Blockchain cache pruning strategy (#3395)

* blockchain cache pruning strategy

* added some internal docs to cache_pruning_strategy

* Update core/client/db/src/cache/mod.rs

Co-Authored-By: DemiMarie-parity <48690212+DemiMarie-parity@users.noreply.github.com>

substrate/core/client/src/backend.rs

@@ -25,7 +25,8 @@ use sr_primitives::{generic::BlockId, Justification, StorageOverlay, ChildrenSto
 use sr_primitives::traits::{Block as BlockT, NumberFor};
 use state_machine::backend::Backend as StateBackend;
 use state_machine::{ChangesTrieStorage as StateChangesTrieStorage, ChangesTrieTransaction};
-use consensus::{well_known_cache_keys, BlockOrigin};
+use crate::blockchain::well_known_cache_keys;
+use consensus::BlockOrigin;
 use hash_db::Hasher;
 use parking_lot::Mutex;
 

substrate/core/client/src/blockchain.rs

@@ -21,7 +21,6 @@ use std::sync::Arc;
 use sr_primitives::traits::{Block as BlockT, Header as HeaderT, NumberFor};
 use sr_primitives::generic::BlockId;
 use sr_primitives::Justification;
-use consensus::well_known_cache_keys;
 
 use crate::error::{Error, Result};
 
@@ -254,3 +253,18 @@ pub fn tree_route<Block: BlockT, F: Fn(BlockId<Block>) -> Result<<Block as Block
 		pivot,
 	})
 }
+
+/// A list of all well known keys in the blockchain cache.
+pub mod well_known_cache_keys {
+	/// The type representing cache keys.
+	pub type Id = consensus::import_queue::CacheKeyId;
+
+	/// A list of authorities.
+	pub const AUTHORITIES: Id = *b"auth";
+
+	/// Current Epoch data.
+	pub const EPOCH: Id = *b"epch";
+
+	/// Changes trie configuration.
+	pub const CHANGES_TRIE_CONFIG: Id = *b"chtr";
+}

substrate/core/client/src/client.rs

@@ -49,7 +49,6 @@ use executor::{RuntimeVersion, RuntimeInfo};
 use consensus::{
 	Error as ConsensusError, BlockImportParams,
 	ImportResult, BlockOrigin, ForkChoiceStrategy,
-	well_known_cache_keys::Id as CacheKeyId,
 	SelectChain, self,
 };
 
@@ -65,6 +64,7 @@ use crate::{
 	blockchain::{
 		self, Info as ChainInfo, Backend as ChainBackend,
 		HeaderBackend as ChainHeaderBackend, ProvideCache, Cache,
+		well_known_cache_keys::Id as CacheKeyId,
 	},
 	call_executor::{CallExecutor, LocalCallExecutor},
 	notifications::{StorageNotifications, StorageEventStream},

substrate/core/client/src/in_mem.rs

@@ -27,13 +27,12 @@ use state_machine::backend::{Backend as StateBackend, InMemory};
 use state_machine::{self, InMemoryChangesTrieStorage, ChangesTrieAnchorBlockId, ChangesTrieTransaction};
 use hash_db::{Hasher, Prefix};
 use trie::MemoryDB;
-use consensus::well_known_cache_keys::Id as CacheKeyId;
 
 use crate::error;
 use crate::backend::{self, NewBlockState, StorageCollection, ChildStorageCollection};
 use crate::light;
 use crate::leaves::LeafSet;
-use crate::blockchain::{self, BlockStatus, HeaderBackend};
+use crate::blockchain::{self, BlockStatus, HeaderBackend, well_known_cache_keys::Id as CacheKeyId};
 
 struct PendingBlock<B: BlockT> {
 	block: StoredBlock<B>,

substrate/core/client/src/lib.rs

@@ -124,6 +124,8 @@ pub use crate::notifications::{StorageEventStream, StorageChangeSet};
 pub use state_machine::ExecutionStrategy;
 #[cfg(feature = "std")]
 pub use crate::leaves::LeafSet;
+#[cfg(feature = "std")]
+pub use crate::blockchain::well_known_cache_keys;
 
 #[doc(inline)]
 pub use sr_api_macros::{decl_runtime_apis, impl_runtime_apis};

substrate/core/client/src/light/backend.rs

@@ -29,12 +29,11 @@ use crate::backend::{
 	AuxStore, Backend as ClientBackend, BlockImportOperation, RemoteBackend, NewBlockState,
 	StorageCollection, ChildStorageCollection,
 };
-use crate::blockchain::HeaderBackend as BlockchainHeaderBackend;
+use crate::blockchain::{HeaderBackend as BlockchainHeaderBackend, well_known_cache_keys};
 use crate::error::{Error as ClientError, Result as ClientResult};
 use crate::light::blockchain::{Blockchain, Storage as BlockchainStorage};
 use hash_db::Hasher;
 use trie::MemoryDB;
-use consensus::well_known_cache_keys;
 
 const IN_MEMORY_EXPECT_PROOF: &str = "InMemory state backend has Void error type and always succeeds; qed";
 

substrate/core/client/src/light/blockchain.rs

@@ -22,11 +22,13 @@ use std::{sync::Arc, collections::HashMap};
 
 use sr_primitives::{Justification, generic::BlockId};
 use sr_primitives::traits::{Block as BlockT, Header as HeaderT, NumberFor, Zero};
-use consensus::well_known_cache_keys;
 
 use crate::backend::{AuxStore, NewBlockState};
-use crate::blockchain::{Backend as BlockchainBackend, BlockStatus, Cache as BlockchainCache,
-	HeaderBackend as BlockchainHeaderBackend, Info as BlockchainInfo, ProvideCache};
+use crate::blockchain::{
+	Backend as BlockchainBackend, BlockStatus, Cache as BlockchainCache,
+	HeaderBackend as BlockchainHeaderBackend, Info as BlockchainInfo, ProvideCache,
+	well_known_cache_keys,
+};
 use crate::cht;
 use crate::error::{Error as ClientError, Result as ClientResult};
 use crate::light::fetcher::{Fetcher, RemoteHeaderRequest};