Refactored brain code for better interface.

Author: tli2

src/include/brain/brain.h

@@ -23,23 +23,45 @@
 namespace peloton {
 namespace brain {
 
+/**
+ * Provides an access point to the various resources available to the jobs in
+ * the brain, such as RPC and Catalog.
+ */
 class BrainEnvironment {
-  // TODO(tianyu): provide interface for accessing various resources of the brain,
-  // such as network connection to a peloton engine.
+  // TODO(tianyu): fill in as needed
 };
 
+/**
+ * Interface that represents a piece of task to be run on Brain. To use this
+ * abstract class, extend it with a concrete class and fill in the method
+ * OnJobInvocation.
+ */
 class BrainJob {
-  friend class Brain;
  public:
   explicit BrainJob(BrainEnvironment *env) : env_(env) {}
+
   virtual ~BrainJob() = default;
+
+  // This is separate from the user-defined OnJobInvocation to allow for better
+  // interfacing with the libevent API.
+  /**
+   * Invokes this job to be run. The brain framework will call this method.
+   *
+   */
   inline void Invoke() { OnJobInvocation(env_); }
-  // TODO(tianyu): Extend this interface for richer interaction
+  // TODO(tianyu): Extend this interface for richer behavior
+  /**
+   * Executed as the main body of the job, filled in by the user. Use the
+   * provided BrainEnvironment for interaction with Brain's resources.
+   */
   virtual void OnJobInvocation(BrainEnvironment *) = 0;
  private:
   BrainEnvironment *env_;
 };
 
+/**
+ * Simple implementation of a BrainJob.
+ */
 class SimpleBrainJob : public BrainJob {
  public:
   explicit SimpleBrainJob(BrainEnvironment *env,
@@ -50,15 +72,19 @@ class SimpleBrainJob : public BrainJob {
   std::function<void(BrainEnvironment *)> task_;
 };
 
+/**
+ * Main running component of the brain. Events can be registered on this event
+ * loop and once Run is called, it will invoke handlers every specified time
+ * interval
+ */
 class Brain {
  public:
   // TODO(tianyu): Add necessary parameters to initialize the brain's resources
   Brain() : scheduler_(0) {}
+
   ~Brain() {
     for (auto entry : jobs_)
       delete entry.second;
-    for (auto entry : job_handles_)
-      event_free(entry.second);
   }
 
   template <typename BrainJob, typename... Args>

src/main/peloton/peloton.cpp

@@ -49,8 +49,9 @@ void RunPelotonBrain() {
   // TODO(tianyu): register jobs here
   struct timeval one_second;
   one_second.tv_sec = 1;
+  one_second.tv_usec = 0;
 
-  constexpr auto example_task = [](peloton::brain::BrainEnvironment *) {
+  auto example_task = [](peloton::brain::BrainEnvironment *) {
     // TODO(tianyu): Replace with real address
     capnp::EzRpcClient client("localhost:15445");
     PelotonService::Client peloton_service = client.getMain<PelotonService>();

src/network/peloton_server.cpp

@@ -270,8 +270,8 @@ void PelotonServer::ServerLoop() {
   if (settings::SettingsManager::GetBool(settings::SettingId::rpc_enabled)) {
     int rpc_port =
         settings::SettingsManager::GetInt(settings::SettingId::rpc_port);
-    auto rpc_task = std::make_shared<PelotonRpcHandlerTask>(("127.0.0.1:"
-        + std::to_string(rpc_port)).c_str());
+    std::string address = "127.0.0.1:" + std::to_string(rpc_port);
+    auto rpc_task = std::make_shared<PelotonRpcHandlerTask>(address.c_str());
     DedicatedThreadRegistry::GetInstance()
         .RegisterDedicatedThread<PelotonRpcHandlerTask>(this, rpc_task);
   }