group:   uuid.New().String(),
+		AutoAck: true,
+	}
+	for _, o := range opts {
+		o(&options)
+	}
+	// TODO RetryLimit
+
+	// setup the subscriber
+	sub := &subscriber{
+		Channel:    make(chan Event),
+		Topic:      topic,
+		Group:      options.Group,
+		retryMap:   map[string]int{},
+		autoAck:    true,
+		retryLimit: options.GetRetryLimit(),
+	}
+
+	if !options.AutoAck {
+		if options.AckWait == 0 {
+			return nil, fmt.Errorf("invalid AckWait passed, should be positive integer")
+		}
+		sub.autoAck = options.AutoAck
+		sub.ackWait = options.AckWait
+	}
+
+	// register the subscriber
+	m.Lock()
+	m.subs = append(m.subs, sub)
+	m.Unlock()
+
+	// lookup previous events if the start time option was passed
+	if options.Offset.Unix() > 0 {
+		go m.lookupPreviousEvents(sub, options.Offset)
+	}
+
+	// return the channel
+	return sub.Channel, nil
+}
+
+// lookupPreviousEvents finds events for a subscriber which occurred before a given time and sends
+// them into the subscribers channel
+func (m *mem) lookupPreviousEvents(sub *subscriber, startTime time.Time) {
+	// lookup all events which match the topic (a blank topic will return all results)
+	recs, err := m.store.Read(sub.Topic+"/", store.ReadPrefix())
+	if err != nil && logger.V(logger.ErrorLevel, logger.DefaultLogger) {
+		logger.Errorf("Error looking up previous events: %v", err)
+		return
+	} else if err != nil {
+		return
+	}
+
+	// loop through the records and send it to the channel if it matches
+	for _, r := range recs {
+		var ev Event
+		if err := json.Unmarshal(r.Value, &ev); err != nil {
+			continue
+		}
+		if ev.Timestamp.Unix() < startTime.Unix() {
+			continue
+		}
+		sendEvent(&ev, sub)
+	}
+}
+
+// handleEvents sends the event to any registered subscribers.
+func (m *mem) handleEvent(ev *Event) {
+	m.RLock()
+	subs := m.subs
+	m.RUnlock()
+
+	// filteredSubs is a KV map of the queue name and subscribers. This is used to prevent a message
+	// being sent to two subscribers with the same queue.
+	filteredSubs := map[string]*subscriber{}
+
+	// filter down to subscribers who are interested in this topic
+	for _, sub := range subs {
+		if len(sub.Topic) == 0 || sub.Topic == ev.Topic {
+			filteredSubs[sub.Group] = sub
+		}
+	}
+
+	// send the message to each channel async (since one channel might be blocked)
+	for _, sub := range filteredSubs {
+		sendEvent(ev, sub)
+	}
+}
+
+func sendEvent(ev *Event, sub *subscriber) {
+	go func(s *subscriber) {
+		evCopy := *ev
+		if s.autoAck {
+			s.Channel <- evCopy
+			return
+		}
+		evCopy.SetAckFunc(ackFunc(s, evCopy))
+		evCopy.SetNackFunc(nackFunc(s, evCopy))
+		s.retryMap[evCopy.ID] = 0
+		tick := time.NewTicker(s.ackWait)
+		defer tick.Stop()
+		for range tick.C {
+			s.Lock()
+			count, ok := s.retryMap[evCopy.ID]
+			s.Unlock()
+			if !ok {
+				// success
+				break
+			}
+
+			if s.retryLimit > -1 && count > s.retryLimit {
+				if logger.V(logger.ErrorLevel, logger.DefaultLogger) {
+					logger.Errorf("Message retry limit reached, discarding: %v %d %d", evCopy.ID, count, s.retryLimit)
+				}
+				s.Lock()
+				delete(s.retryMap, evCopy.ID)
+				s.Unlock()
+				return
+			}
+			s.Channel <- evCopy
+			s.Lock()
+			s.retryMap[evCopy.ID] = count + 1
+			s.Unlock()
+		}
+	}(sub)
+}
+
+func ackFunc(s *subscriber, evCopy Event) func() error {
+	return func() error {
+		s.Lock()
+		delete(s.retryMap, evCopy.ID)
+		s.Unlock()
+		return nil
+	}
+}
+
+func nackFunc(s *subscriber, evCopy Event) func() error {
+	return func() error {
+		return nil
+	}
+}

events/options.go

@@ -0,0 +1,144 @@
+package events
+
+import "time"
+
+type Options struct{}
+
+type Option func(o *Options)
+
+type StoreOptions struct {
+	TTL    time.Duration
+	Backup Backup
+}
+
+type StoreOption func(o *StoreOptions)
+
+// PublishOptions contains all the options which can be provided when publishing an event
+type PublishOptions struct {
+	// Metadata contains any keys which can be used to query the data, for example a customer id
+	Metadata map[string]string
+	// Timestamp to set for the event, if the timestamp is a zero value, the current time will be used
+	Timestamp time.Time
+}
+
+// PublishOption sets attributes on PublishOptions
+type PublishOption func(o *PublishOptions)
+
+// WithMetadata sets the Metadata field on PublishOptions
+func WithMetadata(md map[string]string) PublishOption {
+	return func(o *PublishOptions) {
+		o.Metadata = md
+	}
+}
+
+// WithTimestamp sets the timestamp field on PublishOptions
+func WithTimestamp(t time.Time) PublishOption {
+	return func(o *PublishOptions) {
+		o.Timestamp = t
+	}
+}
+
+// ConsumeOptions contains all the options which can be provided when subscribing to a topic
+type ConsumeOptions struct {
+	// Group is the name of the consumer group, if two consumers have the same group the events
+	// are distributed between them
+	Group string
+	// Offset is the time from which the messages should be consumed from. If not provided then
+	// the messages will be consumed starting from the moment the Subscription starts.
+	Offset time.Time
+	// AutoAck if true (default true), automatically acknowledges every message so it will not be redelivered.
+	// If false specifies that each message need ts to be manually acknowledged by the subscriber.
+	// If processing is successful the message should be ack'ed to remove the message from the stream.
+	// If processing is unsuccessful the message should be nack'ed (negative acknowledgement) which will mean it will
+	// remain on the stream to be processed again.
+	AutoAck bool
+	AckWait time.Duration
+	// RetryLimit indicates number of times a message is retried
+	RetryLimit int
+	// CustomRetries indicates whether to use RetryLimit
+	CustomRetries bool
+}
+
+// ConsumeOption sets attributes on ConsumeOptions
+type ConsumeOption func(o *ConsumeOptions)
+
+// WithGroup sets the consumer group to be part of when consuming events
+func WithGroup(q string) ConsumeOption {
+	return func(o *ConsumeOptions) {
+		o.Group = q
+	}
+}
+
+// WithOffset sets the offset time at which to start consuming events
+func WithOffset(t time.Time) ConsumeOption {
+	return func(o *ConsumeOptions) {
+		o.Offset = t
+	}
+}
+
+// WithAutoAck sets the AutoAck field on ConsumeOptions and an ackWait duration after which if no ack is received
+// the message is requeued in case auto ack is turned off
+func WithAutoAck(ack bool, ackWait time.Duration) ConsumeOption {
+	return func(o *ConsumeOptions) {
+		o.AutoAck = ack
+		o.AckWait = ackWait
+	}
+}
+
+// WithRetryLimit sets the RetryLimit field on ConsumeOptions.
+// Set to -1 for infinite retries (default)
+func WithRetryLimit(retries int) ConsumeOption {
+	return func(o *ConsumeOptions) {
+		o.RetryLimit = retries
+		o.CustomRetries = true
+	}
+}
+
+func (s ConsumeOptions) GetRetryLimit() int {
+	if !s.CustomRetries {
+		return -1
+	}
+	return s.RetryLimit
+}
+
+// WriteOptions contains all the options which can be provided when writing an event to a store
+type WriteOptions struct {
+	// TTL is the duration the event should be recorded for, a zero value TTL indicates the event should
+	// be stored indefinately
+	TTL time.Duration
+}
+
+// WriteOption sets attributes on WriteOptions
+type WriteOption func(o *WriteOptions)
+
+// WithTTL sets the TTL attribute on WriteOptions
+func WithTTL(d time.Duration) WriteOption {
+	return func(o *WriteOptions) {
+		o.TTL = d
+	}
+}
+
+// ReadOptions contains all the options which can be provided when reading events from a store
+type ReadOptions struct {
+	// Limit the number of results to return
+	Limit uint
+	// Offset the results by this number, useful for paginated queries
+	Offset uint
+}
+
+// ReadOption sets attributes on ReadOptions
+type ReadOption func(o *ReadOptions)
+
+// ReadLimit sets the limit attribute on ReadOptions
+func ReadLimit(l uint) ReadOption {
+	return func(o *ReadOptions) {
+		o.Limit = 1
+	}
+}
+
+// ReadOffset sets the offset attribute on ReadOptions
+func ReadOffset(l uint) ReadOption {
+	return func(o *ReadOptions) {
+		o.Offset = 1
+	}
+}

events/store.go

@@ -0,0 +1,127 @@
+package events
+
+import (
+	"encoding/json"
+	"time"
+
+	"github.com/pkg/errors"
+	"go-micro.dev/v4/logger"
+	"go-micro.dev/v4/store"
+)
+
+const joinKey = "/"
+
+// NewStore returns an initialized events store
+func NewStore(opts ...StoreOption) Store {
+	// parse the options
+	var options StoreOptions
+	for _, o := range opts {
+		o(&options)
+	}
+	if options.TTL.Seconds() == 0 {
+		options.TTL = time.Hour * 24
+	}
+
+	// return the store
+	evs := &evStore{
+		opts:  options,
+		store: store.NewMemoryStore(),
+	}
+	if options.Backup != nil {
+		go evs.backupLoop()
+	}
+	return evs
+}
+
+type evStore struct {
+	opts  StoreOptions
+	store store.Store
+}
+
+// Read events for a topic
+func (s *evStore) Read(topic string, opts ...ReadOption) ([]*Event, error) {
+	// validate the topic
+	if len(topic) == 0 {
+		return nil, ErrMissingTopic
+	}
+
+	// parse the options
+	options := ReadOptions{
+		Offset: 0,
+		Limit:  250,
+	}
+	for _, o := range opts {
+		o(&options)
+	}
+
+	// execute the request
+	recs, err := s.store.Read(topic+joinKey,
+		store.ReadPrefix(),
+		store.ReadLimit(options.Limit),
+		store.ReadOffset(options.Offset),
+	)
+	if err != nil {
+		return nil, errors.Wrap(err, "Error reading from store")
+	}
+
+	// unmarshal the result
+	result := make([]*Event, len(recs))
+	for i, r := range recs {
+		var e Event
+		if err := json.Unmarshal(r.Value, &e); err != nil {
+			return nil, errors.Wrap(err, "Invalid event returned from stroe")
+		}
+		result[i] = &e
+	}
+
+	return result, nil
+}
+
+// Write an event to the store
+func (s *evStore) Write(event *Event, opts ...WriteOption) error {
+	// parse the options
+	options := WriteOptions{
+		TTL: s.opts.TTL,
+	}
+	for _, o := range opts {
+		o(&options)
+	}
+
+	// construct the store record
+	bytes, err := json.Marshal(event)
+	if err != nil {
+		return errors.Wrap(err, "Error mashaling event to JSON")
+	}
+	// suffix event ID with hour resolution for easy retrieval in batches
+	timeSuffix := time.Now().Format("2006010215")
+
+	record := &store.Record{
+		// key is such that reading by prefix indexes by topic and reading by suffix indexes by time
+		Key:    event.Topic + joinKey + event.ID + joinKey + timeSuffix,
+		Value:  bytes,
+		Expiry: options.TTL,
+	}
+
+	// write the record to the store
+	if err := s.store.Write(record); err != nil {
+		return errors.Wrap(err, "Error writing to the store")
+	}
+
+	return nil
+}
+
+func (s *evStore) backupLoop() {
+	for {
+		err := s.opts.Backup.Snapshot(s.store)
+		if err != nil {
+			logger.Errorf("Error running backup %s", err)
+		}
+
+		time.Sleep(1 * time.Hour)
+	}
+}
+
+// Backup is an interface for snapshotting the events store to long term storage
+type Backup interface {
+	Snapshot(st store.Store) error
+}

events/store_test.go

@@ -0,0 +1,47 @@
+package events
+
+import (
+	"testing"
+
+	"github.com/google/uuid"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestStore(t *testing.T) {
+	store := NewStore()
+
+	testData := []Event{
+		{ID: uuid.New().String(), Topic: "foo"},
+		{ID: uuid.New().String(), Topic: "foo"},
+		{ID: uuid.New().String(), Topic: "bar"},
+	}
+
+	// write the records to the store
+	t.Run("Write", func(t *testing.T) {
+		for _, event := range testData {
+			err := store.Write(&event)
+			assert.Nilf(t, err, "Writing an event should not return an error")
+		}
+	})
+
+	// should not be able to read events from a blank topic
+	t.Run("ReadMissingTopic", func(t *testing.T) {
+		evs, err := store.Read("")
+		assert.Equal(t, err, ErrMissingTopic, "Reading a blank topic should return an error")
+		assert.Nil(t, evs, "No events should be returned")
+	})
+
+	// should only get the events from the topic requested
+	t.Run("ReadTopic", func(t *testing.T) {
+		evs, err := store.Read("foo")
+		assert.Nilf(t, err, "No error should be returned")
+		assert.Len(t, evs, 2, "Only the events for this topic should be returned")
+	})
+
+	// limits should be honoured
+	t.Run("ReadTopicLimit", func(t *testing.T) {
+		evs, err := store.Read("foo", ReadLimit(1))
+		assert.Nilf(t, err, "No error should be returned")
+		assert.Len(t, evs, 1, "The result should include no more than the read limit")
+	})
+}

events/stream_test.go

@@ -0,0 +1,241 @@
+package events
+
+import (
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/google/uuid"
+	"github.com/stretchr/testify/assert"
+)
+
+type testPayload struct {
+	Message string
+}
+
+type testCase struct {
+	str  Stream
+	name string
+}
+
+func TestStream(t *testing.T) {
+	tcs := []testCase{}
+
+	stream, err := NewStream()
+	assert.Nilf(t, err, "NewStream should not return an error")
+	assert.NotNilf(t, stream, "NewStream should return a stream object")
+	tcs = append(tcs, testCase{str: stream, name: "memory"})
+
+	for _, tc := range tcs {
+		t.Run(tc.name, func(t *testing.T) {
+			runTestStream(t, tc.str)
+		})
+	}
+
+}
+
+func runTestStream(t *testing.T, stream Stream) {
+	// TestMissingTopic will test the topic validation on publish
+	t.Run("TestMissingTopic", func(t *testing.T) {
+		err := stream.Publish("", nil)
+		assert.Equalf(t, err, ErrMissingTopic, "Publishing to a blank topic should return an error")
+	})
+
+	// TestConsumeTopic will publish a message to the test topic. The subscriber will subscribe to the
+	// same test topic.
+	t.Run("TestConsumeTopic", func(t *testing.T) {
+		payload := &testPayload{Message: "HelloWorld"}
+		metadata := map[string]string{"foo": "bar"}
+
+		// create the subscriber
+		evChan, err := stream.Consume("test")
+		assert.Nilf(t, err, "Consume should not return an error")
+
+		// setup the subscriber async
+		var wg sync.WaitGroup
+
+		go func() {
+			timeout := time.NewTimer(time.Millisecond * 250)
+
+			select {
+			case event, _ := <-evChan:
+				assert.NotNilf(t, event, "The message was nil")
+				assert.Equal(t, event.Metadata, metadata, "Metadata didn't match")
+
+				var result testPayload
+				err = event.Unmarshal(&result)
+				assert.Nil(t, err, "Error decoding result")
+				assert.Equal(t, result, *payload, "Payload didn't match")
+
+				wg.Done()
+			case <-timeout.C:
+				t.Fatalf("Event was not recieved")
+			}
+		}()
+
+		err = stream.Publish("test", payload, WithMetadata(metadata))
+		assert.Nil(t, err, "Publishing a valid message should not return an error")
+		wg.Add(1)
+
+		// wait for the subscriber to recieve the message or timeout
+		wg.Wait()
+	})
+
+	// TestConsumeGroup will publish a message to a random topic. Two subscribers will then consume
+	// the message from the firehose topic with different queues. The second subscriber will be registered
+	// after the message is published to test durability.
+	t.Run("TestConsumeGroup", func(t *testing.T) {
+		topic := uuid.New().String()
+		payload := &testPayload{Message: "HelloWorld"}
+		metadata := map[string]string{"foo": "bar"}
+
+		// create the first subscriber
+		evChan1, err := stream.Consume(topic)
+		assert.Nilf(t, err, "Consume should not return an error")
+
+		// setup the subscriber async
+		var wg sync.WaitGroup
+
+		go func() {
+			timeout := time.NewTimer(time.Millisecond * 250)
+
+			select {
+			case event, _ := <-evChan1:
+				assert.NotNilf(t, event, "The message was nil")
+				assert.Equal(t, event.Metadata, metadata, "Metadata didn't match")
+
+				var result testPayload
+				err = event.Unmarshal(&result)
+				assert.Nil(t, err, "Error decoding result")
+				assert.Equal(t, result, *payload, "Payload didn't match")
+
+				wg.Done()
+			case <-timeout.C:
+				t.Fatalf("Event was not recieved")
+			}
+		}()
+
+		err = stream.Publish(topic, payload, WithMetadata(metadata))
+		assert.Nil(t, err, "Publishing a valid message should not return an error")
+		wg.Add(2)
+
+		// create the second subscriber
+		evChan2, err := stream.Consume(topic,
+			WithGroup("second_queue"),
+			WithOffset(time.Now().Add(time.Minute*-1)),
+		)
+		assert.Nilf(t, err, "Consume should not return an error")
+
+		go func() {
+			timeout := time.NewTimer(time.Second * 1)
+
+			select {
+			case event, _ := <-evChan2:
+				assert.NotNilf(t, event, "The message was nil")
+				assert.Equal(t, event.Metadata, metadata, "Metadata didn't match")
+
+				var result testPayload
+				err = event.Unmarshal(&result)
+				assert.Nil(t, err, "Error decoding result")
+				assert.Equal(t, result, *payload, "Payload didn't match")
+
+				wg.Done()
+			case <-timeout.C:
+				t.Fatalf("Event was not recieved")
+			}
+		}()
+
+		// wait for the subscriber to recieve the message or timeout
+		wg.Wait()
+	})
+
+	t.Run("AckingNacking", func(t *testing.T) {
+		ch, err := stream.Consume("foobarAck", WithAutoAck(false, 5*time.Second))
+		assert.NoError(t, err, "Unexpected error subscribing")
+		assert.NoError(t, stream.Publish("foobarAck", map[string]string{"foo": "message 1"}))
+		assert.NoError(t, stream.Publish("foobarAck", map[string]string{"foo": "message 2"}))
+
+		ev := <-ch
+		ev.Ack()
+		ev = <-ch
+		nacked := ev.ID
+		ev.Nack()
+		select {
+		case ev = <-ch:
+			assert.Equal(t, ev.ID, nacked, "Nacked message should have been received again")
+			assert.NoError(t, ev.Ack())
+		case <-time.After(7 * time.Second):
+			t.Fatalf("Timed out waiting for message to be put back on queue")
+		}
+
+	})
+
+	t.Run("Retries", func(t *testing.T) {
+		ch, err := stream.Consume("foobarRetries", WithAutoAck(false, 5*time.Second), WithRetryLimit(1))
+		assert.NoError(t, err, "Unexpected error subscribing")
+		assert.NoError(t, stream.Publish("foobarRetries", map[string]string{"foo": "message 1"}))
+
+		ev := <-ch
+		id := ev.ID
+		ev.Nack()
+		ev = <-ch
+		assert.Equal(t, id, ev.ID, "Nacked message should have been received again")
+		ev.Nack()
+		select {
+		case ev = <-ch:
+			t.Fatalf("Unexpected event received")
+		case <-time.After(7 * time.Second):
+		}
+
+	})
+
+	t.Run("InfiniteRetries", func(t *testing.T) {
+		ch, err := stream.Consume("foobarRetriesInf", WithAutoAck(false, 2*time.Second))
+		assert.NoError(t, err, "Unexpected error subscribing")
+		assert.NoError(t, stream.Publish("foobarRetriesInf", map[string]string{"foo": "message 1"}))
+
+		count := 0
+		id := ""
+		for {
+			select {
+			case ev := <-ch:
+				if id != "" {
+					assert.Equal(t, id, ev.ID, "Nacked message should have been received again")
+				}
+				id = ev.ID
+			case <-time.After(3 * time.Second):
+				t.Fatalf("Unexpected event received")
+			}
+
+			count++
+			if count == 11 {
+				break
+			}
+		}
+
+	})
+
+	t.Run("twoSubs", func(t *testing.T) {
+		ch1, err := stream.Consume("foobarTwoSubs1", WithAutoAck(false, 5*time.Second))
+		assert.NoError(t, err, "Unexpected error subscribing to topic 1")
+		ch2, err := stream.Consume("foobarTwoSubs2", WithAutoAck(false, 5*time.Second))
+		assert.NoError(t, err, "Unexpected error subscribing to topic 2")
+
+		assert.NoError(t, stream.Publish("foobarTwoSubs2", map[string]string{"foo": "message 1"}))
+		assert.NoError(t, stream.Publish("foobarTwoSubs1", map[string]string{"foo": "message 1"}))
+
+		wg := sync.WaitGroup{}
+		wg.Add(2)
+		go func() {
+			ev := <-ch1
+			assert.Equal(t, "foobarTwoSubs1", ev.Topic, "Received message from unexpected topic")
+			wg.Done()
+		}()
+		go func() {
+			ev := <-ch2
+			assert.Equal(t, "foobarTwoSubs2", ev.Topic, "Received message from unexpected topic")
+			wg.Done()
+		}()
+		wg.Wait()
+	})
+}

options.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"time"
 
+	"github.com/urfave/cli/v2"
 	"go-micro.dev/v4/auth"
 	"go-micro.dev/v4/broker"
 	"go-micro.dev/v4/cache"
@@ -18,7 +19,6 @@ import (
 	"go-micro.dev/v4/server"
 	"go-micro.dev/v4/store"
 	"go-micro.dev/v4/transport"
-	"github.com/urfave/cli/v2"
 )
 
 // Options for micro service

registry/memory.go

@@ -5,8 +5,8 @@ import (
 	"sync"
 	"time"
 
-	"go-micro.dev/v4/logger"
 	"github.com/google/uuid"
+	"go-micro.dev/v4/logger"
 )
 
 var (

runtime/default.go

@@ -13,9 +13,9 @@ import (
 	"sync"
 	"time"
 
+	"github.com/nxadm/tail"
 	"go-micro.dev/v4/logger"
 	"go-micro.dev/v4/runtime/local/git"
-	"github.com/nxadm/tail"
 )
 
 // defaultNamespace to use if not provided as an option

runtime/local/build/docker/docker.go

@@ -8,9 +8,9 @@ import (
 	"os"
 	"path/filepath"
 
+	docker "github.com/fsouza/go-dockerclient"
 	"go-micro.dev/v4/logger"
 	"go-micro.dev/v4/runtime/local/build"
-	docker "github.com/fsouza/go-dockerclient"
 )
 
 type Builder struct {

runtime/local/process/os/os.go

@@ -1,3 +1,4 @@
+//go:build !windows
 // +build !windows
 
 // Package os runs processes locally

runtime/local/source/git/git.go

@@ -6,8 +6,8 @@ import (
 	"path/filepath"
 	"strings"
 
-	"go-micro.dev/v4/runtime/local/source"
 	"github.com/go-git/go-git/v5"
+	"go-micro.dev/v4/runtime/local/source"
 )
 
 // Source retrieves source code

server/mock/mock.go

@@ -4,8 +4,8 @@ import (
 	"errors"
 	"sync"
 
-	"go-micro.dev/v4/server"
 	"github.com/google/uuid"
+	"go-micro.dev/v4/server"
 )
 
 type MockServer struct {

server/rpc_codec.go

@@ -4,6 +4,8 @@ import (
 	"bytes"
 	"sync"
 
+	"github.com/oxtoacart/bpool"
+	"github.com/pkg/errors"
 	"go-micro.dev/v4/codec"
 	raw "go-micro.dev/v4/codec/bytes"
 	"go-micro.dev/v4/codec/grpc"
@@ -12,8 +14,6 @@ import (
 	"go-micro.dev/v4/codec/proto"
 	"go-micro.dev/v4/codec/protorpc"
 	"go-micro.dev/v4/transport"
-	"github.com/oxtoacart/bpool"
-	"github.com/pkg/errors"
 )
 
 type rpcCodec struct {

server/rpc_stream_test.go

@@ -9,9 +9,9 @@ import (
 	"testing"
 	"time"
 
+	"github.com/golang/protobuf/proto"
 	"go-micro.dev/v4/codec/json"
 	protoCodec "go-micro.dev/v4/codec/proto"
-	"github.com/golang/protobuf/proto"
 )
 
 // protoStruct implements proto.Message

server/server.go

@@ -7,11 +7,11 @@ import (
 	"os/signal"
 	"time"
 
+	"github.com/google/uuid"
 	"go-micro.dev/v4/codec"
 	"go-micro.dev/v4/logger"
 	"go-micro.dev/v4/registry"
 	signalutil "go-micro.dev/v4/util/signal"
-	"github.com/google/uuid"
 )
 
 // Server is a simple micro server abstraction

store/memory.go

@@ -174,9 +174,21 @@ func (m *memoryStore) Read(key string, opts ...ReadOption) ([]*Record, error) {
 
 	// Handle Prefix / suffix
 	if readOpts.Prefix || readOpts.Suffix {
-		k := m.list(prefix, readOpts.Limit, readOpts.Offset)
+		k := m.list(prefix, 0, 0)
+		limit := int(readOpts.Limit)
+		offset := int(readOpts.Offset)
+
+		if limit > len(k) {
+			limit = len(k)
+		}
+
+		if offset > len(k) {
+			offset = len(k)
+		}
+
+		for i := offset; i < limit; i++ {
+			kk := k[i]
 
-		for _, kk := range k {
 			if readOpts.Prefix && !strings.HasPrefix(kk, key) {
 				continue
 			}

util/mdns/server.go

@@ -8,8 +8,8 @@ import (
 	"sync/atomic"
 	"time"
 
-	log "go-micro.dev/v4/logger"
 	"github.com/miekg/dns"
+	log "go-micro.dev/v4/logger"
 	"golang.org/x/net/ipv4"
 	"golang.org/x/net/ipv6"
 )

util/pool/default.go

@@ -4,8 +4,8 @@ import (
 	"sync"
 	"time"
 
-	"go-micro.dev/v4/transport"
 	"github.com/google/uuid"
+	"go-micro.dev/v4/transport"
 )
 
 type pool struct {

util/sync/manager.go

@@ -3,8 +3,8 @@ package sync
 import (
 	"time"
 
-	"go-micro.dev/v4/store"
 	"github.com/pkg/errors"
+	"go-micro.dev/v4/store"
 )
 
 type operation struct {

util/sync/sync.go

@@ -6,9 +6,9 @@ import (
 	"sync"
 	"time"
 
-	"go-micro.dev/v4/store"
 	"github.com/ef-ds/deque"
 	"github.com/pkg/errors"
+	"go-micro.dev/v4/store"
 )
 
 // Sync implements a sync in for stores

web/options.go

@@ -6,9 +6,9 @@ import (
 	"net/http"
 	"time"
 
+	"github.com/urfave/cli/v2"
 	"go-micro.dev/v4"
 	"go-micro.dev/v4/registry"
-	"github.com/urfave/cli/v2"
 )
 
 //Options for web

web/web_test.go

@@ -7,10 +7,10 @@ import (
 	"testing"
 	"time"
 
+	"github.com/urfave/cli/v2"
 	"go-micro.dev/v4"
 	"go-micro.dev/v4/logger"
 	"go-micro.dev/v4/web"
-	"github.com/urfave/cli/v2"
 )
 
 func TestWeb(t *testing.T) {