Implement ping and disconnect callbacks for DBConnection.

* Proper error handling on connect.

* Implement ping and disconnect.

* Update Dgraph to v1.0.6.

* Bump version.

Changelog.md

@@ -6,6 +6,13 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+## [0.2.0-beta.3] - 2019-07-31
+
+- Test against Dgraph `v1.0.16`
+- Remove dependency `gun`
+- Implement ping callback
+- Implement disconnect callback
+
 ## [0.2.0-beta.2] - 2019-03-28
 
 - Downgrade poison to `v3.1.0`.

README.md

@@ -2,7 +2,7 @@
 
 **ExDgraph is functional but I would be careful using it in production. If you want to help, please drop me a message. Any help is greatly appreciated!**
 
-ExDgraph is a gRPC based client for the [Dgraph](https://github.com/dgraph-io/dgraph) database. It uses the [DBConnection](https://hexdocs.pm/db_connection/DBConnection.html) behaviour to support transactions and connection pooling via [Poolboy](https://github.com/devinus/poolboy). Works with Dgraph v1.0.13 (latest).
+ExDgraph is a gRPC based client for the [Dgraph](https://github.com/dgraph-io/dgraph) database. It uses the [DBConnection](https://hexdocs.pm/db_connection/DBConnection.html) behaviour to support transactions and connection pooling via [Poolboy](https://github.com/devinus/poolboy). Works with Dgraph v1.0.16 (latest).
 
 > Dgraph is an open source, horizontally scalable and distributed graph database, providing ACID transactions, consistent replication and linearizable reads. [...] Dgraph's goal is to provide Google production level scale and throughput, with low enough latency to be serving real time user queries, over terabytes of structured data. ([Source](https://github.com/dgraph-io/dgraph))
 
@@ -31,7 +31,7 @@ Add the package `ex_dgraph` to your list of dependencies in `mix.exs`:
 ```elixir
 def deps do
   [
-    {:ex_dgraph, "~> 0.2.0-beta.2"}
+    {:ex_dgraph, "~> 0.2.0-beta.3"}
   ]
 end
 ```

docker-compose.yml

@@ -1,7 +1,7 @@
 version: "3.2"
 services:
   zero:
-    image: dgraph/dgraph:v1.0.13
+    image: dgraph/dgraph:v1.0.16
     volumes:
       - type: bind
         source: ./dgraph_data
@@ -14,7 +14,7 @@ services:
     restart: on-failure
     command: dgraph zero --my=zero:5080
   server:
-    image: dgraph/dgraph:v1.0.13
+    image: dgraph/dgraph:v1.0.16
     volumes:
       - type: bind
         source: ./dgraph_data
@@ -27,7 +27,7 @@ services:
     restart: on-failure
     command: dgraph alpha --my=server:7080 --lru_mb=2048 --zero=zero:5080
   ratel:
-    image: dgraph/dgraph:v1.0.13
+    image: dgraph/dgraph:v1.0.16
     volumes:
       - type: bind
         source: ./dgraph_data

lib/exdgraph.ex

@@ -1,6 +1,6 @@
 defmodule ExDgraph do
   @moduledoc """
-  ExDgraph is a gRPC based client for the Dgraph database. It uses the DBConnection behaviour to support transactions and connection pooling via Poolboy. Works with Dgraph v1.0.13 (latest).
+  ExDgraph is a gRPC based client for the Dgraph database. It uses the DBConnection behaviour to support transactions and connection pooling via Poolboy. Works with Dgraph v1.0.16 (latest).
 
   ## Installation
 
@@ -9,7 +9,7 @@ defmodule ExDgraph do
   ```elixir
   def deps do
     [
-      {:ex_dgraph, "~> 0.2.0-beta.2"}
+      {:ex_dgraph, "~> 0.2.0-beta.3"}
     ]
   end
   ```

lib/exdgraph/error.ex

@@ -1,3 +1,13 @@
 defmodule ExDgraph.Error do
-  defexception message: "Unknown exception in ExDgraph."
+  @moduledoc """
+  Dgraph or connection error are wrapped in ExDgraph.Error.
+  """
+  defexception [:reason, :action]
+
+  @type t :: %ExDgraph.Error{}
+
+  @impl true
+  def message(%{action: action, reason: reason}) do
+    "#{action} failed with #{inspect(reason)}"
+  end
 end

lib/exdgraph/protocol.ex

@@ -11,9 +11,9 @@ defmodule ExDgraph.Protocol do
   require Logger
 
   alias ExDgraph.Api
-  alias ExDgraph.{Exception, MutationStatement, OperationStatement, QueryStatement}
+  alias ExDgraph.{Error, Exception, MutationStatement, OperationStatement, QueryStatement}
 
-  @doc "Callback for DBConnection.connect/1"
+  @impl true
   def connect(_opts) do
     host = to_charlist(ExDgraph.config(:hostname))
     port = ExDgraph.config(:port)
@@ -27,43 +27,56 @@ defmodule ExDgraph.Protocol do
       {:ok, channel} ->
         {:ok, channel}
 
-      _ ->
-        Logger.error("ExDgraph: Connection Failed")
-        {:error, ExDgraph.Error}
-        # TODO: Proper error handling
+      {:error, reason} ->
+        {:error, %Error{action: :connect, reason: reason}}
     end
   end
 
-  @doc "Callback for DBConnection.checkout/1"
+  @impl true
   def checkout(state) do
     {:ok, state}
-    # TODO: Proper checkout. Only placeholder callback
   end
 
-  @doc "Callback for DBConnection.checkin/1"
+  @impl true
   def checkin(state) do
     {:ok, state}
-    # TODO: Proper checkout. Only placeholder callback
   end
 
-  @doc "Callback for DBConnection.disconnect/1"
-  def disconnect(_err, _state) do
-    :ok
+  @impl true
+  def disconnect(_error, state) do
+    case GRPC.Stub.disconnect(state) do
+      {:ok, _} -> :ok
+      {:error, _reason} -> :ok
+    end
+  end
+
+  @impl true
+  def ping(%{adapter_payload: %{conn_pid: conn_pid}} = channel) do
+    # check if the server is up and wait 5s seconds before disconnect
+    stream = :gun.head(conn_pid, "/")
+    response = :gun.await(conn_pid, stream, 5_000)
+
+    # return based on response
+    case response do
+      {:response, :fin, 200, _} -> {:ok, channel}
+      {:error, reason} -> {:disconnect, reason, channel}
+      _ -> :ok
+    end
   end
 
-  @doc "Callback for DBConnection.handle_begin/1"
+  @impl true
   def handle_begin(_opts, _state) do
   end
 
-  @doc "Callback for DBConnection.handle_rollback/1"
+  @impl true
   def handle_rollback(_opts, _state) do
   end
 
-  @doc "Callback for DBConnection.handle_commit/1"
+  @impl true
   def handle_commit(_opts, _state) do
   end
 
-  @doc "Callback for DBConnection.handle_execute/1"
+  @impl true
   def handle_execute(query, params, opts, channel) do
     # only try to reconnect if the error is about the broken connection
     with {:disconnect, _, _} <- execute(query, params, opts, channel) do
@@ -92,22 +105,7 @@ defmodule ExDgraph.Protocol do
     end
   end
 
-  def handle_info({:gun_up, _pid, _protocol}, state) do
-    Logger.debug(fn ->
-      [inspect(__MODULE__), ?\s, inspect(self()), " received gun_up from server"]
-    end)
-
-    {:ok, state}
-  end
-
-  def handle_info({:gun_down, _pid, _protocol, _level, _, _}, state) do
-    Logger.debug(fn ->
-      [inspect(__MODULE__), ?\s, inspect(self()), " received gun_down from server"]
-    end)
-
-    {:ok, state}
-  end
-
+  @impl true
   def handle_info(msg, state) do
     Logger.error(fn ->
       [inspect(__MODULE__), ?\s, inspect(self()), " received unexpected message: " | inspect(msg)]
@@ -119,6 +117,7 @@ defmodule ExDgraph.Protocol do
   defp execute(%QueryStatement{statement: statement}, _params, _, channel) do
     request = ExDgraph.Api.Request.new(query: statement)
     timeout = ExDgraph.config(:timeout)
+
     case ExDgraph.Api.Dgraph.Stub.query(channel, request, timeout: timeout) do
       {:ok, res} ->
         {:ok, res, channel}
@@ -161,6 +160,7 @@ defmodule ExDgraph.Protocol do
        ) do
     operation = Api.Operation.new(drop_all: drop_all, schema: schema, drop_attr: drop_attr)
     timeout = ExDgraph.config(:timeout)
+
     case ExDgraph.Api.Dgraph.Stub.alter(channel, operation, timeout: timeout) do
       {:ok, res} ->
         {:ok, res, channel}
@@ -175,6 +175,7 @@ defmodule ExDgraph.Protocol do
 
   defp do_mutate(channel, request) do
     timeout = ExDgraph.config(:timeout)
+
     case ExDgraph.Api.Dgraph.Stub.mutate(channel, request, timeout: timeout) do
       {:ok, res} ->
         {:ok, res, channel}

mix.exs

@@ -4,7 +4,7 @@ defmodule ExDgraph.MixProject do
   def project do
     [
       app: :ex_dgraph,
-      version: "0.2.0-beta.2",
+      version: "0.2.0-beta.3",
       elixir: "~> 1.6",
       start_permanent: Mix.env() == :prod,
       deps: deps(),
@@ -32,7 +32,6 @@ defmodule ExDgraph.MixProject do
     [
       applications: [
         :logger,
-        :poolboy,
         :db_connection,
         :retry,
         :grpc
@@ -44,7 +43,6 @@ defmodule ExDgraph.MixProject do
   defp deps do
     [
       {:grpc, "~> 0.3.1"},
-      {:gun, "1.3.0"},
       {:protobuf, "~> 0.6.1"},
       {:poison, "~> 3.1"},
       {:poolboy, "~> 1.5.2"},