best_containing operations (issue 603) (#740)

* add stub for Client.best_chain_containing_block_hash

* add fn blockchain::Backend::leaf_hashes

* fix typo

* sketch out Client.best_chain_containing_block_hash

* fix indent

* Blockchain.leaf_hashes -> Blockchain.leaves

* add unimplemented! stub impls for Blockchain.leaves

* start impl of Blockchain.leaves for in-memory client db

* Client.best_chain_containing...: check canonical first and make compile

* first rough attempt at maintaining leaf list in in-memory db

* fix tab indent

* add test best_chain_containing_single_block

* add failing test best_chain_containing_with_fork

* pub use client::blockchain; in test-client to prevent circular dep in client tests

* best_chain_containing_with_single_block: improve and test leaves

* far improve in-memory Backend::leaves impl

* test blockchain::Backend::leaves more thoroughly

* handle more edge cases in blockchain::Backend::leaves impl for in memory

* fix test best_chain_containing_with_fork (two distinct test blocks had same hash)

* make best_chain_containing_block_hash pass existing tests

* improve docstring for Blockchain::leaves

* Client.best_chain_containing: some cleanup. support max_block_number

* best_chain_containing: remove broken outcommented fast check for best = canonical

* remove blank line

* best_block_containing: return None if target_hash not found

* best_chain_containing: add unreachable! at end of function

* improve tests for best_chain_containing

* renames

* more elaborate test scenario for best_containing

* best_containing: fix restriction of search through maybe_max_number

* best_containing: tests for restriction of search

* get rid of unnecessary clones

* replace Client::new_in_mem by new_with_backend which is useful for testing backends

* add test_client::new_with_backend for testing different backend impls

* add test for in_mem::Backend::leaves

* remove unused imports

* in_mem test_leaves: simplify

* flesh out tests for in_mem leaves impl

* remove tests for leaves from client which are now covered in implementing module

* improve comment

* add Client.new_in_mem again

* unwrap in test_client::new_with_backend

* make test_client::BlockBuilderExt work not just with in-mem backend

* make test client ext not just work with in mem backend

* add failing Backend.leaves test for client-db

* update Cargo.lock

* replace KeccakHasher with Blake2Hasher

* refactor

address grumble https://github.com/paritytech/substrate/pull/740#discussion_r217822862

* refactor using NumberFor

address grumble https://github.com/paritytech/substrate/pull/740#discussion_r217823341

* add test that exposes possible problem

* update docstring for Client.best_containing

* extract test for Backend.leaves for reuse

* improve test blockchain_header_and_hash_return_blocks_from_canonical_chain_given_block_numbers

* extract test_blockchain_query_by_number_gets_canonical to easily test multiple impls

* remove whitespace

* remove todo

* Client.best_containing: pre-empt search loop when target in canonical

* best_containing: prevent race condition by holding import lock

* add todo

* extract leaf list update code into function

* add comment

* client-db: use in-memory-kvdb for tests

* use BTreeSet to store leaves for in-mem which is faster and simpler

* add docstring

* add comments and fix formatting

* add initial raw version of LeafSet

* remove Client::update_leaves which has been superceded by LeafSet

* use LeafSet in in-mem backend

* keccak -> blake2

* don't reexport codec traits in primitives

addresses https://github.com/paritytech/substrate/pull/740#discussion_r219538185

* fix rebase mistake

* improve LeafSet and use it in state-db

* correct Transfer nonces to fix ApplyExtinsicFailed(Stale)

* use given backend in canoncal test

* kill dead tree-route code in util

* fix warnings

* tests for leafset

* reorganizations in in_mem backend

* fix reorganization canon block logic

* DB commit and safe reversion on write error

* fix style nits

substrate/core/test-client/src/client_ext.rs

@@ -18,18 +18,13 @@
 
 use client::{self, Client};
 use keyring::Keyring;
-use runtime_primitives::{generic::BlockId, StorageMap};
-use runtime::genesismap::{GenesisConfig, additional_storage_with_genesis};
-use executor::NativeExecutor;
+use runtime_primitives::generic::BlockId;
+use primitives::Blake2Hasher;
 use runtime;
 use bft;
-use {Backend, Executor};
 
 /// Extension trait for a test client.
 pub trait TestClient {
-	/// Crates new client instance for tests.
-	fn new_for_tests() -> Self;
-
 	/// Justify and import block to the chain. No finality.
 	fn justify_and_import(&self, origin: client::BlockOrigin, block: runtime::Block) -> client::error::Result<()>;
 
@@ -40,11 +35,11 @@ pub trait TestClient {
 	fn genesis_hash(&self) -> runtime::Hash;
 }
 
-impl TestClient for Client<Backend, Executor, runtime::Block> {
-	fn new_for_tests() -> Self {
-		client::new_in_mem(NativeExecutor::new(), genesis_storage()).unwrap()
-	}
-
+impl<B, E> TestClient for Client<B, E, runtime::Block>
+    where
+        B: client::backend::Backend<runtime::Block, Blake2Hasher>,
+        E: client::CallExecutor<runtime::Block, Blake2Hasher>
+{
 	fn justify_and_import(&self, origin: client::BlockOrigin, block: runtime::Block) -> client::error::Result<()> {
 		let justification = fake_justify(&block.header);
 		let justified = self.check_justification(block.header, justification)?;
@@ -93,18 +88,3 @@ fn fake_justify(header: &runtime::Header) -> bft::UncheckedJustification<runtime
 		1,
 	)
 }
-
-fn genesis_config() -> GenesisConfig {
-	GenesisConfig::new_simple(vec![
-		Keyring::Alice.to_raw_public().into(),
-		Keyring::Bob.to_raw_public().into(),
-		Keyring::Charlie.to_raw_public().into(),
-	], 1000)
-}
-
-fn genesis_storage() -> StorageMap {
-		let mut storage = genesis_config().genesis_map();
-		let block: runtime::Block = client::genesis::construct_genesis_block(&storage);
-		storage.extend(additional_storage_with_genesis(&block));
-		storage
-}