fix POSDAO snapshotting and remove temporary code

.dialyzer-ignore

@@ -25,4 +25,4 @@ lib/explorer/exchange_rates/source.ex:113
 lib/explorer/smart_contract/verifier.ex:89
 lib/block_scout_web/templates/address_contract/index.html.eex:118
 lib/explorer/staking/stake_snapshotting.ex:15: Function do_snapshotting/7 has no local return
-lib/explorer/staking/stake_snapshotting.ex:216
+lib/explorer/staking/stake_snapshotting.ex:207

apps/explorer/lib/explorer/staking/contract_reader.ex

@@ -46,18 +46,10 @@ defmodule Explorer.Staking.ContractReader do
     ]
   end
 
-  def active_delegators_request(pool_id, block_number, new_signatures) do
-    pool_delegators_signature =
-      if new_signatures do
-        # 561c4c81 = keccak256(poolDelegators(uint256))
-        "561c4c81"
-      else
-        # 9ea8082b = keccak256(poolDelegators(address))
-        "9ea8082b"
-      end
-
+  def active_delegators_request(pool_id, block_number) do
     [
-      active_delegators: {:staking, pool_delegators_signature, [pool_id], block_number}
+      # 561c4c81 = keccak256(poolDelegators(uint256))
+      active_delegators: {:staking, "561c4c81", [pool_id], block_number}
     ]
   end
 
@@ -387,7 +379,7 @@ defmodule Explorer.Staking.ContractReader do
 
   def pool_staking_requests(pool_id, block_number) do
     [
-      active_delegators: active_delegators_request(pool_id, block_number, true)[:active_delegators],
+      active_delegators: active_delegators_request(pool_id, block_number)[:active_delegators],
       # a1fc2753 = keccak256(poolDelegatorsInactive(uint256))
       inactive_delegators: {:staking, "a1fc2753", [pool_id], block_number},
       # bbbaf8c8 = keccak256(isPoolActive(uint256))
@@ -509,6 +501,34 @@ defmodule Explorer.Staking.ContractReader do
     |> parse_grouped_responses(keys, requests)
   end
 
+  def get_contract_events(contract_address, from_block, to_block, event_hash) do
+    json_rpc_named_arguments = Application.get_env(:explorer, :json_rpc_named_arguments)
+
+    result =
+      %{
+        id: 0,
+        method: "eth_getLogs",
+        params: [
+          %{
+            fromBlock: "0x" <> Integer.to_string(from_block, 16),
+            toBlock: "0x" <> Integer.to_string(to_block, 16),
+            address: contract_address,
+            topics: [event_hash]
+          }
+        ]
+      }
+      |> EthereumJSONRPC.request()
+      |> EthereumJSONRPC.json_rpc(json_rpc_named_arguments)
+
+    case result do
+      {:ok, events} ->
+        events
+
+      {:error, _reason} ->
+        []
+    end
+  end
+
   defp address_pad_to_64(address) do
     address
     |> String.replace_leading("0x", "")

apps/explorer/lib/explorer/staking/contract_state.ex

@@ -31,6 +31,7 @@ defmodule Explorer.Staking.ContractState do
     :pool_rewards,
     :seen_block,
     :snapshotted_epoch_number,
+    :snapshotting_scheduled,
     :staking_allowed,
     :staking_contract,
     :token_contract,
@@ -136,6 +137,7 @@ defmodule Explorer.Staking.ContractState do
       pool_rewards: %{},
       seen_block: 0,
       snapshotted_epoch_number: -1,
+      snapshotting_scheduled: false,
       staking_contract: %{abi: staking_abi, address: staking_contract_address},
       token_contract: %{abi: token_abi, address: token_contract_address},
       token: get_token(token_contract_address),
@@ -231,7 +233,7 @@ defmodule Explorer.Staking.ContractState do
 
     epoch_very_beginning = global_responses.epoch_start_block == block_number + 1
 
-    start_snapshotting = start_snapshotting?(global_responses)
+    start_snapshotting = start_snapshotting?(global_responses, state, block_number)
 
     # determine if something changed in contracts state since the previous seen block.
     # if something changed or the `fetch_state` function is called for the first time
@@ -348,9 +350,62 @@ defmodule Explorer.Staking.ContractState do
     end
   end
 
-  defp start_snapshotting?(global_responses) do
-    global_responses.epoch_number > get(:snapshotted_epoch_number) && global_responses.epoch_number > 0 &&
-      not get(:is_snapshotting)
+  defp start_snapshotting?(global_responses, state, block_number) do
+    if global_responses.epoch_number == 0 do
+      # we never snapshot at initial staking epoch
+      false
+    else
+      already_snapshotting = get(:is_snapshotting)
+
+      start =
+        (global_responses.epoch_number > get(:snapshotted_epoch_number) or get(:snapshotting_scheduled)) and
+          not already_snapshotting
+
+      if start do
+        :ets.insert(@table_name, snapshotting_scheduled: false)
+        true
+      else
+        # check for ChangedMiningAddress and ChangedStakingAddress events
+        # from the ValidatorSetAuRa contract: if one of these events
+        # emitted, we need to do snapshotting
+        seen_block = get(:seen_block, 0)
+
+        from_block =
+          if seen_block > 0 do
+            seen_block + 1
+          else
+            block_number
+          end
+
+        change_pool_address_events =
+          ContractReader.get_contract_events(
+            state.contracts.validator_set,
+            from_block,
+            block_number,
+            [
+              # keccak-256 of `ChangedMiningAddress(uint256,address,address)`
+              "0xad4c947995a3daa512a7371d31325a21227249f8dc1c52c1a4c6fe8475a3ebb1",
+              # keccak-256 of `ChangedStakingAddress(uint256,address,address)`
+              "0x5c44164828293bba0353472e907f7ee26a8659f916e6311fe826a7c70510e352"
+            ]
+          )
+
+        if Enum.count(change_pool_address_events) > 0 do
+          # we see at least one of the events, so start snapshotting
+          if already_snapshotting do
+            # since the snapshotting procedure is already in progress,
+            # we schedule snapshotting restart after the current
+            # procedure is finished
+            :ets.insert(@table_name, snapshotting_scheduled: true)
+            false
+          else
+            true
+          end
+        else
+          false
+        end
+      end
+    end
   end
 
   defp update_database(

apps/explorer/lib/explorer/staking/stake_snapshotting.ex

@@ -21,12 +21,6 @@ defmodule Explorer.Staking.StakeSnapshotting do
         mining_address_to_id,
         block_number
       ) do
-    # temporary code (should be removed after staking epoch #48 on xDai is finished).
-    # this is a block number from which POSDAO on xDai chain started to use other signatures
-    # in the StakingAuRa contract
-    {:ok, net_version} = EthereumJSONRPC.fetch_net_version(Application.get_env(:explorer, :json_rpc_named_arguments))
-    new_signatures = (net_version == 100 and block_number > 14_994_040) or net_version != 100
-
     # get pool ids and staking addresses for the pending validators
     pool_ids =
       pools_mining_addresses
@@ -46,8 +40,6 @@ defmodule Explorer.Staking.StakeSnapshotting do
       |> Enum.zip(pool_staking_addresses)
       |> Map.new()
 
-    abi = abi_clarify_signatures(abi, new_signatures)
-
     # get snapshotted amounts and active delegator list for the pool for each
     # pending validator by their pool id.
     # use `cached_pool_staking_responses` when possible
@@ -59,7 +51,7 @@ defmodule Explorer.Staking.StakeSnapshotting do
             Map.merge(
               resp,
               ContractReader.perform_requests(
-                snapshotted_pool_amounts_requests(pool_id, resp.staking_address_hash, block_number, new_signatures),
+                snapshotted_pool_amounts_requests(pool_id, resp.staking_address_hash, block_number),
                 contracts,
                 abi
               )
@@ -73,8 +65,8 @@ defmodule Explorer.Staking.StakeSnapshotting do
                 staking_address_hash: pool_staking_address
               },
               ContractReader.perform_requests(
-                ContractReader.active_delegators_request(pool_id, block_number, new_signatures) ++
-                  snapshotted_pool_amounts_requests(pool_id, pool_staking_address, block_number, new_signatures),
+                ContractReader.active_delegators_request(pool_id, block_number) ++
+                  snapshotted_pool_amounts_requests(pool_id, pool_staking_address, block_number),
                 contracts,
                 abi
               )
@@ -101,8 +93,7 @@ defmodule Explorer.Staking.StakeSnapshotting do
             pool_id,
             pool_staking_address,
             staker_address,
-            block_number,
-            new_signatures
+            block_number
           ),
           contracts,
           abi
@@ -231,42 +222,23 @@ defmodule Explorer.Staking.StakeSnapshotting do
     Publisher.broadcast(:stake_snapshotting_finished)
   end
 
-  defp abi_clarify_signatures(abi, new_signatures) do
-    if new_signatures do
-      abi
-    else
-      Jason.decode!(
-        ~s([{"constant":true,"inputs":[{"name":"","type":"address"}],"name":"stakeAmountTotal","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"","type":"address"},{"name":"","type":"address"}],"name":"stakeAmount","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"","type":"address"}],"name":"poolDelegators","outputs":[{"name":"","type":"address[]"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"","type":"uint256"},{"name":"","type":"uint256"},{"name":"","type":"uint256"},{"name":"","type":"uint256"}],"name":"validatorShare","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"","type":"uint256"},{"name":"","type":"uint256"},{"name":"","type":"uint256"},{"name":"","type":"uint256"},{"name":"","type":"uint256"}],"name":"delegatorShare","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"}])
-      )
-    end
-  end
-
   defp address_bytes_to_string(hash), do: "0x" <> Base.encode16(hash, case: :lower)
 
-  defp snapshotted_pool_amounts_requests(pool_id, pool_staking_address, block_number, new_signatures) do
-    stake_amount_total_signature =
-      if new_signatures do
-        # keccak256(stakeAmountTotal(uint256))
-        "2a8f6ecd"
-      else
-        # keccak256(stakeAmountTotal(address))
-        "5267e1d6"
-      end
-
+  defp snapshotted_pool_amounts_requests(pool_id, pool_staking_address, block_number) do
     [
-      snapshotted_total_staked_amount: {:staking, stake_amount_total_signature, [pool_id], block_number},
+      # 2a8f6ecd = keccak256(stakeAmountTotal(uint256))
+      snapshotted_total_staked_amount: {:staking, "2a8f6ecd", [pool_id], block_number},
       snapshotted_self_staked_amount:
         snapshotted_staker_amount_request(
           pool_id,
           pool_staking_address,
           pool_staking_address,
-          block_number,
-          new_signatures
+          block_number
         )[:snapshotted_stake_amount]
     ]
   end
 
-  defp snapshotted_staker_amount_request(pool_id, pool_staking_address, staker_address, block_number, new_signatures) do
+  defp snapshotted_staker_amount_request(pool_id, pool_staking_address, staker_address, block_number) do
     delegator_or_zero =
       if staker_address == pool_staking_address do
         "0x0000000000000000000000000000000000000000"
@@ -274,17 +246,9 @@ defmodule Explorer.Staking.StakeSnapshotting do
         staker_address
       end
 
-    stake_amount_signature =
-      if new_signatures do
-        # keccak256(stakeAmount(uint256,address))
-        "3fb1a1e4"
-      else
-        # keccak256(stakeAmount(address,address))
-        "a697ecff"
-      end
-
     [
-      snapshotted_stake_amount: {:staking, stake_amount_signature, [pool_id, delegator_or_zero], block_number}
+      # 3fb1a1e4 = keccak256(stakeAmount(uint256,address))
+      snapshotted_stake_amount: {:staking, "3fb1a1e4", [pool_id, delegator_or_zero], block_number}
     ]
   end