more options for the EventHandler, updated documentation

Author: zookzook

CHANGELOG.md

@@ -5,8 +5,11 @@
     * added support for retryable reads and writes
     * refactored the test cases
     * now using mtools for a MongoDB deployment in the travis ci environment
-    * travis ci uses only the latest MongoDB version [The failCommand](https://github.com/mongodb/mongo/wiki/The-%22failCommand%22-fail-point) 
-    
+    * travis ci uses only the latest MongoDB version [The failCommand](https://github.com/mongodb/mongo/wiki/The-%22failCommand%22-fail-point)
+
+* Bugfixes
+    * Using `max_staleness_ms` > 0 results in a crash
+      
 ## 0.6.5
 
 * Enhancements

README.md

@@ -371,7 +371,18 @@ and have a look at the test units as well.
 
 ### Command Monitoring
 
-You can watch all events that are triggered while the driver send requests and processes responses.
+You can watch all events that are triggered while the driver send requests and processes responses. You can use the 
+`Mongo.EventHandler` as a starting point. It logs the events from the topic `:commands` (by ignoring the `:isMaster` command)
+to `Logger.info`:
+
+```elixir
+iex> Mongo.EventHandler.start()
+iex> {:ok, conn} = Mongo.start_link(url: "mongodb://localhost:27017/test")
+{:ok, #PID<0.226.0>}
+iex> Mongo.find_one(conn, "test", %{})
+[info] Received command: %Mongo.Events.CommandStartedEvent{command: [find: "test", ...
+[info] Received command: %Mongo.Events.CommandSucceededEvent{command_name: :find, ...
+```
 
 ## Testing and Travis CI
 
@@ -389,10 +400,9 @@ mlaunch init --setParameter enableTestCommands=1 --replicaset --name "rs_1"
 mix test --exclude ssl --exclude socket
 ``` 
 
-The SSL test suite is enabled by default. You have two options. Either exclude
-the SSL tests or enable SSL on your Mongo server.
+The SSL test suite is disabled by default.
 
-### Disable the SSL tests
+### Enable the SSL tests
 
 `mix test --exclude ssl`
 
@@ -407,7 +417,6 @@ $ mongod --sslMode allowSSL --sslPEMKeyFile /path/to/mongodb.pem
 * For `--sslMode` you can use one of `allowSSL` or `preferSSL`
 * You can enable any other options you want when starting `mongod`
 
-
 ## Special thanks
 
 Special thanks to [JetBrains](https://www.jetbrains.com/?from=elixir-mongodb-driver) for providing a free JetBrains Open Source license for their complete toolbox.

lib/mongo/event_handler.ex

@@ -5,33 +5,39 @@ defmodule Mongo.EventHandler do
 
   @all [:commands, :topology]
 
-  def start(opts \\ [:commands]) do
-    Logger.info("Starting EventHandler")
+  def start(opts \\ [topics: [:commands]]) do
     spawn(__MODULE__, :register, [opts])
   end
 
-  def register([]) do
-    register(@all)
-  end
-
   def register(opts) do
-    with true <- opts
+    with true <- (opts[:topics] || @all)
                 |> Enum.map(fn topic -> Registry.register(:events_registry, topic, []) end)
                 |> Enum.all?(fn
                   {:ok, _} -> true
                   _other   -> false
                 end) do
-      listen()
+      listen(opts)
       :ok
     end
   end
 
-  def listen() do
-    # fun.(topic, message)
+  def listen(opts) do
     receive do
+      {:broadcast, :commands, %{command_name: cmd} = message} when cmd != :isMaster ->
+        Logger.info("Received command: " <> (inspect message))
+        listen(opts)
+
+      {:broadcast, :commands, is_master} ->
+        case opts[:is_master] do
+          true -> Logger.info("Received is master:" <> (inspect is_master))
+          _ -> []
+        end
+        listen(opts)
+
       {:broadcast, topic, message} ->
-        Logger.info("Received #{topic}-message:" <> (inspect message))
-        listen()
+        Logger.info("Received #{topic}: " <> (inspect message))
+        listen(opts)
+
       other ->
         Logger.info("Stopping EventHandler received unknown message:" <> inspect other)
     end

test/test_helper.exs

@@ -12,7 +12,7 @@ version =
   |> List.to_tuple
 
 options = [ssl: true, socket: true]
-options = if System.get_env("CI") do [tag_sets: true] ++ options else options end
+options = if System.get_env("CI") do [tag_set: true] ++ options else options end
 options = if version < {3, 4, 0} do [mongo_3_4: true] ++ options else options end
 options = if version < {3, 6, 0} do [mongo_3_6: true] ++ options else options end
 options = if version < {4, 2, 0} do [mongo_4_2: true] ++ options else options end