[ECO-5380] Updated LiveObjectsAdaopter interface

1. Added and implemented method to calculate maxMessageSizeLimit
2. Added extension method ensureMessageSizeWithinLimit to validate object msg sizes
3. Added unit test to validate objectMessageSizeWithinLimit

Author: sacOO7

lib/src/main/java/io/ably/lib/objects/Adapter.java

@@ -29,4 +29,9 @@ public void send(@NotNull ProtocolMessage msg, @NotNull CompletionListener liste
         // Always queue LiveObjects messages to ensure reliable state synchronization and proper acknowledgment
         ably.connection.connectionManager.send(msg, true, listener);
     }
+
+    @Override
+    public long maxMessageSizeLimit() {
+        return ably.connection.connectionManager.maxMessageSize;
+    }
 }

lib/src/main/java/io/ably/lib/objects/LiveObjectsAdapter.java

@@ -23,5 +23,13 @@ public interface LiveObjectsAdapter {
      * @param channelSerial the serial to set for the channel
      */
     void setChannelSerial(@NotNull String channelName, @NotNull String channelSerial);
+
+    /**
+     * Retrieves the maximum message size allowed for the messages.
+     * This method returns the maximum size in bytes that a message can have.
+     *
+     * @return the maximum message size limit in bytes.
+     */
+    long maxMessageSizeLimit();
 }
 

lib/src/main/java/io/ably/lib/transport/ConnectionManager.java

@@ -1286,6 +1286,7 @@ private synchronized void onConnected(ProtocolMessage message) {
         connection.key = connectionDetails.connectionKey; //RTN16d
         maxIdleInterval = connectionDetails.maxIdleInterval;
         connectionStateTtl = connectionDetails.connectionStateTtl;
+        maxMessageSize = connectionDetails.maxMessageSize;
 
         /* set the clientId resolved from token, if any */
         String clientId = connectionDetails.clientId;
@@ -1981,6 +1982,7 @@ private boolean isFatalError(ErrorInfo err) {
     private long lastActivity;
     private CMConnectivityListener connectivityListener;
     private long connectionStateTtl = Defaults.connectionStateTtl;
+    public long maxMessageSize = Defaults.maxMessageSize;
     long maxIdleInterval = Defaults.maxIdleInterval;
     private int disconnectedRetryAttempt = 0;
 

lib/src/main/java/io/ably/lib/transport/Defaults.java

@@ -52,6 +52,8 @@ public class Defaults {
     public static long fallbackRetryTimeout = 10*60*1000L;
     /* CD2h (but no default in the spec) */
     public static long maxIdleInterval = 20000L;
+    // 64kB, as per CD2c
+    public static long maxMessageSize = 65536L;
     /* DF1a */
     public static long connectionStateTtl = 120000L;
 

lib/src/main/java/io/ably/lib/types/Message.java

@@ -543,29 +543,6 @@ protected void read(final JsonObject map) throws MessageDecodeException {
         }
     }
 
-    /**
-     * Calculates the size of the message.
-     * Spec: TM6
-     */
-    protected int size() {
-        // Spec: TM6a - Sum of sizes of name, data, clientId, and extras
-        int nameSize = name != null ? name.length() : 0; // Spec: TM6a
-        int dataSize = 0;
-
-        if (data != null) {
-            if (data instanceof byte[]) {
-                dataSize = ((byte[]) data).length; // Spec: TM6c
-            } else {
-                dataSize = Serialisation.gson.toJson(data).length(); // Spec: TM6b
-            }
-        }
-
-        int clientIdSize = clientId != null ? clientId.length() : 0; // Spec: TM6f
-        int extrasSize = extras != null ? Serialisation.gson.toJson(extras).length() : 0; // Spec: TM6d
-
-        return nameSize + dataSize + clientIdSize + extrasSize;
-    }
-
     public static class Serializer implements JsonSerializer<Message>, JsonDeserializer<Message> {
         @Override
         public JsonElement serialize(Message message, Type typeOfMessage, JsonSerializationContext ctx) {

live-objects/src/main/kotlin/io/ably/lib/objects/ErrorCodes.kt

@@ -3,6 +3,7 @@ package io.ably.lib.objects
 internal enum class ErrorCode(public val code: Int) {
   BadRequest(40_000),
   InternalError(50_000),
+  MaxMessageSizeExceeded(40_009),
 }
 
 internal enum class HttpStatusCode(public val code: Int) {

live-objects/src/main/kotlin/io/ably/lib/objects/Helpers.kt

@@ -23,6 +23,15 @@ internal suspend fun LiveObjectsAdapter.sendAsync(message: ProtocolMessage) = su
   }
 }
 
+internal fun LiveObjectsAdapter.ensureMessageSizeWithinLimit(objectMessages: Array<ObjectMessage>) {
+  val maximumAllowedSize = maxMessageSizeLimit()
+  val objectsTotalMessageSize = objectMessages.sumOf { it.size() }
+  if (objectsTotalMessageSize > maximumAllowedSize) {
+    throw ablyException("ObjectMessage size $objectsTotalMessageSize exceeds maximum allowed size of $maximumAllowedSize bytes",
+      ErrorCode.MaxMessageSizeExceeded)
+  }
+}
+
 internal enum class ProtocolMessageFormat(private val value: String) {
   Msgpack("msgpack"),
   Json("json");

live-objects/src/main/kotlin/io/ably/lib/objects/ObjectMessage.kt

@@ -1,7 +1,5 @@
 package io.ably.lib.objects
 
-import com.google.gson.Gson
-
 /**
  * An enum class representing the different actions that can be performed on an object.
  * Spec: OOP2
@@ -339,11 +337,11 @@ internal data class ObjectMessage(
  * Calculates the size of an ObjectMessage in bytes.
  * Spec: OM3
  */
-internal fun ObjectMessage.size(): Int {
+internal fun ObjectMessage.size(): Long {
   val clientIdSize = clientId?.length ?: 0 // Spec: OM3f
   val operationSize = operation?.size() ?: 0 // Spec: OM3b, OOP4
   val objectStateSize = objectState?.size() ?: 0 // Spec: OM3c, OST3
-  val extrasSize = extras?.let { Gson().toJson(it).length } ?: 0 // Spec: OM3d
+  val extrasSize = extras?.let { gson.toJson(it).length } ?: 0 // Spec: OM3d
 
   return clientIdSize + operationSize + objectStateSize + extrasSize
 }
@@ -352,7 +350,7 @@ internal fun ObjectMessage.size(): Int {
  * Calculates the size of an ObjectOperation in bytes.
  * Spec: OOP4
  */
-private fun ObjectOperation.size(): Int {
+private fun ObjectOperation.size(): Long {
   val mapOpSize = mapOp?.size() ?: 0 // Spec: OOP4b, OMO3
   val counterOpSize = counterOp?.size() ?: 0 // Spec: OOP4c, OCO3
   val mapSize = map?.size() ?: 0 // Spec: OOP4d, OMP4
@@ -365,7 +363,7 @@ private fun ObjectOperation.size(): Int {
  * Calculates the size of an ObjectState in bytes.
  * Spec: OST3
  */
-private fun ObjectState.size(): Int {
+private fun ObjectState.size(): Long {
   val mapSize = map?.size() ?: 0 // Spec: OST3b, OMP4
   val counterSize = counter?.size() ?: 0 // Spec: OST3c, OCN3
   val createOpSize = createOp?.size() ?: 0 // Spec: OST3d, OOP4
@@ -374,10 +372,10 @@ private fun ObjectState.size(): Int {
 }
 
 /**
- * Calculates the size of an ObjectMap in bytes.
+ * Calculates the size of an ObjectMapOp in bytes.
  * Spec: OMO3
  */
-private fun ObjectMapOp.size(): Int {
+private fun ObjectMapOp.size(): Long {
   val keySize = key.length // Spec: OMO3d - Size of the key
   val dataSize = data?.size() ?: 0 // Spec: OMO3b - Size of the data, calculated per "OD3"
   return keySize + dataSize
@@ -387,7 +385,7 @@ private fun ObjectMapOp.size(): Int {
  * Calculates the size of a CounterOp in bytes.
  * Spec: OCO3
  */
-private fun ObjectCounterOp.size(): Int {
+private fun ObjectCounterOp.size(): Long {
   // Size is 8 if amount is a number, 0 if amount is null or omitted
   return if (amount != null) 8 else 0 // Spec: OCO3a, OCO3b
 }
@@ -396,7 +394,7 @@ private fun ObjectCounterOp.size(): Int {
  * Calculates the size of an ObjectMap in bytes.
  * Spec: OMP4
  */
-private fun ObjectMap.size(): Int {
+private fun ObjectMap.size(): Long {
   // Calculate the size of all map entries in the map property
   val entriesSize = entries?.entries?.sumOf {
     it.key.length + it.value.size() // // Spec: OMP4a1, OMP4a2
@@ -409,7 +407,7 @@ private fun ObjectMap.size(): Int {
  * Calculates the size of an ObjectCounter in bytes.
  * Spec: OCN3
  */
-private fun ObjectCounter.size(): Int {
+private fun ObjectCounter.size(): Long {
   // Size is 8 if count is a number, 0 if count is null or omitted
   return if (count != null) 8 else 0
 }
@@ -418,7 +416,7 @@ private fun ObjectCounter.size(): Int {
  * Calculates the size of a MapEntry in bytes.
  * Spec: OME3
  */
-private fun ObjectMapEntry.size(): Int {
+private fun ObjectMapEntry.size(): Long {
   // The size is equal to the size of the data property, calculated per "OD3"
   return data?.size() ?: 0
 }
@@ -427,20 +425,20 @@ private fun ObjectMapEntry.size(): Int {
  * Calculates the size of an ObjectData in bytes.
  * Spec: OD3
  */
-private fun ObjectData.size(): Int {
+private fun ObjectData.size(): Long {
   return value?.size() ?: 0 // Spec: OD3f
 }
 
 /**
  * Calculates the size of an ObjectValue in bytes.
  * Spec: OD3*
  */
-private fun ObjectValue.size(): Int {
+private fun ObjectValue.size(): Long {
   return when (value) {
     is Boolean -> 1 // Spec: OD3b
-    is Binary -> value.size() // Spec: OD3c
+    is Binary -> value.size().toLong() // Spec: OD3c
     is Number -> 8 // Spec: OD3d
-    is String -> value.length // Spec: OD3e
+    is String -> value.byteSize.toLong() // Spec: OD3e
     else -> 0  // Spec: OD3f
   }
 }

live-objects/src/main/kotlin/io/ably/lib/objects/Serialization.kt

@@ -0,0 +1,10 @@
+package io.ably.lib.objects
+
+import com.google.gson.Gson
+import com.google.gson.GsonBuilder
+
+internal val gson: Gson = createGsonSerializer()
+
+private fun createGsonSerializer(): Gson {
+  return GsonBuilder().create() // Do not call serializeNulls() to omit null values
+}

live-objects/src/main/kotlin/io/ably/lib/objects/Utils.kt

@@ -33,3 +33,10 @@ private fun createAblyException(
 internal fun clientError(errorMessage: String) = ablyException(errorMessage, ErrorCode.BadRequest, HttpStatusCode.BadRequest)
 
 internal fun serverError(errorMessage: String) = ablyException(errorMessage, ErrorCode.InternalError, HttpStatusCode.InternalServerError)
+
+/**
+ * Calculates the byte size of a string.
+ * For non-ASCII, the byte size can be 2–4x the character count. For ASCII, there is no difference.
+ */
+internal val String.byteSize: Int
+  get() = this.toByteArray(Charsets.UTF_8).size