Basic infrastructure for dependency between shards

1 files changed, 168 insertions, 0 deletions

diff --git a/shard/lib/app/directory.ex b/shard/lib/app/directory.ex
new file mode 100644
index 0000000..f7d871a
--- /dev/null
+++ b/shard/lib/app/directory.ex
@@ -0,0 +1,168 @@
+defmodule SApp.Directory do
+  @moduledoc"""
+  Shard application for a directory of other shards.
+
+  TODO: use MST for file list instead of plain list
+  """
+
+  use GenServer
+
+  require Logger
+
+  defmodule Manifest do
+    @moduledoc"""
+    Manifest for a directory. This directory is owned by a user,
+    has a name, and can be either public or private.
+    """
+
+    defstruct [:owner, :public, :name]
+
+    defimpl Shard.Manifest do
+      def module(_m), do: SApp.Directory
+    end
+  end
+
+  def start_link(manifest) do
+    GenServer.start_link(__MODULE__, manifest)
+  end
+
+  def init(manifest) do
+    %Manifest{owner: owner, public: public, name: name} = manifest
+    id = SData.term_hash manifest
+
+    Shard.Manager.dispatch_to(id, nil, self())
+    files = case Shard.Manager.load_state(id) do
+      nil ->
+        SData.SignRev.new %{}
+      st -> st
+    end
+    netgroup = case public do
+      true -> %SNet.PubShardGroup{id: id}
+      false -> %SNet.PrivGroup{pk_list: [owner]}
+    end
+    SNet.Group.init_lookup(netgroup, self())
+
+    {:ok, %{
+      owner: owner, public: public, name: name,
+      manifest: manifest, id: id, netgroup: netgroup,
+      files: files}}
+  end
+
+  def handle_call(:manifest, _from, state) do
+    {:reply, state.manifest, state}
+  end
+
+  def handle_call(:get_files, _from, state) do
+    {:reply, SData.SignRev.get(state.files), state}
+  end
+
+  def handle_call({:add_file, name, manifest}, _from, state) do
+    if Shard.Keys.have_sk?(state.owner) do
+      dict = SData.SignRev.get(state.files)
+      if dict[name] != nil and dict[name] != manifest do
+        {:reply, :exists_already, state}
+      else
+        dict = Map.put(dict, name, manifest)
+        GenServer.cast(Shard.Manager, {:dep_list, state.id, Map.values(dict)})
+        {:ok, st2} = SData.SignRev.set(state.files, dict, state.owner)
+        Shard.Manager.save_state(state.id, st2)
+        state = put_in(state.files, st2)
+        bcast_state(state)
+        {:reply, :ok, state}
+      end
+    else
+      {:reply, :impossible, state}
+    end
+  end
+
+  def handle_call({:rm_file, name}, _from, state) do
+    if Shard.Keys.have_sk?(state.owner) do
+      dict = SData.SignRev.get(state.files)
+      if dict[name] == nil do
+        {:reply, :not_found, state}
+      else
+        dict = Map.delete(dict, name)
+        GenServer.cast(Shard.Manager, {:dep_list, state.id, Map.values(dict)})
+        {:ok, st2} = SData.SignRev.set(state.files, dict, state.owner)
+        Shard.Manager.save_state(state.id, st2)
+        state = put_in(state.files, st2)
+        bcast_state(state)
+        {:reply, :ok, state}
+      end
+    else
+      {:reply, :impossible, state}
+    end
+  end
+
+  def handle_cast(:send_deps, state) do
+    dict = SData.SignRev.get(state.files)
+    GenServer.cast(Shard.Manager, {:dep_list, state.id, Map.values(dict)})
+    {:noreply, state}
+  end
+
+  def handle_cast({:interested, peer_pid, auth}, state) do
+    if SNet.Group.in_group?(state.netgroup, peer_pid, auth) do
+      SNet.Manager.send_pid(peer_pid, {state.id, nil, {:update, SData.SignRev.signed(state.files), true}})
+    end
+    {:noreply, state}
+  end
+
+  def handle_cast({:msg, conn_pid, auth, _shard_id, nil, msg}, state) do
+    if not SNet.Group.in_group?(state.netgroup, conn_pid, auth) do
+      {:noreply, state}
+    else
+      state = case msg do
+        {:update, signed, ask_reply} when signed != nil ->
+          state = case SData.SignRev.merge(state.files, signed, state.pk) do
+            {true, newfiles} ->
+              Shard.Manager.save_state(state.id, newfiles)
+              state = put_in(state.files, newfiles)
+              bcast_state(state, [conn_pid])
+              state
+            {false, _} ->
+              state
+          end
+          if ask_reply do
+            SNet.Manager.send_pid(conn_pid, {state.id, nil, {:update, SData.SignRev.signed(state.files), false}})
+          end
+          state
+      _ -> state
+      end
+      {:noreply, state}
+    end
+  end
+
+  defp bcast_state(state, exclude \\ []) do
+    msg = {state.id, nil, {:update, SData.SignRev.signed(state.files), false}}
+    SNet.Group.broadcast(state.netgroup, msg, exclude_pid: exclude)
+  end
+
+  # ================
+  # PUBLIC INTERFACE
+  # ================
+
+  @doc"""
+  Return list of files stored in this directory.
+
+  Returns a list of {name, manifests}.
+  """
+  def get_files(pid) do
+    GenServer.call(pid, :get_files)
+  end
+
+  @doc"""
+  Add a file to this directory. A file is a name for a shard manifest.
+  A file added to a directory becomes a dependency of the directory, i.e.
+  if the directory is pinned then all files inside are pinned as well.
+  """
+  def add_file(pid, name, manifest) do
+    GenServer.call(pid, {:add_file, name, manifest})
+  end
+
+  @doc"""
+  Remove a named file from this directory.
+  """
+  def rm_file(pid, name) do
+    GenServer.call(pid, {:rm_file, name})
+  end
+end