Add support for pooling in codecs, partition_table, view etc.

codec.go

@@ -1,7 +1,17 @@
 package goka
 
+import "io"
+
 // Codec decodes and encodes from and to []byte
 type Codec interface {
 	Encode(value interface{}) (data []byte, err error)
 	Decode(data []byte) (value interface{}, err error)
+	DecodeP(data []byte) (value interface{}, closer io.Closer, err error)
+}
+
+// FuncCloser implements io.Closer-interface for convenience
+type FuncCloser func() error
+
+func (f FuncCloser) Close() error {
+	return f()
 }

codec/closer.go

@@ -0,0 +1,11 @@
+package codec
+
+type Closer interface {
+	Close()
+}
+
+type nullCloser struct{}
+
+func (n *nullCloser) Close() error { return nil }
+
+var NoopCloser = new(nullCloser)

codec/codec.go

@@ -2,6 +2,7 @@ package codec
 
 import (
 	"fmt"
+	"io"
 	"strconv"
 )
 
@@ -23,6 +24,11 @@ func (d *Bytes) Decode(data []byte) (interface{}, error) {
 	return data, nil
 }
 
+// Decode of defaultCodec simply returns the data
+func (d *Bytes) DecodeP(data []byte) (interface{}, io.Closer, error) {
+	return data, NoopCloser, nil
+}
+
 // String is a commonly used codec to encode and decode string <-> []byte
 type String struct{}
 
@@ -40,6 +46,10 @@ func (c *String) Decode(data []byte) (interface{}, error) {
 	return string(data), nil
 }
 
+func (c *String) DecodeP(data []byte) (interface{}, io.Closer, error) {
+	return string(data), NoopCloser, nil
+}
+
 // Int64 is a commonly used codec to encode and decode string <-> []byte
 type Int64 struct{}
 
@@ -60,3 +70,8 @@ func (c *Int64) Decode(data []byte) (interface{}, error) {
 	}
 	return intVal, nil
 }
+
+func (c *Int64) DecodeP(data []byte) (interface{}, io.Closer, error) {
+	dec, err := c.Decode(data)
+	return dec, NoopCloser, err
+}

context.go

@@ -170,6 +170,8 @@ type cbContext struct {
 	// tracking statistics for the output topic
 	trackOutputStats func(ctx context.Context, topic string, size int)
 
+	deferreds []func() error
+
 	msg      *message
 	done     bool
 	counters struct {
@@ -310,17 +312,25 @@ func (ctx *cbContext) Join(topic Table) interface{} {
 	if !ok {
 		ctx.Fail(fmt.Errorf("table %s not subscribed", topic))
 	}
-	data, err := v.st.Get(ctx.Key())
+	data, getCloser, err := v.st.GetP(ctx.Key())
 	if err != nil {
 		ctx.Fail(fmt.Errorf("error getting key %s of table %s: %v", ctx.Key(), topic, err))
 	} else if data == nil {
 		return nil
 	}
 
-	value, err := ctx.graph.codec(string(topic)).Decode(data)
+	if getCloser != nil {
+		ctx.addDeferred(getCloser.Close)
+	}
+
+	value, decodeCloser, err := ctx.graph.codec(string(topic)).DecodeP(data)
 	if err != nil {
 		ctx.Fail(fmt.Errorf("error decoding value key %s of table %s: %v", ctx.Key(), topic, err))
 	}
+	if decodeCloser != nil {
+		ctx.addDeferred(decodeCloser.Close)
+	}
+
 	return value
 }
 
@@ -332,10 +342,13 @@ func (ctx *cbContext) Lookup(topic Table, key string) interface{} {
 	if !ok {
 		ctx.Fail(fmt.Errorf("topic %s not subscribed", topic))
 	}
-	val, err := v.Get(key)
+	val, getCloser, err := v.GetP(key)
 	if err != nil {
 		ctx.Fail(fmt.Errorf("error getting key %s of table %s: %v", key, topic, err))
 	}
+	if getCloser != nil {
+		ctx.addDeferred(getCloser.Close)
+	}
 	return val
 }
 
@@ -345,17 +358,26 @@ func (ctx *cbContext) valueForKey(key string) (interface{}, error) {
 		return nil, fmt.Errorf("Cannot access state in stateless processor")
 	}
 
-	data, err := ctx.table.Get(key)
+	data, closer, err := ctx.table.Get(key)
 	if err != nil {
 		return nil, fmt.Errorf("error reading value: %v", err)
-	} else if data == nil {
+	}
+	if closer != nil {
+		ctx.addDeferred(closer.Close)
+	}
+
+	if data == nil {
 		return nil, nil
 	}
 
-	value, err := ctx.graph.GroupTable().Codec().Decode(data)
+	value, decodeCloser, err := ctx.graph.GroupTable().Codec().DecodeP(data)
 	if err != nil {
 		return nil, fmt.Errorf("error decoding value: %v", err)
 	}
+	if decodeCloser != nil {
+		ctx.addDeferred(decodeCloser.Close)
+	}
+
 	return value, nil
 }
 
@@ -450,6 +472,14 @@ func (ctx *cbContext) tryCommit(err error) {
 	if ctx.errors.ErrorOrNil() != nil {
 		ctx.asyncFailer(fmt.Errorf("could not commit message with key '%s': %w", ctx.Key(), ctx.errors.ErrorOrNil()))
 	} else {
+
+		// execute deferred commit functions in reverse order
+		for i := len(ctx.deferreds) - 1; i >= 0; i-- {
+			if err := ctx.deferreds[i](); err != nil {
+				ctx.asyncFailer(fmt.Errorf("error executing context deferred: %w", err))
+			}
+		}
+
 		ctx.commit()
 	}
 
@@ -483,3 +513,7 @@ func (ctx *cbContext) DeferCommit() func(err error) {
 		})
 	}
 }
+
+func (ctx *cbContext) addDeferred(def func() error) {
+	ctx.deferreds = append(ctx.deferreds, def)
+}

context_test.go

@@ -380,9 +380,9 @@ func TestContext_GetSetStateful(t *testing.T) {
 		}
 	)
 
-	st.EXPECT().Get(key).Return(nil, nil)
+	st.EXPECT().GetP(key).Return(nil, nil, nil)
 	st.EXPECT().Set(key, []byte(value)).Return(nil)
-	st.EXPECT().Get(key).Return([]byte(value), nil)
+	st.EXPECT().GetP(key).Return([]byte(value), codec.NoopCloser, nil)
 
 	graph := DefineGroup(group, Persist(new(codec.String)))
 	ctx := &cbContext{
@@ -537,11 +537,11 @@ func TestContext_Join(t *testing.T) {
 		syncFailer: func(err error) { panic(err) },
 	}
 
-	st.EXPECT().Get(key).Return([]byte(value), nil)
+	st.EXPECT().GetP(key).Return([]byte(value), codec.NoopCloser, nil)
 	v := ctx.Join(table)
 	require.Equal(t, value, v)
 
-	st.EXPECT().Get(key).Return(nil, errSome)
+	st.EXPECT().GetP(key).Return(nil, codec.NoopCloser, errSome)
 	require.Panics(t, func() { ctx.Join(table) })
 
 	require.Panics(t, func() { ctx.Join("other-table") })
@@ -586,11 +586,11 @@ func TestContext_Lookup(t *testing.T) {
 		syncFailer: func(err error) { panic(err) },
 	}
 
-	st.EXPECT().Get(key).Return([]byte(value), nil)
+	st.EXPECT().GetP(key).Return([]byte(value), codec.NoopCloser, nil)
 	v := ctx.Lookup(table, key)
 	require.Equal(t, value, v)
 
-	st.EXPECT().Get(key).Return(nil, errSome)
+	st.EXPECT().GetP(key).Return(nil, codec.NoopCloser, errSome)
 	require.Panics(t, func() { ctx.Lookup(table, key) })
 	require.Panics(t, func() { ctx.Lookup("other-table", key) })
 

examples/2-clicks/main.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"io"
 	"log"
 	"net/http"
 	"time"
@@ -58,6 +59,11 @@ func (jc *userCodec) Decode(data []byte) (interface{}, error) {
 	return &c, nil
 }
 
+func (jc *userCodec) DecodeP(data []byte) (interface{}, io.Closer, error) {
+	dec, err := jc.Decode(data)
+	return dec, codec.NoopCloser, err
+}
+
 func runEmitter() {
 	emitter, err := goka.NewEmitter(brokers, topic,
 		new(codec.String))

examples/3-messaging/blocker/blocker.go

@@ -3,7 +3,10 @@ package blocker
 import (
 	"context"
 	"encoding/json"
+	"io"
+
 	"github.com/lovoo/goka"
+	"github.com/lovoo/goka/codec"
 	"github.com/lovoo/goka/examples/3-messaging/topicinit"
 )
 
@@ -28,6 +31,11 @@ func (c *BlockEventCodec) Decode(data []byte) (interface{}, error) {
 	return &m, json.Unmarshal(data, &m)
 }
 
+func (c *BlockEventCodec) DecodeP(data []byte) (interface{}, io.Closer, error) {
+	dec, err := c.Decode(data)
+	return dec, codec.NoopCloser, err
+}
+
 type BlockValue struct {
 	Blocked bool
 }
@@ -42,6 +50,11 @@ func (c *BlockValueCodec) Decode(data []byte) (interface{}, error) {
 	return &m, json.Unmarshal(data, &m)
 }
 
+func (c *BlockValueCodec) DecodeP(data []byte) (interface{}, io.Closer, error) {
+	dec, err := c.Decode(data)
+	return dec, codec.NoopCloser, err
+}
+
 func block(ctx goka.Context, msg interface{}) {
 	var s *BlockValue
 	if v := ctx.Value(); v == nil {

examples/3-messaging/collector/collector.go

@@ -3,8 +3,11 @@ package collector
 import (
 	"context"
 	"encoding/json"
+	"io"
+
 	"github.com/lovoo/goka"
-	"github.com/lovoo/goka/examples/3-messaging"
+	"github.com/lovoo/goka/codec"
+	messaging "github.com/lovoo/goka/examples/3-messaging"
 	"github.com/lovoo/goka/examples/3-messaging/topicinit"
 )
 
@@ -27,6 +30,11 @@ func (c *MessageListCodec) Decode(data []byte) (interface{}, error) {
 	return m, err
 }
 
+func (c *MessageListCodec) DecodeP(data []byte) (interface{}, io.Closer, error) {
+	dec, err := c.Decode(data)
+	return dec, codec.NoopCloser, err
+}
+
 func collect(ctx goka.Context, msg interface{}) {
 	var ml []messaging.Message
 	if v := ctx.Value(); v != nil {

examples/3-messaging/detector/detector.go

@@ -3,8 +3,11 @@ package detector
 import (
 	"context"
 	"encoding/json"
+	"io"
+
 	"github.com/lovoo/goka"
-	"github.com/lovoo/goka/examples/3-messaging"
+	"github.com/lovoo/goka/codec"
+	messaging "github.com/lovoo/goka/examples/3-messaging"
 	"github.com/lovoo/goka/examples/3-messaging/blocker"
 	"github.com/lovoo/goka/examples/3-messaging/topicinit"
 )
@@ -14,9 +17,7 @@ const (
 	maxRate     = 0.5
 )
 
-var (
-	group goka.Group = "detector"
-)
+var group goka.Group = "detector"
 
 type Counters struct {
 	Sent     int
@@ -34,6 +35,11 @@ func (c *CountersCodec) Decode(data []byte) (interface{}, error) {
 	return &m, json.Unmarshal(data, &m)
 }
 
+func (c *CountersCodec) DecodeP(data []byte) (interface{}, io.Closer, error) {
+	dec, err := c.Decode(data)
+	return dec, codec.NoopCloser, err
+}
+
 func getValue(ctx goka.Context) *Counters {
 	if v := ctx.Value(); v != nil {
 		return v.(*Counters)

examples/3-messaging/message.go

@@ -2,8 +2,10 @@ package messaging
 
 import (
 	"encoding/json"
+	"io"
 
 	"github.com/lovoo/goka"
+	"github.com/lovoo/goka/codec"
 )
 
 var (
@@ -28,6 +30,11 @@ func (c *MessageCodec) Decode(data []byte) (interface{}, error) {
 	return &m, json.Unmarshal(data, &m)
 }
 
+func (c *MessageCodec) DecodeP(data []byte) (interface{}, io.Closer, error) {
+	dec, err := c.Decode(data)
+	return dec, codec.NoopCloser, err
+}
+
 type MessageListCodec struct{}
 
 func (c *MessageListCodec) Encode(value interface{}) ([]byte, error) {
@@ -39,3 +46,8 @@ func (c *MessageListCodec) Decode(data []byte) (interface{}, error) {
 	err := json.Unmarshal(data, &m)
 	return m, err
 }
+
+func (c *MessageListCodec) DecodeP(data []byte) (interface{}, io.Closer, error) {
+	dec, err := c.Decode(data)
+	return dec, codec.NoopCloser, err
+}