Make InstantSeal Instant again (#11186)

* Make InstantSeal Instant again

* update_sealing if there are transactions in pool after impoerting a block, some line formatting

* Apply suggestions from code review

Co-Authored-By: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

* InstantSeal specific behaviour

* introduce engine.should_reseal_on_update, remove InstantSealService

* remove unused code

* add force param to update_sealing

* better docc

* even better docs

* revert code changes, doc corrections, sort dep

* code optimization

* fix test

* fix bench

ethcore/client-traits/src/lib.rs

@@ -146,10 +146,18 @@ pub trait TransactionInfo {
 /// Provides various blockchain information, like block header, chain state etc.
 pub trait BlockChain: ChainInfo + BlockInfo + TransactionInfo {}
 
+/// Do we want to force update sealing?
+#[derive(Debug, Copy, Clone, PartialEq)]
+pub enum ForceUpdateSealing {
+	/// Ideally you want to use `No` at all times as `Yes` skips `reseal_required` checks.
+	Yes,
+	/// Don't skip `reseal_required` checks
+	No
+}
 /// Client facilities used by internally sealing Engines.
 pub trait EngineClient: Sync + Send + ChainInfo {
 	/// Make a new block and seal it.
-	fn update_sealing(&self);
+	fn update_sealing(&self, force: ForceUpdateSealing);
 
 	/// Submit a seal for a block in the mining queue.
 	fn submit_seal(&self, block_hash: H256, seal: Vec<Bytes>);