UNET 32 [SyncVar] Limit Workaround

UNET only allows us to use 32 Syncvars+SyncLists per Script. That's fine in most cases, but sometimes we need more, which will result in the following errors:

• UNetWeaver error: Script class [Name] has too many SyncVars (32). (This could include base classes)

• Failure generating network code. UnityEditor.Scripting.Serialization.Weaver:WeaveUnetFromEditor(String, String, String, String, Boolean)

The reason for '32' SyncVars is that the UNET Weaver uses a 32 bit dirty mask, hence 32 SyncVars. Right now there's just no way to modify this value without reverse engineering Unity DLLs. I hope one of the UNET developers can at least give us the option to use a 64 bit dirty mask for SyncVars in the future, so that we can use 64 of them too. Perhaps with a flag in the Global Config, similar to the new 'use ack long' property? 32 sounds like a lot, but I had plenty of people add dozens of attributes to uMMORPG's Player script, running into the limit over and over again. Sending around 32 more bits should be worth making a developer's life easier.
@aabramychev @Erik-Juhl @larus

In the meantime, there is a way around it. I implemented my own [SyncVar_] attribute that allows for abitrary amounts of SyncVars in your scripts by mapping them to SyncList entries. Here is how to use it:

1. Create SyncVarLimitWorkaround.cs:

Code (CSharp):

1. // (c) ummorpg.net
2. //
3. // This script provides a custom [SyncVar_] attribute to work around UNET's 32
4. // SyncVar limit.
5. //
6. // Usage: attach it to the Prefab; use [SyncVar_] in any component.
7. //
8. // This script uses reflection and is kind of hack. It works fine, but it would
9. // be even better if UNET allows more than 32 SyncVars by default some day.
10. using System;
11. using System.Reflection;
12. using System.Collections.Generic;
13. using System.Linq;
14. using UnityEngine;
15. using UnityEngine.Networking;
16.  
17. [AttributeUsage(AttributeTargets.Field)]
18. public class SyncVar_Attribute : Attribute{}
19.  
20. // UNET has no SyncListLong. Workaround via SyncListStruct
21. public struct LongWrapper {
22.     public long value;
23.     public LongWrapper(long value) { this.value = value; }
24. }
25. public class SyncListLongWrapper : SyncListStruct<LongWrapper> { }
26.  
27. // we need a list of field,obj. a dictionary can't guarantee order.
28. public class FieldInfoAndObject {
29.     public FieldInfo field;
30.     public object obj;
31.     public FieldInfoAndObject(FieldInfo field, object obj) {
32.         this.field = field;
33.         this.obj = obj;
34.     }
35. }
36.  
37. public class SyncVarLimitWorkaround : NetworkBehaviour {
38.     List<FieldInfoAndObject> stringFields = new List<FieldInfoAndObject>();
39.     SyncListString strings = new SyncListString();
40.  
41.     List<FieldInfoAndObject> floatFields = new List<FieldInfoAndObject>();
42.     SyncListFloat floats = new SyncListFloat();
43.  
44.     List<FieldInfoAndObject> intFields = new List<FieldInfoAndObject>();
45.     SyncListInt ints = new SyncListInt();
46.  
47.     List<FieldInfoAndObject> uintFields = new List<FieldInfoAndObject>();
48.     SyncListUInt uints = new SyncListUInt();
49.  
50.     List<FieldInfoAndObject> longFields = new List<FieldInfoAndObject>();
51.     SyncListLongWrapper longs = new SyncListLongWrapper();
52.  
53.     List<FieldInfoAndObject> boolFields = new List<FieldInfoAndObject>();
54.     SyncListBool bools = new SyncListBool();
55.  
56.     public static List<FieldInfo> GetFieldsWithAttribute(Type objectType, Type attributeType) {
57.         // getfields with all binding flags still doesn't get base type's private
58.         // fields. we have to iterate through base types to get all of them.
59.         var result = new List<FieldInfo>();
60.         while (true) {
61.             var fields = objectType.GetFields(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic).Where(
62.                 field => field.IsDefined(attributeType, true)
63.             );
64.             result.AddRange(fields);
65.             objectType = objectType.BaseType;
66.             if (objectType == null) break;
67.         }
68.         return result;
69.     }
70.  
71.     // server & client: build field lists for each type. we assume that the
72.     // order is the same on client and server.
73.     void Awake() {
74.         // go through each networkbehaviour component
75.         foreach (var component in GetComponents<NetworkBehaviour>()) {
76.             // find all the custom syncvars
77.             foreach (var field in GetFieldsWithAttribute(component.GetType(), typeof(SyncVar_Attribute))) {
78.                 //Debug.LogWarning(component.GetType() + " => " + field + "=>" + field.GetValue(component));
79.                 // add them to the field lists
80.                 if (field.FieldType == typeof(string))
81.                     stringFields.Add(new FieldInfoAndObject(field, component));
82.                 else if (field.FieldType == typeof(float))
83.                     floatFields.Add(new FieldInfoAndObject(field, component));
84.                 else if (field.FieldType == typeof(int))
85.                     intFields.Add(new FieldInfoAndObject(field, component));
86.                 else if (field.FieldType == typeof(uint))
87.                     uintFields.Add(new FieldInfoAndObject(field, component));
88.                 else if (field.FieldType == typeof(long))
89.                     longFields.Add(new FieldInfoAndObject(field, component));
90.                 else if (field.FieldType == typeof(bool))
91.                     boolFields.Add(new FieldInfoAndObject(field, component));
92.                 else Debug.LogError("Unsupported [SyncVar_] type: " + field);
93.             }
94.         }
95.     }
96.  
97.     // server: populate the synclists with the field values
98.     public override void OnStartServer() {
99.         foreach (var fieldAndObject in stringFields) {
100.             //print("add string: " + fieldAndObject.field.GetValue(fieldAndObject.obj));
101.             strings.Add((string)fieldAndObject.field.GetValue(fieldAndObject.obj));
102.         }
103.  
104.         foreach (var fieldAndObject in floatFields) {
105.             //print("add float: " + fieldAndObject.field.GetValue(fieldAndObject.obj));
106.             floats.Add((float)fieldAndObject.field.GetValue(fieldAndObject.obj));
107.         }
108.  
109.         foreach (var fieldAndObject in intFields) {
110.             //print("add int: " + fieldAndObject.field.GetValue(fieldAndObject.obj));
111.             ints.Add((int)fieldAndObject.field.GetValue(fieldAndObject.obj));
112.         }
113.  
114.         foreach (var fieldAndObject in uintFields) {
115.             //print("add uint: " + fieldAndObject.field.GetValue(fieldAndObject.obj));
116.             uints.Add((uint)fieldAndObject.field.GetValue(fieldAndObject.obj));
117.         }
118.  
119.         foreach (var fieldAndObject in longFields) {
120.             //print("add long: " + fieldAndObject.field.GetValue(fieldAndObject.obj));
121.             longs.Add(new LongWrapper((long)fieldAndObject.field.GetValue(fieldAndObject.obj)));
122.         }
123.  
124.         foreach (var fieldAndObject in boolFields) {
125.             //print("add bool: " + fieldAndObject.field.GetValue(fieldAndObject.obj));
126.             bools.Add((bool)fieldAndObject.field.GetValue(fieldAndObject.obj));
127.         }
128.     }
129.  
130.     // server: copy field values to synclists all the time
131.     // (still works if obj becomes null)
132.     [ServerCallback]
133.     void Update() {
134.         for (int i = 0; i < stringFields.Count; ++i) {
135.             var fieldAndObject = stringFields[i];
136.             string value = (string)fieldAndObject.field.GetValue(fieldAndObject.obj);
137.             // only update if changed. don't mess with dirty flags.
138.             if (strings[i] != value) strings[i] = value;
139.         }
140.  
141.         for (int i = 0; i < floatFields.Count; ++i) {
142.             var fieldAndObject = floatFields[i];
143.             float value = (float)fieldAndObject.field.GetValue(fieldAndObject.obj);
144.             // only update if changed. don't mess with dirty flags.
145.             if (floats[i] != value) floats[i] = value;
146.         }
147.  
148.         for (int i = 0; i < intFields.Count; ++i) {
149.             var fieldAndObject = intFields[i];
150.             int value = (int)fieldAndObject.field.GetValue(fieldAndObject.obj);
151.             // only update if changed. don't mess with dirty flags.
152.             if (ints[i] != value) ints[i] = value;
153.         }
154.  
155.         for (int i = 0; i < uintFields.Count; ++i) {
156.             var fieldAndObject = uintFields[i];
157.             uint value = (uint)fieldAndObject.field.GetValue(fieldAndObject.obj);
158.             // only update if changed. don't mess with dirty flags.
159.             if (uints[i] != value) uints[i] = value;
160.         }
161.  
162.         for (int i = 0; i < longFields.Count; ++i) {
163.             var fieldAndObject = longFields[i];
164.             long value = (long)fieldAndObject.field.GetValue(fieldAndObject.obj);
165.             // only update if changed. don't mess with dirty flags.
166.             if (longs[i].value != value) longs[i] = new LongWrapper(value);
167.         }
168.  
169.         for (int i = 0; i < boolFields.Count; ++i) {
170.             var fieldAndObject = boolFields[i];
171.             bool value = (bool)fieldAndObject.field.GetValue(fieldAndObject.obj);
172.             // only update if changed. don't mess with dirty flags.
173.             if (bools[i] != value) bools[i] = value;
174.         }
175.     }
176.  
177.     // client: hook synclists and update fields when changed
178.     // (still works if obj becomes null)
179.     // we also call all hooks once to apply initial values
180.     // e.g. if a syncvar was set when loading from database before starting
181.     public override void OnStartClient() {
182.         strings.Callback += OnStringsChanged;
183.         for (int i = 0; i < strings.Count; ++i)
184.             OnStringsChanged(SyncListString.Operation.OP_ADD, i);
185.  
186.         floats.Callback += OnFloatsChanged;
187.         for (int i = 0; i < floats.Count; ++i)
188.             OnFloatsChanged(SyncListFloat.Operation.OP_ADD, i);
189.  
190.         ints.Callback += OnIntsChanged;
191.         for (int i = 0; i < ints.Count; ++i)
192.             OnIntsChanged(SyncListInt.Operation.OP_ADD, i);
193.  
194.         uints.Callback += OnUIntsChanged;
195.         for (int i = 0; i < uints.Count; ++i)
196.             OnUIntsChanged(SyncListUInt.Operation.OP_ADD, i);
197.  
198.         longs.Callback += OnLongsChanged;
199.         for (int i = 0; i < longs.Count; ++i)
200.             OnLongsChanged(SyncListLongWrapper.Operation.OP_ADD, i);
201.  
202.         bools.Callback += OnBoolsChanged;
203.         for (int i = 0; i < bools.Count; ++i)
204.             OnBoolsChanged(SyncListBool.Operation.OP_ADD, i);
205.     }
206.  
207.     void OnStringsChanged(SyncListString.Operation op, int index) {
208.         var fieldAndObject = stringFields[index];
209.         string value = strings[index];
210.         fieldAndObject.field.SetValue(fieldAndObject.obj, value);
211.         //print("STRING CHANGED: " + fieldAndObject.field + " => " + value);
212.     }
213.  
214.     void OnFloatsChanged(SyncListFloat.Operation op, int index) {
215.         var fieldAndObject = floatFields[index];
216.         float value = floats[index];
217.         fieldAndObject.field.SetValue(fieldAndObject.obj, value);
218.         //print("FLOAT CHANGED: " + fieldAndObject.field + " => " + value);
219.     }
220.  
221.     void OnIntsChanged(SyncListInt.Operation op, int index) {
222.         var fieldAndObject = intFields[index];
223.         int value = ints[index];
224.         fieldAndObject.field.SetValue(fieldAndObject.obj, value);
225.         //print("INT CHANGED: " + fieldAndObject.field + " => " + value);
226.     }
227.  
228.     void OnUIntsChanged(SyncListUInt.Operation op, int index) {
229.         var fieldAndObject = uintFields[index];
230.         uint value = uints[index];
231.         fieldAndObject.field.SetValue(fieldAndObject.obj, value);
232.         //print("UINT CHANGED: " + fieldAndObject.field + " => " + value);
233.     }
234.  
235.     void OnLongsChanged(SyncListLongWrapper.Operation op, int index) {
236.         var fieldAndObject = longFields[index];
237.         long value = longs[index].value;
238.         fieldAndObject.field.SetValue(fieldAndObject.obj, value);
239.         //print("LONG CHANGED: " + fieldAndObject.field + " => " + value);
240.     }
241.  
242.     void OnBoolsChanged(SyncListBool.Operation op, int index) {
243.         var fieldAndObject = boolFields[index];
244.         bool value = bools[index];
245.         fieldAndObject.field.SetValue(fieldAndObject.obj, value);
246.         //print("BOOL CHANGED: " + fieldAndObject.field + " => " + value);
247.     }
248. }
249.  

2. Use [SyncVar_] instead of [SyncVar] after reaching the limit. Example:

Code (CSharp):

1. [SyncVar_] int health = 0;

3. Make sure that each Prefab that uses [SyncVar_] also has the above Script attached to it.

Enjoy!

 

that just works great, hope someone from unet team will see that.

 

@vis2k i am facing a problem with syncVar and Command both. I have used syncVar and command attributes in my project and they are working fine but when i am adding one more at that time i m getting a problem the value are not syncing over network not even from Client to server and server to client. When i go through your answer i got to know that there will be a limit for using SyncVars but my question is what about the Command. Please help me out this got stuck.

 

This solution is outdated, try my HLAPI Pro library: https://forum.unity.com/threads/unet-hlapi-pro-taking-unet-to-the-next-level.425437/ to get 'true' 64 SyncVars without workarounds.