chore: Set default maximum number of canisters

rs/config/src/execution_environment.rs

@@ -170,6 +170,9 @@ pub const MAX_COMPILATION_CACHE_SIZE: NumBytes = NumBytes::new(10 * GIB);
 /// Maximum number of controllers allowed in a request (specified in the interface spec).
 pub const MAX_ALLOWED_CONTROLLERS_COUNT: usize = 10;
 
+/// Default maximum number of canisters per subnet if not set in the registry.
+pub const DEFAULT_MAX_NUMBER_OF_CANISTERS: u64 = 120_000;
+
 /// Maximum number of canister snapshots that can be stored for a single canister.
 pub const MAX_NUMBER_OF_SNAPSHOTS_PER_CANISTER: usize = 10;
 

rs/messaging/src/message_routing.rs

@@ -1,6 +1,8 @@
 use crate::state_machine::{StateMachine, StateMachineImpl};
 use crate::{routing, scheduling};
-use ic_config::execution_environment::{BitcoinConfig, Config as HypervisorConfig};
+use ic_config::execution_environment::{
+    BitcoinConfig, Config as HypervisorConfig, DEFAULT_MAX_NUMBER_OF_CANISTERS,
+};
 use ic_config::message_routing::{MAX_STREAM_MESSAGES, TARGET_STREAM_SIZE_BYTES};
 use ic_cycles_account_manager::CyclesAccountManager;
 use ic_interfaces::execution_environment::{
@@ -869,7 +871,11 @@ impl<RegistryClient_: RegistryClient> BatchProcessorImpl<RegistryClient_> {
         let node_public_keys = self.try_to_populate_node_public_keys(&nodes, registry_version)?;
 
         let subnet_features = subnet_record.features.unwrap_or_default().into();
-        let max_number_of_canisters = subnet_record.max_number_of_canisters;
+        let max_number_of_canisters = if subnet_record.max_number_of_canisters == 0 {
+            DEFAULT_MAX_NUMBER_OF_CANISTERS
+        } else {
+            subnet_record.max_number_of_canisters
+        };
 
         let chain_key_settings = if let Some(chain_key_config) = subnet_record.chain_key_config {
             let chain_key_config = ChainKeyConfig::try_from(chain_key_config).map_err(|err| {

rs/protobuf/def/registry/subnet/v1/subnet.proto

@@ -49,8 +49,7 @@ message SubnetRecord {
 
   // The maximum number of canisters that may be present on the subnet at any given time.
   //
-  // A value of 0 is equivalent to setting no limit. This also provides an easy way
-  // to maintain compatibility of different versions of replica and registry.
+  // A value of 0 means that the replica's default value will be used.
   uint64 max_number_of_canisters = 24;
 
   // The list of public keys whose owners have "readonly" SSH access to all replicas on this subnet,

rs/protobuf/src/gen/registry/registry.subnet.v1.rs

@@ -45,8 +45,7 @@ pub struct SubnetRecord {
     pub features: ::core::option::Option<SubnetFeatures>,
     /// The maximum number of canisters that may be present on the subnet at any given time.
     ///
-    /// A value of 0 is equivalent to setting no limit. This also provides an easy way
-    /// to maintain compatibility of different versions of replica and registry.
+    /// A value of 0 means that the replica's default value will be used.
     #[prost(uint64, tag = "24")]
     pub max_number_of_canisters: u64,
     /// The list of public keys whose owners have "readonly" SSH access to all replicas on this subnet,

rs/protobuf/src/gen/state/registry.subnet.v1.rs

@@ -45,8 +45,7 @@ pub struct SubnetRecord {
     pub features: ::core::option::Option<SubnetFeatures>,
     /// The maximum number of canisters that may be present on the subnet at any given time.
     ///
-    /// A value of 0 is equivalent to setting no limit. This also provides an easy way
-    /// to maintain compatibility of different versions of replica and registry.
+    /// A value of 0 means that the replica's default value will be used.
     #[prost(uint64, tag = "24")]
     pub max_number_of_canisters: u64,
     /// The list of public keys whose owners have "readonly" SSH access to all replicas on this subnet,

rs/protobuf/src/gen/types/registry.subnet.v1.rs

@@ -45,8 +45,7 @@ pub struct SubnetRecord {
     pub features: ::core::option::Option<SubnetFeatures>,
     /// The maximum number of canisters that may be present on the subnet at any given time.
     ///
-    /// A value of 0 is equivalent to setting no limit. This also provides an easy way
-    /// to maintain compatibility of different versions of replica and registry.
+    /// A value of 0 means that the replica's default value will be used.
     #[prost(uint64, tag = "24")]
     pub max_number_of_canisters: u64,
     /// The list of public keys whose owners have "readonly" SSH access to all replicas on this subnet,