Github user cloud-fan commented on a diff in the pull request:
https://github.com/apache/spark/pull/18884#discussion_r132447263
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/WriteStatsTracker.scala
---
@@ -0,0 +1,123 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.sql.execution.datasources
+
+import org.apache.spark.sql.catalyst.InternalRow
+
+
+/**
+ * To be implemented by classes that represent data statistics collected
during a Write Task.
+ * It is important that instances of this type are [[Serializable]], as
they will be gathered
+ * on the driver from all executors.
+ */
+trait WriteTaskStats
+ extends Serializable
+
+
+/**
+ * A trait for classes that are capable of collecting statistics on data
that's being processed by
+ * a single write task in [[FileFormatWriter]] - i.e. there should be one
instance per executor.
+ *
+ * This trait is coupled with the way [[FileFormatWriter]] works, in the
sense that its methods
+ * will be called according to how tuples are being written out to disk,
namely in sorted order
+ * according to partitionValue(s), then bucketId.
+ *
+ * As such, a typical call scenario is:
+ *
+ * newPartition -> newBucket -> newFile -> newRow -.
+ * ^ |______^___________^ ^ ^____|
+ * | | |______________|
+ * | |____________________________|
+ * |____________________________________________|
+ *
+ * newPartition and newBucket events are only triggered if the relation to
be written out is
+ * partitioned and/or bucketed, respectively.
+ */
+trait WriteTaskStatsTracker {
+
+ /**
+ * Process the fact that a new partition is about to be written.
+ * Only triggered when the relation is partitioned by a (non-empty)
sequence of columns.
+ * @param partitionValues The values that define this new partition.
+ */
+ def newPartition(partitionValues: InternalRow): Unit
+
+ /**
+ * Process the fact that a new bucket is about to written.
+ * Only triggered when the relation is bucketed by a (non-empty)
sequence of columns.
+ * @param bucketId The bucket number.
+ */
+ def newBucket(bucketId: Int): Unit
+
+ /**
+ * Process the fact that a new file is about to be written.
+ * @param filePath Path of the file into which future rows will be
written.
+ */
+ def newFile(filePath: String): Unit
+
+ /**
+ * Process the fact that a new row to update the tracked statistics
accordingly.
+ * The row will be written to the most recently witnessed file (via
`newFile`).
+ * @note Keep in mind that any overhead here is per-row, obviously,
+ * so implementations should be as lightweight as possible.
+ * @param row Current data row to be processed.
+ */
+ def newRow(row: InternalRow): Unit
+
+ /**
+ * Returns the final statistics computed so far.
+ * @note This may only be called once. Further use of the object may
lead to undefined behavior.
+ * @return An object of subtype of [[WriteTaskStats]], to be sent to the
driver.
+ */
+ def getFinalStats(): WriteTaskStats
+}
+
+
+/**
+ * A class implementing this trait is basically a collection of parameters
that are necessary
+ * for instantiating a (derived type of) [[WriteTaskStatsTracker]] on all
executors and then
+ * process the statistics produced by them (e.g. save them to memory/disk,
issue warnings, etc).
+ * It is therefore important that such an objects is [[Serializable]], as
it will be sent
+ * from the driver to all executors.
+ */
+trait WriteJobStatsTracker
+ extends Serializable {
+
+ /**
+ * Instantiates a [[WriteTaskStatsTracker]], based on (non-transient)
members of this class.
+ * To be called by executors.
+ * @return A [[WriteTaskStatsTracker]] instance to be used for computing
stats during a write task
+ */
+ def newTaskInstance(): WriteTaskStatsTracker
+
+ /**
+ * Process the given collection of stats computed during this job.
+ * E.g. aggregate them, write them to memory / disk, issue warnings,
whatever.
+ * @param stats One [[WriteTaskStats]] object from each successful write
task.
+ * @note The type here is too generic. These classes should
probably be parametrized:
--- End diff --
nit: no spaces before `@note`
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at infrastruct...@apache.org or file a JIRA ticket
with INFRA.
---
---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org
For additional commands, e-mail: reviews-h...@spark.apache.org
