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author | Denton Cockburn <kanielc@gmail.com> | 2014-12-13 21:46:25 -0500 |
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committer | Denton Cockburn <kanielc@gmail.com> | 2014-12-14 10:57:04 -0500 |
commit | 6e8c60eabbbf0f21ef8e0b87267952bec2f85159 (patch) | |
tree | 8c543503f0d4a815f24cd5dcc31fa7229db3e443 /src/library | |
parent | d9f623db0ff1d20040939fbb9e15d4d4e5887c75 (diff) | |
download | scala-6e8c60eabbbf0f21ef8e0b87267952bec2f85159.tar.gz scala-6e8c60eabbbf0f21ef8e0b87267952bec2f85159.tar.bz2 scala-6e8c60eabbbf0f21ef8e0b87267952bec2f85159.zip |
SI-9043 ArrayBuffer.insert and insertAll are very slow
insert and insertAll were slower than their java equivalents by factors
of 5 and 10 respectively.
Benchmark code was provided here:
https://gist.github.com/rklaehn/3e9290118fcf63d1feae
We are using a toList to the source Traversable
Then doing a length and a copy on that collection.
By using an array, we can make use of faster methods.
Managed to get the ratios down to 1.5 and 1.5 respectively.
In addition to this, I think we should consider breaking insert into 2
separate methods, one for a single item and one for a collection. The
varags version is very expensive when a single item is being inserted.
@phaller @axel22
Diffstat (limited to 'src/library')
-rw-r--r-- | src/library/scala/collection/mutable/ArrayBuffer.scala | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/src/library/scala/collection/mutable/ArrayBuffer.scala b/src/library/scala/collection/mutable/ArrayBuffer.scala index 8f77114746..011fd415ee 100644 --- a/src/library/scala/collection/mutable/ArrayBuffer.scala +++ b/src/library/scala/collection/mutable/ArrayBuffer.scala @@ -128,7 +128,7 @@ class ArrayBuffer[A](override protected val initialSize: Int) override def ++=:(xs: TraversableOnce[A]): this.type = { insertAll(0, xs.toTraversable); this } /** Inserts new elements at the index `n`. Opposed to method - * `update`, this method will not replace an element with a + * `update`, this method will not replace an element with a new * one. Instead, it will insert a new element at index `n`. * * @param n the index where a new element will be inserted. @@ -137,12 +137,13 @@ class ArrayBuffer[A](override protected val initialSize: Int) */ def insertAll(n: Int, seq: Traversable[A]) { if (n < 0 || n > size0) throw new IndexOutOfBoundsException(n.toString) - val xs = seq.toList - val len = xs.length - ensureSize(size0 + len) + val len = seq.size + val newSize = size0 + len + ensureSize(newSize) + copy(n, n + len, size0 - n) - xs.copyToArray(array.asInstanceOf[scala.Array[Any]], n) - size0 += len + seq.copyToArray(array.asInstanceOf[Array[Any]], n) + size0 = newSize } /** Removes the element on a given index position. It takes time linear in |