Cache representative keys to optimize wallets::foreach_representative (...) hot path (nanocurrency#5060)

* Cache representative keys for voting

Store unlocked representative keys in a cache so
`foreach_representative` can iterate preloaded keys instead of
walking wallet state and fetching them on every call.

Refresh the cache when representative membership or wallet lock
state changes, use `wallet::lock()` in the RPC handler, and remove
the recursive representative iteration test since recursion is no
longer supported.

* Rename compute_reps to refresh_reps

* Wallet rep key cache tests

* Refresh rep cache after wallet write txns

Move representative cache rebuilds out of active write transaction
scopes for unlock, rekey, seed, and deterministic wallet updates.

Author: pwojcikdev

nano/core_test/vote_generator.cpp

@@ -681,7 +681,7 @@ TEST (vote_generator, multiple_representatives)
 	wallet.insert_adhoc (rep1.prv);
 	wallet.insert_adhoc (rep2.prv);
 	wallet.insert_adhoc (rep3.prv);
-	node.wallets.compute_reps ();
+	node.wallets.refresh_reps ();
 	ASSERT_EQ (4, node.wallets.reps ().voting);
 
 	nano::shared_locked<std::vector<std::shared_ptr<nano::vote>>> votes;

nano/core_test/vote_replier.cpp

@@ -117,7 +117,7 @@ TEST (vote_replier, single_hash_reply)
 	config.enable_voting = true;
 	auto & node = *system.add_node (config);
 	system.wallet (0)->insert_adhoc (nano::dev::genesis_key.prv);
-	node.wallets.compute_reps ();
+	node.wallets.refresh_reps ();
 
 	auto blocks = nano::test::setup_chain (system, node, 1);
 
@@ -145,7 +145,7 @@ TEST (vote_replier, multiple_hashes_reply)
 	config.enable_voting = true;
 	auto & node = *system.add_node (config);
 	system.wallet (0)->insert_adhoc (nano::dev::genesis_key.prv);
-	node.wallets.compute_reps ();
+	node.wallets.refresh_reps ();
 
 	auto blocks = nano::test::setup_chain (system, node, 3);
 
@@ -182,7 +182,7 @@ TEST (vote_replier, mixed_known_unknown)
 	config.enable_voting = true;
 	auto & node = *system.add_node (config);
 	system.wallet (0)->insert_adhoc (nano::dev::genesis_key.prv);
-	node.wallets.compute_reps ();
+	node.wallets.refresh_reps ();
 
 	auto blocks = nano::test::setup_chain (system, node, 1);
 
@@ -248,7 +248,7 @@ TEST (vote_replier, per_channel_fairness)
 	config.vote_replier.channel_limit = 1;
 	auto & node = *system.add_node (config);
 	system.wallet (0)->insert_adhoc (nano::dev::genesis_key.prv);
-	node.wallets.compute_reps ();
+	node.wallets.refresh_reps ();
 
 	auto blocks = nano::test::setup_chain (system, node, 1);
 
@@ -281,7 +281,7 @@ TEST (vote_replier, integration_confirm_req)
 	config.optimistic_scheduler.enable = false;
 	auto & node = *system.add_node (config);
 	system.wallet (0)->insert_adhoc (nano::dev::genesis_key.prv);
-	node.wallets.compute_reps ();
+	node.wallets.refresh_reps ();
 
 	// Create and confirm a block
 	nano::keypair key;
@@ -528,7 +528,7 @@ TEST (vote_replier, multiple_representatives)
 	ASSERT_TIMELY (5s, node.balance (rep2.pub) == amount);
 	wallet.change_sync (rep2.pub, rep2.pub);
 	ASSERT_EQ (node.weight (rep2.pub), amount);
-	node.wallets.compute_reps ();
+	node.wallets.refresh_reps ();
 	ASSERT_EQ (2, node.wallets.reps ().voting);
 
 	auto blocks = nano::test::setup_chain (system, node, 1);

nano/core_test/wallet.cpp

@@ -995,28 +995,6 @@ TEST (wallet, epoch_2_receive_unopened)
 	ASSERT_LT (tries, max_tries);
 }
 
-/**
- * This test checks that wallets::foreach_representative can be used recursively
- */
-TEST (wallet, foreach_representative_deadlock)
-{
-	nano::test::system system (1);
-	auto & node (*system.nodes[0]);
-	system.wallet (0)->insert_adhoc (nano::dev::genesis_key.prv);
-	node.wallets.compute_reps ();
-	ASSERT_EQ (1, node.wallets.reps ().voting);
-
-	bool set = false;
-	node.wallets.foreach_representative ([&node, &set, &system] (nano::public_key const & pub, nano::raw_key const & prv) {
-		node.wallets.foreach_representative ([&node, &set, &system] (nano::public_key const & pub, nano::raw_key const & prv) {
-			ASSERT_TIMELY (5s, node.wallets.mutex.try_lock () == 1);
-			node.wallets.mutex.unlock ();
-			set = true;
-		});
-	});
-	ASSERT_TRUE (set);
-}
-
 TEST (wallet, search_receivable)
 {
 	nano::test::system system;