[SPARK-10001] [CORE] Interrupt tasks in repl with Ctrl+C

## What changes were proposed in this pull request?

Improve signal handling to allow interrupting running tasks from the REPL (with Ctrl+C).
If no tasks are running or Ctrl+C is pressed twice, the signal is forwarded to the default handler resulting in the usual termination of the application.

This PR is a rewrite of -- and therefore closes #8216 -- as per piaozhexiu's request

## How was this patch tested?
Signal handling is not easily testable therefore no unit tests were added. Nevertheless, the new functionality is implemented in a best-effort approach, soft-failing in case signals aren't available on a specific OS.

Author: Jakob Odersky <jakob@odersky.com>

Closes #12557 from jodersky/SPARK-10001-sigint.

1 files changed, 42 insertions, 0 deletions

diff --git a/repl/src/main/scala/org/apache/spark/repl/Signaling.scala b/repl/src/main/scala/org/apache/spark/repl/Signaling.scala
new file mode 100644
index 0000000000..c305ed545c
--- /dev/null
+++ b/repl/src/main/scala/org/apache/spark/repl/Signaling.scala
@@ -0,0 +1,42 @@
+/*
+ * 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.repl
+
+import org.apache.spark.SparkContext
+import org.apache.spark.internal.Logging
+import org.apache.spark.util.{Signaling => USignaling}
+
+private[repl] object Signaling extends Logging {
+
+  /**
+   * Register a SIGINT handler, that terminates all active spark jobs or terminates
+   * when no jobs are currently running.
+   * This makes it possible to interrupt a running shell job by pressing Ctrl+C.
+   */
+  def cancelOnInterrupt(ctx: SparkContext): Unit = USignaling.register("INT") {
+    if (!ctx.statusTracker.getActiveJobIds().isEmpty) {
+      logWarning("Cancelling all active jobs, this can take a while. " +
+        "Press Ctrl+C again to exit now.")
+      ctx.cancelAllJobs()
+      true
+    } else {
+      false
+    }
+  }
+
+}