Use DETS to store shard & peer list to disk

1 files changed, 30 insertions, 11 deletions

diff --git a/shard/lib/identity.ex b/shard/lib/identity.ex
index f1899df..01b3c9e 100644
--- a/shard/lib/identity.ex
+++ b/shard/lib/identity.ex
@@ -3,21 +3,36 @@ defmodule Shard.Identity do
   require Salty.Sign.Ed25519, as: Sign
   require Logger
 
+  @identity_db [Application.get_env(:shard, :data_path), "identity_db"] |> Path.join |> String.to_atom
+
   def start_link(_) do
     Agent.start_link(__MODULE__, :init, [], name: __MODULE__)
   end
 
   def init() do
-    Logger.info "Generating keypair..."
-    {pk, sk} = gen_keypair(Application.get_env(:shard, :peer_id_suffix))
-    nick_suffix = pk
-                  |> binary_part(0, 3)
-                  |> Base.encode16
-                  |> String.downcase
-    %{
-      keypair:  {pk, sk},
-      nickname: "Anon" <> nick_suffix,
-    }
+    :dets.start
+    {:ok, @identity_db} = :dets.open_file @identity_db, type: :set
+
+    case :dets.match @identity_db, :"$1" do
+      [] ->
+        Logger.info "Generating keypair..."
+        {pk, sk} = gen_keypair(Application.get_env(:shard, :peer_id_suffix))
+        nick_suffix = pk
+                      |> binary_part(0, 3)
+                      |> Base.encode16
+                      |> String.downcase
+        nick = "Anon" <> nick_suffix
+        :dets.insert @identity_db, {pk, sk, nick}
+        %{
+          keypair:  {pk, sk},
+          nickname: nick
+        }
+      [[{pk, sk, nick}] | _] ->
+        %{
+          keypair:  {pk, sk},
+          nickname: nick
+        }
+    end
   end
 
   defp gen_keypair(suffix, n \\ 0) do
@@ -41,6 +56,10 @@ defmodule Shard.Identity do
   end
 
   def set_nickname(newnick) do
-    Agent.update(__MODULE__, &(%{&1 | nickname: newnick}))
+    Agent.update(__MODULE__, fn state ->
+      {pk, sk} = state.keypair
+      :dets.insert @identity_db, {pk, sk, newnick}
+      %{state | nickname: newnick}
+    end)
   end
 end