Change default memory allocation policy and size of the queue (#1751)

* Lazy allocation of batches in transmission pipeline

* Add config support for lazy allocation of tx batches

* Fix typos

* Properly consider config parameters

* Limit allocation when really needed

* Remove unnecessary println

* Default to 1 RX buffer

* Change default memory allocation policy and size of queue

Author: Mallets

DEFAULT_CONFIG.json5

@@ -440,14 +440,14 @@
           /// then amount of memory being allocated for each queue is SIZE_XXX * LINK_MTU.
           /// If qos is false, then only the DATA priority will be allocated.
           size: {
-            control: 1,
-            real_time: 1,
-            interactive_high: 1,
-            interactive_low: 1,
+            control: 2,
+            real_time: 2,
+            interactive_high: 2,
+            interactive_low: 2,
             data_high: 2,
-            data: 4,
-            data_low: 4,
-            background: 4,
+            data: 2,
+            data_low: 2,
+            background: 2,
           },
           /// Congestion occurs when the queue is empty (no available batch).
           congestion_control: {
@@ -479,7 +479,7 @@
             /// Mode for memory allocation of batches in the priority queues. 
             /// - "init": batches are allocated at queue initialization time. 
             /// - "lazy": batches are allocated when needed up to the maximum number of batches configured in the size configuration parameter.
-            mode: "init",
+            mode: "lazy",
           },
         },
       },

commons/zenoh-config/src/defaults.rs

@@ -256,14 +256,14 @@ impl QueueSizeConf {
 impl Default for QueueSizeConf {
     fn default() -> Self {
         Self {
-            control: 1,
-            real_time: 1,
-            interactive_low: 1,
-            interactive_high: 1,
+            control: 2,
+            real_time: 2,
+            interactive_low: 2,
+            interactive_high: 2,
             data_high: 2,
-            data: 4,
+            data: 2,
             data_low: 2,
-            background: 1,
+            background: 2,
         }
     }
 }

commons/zenoh-config/src/lib.rs

@@ -629,8 +629,8 @@ validated_struct::validator! {
 #[derive(Default, Debug, Clone, Copy, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
 #[serde(rename_all = "snake_case")]
 pub enum QueueAllocMode {
-    #[default]
     Init,
+    #[default]
     Lazy,
 }