hvanhovell commented on a change in pull request #23406: [SPARK-26504][SQL]
Rope-wise dumping of Spark plans
URL: https://github.com/apache/spark/pull/23406#discussion_r244539485
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/StringUtils.scala
##########
@@ -87,4 +89,35 @@ object StringUtils {
}
funcNames.toSeq
}
+
+ /**
+ * Concatenation of sequence of strings to final string with cheap append
method
+ * and one memory allocation for the final string.
+ */
+ class StringRope {
+ private val rope = new ArrayBuffer[String]
+ private var length: Int = 0
+
+ /**
+ * Appends a string and accumulates its length to allocate a string buffer
for all
+ * appended strings once in the toString method.
+ */
+ def append(s: String): Unit = {
+ if (s != null) {
+ rope.append(s)
+ length += s.length
+ }
+ }
+
+ /**
+ * The method allocates memory for all appended strings, writes them to
the memory and
+ * returns concatenated string.
+ */
+ override def toString: String = {
+ val buffer = new StringBuffer(length)
+
Review comment:
Why the new line?
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