Disable asynchronous deletes for Hudi (#94)

In #82 we added a feature to delete files asynchronously. This has
worked great for Delta, which is tolerant to deletes that happen
eventually not immediately. But it is not working great for Hudi, which
does delete-and-replace of the `hoodie.properties` file.

This commit disables the feature again for Hudi only.

modules/core/src/main/scala/com.snowplowanalytics.snowplow.lakes/processing/SparkUtils.scala

@@ -51,10 +51,12 @@ private[processing] object SparkUtils {
     Resource
       .make(openLogF >> buildF)(s => closeLogF >> Sync[F].blocking(s.close()))
       .evalTap { session =>
-        Sync[F].delay {
-          // Forces Spark to use `LakeLoaderFileSystem` when writing to the Lake via Hadoop
-          LakeLoaderFileSystem.overrideHadoopFileSystemConf(targetLocation, session.sparkContext.hadoopConfiguration)
-        }
+        if (writer.toleratesAsyncDelete) {
+          Sync[F].delay {
+            // Forces Spark to use `LakeLoaderFileSystem` when writing to the Lake via Hadoop
+            LakeLoaderFileSystem.overrideHadoopFileSystemConf(targetLocation, session.sparkContext.hadoopConfiguration)
+          }
+        } else Sync[F].unit
       }
   }
 

modules/core/src/main/scala/com.snowplowanalytics.snowplow.lakes/tables/DeltaWriter.scala

@@ -104,4 +104,11 @@ class DeltaWriter(config: Config.Delta) extends Writer {
         }
     }
 
+  /**
+   * Delta tolerates async deletes; in other words when we delete a file, there is no strong
+   * requirement that the file must be deleted immediately. Delta uses unique file names and never
+   * re-writes a file that was previously deleted
+   */
+  override def toleratesAsyncDelete: Boolean = true
+
 }

modules/core/src/main/scala/com.snowplowanalytics.snowplow.lakes/tables/HudiWriter.scala

@@ -85,4 +85,13 @@ class HudiWriter(config: Config.Hudi) extends Writer {
         .options(config.hudiWriteOptions)
         .save(config.location.toString)
     }
+
+  /**
+   * Hudi cannot tolerate async deletes. When Hudi deletes a file, the file MUST be deleted
+   * immediately.
+   *
+   * In particular, the `hoodie.properties` file gets deleted and re-created by Hudi, and those
+   * steps must happen in order.
+   */
+  override def toleratesAsyncDelete: Boolean = false
 }

modules/core/src/main/scala/com.snowplowanalytics.snowplow.lakes/tables/IcebergWriter.scala

@@ -107,4 +107,10 @@ class IcebergWriter(config: Config.Iceberg) extends Writer {
       }
       .mkString(", ")
 
+  /**
+   * Iceberg tolerates async deletes; in other words when we delete a file, there is no strong
+   * requirement that the file must be deleted immediately. Iceberg uses unique file names and never
+   * re-writes a file that was previously deleted
+   */
+  override def toleratesAsyncDelete: Boolean = true
 }

modules/core/src/main/scala/com.snowplowanalytics.snowplow.lakes/tables/Writer.scala

@@ -29,4 +29,11 @@ trait Writer {
 
   /** Write Snowplow events into the table */
   def write[F[_]: Sync](df: DataFrame): F[Unit]
+
+  /**
+   * Whether this lake format tolerates deletes to happen asynchronously instead of immediately
+   *
+   * If tolerated, then we use our customized `LakeLoaderFileSystem`.
+   */
+  def toleratesAsyncDelete: Boolean
 }