GH-77 periodic check for peers current block hash

apps/aecore/lib/aecore.ex

@@ -9,7 +9,7 @@ defmodule Aecore do
       supervisor(Aecore.Chain.Worker.Supervisor, []),
       supervisor(Aecore.Miner.Worker.Supervisor, []),
       supervisor(Aecore.Txs.Pool.Worker.Supervisor, []),
-      supervisor(Aecore.Peers.Worker, [])
+      supervisor(Aecore.Peers.Worker.Supervisor, [])
     ]
 
     Supervisor.start_link(children, strategy: :one_for_one)

apps/aecore/lib/aecore/peers/scheduler.ex

@@ -0,0 +1,26 @@
+defmodule Aecore.Peers.Scheduler do
+  use GenServer
+
+  alias Aecore.Peers.Worker, as: Peers
+
+  @check_time 60_000
+
+  def start_link do
+    GenServer.start_link(__MODULE__, %{})
+  end
+
+  def init(state) do
+    schedule_work()
+    {:ok, state}
+  end
+
+  def handle_info(:work, state) do
+    Peers.check_peers()
+    schedule_work()
+    {:noreply, state}
+  end
+
+  defp schedule_work() do
+    Process.send_after(self(), :work, @check_time)
+  end
+end

apps/aecore/lib/aecore/peers/worker.ex

@@ -10,7 +10,7 @@ defmodule Aecore.Peers.Worker do
   alias Aecore.Utils.Blockchain.BlockValidation
 
   def start_link do
-    GenServer.start_link(__MODULE__, [], name: __MODULE__)
+    GenServer.start_link(__MODULE__, %{}, name: __MODULE__)
   end
 
   def init(initial_peers) do
@@ -32,7 +32,7 @@ defmodule Aecore.Peers.Worker do
     GenServer.call(__MODULE__, :check_peers)
   end
 
-  @spec all_peers() :: list()
+  @spec all_peers() :: map()
   def all_peers() do
     GenServer.call(__MODULE__, :all_peers)
   end
@@ -45,36 +45,47 @@ defmodule Aecore.Peers.Worker do
   end
 
   def handle_call({:add_peer,uri}, _from, peers) do
-    if(!Enum.member?(peers,uri)) do
-      case(Client.get_info(uri)) do
-        {:ok, info} ->
-          if(Map.get(info,:genesis_block_hash) == genesis_block_header_hash()) do
-            {:reply, :ok, [uri | peers]}
-          else
-            {:reply, {:error, "Genesis header hash not valid"}, peers}
-          end
-        :error ->
-          {:reply, :error, peers}
-      end
-    else
-      {:reply, {:error, "Peer already in list"}, peers}
+    case(Client.get_info(uri)) do
+      {:ok, info} ->
+        if(info.genesis_block_hash == genesis_block_header_hash()) do
+          updated_peers = Map.put(peers, uri, info.current_block_hash)
+          {:reply, :ok, updated_peers}
+        else
+          {:reply, {:error, "Genesis header hash not valid"}, peers}
+        end
+      :error ->
+        {:reply, :error, peers}
     end
   end
 
   def handle_call({:remove_peer, uri}, _from, peers) do
-    if(Enum.member?(peers,uri)) do
-      {:reply, :ok, List.delete(peers, uri)}
+    if(Map.has_key?(peers, uri)) do
+      {:reply, :ok, Map.delete(peers, uri)}
     else
       {:reply, {:error, "Peer not found"}, peers}
     end
   end
 
+  @doc """
+  Filters the peers map by checking if the response status from a GET /info
+  request is :ok and if the genesis block hash is the same as the one
+  in the current node. After that the current block hash for every peer
+  is updated if the one in the latest GET /info request is different.
+  """
   def handle_call(:check_peers, _from, peers) do
-    updated_peers = Enum.filter(peers, fn(peer) ->
-      {status, info} = Client.get_info(peer)
-      :ok == status &&
-        Map.get(info, :genesis_block_hash) == genesis_block_header_hash()
-      end)
+    filtered_peers = :maps.filter(fn(peer, _) ->
+        {status, info} = Client.get_info(peer)
+        :ok == status && info.genesis_block_hash == genesis_block_header_hash()
+      end, peers)
+    updated_peers =
+      for {peer, current_block_hash} <- filtered_peers, into: %{} do
+        {_, info} = Client.get_info(peer)
+        if(info.current_block_hash != current_block_hash) do
+          {peer, info.current_block_hash}
+        else
+          {peer, current_block_hash}
+        end
+      end
     {:reply, :ok, updated_peers}
   end
 

apps/aecore/lib/aecore/peers/worker/supervisor.ex

@@ -1,4 +1,4 @@
-defmodule Aecore.Peers.Supervisor do
+defmodule Aecore.Peers.Worker.Supervisor do
   use Supervisor
 
   def start_link() do
@@ -7,7 +7,8 @@ defmodule Aecore.Peers.Supervisor do
 
   def init(:ok) do
     children = [
-      worker(Aecore.Peers.Worker, [])
+      worker(Aecore.Peers.Worker, []),
+      worker(Aecore.Peers.Scheduler, [])
     ]
 
     supervise(children, strategy: :one_for_one)

apps/aecore/lib/aecore/utils/blockchain/block_validation.ex

@@ -7,7 +7,6 @@ defmodule Aecore.Utils.Blockchain.BlockValidation do
   alias Aecore.Structures.Header
   alias Aecore.Structures.SignedTx
   alias Aecore.Chain.ChainState
-  alias Aecore.Chain.Worker, as: Chain
 
   @spec validate_block!(Block.block(), Block.block(), map()) :: {:error, term()} | :ok
   def validate_block!(new_block, previous_block, chain_state) do

apps/aecore/test/aecore_peers_test.exs

@@ -11,7 +11,7 @@ defmodule AecorePeersTest do
 
   test "add peer, get all peers, check peers and remove the peer" do
     assert :ok = Peers.add_peer("localhost:4000")
-    assert {:error, "Peer already in list"} = Peers.add_peer("localhost:4000")
+    Peers.add_peer("localhost:4000")
     assert Enum.count(Peers.all_peers) == 1
     assert :ok = Peers.check_peers
     assert :ok = Peers.remove_peer("localhost:4000")