Decrease number of GRANDPA authorities in Polkadot-like chains from 1…

…00_000 to 2_048 (paritytech#1852)

* decrease number of GRANDPA authorities in Polkadot-like chains from 100_000 to 2048

* spelling

bridges/primitives/chain-rococo/src/lib.rs

@@ -42,9 +42,4 @@ pub const WITH_ROCOCO_GRANDPA_PALLET_NAME: &str = "BridgeRococoGrandpa";
 /// reserve.
 pub const MAX_NESTED_PARACHAIN_HEAD_DATA_SIZE: u32 = 128;
 
-/// Maximal number of GRANDPA authorities at Rococo.
-///
-/// Corresponds to the `MaxAuthorities` constant value from the Rococo runtime configuration.
-pub const MAX_AUTHORITIES_COUNT: u32 = 100_000;
-
 decl_bridge_finality_runtime_apis!(rococo);

bridges/primitives/chain-westend/src/lib.rs

@@ -63,11 +63,6 @@ pub const WITH_WESTEND_GRANDPA_PALLET_NAME: &str = "BridgeWestendGrandpa";
 /// Name of the With-Westend parachains bridge pallet instance that is deployed at bridged chains.
 pub const WITH_WESTEND_BRIDGE_PARAS_PALLET_NAME: &str = "BridgeWestendParachains";
 
-/// Maximal number of GRANDPA authorities at Westend.
-///
-/// Corresponds to the `MaxAuthorities` constant value from the Westend runtime configuration.
-pub const MAX_AUTHORITIES_COUNT: u32 = 100_000;
-
 /// Maximal SCALE-encoded size of parachains headers that are stored at Westend `Paras` pallet.
 ///
 /// It includes the block number and state root, so it shall be near 40 bytes, but let's have some

bridges/primitives/polkadot-core/src/lib.rs

@@ -43,6 +43,16 @@ pub use sp_runtime::{traits::Convert, Perbill};
 
 pub mod parachains;
 
+/// Maximal number of GRANDPA authorities at Polkadot-like chains.
+///
+/// Ideally, we would set it to the value of `MaxAuthorities` constant from bridged runtime
+/// configurations. But right now it is set to the `100_000`, which makes PoV size for
+/// our bridge hub parachains huge. So let's stick to the real-world value here.
+///
+/// Right now both Kusama and Polkadot aim to have around 1000 validators. Let's be safe here and
+/// take twice as much here.
+pub const MAX_AUTHORITIES_COUNT: u32 = 2_048;
+
 /// Number of extra bytes (excluding size of storage value itself) of storage proof, built at
 /// Polkadot-like chain. This mostly depends on number of entries in the storage trie.
 /// Some reserve is reserved to account future chain growth.