Slf4j to log exceptions in user-supplied callbacks (close #153)

snowplow · Dec 23, 2020 · c8f4db0 · c8f4db0
1 parent 0cdf3f7
commit c8f4db0
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Showing 4 changed files with 28 additions and 9 deletions.
diff --git a/build.sbt b/build.sbt
@@ -54,6 +54,7 @@ lazy val idEmitter = project
     name := "snowplow-scala-tracker-emitter-id",
     libraryDependencies ++= Seq(
       Dependencies.Libraries.scalajHttp,
+      Dependencies.Libraries.slf4jApi
     )
   ))
   .dependsOn(core % "test->test;compile->compile")
@@ -75,7 +76,8 @@ lazy val http4sEmitter = project
   .settings(Seq(
     name := "snowplow-scala-tracker-emitter-http4s",
     libraryDependencies ++= List(
-      Dependencies.Libraries.http4sClient
+      Dependencies.Libraries.http4sClient,
+      Dependencies.Libraries.slf4jApi
     )
   ))
   .dependsOn(core % "test->test;compile->compile")
diff --git a/...ain/scala/com.snowplowanalytics.snowplow.scalatracker.emitters.http4s/Http4sEmitter.scala b/...ain/scala/com.snowplowanalytics.snowplow.scalatracker.emitters.http4s/Http4sEmitter.scala
@@ -20,6 +20,7 @@ import fs2.concurrent.{Dequeue, Enqueue, Queue}
 import org.http4s.client.Client
 import org.http4s.headers.`Content-Type`
 import org.http4s.{MediaType, Method, Request => HttpRequest, Uri}
+import org.slf4j.LoggerFactory
 import scala.concurrent.duration._
 import scala.util.Random
 
@@ -183,13 +184,21 @@ object Http4sEmitter {
         .handleError(Result.TrackerFailure(_))
     }
 
-  private def invokeCallback[F[_]: MonadError[?[_], Throwable]](callback: Option[Callback[F]],
-                                                                collector: EndpointParams,
-                                                                request: Request,
-                                                                result: Result): F[Unit] =
+  lazy val logger = LoggerFactory.getLogger(getClass.getName)
+
+  private def invokeCallback[F[_]: Sync](callback: Option[Callback[F]],
+                                         collector: EndpointParams,
+                                         request: Request,
+                                         result: Result): F[Unit] =
     callback match {
       case Some(cb) =>
-        cb(collector, request, result).handleError(_ => ())
+        cb(collector, request, result).handleErrorWith { throwable =>
+          if (logger.isWarnEnabled)
+            Sync[F].delay(
+              logger.warn(s"Snowplow Tracker bounded to ${collector.getUri} failed to execute callback", throwable))
+          else
+            Sync[F].unit
+        }
       case None => Monad[F].unit
     }
 

diff --git a/...main/scala/com/snowplowanalytics/snowplow/scalatracker/emitters/id/RequestProcessor.scala b/...main/scala/com/snowplowanalytics/snowplow/scalatracker/emitters/id/RequestProcessor.scala
@@ -12,6 +12,7 @@
  */
 package com.snowplowanalytics.snowplow.scalatracker.emitters.id
 
+import org.slf4j.LoggerFactory
 import scala.concurrent.{ExecutionContext, Future, blocking}
 import scala.util.{Failure, Random, Success, Try}
 import scala.util.control.NonFatal
@@ -51,6 +52,8 @@ private[id] object RequestProcessor {
           .options(options)
     }
 
+  lazy val logger = LoggerFactory.getLogger(getClass.getName)
+
   /**
    * Executes user-provided callback against event and collector response
    * If callback fails to execute - message will be printed to stderr
@@ -67,9 +70,8 @@ private[id] object RequestProcessor {
         cb(collector, payload, result)
       } catch {
         case NonFatal(throwable) =>
-          val error   = Option(throwable.getMessage).getOrElse(throwable.toString)
-          val message = s"Snowplow Tracker bounded to ${collector.getUri} failed to execute callback: $error"
-          System.err.println(message)
+          if (logger.isWarnEnabled)
+            logger.warn(s"Snowplow Tracker bounded to ${collector.getUri} failed to execute callback", throwable)
       }
     }
 

diff --git a/project/Dependencies.scala b/project/Dependencies.scala
@@ -23,6 +23,9 @@ object Dependencies {
     val catsEffect  = "2.2.0"
     val http4s      = "0.21.14"
 
+    // Java
+    val slf4j       = "1.7.30"
+
     // Scala (test only)
     val specs2      = "4.10.5"
     val scalaCheck  = "1.14.3"
@@ -37,6 +40,9 @@ object Dependencies {
     val catsEffect     = "org.typelevel"         %% "cats-effect"     % V.catsEffect
     val http4sClient   = "org.http4s"            %% "http4s-client"   % V.http4s
 
+    // Java
+    val slf4jApi = "org.slf4j" % "slf4j-api" % V.slf4j
+
     // Scala (test only)
     val specs2        = "org.specs2"             %% "specs2-core"         % V.specs2      % "test"
     val scalaCheck    = "org.scalacheck"         %% "scalacheck"          % V.scalaCheck  % "test"