Flag for rejecting all outbound messages (#982)

* flag for rejecting all outbound messages

* update weights

* Revert "update weights"

This reverts commit 992b866edc7c9fd97013cee9cd68b9d783f8681e.

* Revert "flag for rejecting all outbound messages"

This reverts commit d094964bb4f8800ab6978b9d4b12aade2f80d266.

* OperatingMode

* Update modules/messages/src/lib.rs

Co-authored-by: Hernando Castano <HCastano@users.noreply.github.com>

* Poke CI

* RustFmt

Co-authored-by: Hernando Castano <HCastano@users.noreply.github.com>
Co-authored-by: Hernando Castano <hernando@hcastano.com>

bridges/primitives/messages/Cargo.toml

@@ -8,6 +8,7 @@ license = "GPL-3.0-or-later WITH Classpath-exception-2.0"
 
 [dependencies]
 codec = { package = "parity-scale-codec", version = "2.0.0", default-features = false, features = ["derive"] }
+serde = { version = "1.0.101", optional = true, features = ["derive"] }
 
 # Bridge dependencies
 
@@ -26,5 +27,6 @@ std = [
 	"codec/std",
 	"frame-support/std",
 	"frame-system/std",
+	"serde",
 	"sp-std/std"
 ]

bridges/primitives/messages/src/lib.rs

@@ -32,6 +32,30 @@ pub mod target_chain;
 // Weight is reexported to avoid additional frame-support dependencies in related crates.
 pub use frame_support::weights::Weight;
 
+/// Messages pallet operating mode.
+#[derive(Encode, Decode, Clone, Copy, PartialEq, Eq, RuntimeDebug)]
+#[cfg_attr(feature = "std", derive(serde::Serialize, serde::Deserialize))]
+pub enum OperatingMode {
+	/// Normal mode, when all operations are allowed.
+	Normal,
+	/// The pallet is not accepting outbound messages. Inbound messages and receival proofs
+	/// are still accepted.
+	///
+	/// This mode may be used e.g. when bridged chain expects upgrade. Then to avoid dispatch
+	/// failures, the pallet owner may stop accepting new messages, while continuing to deliver
+	/// queued messages to the bridged chain. Once upgrade is completed, the mode may be switched
+	/// back to `Normal`.
+	RejectingOutboundMessages,
+	/// The pallet is halted. All operations (except operating mode change) are prohibited.
+	Halted,
+}
+
+impl Default for OperatingMode {
+	fn default() -> Self {
+		OperatingMode::Normal
+	}
+}
+
 /// Messages pallet parameter.
 pub trait Parameter: frame_support::Parameter {
 	/// Save parameter value in the runtime storage.