Removed database update every signal process(need to find a replacement still), updated graphiql cmd, and made lockable more efficient at high numbers of requirements

cmd/graphiql/main.go

@@ -17,7 +17,9 @@ func main() {
   db, err := badger.Open(badger.DefaultOptions("").WithInMemory(true))
   check(err)
 
-  ctx, err := gv.NewContext(db, gv.NewConsoleLogger([]string{"test", "signal"}))
+  ctx, err := gv.NewContext(&gv.BadgerDB{
+    DB: db,
+  }, gv.NewConsoleLogger([]string{"test"}))
   check(err)
 
   gql_ext, err := gv.NewGQLExt(ctx, ":8080", nil, nil)
@@ -25,13 +27,16 @@ func main() {
 
   listener_ext := gv.NewListenerExt(1000)
 
-  n1, err := gv.NewNode(ctx, nil, "Lockable", 1000, gv.NewLockableExt(nil))
+  n1, err := gv.NewNode(ctx, nil, "LockableNode", 1000, gv.NewLockableExt(nil))
   check(err)
 
-  n2, err := gv.NewNode(ctx, nil, "Lockable", 1000, gv.NewLockableExt([]gv.NodeID{n1.ID}))
+  n2, err := gv.NewNode(ctx, nil, "LockableNode", 1000, gv.NewLockableExt([]gv.NodeID{n1.ID}))
   check(err)
 
-  _, err = gv.NewNode(ctx, nil, "Lockable", 1000, gql_ext, listener_ext, gv.NewLockableExt([]gv.NodeID{n2.ID}))
+  n3, err := gv.NewNode(ctx, nil, "LockableNode", 1000, gv.NewLockableExt(nil))
+  check(err)
+
+  _, err = gv.NewNode(ctx, nil, "LockableNode", 1000, gql_ext, listener_ext, gv.NewLockableExt([]gv.NodeID{n2.ID, n3.ID}))
   check(err)
 
   for true {

context.go

@@ -10,6 +10,7 @@ import (
 	"strconv"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"golang.org/x/exp/constraints"
@@ -25,6 +26,7 @@ var (
 )
 
 type SerializeFn func(ctx *Context, value reflect.Value, data []byte) (int, error)
+type SerializedSizeFn func(ctx *Context, value reflect.Value) (int, error)
 type DeserializeFn func(ctx *Context, data []byte) (reflect.Value, []byte, error)
 
 type NodeFieldInfo struct {
@@ -47,6 +49,7 @@ type TypeInfo struct {
   PostDeserializeIndex int
 
   Serialize SerializeFn
+  SerializedSize SerializedSizeFn
   Deserialize DeserializeFn
 }
 
@@ -76,6 +79,12 @@ type InterfaceInfo struct {
   Fields map[string]graphql.Type
 }
 
+type ContextNode struct {
+  Node *Node
+  Status chan string
+  Command chan string
+}
+
 // A Context stores all the data to run a graphvent process
 type Context struct {
 
@@ -99,7 +108,9 @@ type Context struct {
 
   // Routing map to all the nodes local to this context
   nodesLock sync.RWMutex
-  nodes map[NodeID]*Node
+  nodes map[NodeID]ContextNode
+
+  running atomic.Bool
 }
 
 func gqltype(ctx *Context, t reflect.Type, node_type string) graphql.Type {
@@ -793,7 +804,7 @@ func RegisterEnum[E comparable](ctx *Context, str_map map[E]string) error {
   return nil
 }
 
-func RegisterScalar[S any](ctx *Context, to_json func(interface{})interface{}, from_json func(interface{})interface{}, from_ast func(ast.Value)interface{}, serialize SerializeFn, deserialize DeserializeFn) error {
+func RegisterScalar[S any](ctx *Context, to_json func(interface{})interface{}, from_json func(interface{})interface{}, from_ast func(ast.Value)interface{}, serialize SerializeFn, sizefn SerializedSizeFn, deserialize DeserializeFn) error {
   reflect_type := reflect.TypeFor[S]()
   serialized_type := SerializedTypeFor[S]()
 
@@ -816,6 +827,7 @@ func RegisterScalar[S any](ctx *Context, to_json func(interface{})interface{}, f
     Type: gql,
 
     Serialize: serialize,
+    SerializedSize: sizefn,
     Deserialize: deserialize,
   }
   ctx.TypesReverse[serialized_type] = ctx.Types[reflect_type]
@@ -823,9 +835,13 @@ func RegisterScalar[S any](ctx *Context, to_json func(interface{})interface{}, f
   return nil
 }
 
-func (ctx *Context) AddNode(id NodeID, node *Node) {
+func (ctx *Context) AddNode(id NodeID, node *Node, status chan string, command chan string) {
   ctx.nodesLock.Lock()
-  ctx.nodes[id] = node
+  ctx.nodes[id] = ContextNode{
+    Node: node,
+    Status: status,
+    Command: command,
+  }
   ctx.nodesLock.Unlock()
 }
 
@@ -833,7 +849,7 @@ func (ctx *Context) Node(id NodeID) (*Node, bool) {
   ctx.nodesLock.RLock()
   node, exists := ctx.nodes[id]
   ctx.nodesLock.RUnlock()
-  return node, exists
+  return node.Node, exists
 }
 
 func (ctx *Context) Delete(id NodeID) error {
@@ -841,7 +857,7 @@ func (ctx *Context) Delete(id NodeID) error {
   if err != nil {
     return err
   }
-  // TODO: also delete any associated data
+  // TODO: also delete any associated data from DB
   return nil
 }
 
@@ -853,7 +869,14 @@ func (ctx *Context) Unload(id NodeID) error {
     return fmt.Errorf("%s is not a node in ctx", id)
   }
 
-  err := node.Unload(ctx)
+  node.Command <- "stop"
+  returned := <- node.Status
+  
+  if returned != "stopped" {
+    return fmt.Errorf(returned)
+  }
+
+  err := node.Node.Unload(ctx)
   delete(ctx.nodes, id)
   return err
 }
@@ -861,9 +884,19 @@ func (ctx *Context) Unload(id NodeID) error {
 func (ctx *Context) Stop() {
   ctx.nodesLock.Lock()
   for id, node := range(ctx.nodes) {
-    node.Unload(ctx)
+    node.Command <- "stop"
+    returned := <- node.Status
+
+    if returned != "stopped" {
+      ctx.Log.Logf("node", "Node returned %s when commanded to stop", returned)
+    } else {
+      err := node.Node.Unload(ctx)
+      if err != nil {
+        ctx.Log.Logf("node", "Error unloading %s: %s", id, err)
+      }
       delete(ctx.nodes, id)
     }
+  }
   ctx.nodesLock.Unlock()
 }
 
@@ -873,14 +906,17 @@ func (ctx *Context) Load(id NodeID) (*Node, error) {
     return nil, err
   }
 
-  ctx.AddNode(id, node)
+  status := make(chan string, 0)
-  started := make(chan error, 1)
+  command := make(chan string, 0)
-  go runNode(ctx, node, started)
+  go runNode(ctx, node, status, command)
-  err = <- started
+
-  if err != nil {
+  returned := <- status
-    return nil, err
+  if returned != "active" {
+    return nil, fmt.Errorf(returned)
   }
 
+  ctx.AddNode(id, node, status, command)
+
   return node, nil
 }
 
@@ -927,7 +963,7 @@ func (ctx *Context) Send(node *Node, messages []SendMsg) error {
 }
 
 func resolveNodeID(val interface{}, p graphql.ResolveParams) (interface{}, error) {
-  id, ok := p.Source.(NodeID)
+  id, ok := val.(NodeID)
   if ok == false {
     return nil, fmt.Errorf("%+v is not NodeID", p.Source)
   }
@@ -984,7 +1020,7 @@ func NewContext(db Database, log Logger) (*Context, error) {
     Interfaces: map[string]InterfaceInfo{},
     NodeTypes: map[NodeType]NodeInfo{},
 
-    nodes: map[NodeID]*Node{},
+    nodes: map[NodeID]ContextNode{},
   }
 
   var err error
@@ -993,6 +1029,8 @@ func NewContext(db Database, log Logger) (*Context, error) {
   func(ctx *Context, value reflect.Value, data []byte) (int, error) {
     copy(data, value.Bytes())
     return 16, nil
+  }, func(ctx *Context, value reflect.Value) (int, error) {
+    return 16, nil
   }, func(ctx *Context, data []byte) (reflect.Value, []byte, error) {
     if len(data) < 16 {
       return reflect.Value{}, nil, fmt.Errorf("Not enough bytes to decode NodeID(got %d, want 16)", len(data))
@@ -1014,6 +1052,8 @@ func NewContext(db Database, log Logger) (*Context, error) {
   func(ctx *Context, value reflect.Value, data []byte) (int, error) {
     copy(data, value.Bytes())
     return 16, nil
+  }, func(ctx *Context, value reflect.Value) (int, error) {
+    return 16, nil
   }, func(ctx *Context, data []byte) (reflect.Value, []byte, error) {
     if len(data) < 16 {
       return reflect.Value{}, nil, fmt.Errorf("Not enough bytes to decode uuid.UUID(got %d, want 16)", len(data))
@@ -1031,12 +1071,12 @@ func NewContext(db Database, log Logger) (*Context, error) {
     return nil, fmt.Errorf("Failed to register uuid.UUID: %w", err)
   }
   
-  err = RegisterScalar[NodeType](ctx, identity, coerce[NodeType], astInt[NodeType], nil, nil) 
+  err = RegisterScalar[NodeType](ctx, identity, coerce[NodeType], astInt[NodeType], nil, nil, nil) 
   if err != nil {
     return nil, fmt.Errorf("Failed to register NodeType: %w", err)
   }
 
-  err = RegisterScalar[ExtType](ctx, identity, coerce[ExtType], astInt[ExtType], nil, nil)
+  err = RegisterScalar[ExtType](ctx, identity, coerce[ExtType], astInt[ExtType], nil, nil, nil)
   if err != nil {
     return nil, fmt.Errorf("Failed to register ExtType: %w", err)
   }
@@ -1051,32 +1091,32 @@ func NewContext(db Database, log Logger) (*Context, error) {
     return nil, fmt.Errorf("Failed to register NodeType Node: %w", err)
   }
 
-  err = RegisterScalar[bool](ctx, identity, coerce[bool], astBool[bool], nil, nil)
+  err = RegisterScalar[bool](ctx, identity, coerce[bool], astBool[bool], nil, nil, nil)
   if err != nil {
     return nil, fmt.Errorf("Failed to register bool: %w", err)
   }
 
-  err = RegisterScalar[int](ctx, identity, coerce[int], astInt[int], nil, nil)
+  err = RegisterScalar[int](ctx, identity, coerce[int], astInt[int], nil, nil, nil)
   if err != nil {
     return nil, fmt.Errorf("Failed to register int: %w", err)
   }
 
-  err = RegisterScalar[uint32](ctx, identity, coerce[uint32], astInt[uint32], nil, nil)
+  err = RegisterScalar[uint32](ctx, identity, coerce[uint32], astInt[uint32], nil, nil, nil)
   if err != nil {
     return nil, fmt.Errorf("Failed to register uint32: %w", err)
   }
 
-  err = RegisterScalar[uint8](ctx, identity, coerce[uint8], astInt[uint8], nil, nil)
+  err = RegisterScalar[uint8](ctx, identity, coerce[uint8], astInt[uint8], nil, nil, nil)
   if err != nil {
     return nil, fmt.Errorf("Failed to register uint8: %w", err)
   }
 
-  err = RegisterScalar[time.Time](ctx, stringify, unstringify[time.Time], unstringifyAST[time.Time], nil, nil)
+  err = RegisterScalar[time.Time](ctx, stringify, unstringify[time.Time], unstringifyAST[time.Time], nil, nil, nil)
   if err != nil {
     return nil, fmt.Errorf("Failed to register time.Time: %w", err)
   }
   
-  err = RegisterScalar[string](ctx, identity, coerce[string], astString[string], nil, nil)
+  err = RegisterScalar[string](ctx, identity, coerce[string], astString[string], nil, nil, nil)
   if err != nil {
     return nil, fmt.Errorf("Failed to register string: %w", err)
   }
@@ -1086,7 +1126,7 @@ func NewContext(db Database, log Logger) (*Context, error) {
     return nil, fmt.Errorf("Failed to register ReqState: %w", err)
   }
 
-  err = RegisterScalar[Tag](ctx, identity, coerce[Tag], astString[Tag], nil, nil)
+  err = RegisterScalar[Tag](ctx, identity, coerce[Tag], astString[Tag], nil, nil, nil)
   if err != nil {
     return nil, fmt.Errorf("Failed to register Tag: %w", err)
   }

lockable.go

@@ -30,21 +30,43 @@ func (state ReqState) String() string {
   }
 }
 
+
 type LockableExt struct{
   State ReqState `gv:"state"`
   ReqID *uuid.UUID `gv:"req_id"`
   Owner *NodeID `gv:"owner"`
   PendingOwner *NodeID `gv:"pending_owner"`
   Requirements map[NodeID]ReqState `gv:"requirements" node:"Lockable:"`
+
+  Locked map[NodeID]any
+  Unlocked map[NodeID]any
+
   Waiting WaitMap `gv:"waiting_locks" node:":Lockable"`
 }
 
+func (ext *LockableExt) PostDeserialize(ctx *Context) error {
+  ext.Locked = map[NodeID]any{}
+  ext.Unlocked = map[NodeID]any{}
+
+  for id, state := range(ext.Requirements) {
+    if state == Unlocked {
+      ext.Unlocked[id] = nil
+    } else if state == Locked {
+      ext.Locked[id] = nil
+    }
+  }
+  return nil
+}
+
 func NewLockableExt(requirements []NodeID) *LockableExt {
   var reqs map[NodeID]ReqState = nil
+  var unlocked map[NodeID]any = map[NodeID]any{}
+
   if len(requirements) != 0 {
     reqs = map[NodeID]ReqState{}
     for _, req := range(requirements) {
       reqs[req] = Unlocked
+      unlocked[req] = nil
     }
   }
 
@@ -54,6 +76,9 @@ func NewLockableExt(requirements []NodeID) *LockableExt {
     PendingOwner: nil,
     Requirements: reqs,
     Waiting: WaitMap{},
+
+    Locked: map[NodeID]any{},
+    Unlocked: unlocked,
   }
 }
 
@@ -295,16 +320,11 @@ func (ext *LockableExt) HandleSuccessSignal(ctx *Context, node *Node, source Nod
     switch ext.State {
     case Locking:
       ext.Requirements[id] = Locked
-      locked := 0
+      ext.Locked[id] = nil
-      for _, req_state := range(ext.Requirements) {
+      delete(ext.Unlocked, id)
-        switch req_state {
-        case Locked:
-          locked += 1
-        }
-      }
 
-      if locked == len(ext.Requirements) {
+      if len(ext.Locked) == len(ext.Requirements) {
-        ctx.Log.Logf("lockable", "%s FULL_LOCK: %d", node.ID, locked)
+        ctx.Log.Logf("lockable", "%s FULL_LOCK: %d", node.ID, len(ext.Locked))
         changes = append(changes, "state", "owner", "req_id")
         ext.State = Locked
 
@@ -313,7 +333,7 @@ func (ext *LockableExt) HandleSuccessSignal(ctx *Context, node *Node, source Nod
         messages = append(messages, SendMsg{*ext.Owner, NewSuccessSignal(*ext.ReqID)})
         ext.ReqID = nil
       } else {
-        ctx.Log.Logf("lockable", "%s PARTIAL_LOCK: %d/%d", node.ID, locked, len(ext.Requirements))
+        ctx.Log.Logf("lockable", "%s PARTIAL_LOCK: %d/%d", node.ID, len(ext.Locked), len(ext.Requirements))
       }
     case AbortingLock:
       req_state := ext.Requirements[id]
@@ -325,6 +345,8 @@ func (ext *LockableExt) HandleSuccessSignal(ctx *Context, node *Node, source Nod
         messages = append(messages, SendMsg{id, unlock_signal})
       case Unlocking:
         ext.Requirements[id] = Unlocked
+        ext.Unlocked[id] = nil
+        delete(ext.Locked, id)
 
         unlocked := 0
         for _, req_state := range(ext.Requirements) {
@@ -347,15 +369,10 @@ func (ext *LockableExt) HandleSuccessSignal(ctx *Context, node *Node, source Nod
 
     case Unlocking:
       ext.Requirements[id] = Unlocked
-      unlocked := 0
+      ext.Unlocked[id] = Unlocked
-      for _, req_state := range(ext.Requirements) {
+      delete(ext.Locked, id)
-        switch req_state {
-        case Unlocked:
-          unlocked += 1
-        }
-      }
 
-      if unlocked == len(ext.Requirements) {
+      if len(ext.Unlocked) == len(ext.Requirements) {
         changes = append(changes, "state", "owner", "req_id")
 
         messages = append(messages, SendMsg{*ext.Owner, NewSuccessSignal(*ext.ReqID)})

lockable_test.go

@@ -46,6 +46,10 @@ func Test10Lock(t *testing.T) {
   testLockN(t, 10)
 }
 
+func Test100Lock(t *testing.T) {
+  testLockN(t, 100)
+}
+
 func Test1000Lock(t *testing.T) {
   testLockN(t, 1000)
 }

node.go

@@ -8,6 +8,7 @@ import (
   "reflect"
   "sync/atomic"
   "time"
+  "sync"
 
   _ "github.com/dgraph-io/badger/v3"
   "github.com/google/uuid"
@@ -72,7 +73,37 @@ func (q QueuedSignal) String() string {
 
 type WaitMap map[uuid.UUID]NodeID
 
-// Default message channel size for nodes
+type Queue[T any] struct {
+  out chan T
+  in chan T
+  buffer []T
+  resize sync.Mutex
+}
+
+func NewQueue[T any](initial int) *Queue[T] {
+  queue := Queue[T]{
+    out: make(chan T, 0),
+    in: make(chan T, 0),
+    buffer: make([]T, 0, initial),
+  }
+
+  go func(queue *Queue[T]) {
+  }(&queue)
+
+  go func(queue *Queue[T]) {
+  }(&queue)
+
+  return &queue
+}
+
+func (queue *Queue[T]) Put(value T) error {
+  return nil
+}
+
+func (queue *Queue[T]) Get(value T) error {
+  return nil
+}
+
 // Nodes represent a group of extensions that can be collectively addressed
 type Node struct {
   Key ed25519.PrivateKey `gv:"key"`
@@ -155,9 +186,9 @@ func SoonestSignal(signals []QueuedSignal) (*QueuedSignal, <-chan time.Time) {
   }
 }
 
-func runNode(ctx *Context, node *Node, started chan error) {
+func runNode(ctx *Context, node *Node, status chan string, control chan string) {
   ctx.Log.Logf("node", "RUN_START: %s", node.ID)
-  err := nodeLoop(ctx, node, started)
+  err := nodeLoop(ctx, node, status, control)
   if err != nil {
     ctx.Log.Logf("node", "%s runNode err %s", node.ID, err)
   }
@@ -195,7 +226,7 @@ func (node *Node) ReadFields(ctx *Context, fields []string)map[string]any {
 }
 
 // Main Loop for nodes
-func nodeLoop(ctx *Context, node *Node, started chan error) error {
+func nodeLoop(ctx *Context, node *Node, status chan string, control chan string) error {
   is_started := node.Active.CompareAndSwap(false, true)
   if is_started == false {
     return fmt.Errorf("%s is already started, will not start again", node.ID)
@@ -219,13 +250,31 @@ func nodeLoop(ctx *Context, node *Node, started chan error) error {
 
   ctx.Log.Logf("node_ext", "Loaded extensions for %s", node.ID)
 
-  started <- nil
+  status <- "active"
 
-  run := true
+  running := true
-  for run == true {
+  for running {
     var signal Signal
     var source NodeID
+
+
     select {
+    case command := <-control:
+      switch command {
+      case "stop":
+        running = false
+      case "pause":
+        status <- "paused"
+        command := <- control
+        switch command {
+        case "resume":
+          status <- "resumed"
+        case "stop":
+          running = false
+        }
+      default:
+        ctx.Log.Logf("node", "Unknown control command %s", command)
+      }
     case <-node.TimeoutChan:
       signal = node.NextSignal.Signal
       source = node.ID
@@ -282,18 +331,17 @@ func nodeLoop(ctx *Context, node *Node, started chan error) error {
   if stopped == false {
     panic("BAD_STATE: stopping already stopped node")
   }
+
+  status <- "stopped"
+
   return nil
 }
 
 func (node *Node) Unload(ctx *Context) error {
-  if node.Active.Load() {
   for _, extension := range(node.Extensions) {
     extension.Unload(ctx, node)
   }
   return nil
-  } else {
-    return fmt.Errorf("Node not active")
-  }
 }
 
 func (node *Node) QueueChanges(ctx *Context, changes map[ExtType]Changes) error {
@@ -342,13 +390,6 @@ func (node *Node) Process(ctx *Context, source NodeID, signal Signal) error {
     }
   }
 
-  if (len(changes) != 0) || node.writeSignalQueue {
-    write_err := ctx.DB.WriteNodeChanges(ctx, node, changes)
-    if write_err != nil {
-      return write_err
-    }
-  }
-
   if len(changes) != 0 {
     status_err := node.QueueChanges(ctx, changes)
     if status_err != nil {
@@ -460,13 +501,16 @@ func NewNode(ctx *Context, key ed25519.PrivateKey, type_name string, buffer_size
     return nil, err
   }
 
-  ctx.AddNode(id, node)
+  status := make(chan string, 0)
-  started := make(chan error, 1)
+  command := make(chan string, 0)
-  go runNode(ctx, node, started)
+  go runNode(ctx, node, status, command)
-  err = <- started
+
-  if err != nil {
+  returned := <- status
-    return nil, err
+  if returned != "active" {
+    return nil, fmt.Errorf(returned)
   }
 
+  ctx.AddNode(id, node, status, command)
+
   return node, nil
 }

node_test.go

@@ -22,7 +22,6 @@ func TestNodeDB(t *testing.T) {
   err = ctx.Unload(node.ID)
   fatalErr(t, err)
 
-  ctx.nodes = map[NodeID]*Node{}
   _, err = ctx.getNode(node.ID)
   fatalErr(t, err)
 }

serialize.go

@@ -202,6 +202,152 @@ func Deserialize[T any](ctx *Context, data []byte) (T, error) {
   return value.Interface().(T), nil
 }
 
+func SerializedSize(ctx *Context, value reflect.Value) (int, error) {
+  var sizefn SerializedSizeFn = nil
+
+  info, registered := ctx.Types[value.Type()]
+  if registered {
+    sizefn = info.SerializedSize
+  }
+
+  if sizefn == nil {
+    switch value.Type().Kind() {
+    case reflect.Bool:
+      return 1, nil 
+
+    case reflect.Int8:
+      return 1, nil
+    case reflect.Int16:
+      return 2, nil
+    case reflect.Int32:
+      return 4, nil
+    case reflect.Int64:
+      fallthrough
+    case reflect.Int:
+      return 8, nil
+  
+    case reflect.Uint8:
+      return 1, nil
+    case reflect.Uint16:
+      return 2, nil
+    case reflect.Uint32:
+      return 4, nil
+    case reflect.Uint64:
+      fallthrough
+    case reflect.Uint:
+      return 8, nil
+
+    case reflect.Float32:
+      return 4, nil 
+    case reflect.Float64:
+      return 8, nil
+
+    case reflect.String:
+      return 8 + value.Len(), nil
+
+    case reflect.Pointer:
+      if value.IsNil() {
+        return 1, nil
+      } else {
+        elem_len, err := SerializedSize(ctx, value.Elem())
+        if err != nil {
+          return 0, err
+        } else {
+          return 1 + elem_len, nil
+        }
+      }
+
+    case reflect.Slice:
+      if value.IsNil() {
+        return 1, nil
+      } else {
+        elem_total := 0
+        for i := 0; i < value.Len(); i++ {
+          elem_len, err := SerializedSize(ctx, value.Index(i))
+          if err != nil {
+            return 0, err
+          }
+          elem_total += elem_len
+        }
+        return 9 + elem_total, nil 
+      }
+
+    case reflect.Array:
+      total := 0
+      for i := 0; i < value.Len(); i++ {
+        elem_len, err := SerializedSize(ctx, value.Index(i))
+        if err != nil {
+          return 0, err
+        }
+        total += elem_len
+      }
+      return total, nil
+
+    case reflect.Map:
+      if value.IsNil() {
+        return 1, nil
+      } else {
+        key := reflect.New(value.Type().Key()).Elem()
+        val := reflect.New(value.Type().Elem()).Elem()
+        iter := value.MapRange()
+
+        total := 0
+        for iter.Next() {
+          key.SetIterKey(iter)
+          k, err := SerializedSize(ctx, key)
+          if err != nil {
+            return 0, err
+          }
+
+          total += k
+
+          val.SetIterValue(iter)
+          v, err := SerializedSize(ctx, val)
+          if err != nil {
+            return 0, err
+          }
+
+          total += v
+        }
+
+        return 9 + total, nil
+      }
+
+    case reflect.Struct:
+      if registered == false {
+        return 0, fmt.Errorf("Can't serialize unregistered struct %s", value.Type())
+      } else {
+        field_total := 0
+        for _, field_info := range(info.Fields) {
+          field_size, err := SerializedSize(ctx, value.FieldByIndex(field_info.Index))
+          if err != nil {
+            return 0, err
+          }
+
+          field_total += 8
+          field_total += field_size
+        }
+
+        return 8 + field_total, nil
+      }
+
+    case reflect.Interface:
+      // TODO get size of TypeStack instead of just using 128
+      elem_size, err := SerializedSize(ctx, value.Elem())
+      if err != nil {
+        return 0, err
+      }
+
+      return 128 + elem_size, nil
+
+    default:
+      return 0, fmt.Errorf("Don't know how to serialize %s", value.Type())
+    }
+  } else {
+    return sizefn(ctx, value)
+  }
+}
+
 func SerializeValue(ctx *Context, value reflect.Value, data []byte) (int, error) {
   var serialize SerializeFn = nil
 
@@ -294,7 +440,6 @@ func SerializeValue(ctx *Context, value reflect.Value, data []byte) (int, error)
       }
 
     case reflect.Array:
-      data := []byte{}
       total_written := 0
       for i := 0; i < value.Len(); i++ {
         written, err := SerializeValue(ctx, value.Index(i), data[total_written:])
@@ -306,7 +451,12 @@ func SerializeValue(ctx *Context, value reflect.Value, data []byte) (int, error)
       return total_written, nil
 
     case reflect.Map:
-      binary.BigEndian.PutUint64(data, uint64(value.Len()))
+      if value.IsNil() {
+        data[0] = 0x00
+        return 1, nil
+      } else {
+        data[0] = 0x01
+        binary.BigEndian.PutUint64(data[1:], uint64(value.Len()))
 
         key := reflect.New(value.Type().Key()).Elem()
         val := reflect.New(value.Type().Elem()).Elem()
@@ -316,19 +466,20 @@ func SerializeValue(ctx *Context, value reflect.Value, data []byte) (int, error)
           key.SetIterKey(iter)
           val.SetIterValue(iter)
 
-        k, err := SerializeValue(ctx, key, data[8+total_written:])
+          k, err := SerializeValue(ctx, key, data[9+total_written:])
           if err != nil {
             return 0, err
           }
           total_written += k
 
-        v, err := SerializeValue(ctx, val, data[8+total_written:]) 
+          v, err := SerializeValue(ctx, val, data[9+total_written:]) 
           if err != nil {
             return 0, err
           }
           total_written += v
         }
-      return 8 + total_written, nil
+        return 9 + total_written, nil
+      }
     
     case reflect.Struct:
       if registered == false {
@@ -501,7 +652,11 @@ func DeserializeValue(ctx *Context, data []byte, t reflect.Type) (reflect.Value,
       return value, left, nil
 
     case reflect.Map:
-      len_bytes, left := split(data, 8)
+      flags, after_flags := split(data, 1)
+      if flags[0] == 0x00 {
+        return reflect.New(t).Elem(), after_flags, nil
+      } else {
+        len_bytes, left := split(after_flags, 8)
         length := int(binary.BigEndian.Uint64(len_bytes))
 
         value := reflect.MakeMapWithSize(t, length)
@@ -525,6 +680,7 @@ func DeserializeValue(ctx *Context, data []byte, t reflect.Type) (reflect.Value,
         }
 
         return value, left, nil
+      }
 
     case reflect.Struct:
       info, mapped := ctx.Types[t]

serialize_test.go

@@ -160,6 +160,14 @@ func TestSerializeValues(t *testing.T) {
   testSerializeCompare[*int](t, ctx, nil)
   testSerializeCompare(t, ctx, "string")
 
+  testSerialize(t, ctx, map[string]string{
+    "Test": "Test",
+    "key": "String",
+    "": "",
+  })
+
+  testSerialize[map[string]string](t, ctx, nil)
+
   testSerialize(t, ctx, NewListenerExt(10))
 
   node, err := NewNode(ctx, nil, "Node", 100)