1 files changed, 67 insertions, 0 deletions
diff --git a/core-rest/src/main/scala/xyz/driver/core/rest/PooledHttpClient.scala b/core-rest/src/main/scala/xyz/driver/core/rest/PooledHttpClient.scala
new file mode 100644
index 0000000..2854257
--- /dev/null
+++ b/core-rest/src/main/scala/xyz/driver/core/rest/PooledHttpClient.scala
@@ -0,0 +1,67 @@
+package xyz.driver.core.rest
+
+import akka.actor.ActorSystem
+import akka.http.scaladsl.Http
+import akka.http.scaladsl.model.headers.`User-Agent`
+import akka.http.scaladsl.model.{HttpRequest, HttpResponse, Uri}
+import akka.http.scaladsl.settings.{ClientConnectionSettings, ConnectionPoolSettings}
+import akka.stream.scaladsl.{Keep, Sink, Source}
+import akka.stream.{ActorMaterializer, OverflowStrategy, QueueOfferResult, ThrottleMode}
+import xyz.driver.core.Name
+
+import scala.concurrent.{ExecutionContext, Future, Promise}
+import scala.concurrent.duration._
+import scala.util.{Failure, Success}
+
+class PooledHttpClient(
+    baseUri: Uri,
+    applicationName: Name[App],
+    applicationVersion: String,
+    requestRateLimit: Int = 64,
+    requestQueueSize: Int = 1024)(implicit actorSystem: ActorSystem, executionContext: ExecutionContext)
+    extends HttpClient {
+
+  private val host   = baseUri.authority.host.toString()
+  private val port   = baseUri.effectivePort
+  private val scheme = baseUri.scheme
+
+  protected implicit val materializer: ActorMaterializer = ActorMaterializer()(actorSystem)
+
+  private val clientConnectionSettings: ClientConnectionSettings =
+    ClientConnectionSettings(actorSystem).withUserAgentHeader(
+      Option(`User-Agent`(applicationName.value + "/" + applicationVersion)))
+
+  private val connectionPoolSettings: ConnectionPoolSettings = ConnectionPoolSettings(actorSystem)
+    .withConnectionSettings(clientConnectionSettings)
+
+  private val pool = if (scheme.equalsIgnoreCase("https")) {
+    Http().cachedHostConnectionPoolHttps[Promise[HttpResponse]](host, port, settings = connectionPoolSettings)
+  } else {
+    Http().cachedHostConnectionPool[Promise[HttpResponse]](host, port, settings = connectionPoolSettings)
+  }
+
+  private val queue = Source
+    .queue[(HttpRequest, Promise[HttpResponse])](requestQueueSize, OverflowStrategy.dropNew)
+    .via(pool)
+    .throttle(requestRateLimit, 1.second, maximumBurst = requestRateLimit, ThrottleMode.shaping)
+    .toMat(Sink.foreach({
+      case ((Success(resp), p)) => p.success(resp)
+      case ((Failure(e), p))    => p.failure(e)
+    }))(Keep.left)
+    .run
+
+  def makeRequest(request: HttpRequest): Future[HttpResponse] = {
+    val responsePromise = Promise[HttpResponse]()
+
+    queue.offer(request -> responsePromise).flatMap {
+      case QueueOfferResult.Enqueued =>
+        responsePromise.future
+      case QueueOfferResult.Dropped =>
+        Future.failed(new Exception(s"Request queue to the host $host is overflown"))
+      case QueueOfferResult.Failure(ex) =>
+        Future.failed(ex)
+      case QueueOfferResult.QueueClosed =>
+        Future.failed(new Exception("Queue was closed (pool shut down) while running the request"))
+    }
+  }
+}