From 3de6739b8b6f04956c8908bc9717990807254a6b Mon Sep 17 00:00:00 2001
From: Jakob Odersky <jakob@inpher.io>
Date: Fri, 11 Oct 2019 20:38:55 -0400
Subject: add logging and some comments

---
 server/src/LiveMessages.scala | 11 ++++++++---
 server/src/Main.scala         | 37 +++++++++++++++++++++++++++++--------
 server/src/Repository.scala   |  1 +
 server/src/Routes.scala       |  7 +++----
 4 files changed, 41 insertions(+), 15 deletions(-)

diff --git a/server/src/LiveMessages.scala b/server/src/LiveMessages.scala
index b2d27c1..307dd81 100644
--- a/server/src/LiveMessages.scala
+++ b/server/src/LiveMessages.scala
@@ -7,8 +7,10 @@ import akka.stream.scaladsl.{
   Source,
   SourceQueueWithComplete
 }
-import akka.stream.{Materializer, OverflowStrategy}
+import akka.stream.{Materializer, OverflowStrategy, QueueOfferResult}
+import scala.concurrent.Future
 
+/** A very basic streaming message router. */
 class LiveMessages(implicit materializer: Materializer) {
 
   private val (
@@ -19,7 +21,10 @@ class LiveMessages(implicit materializer: Materializer) {
     .toMat(BroadcastHub.sink[Message])(Keep.both)
     .run()
 
-  def push(message: Message) = in.offer(message)
-  def feed = out
+  /** Push a single message into the stream. */
+  def push(message: Message): Future[QueueOfferResult] = in.offer(message)
+
+  /** Obtain a stream of the message feed. */
+  def feed: Source[Message, NotUsed] = out
 
 }
diff --git a/server/src/Main.scala b/server/src/Main.scala
index 51e4f28..91649a2 100644
--- a/server/src/Main.scala
+++ b/server/src/Main.scala
@@ -11,18 +11,39 @@ import scala.concurrent.duration._
 
 object Main extends App {
 
+  def log(message: String) = System.err.println(message)
+
+  log("Initializing contexts...")
   implicit val system = ActorSystem("triad")
   implicit val materializer = ActorMaterializer()
-
-  val repository = {
-    Files.deleteIfExists(Paths.get("database.sqlite"))
-    Repository.sqlite("database.sqlite")
+  system.registerOnTermination {
+    log("Bye!")
   }
-  val liveMessages = new LiveMessages
-  val routes = new Routes(repository, liveMessages)
 
-  Await.result(repository.database.run(repository.initAction), 10.seconds)
+  try {
+    log("Initializing database...")
+    val repository = {
+      Files.deleteIfExists(Paths.get("database.sqlite"))
+      Repository.sqlite("database.sqlite")
+    }
+
+    log("Preparing live message relay...")
+    val liveMessages = new LiveMessages
+
+    log("Setting up routes...")
+    val routes = new Routes(repository, liveMessages)
 
-  Await.result(Http().bindAndHandle(routes.all, "0.0.0.0", 9090), 10.seconds)
+    log("Populating database tables...")
+    Await.result(repository.database.run(repository.initAction), 10.seconds)
+
+    log("Binding to network...")
+    Await.result(Http().bindAndHandle(routes.all, "0.0.0.0", 9090), 10.seconds)
+
+    log("Ready")
+  } catch {
+    case ex: Exception =>
+      log("Error in initialization. Shutting down...")
+      system.terminate()
+  }
 
 }
diff --git a/server/src/Repository.scala b/server/src/Repository.scala
index 003ac92..fe7ecab 100644
--- a/server/src/Repository.scala
+++ b/server/src/Repository.scala
@@ -4,6 +4,7 @@ import java.time.Instant
 
 import slick.jdbc.{JdbcProfile, SQLiteProfile}
 
+/** Slick wrapper around the persisted message database. */
 class Repository(val profile: JdbcProfile, url: String, driver: String) {
   val database: profile.backend.DatabaseDef =
     profile.api.Database.forURL(url, driver)
diff --git a/server/src/Routes.scala b/server/src/Routes.scala
index 0b08a11..d1bbefd 100644
--- a/server/src/Routes.scala
+++ b/server/src/Routes.scala
@@ -25,12 +25,11 @@ class Routes(repository: Repository, liveMessages: LiveMessages) {
 
   private val lastMessages = repository.Messages.take(100).result
 
-  private val messageStream: Source[Message, _] = {
-    val publisher = repository.database.stream(lastMessages)
+  // stream persisted messages first, followed by live ones
+  private val messageStream: Source[Message, _] =
     Source
-      .fromPublisher(publisher)
+      .fromPublisher(repository.database.stream(lastMessages))
       .concat(liveMessages.feed)
-  }
 
   val messages = path("messages") {
     get {
-- 
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