=act clean up ByteString#drop(...) (#21440)
* =act clean up ByteString#drop(...) Current implementation has a good algorithm but seems a little bit complicated. Clening-up does not suffer the performance (actually seems to have the better performance when dropping(N-1)) where N is the length, and is easy to understand almost the same algorithm now. * Change private[akka] to priavte * Rename go(...) and some variables They should be easy for us to understand what they are. * Add benchmark of ByteString#drop(...)
This commit is contained in:
monkey-mas
Konrad Malawski
parent
cc845c84b0
commit
19dbe9a487
3 changed files with 150 additions and 70 deletions
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@ -292,22 +292,23 @@ class ByteStringSpec extends WordSpec with Matchers with Checkers {
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}
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"ByteString1" must {
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"drop(0)" in {
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ByteString1.fromString("").drop(0) should ===(ByteString.empty)
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"drop" in {
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ByteString1.empty.drop(-1) should ===(ByteString(""))
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ByteString1.empty.drop(0) should ===(ByteString(""))
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ByteString1.empty.drop(1) should ===(ByteString(""))
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ByteString1.fromString("a").drop(-1) should ===(ByteString("a"))
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ByteString1.fromString("a").drop(0) should ===(ByteString("a"))
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}
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"drop(1)" in {
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ByteString1.fromString("").drop(1) should ===(ByteString(""))
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ByteString1.fromString("a").drop(1) should ===(ByteString(""))
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ByteString1.fromString("ab").drop(1) should ===(ByteString("b"))
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ByteString1.fromString("xaaa").drop(1) should ===(ByteString("aaa"))
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ByteString1.fromString("xaab").drop(1).take(2) should ===(ByteString("aa"))
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ByteString1.fromString("a").drop(2) should ===(ByteString(""))
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ByteString1.fromString("abc").drop(-1) should ===(ByteString("abc"))
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ByteString1.fromString("abc").drop(0) should ===(ByteString("abc"))
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ByteString1.fromString("abc").drop(1) should ===(ByteString("bc"))
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ByteString1.fromString("abc").drop(2) should ===(ByteString("c"))
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ByteString1.fromString("abc").drop(3) should ===(ByteString(""))
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ByteString1.fromString("abc").drop(4) should ===(ByteString(""))
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ByteString1.fromString("0123456789").drop(1).take(2) should ===(ByteString("12"))
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ByteString1.fromString("0123456789").drop(5).take(4).drop(1).take(2) should ===(ByteString("67"))
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}
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"drop(n)" in {
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ByteString1.fromString("ab").drop(2) should ===(ByteString(""))
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ByteString1.fromString("ab").drop(3) should ===(ByteString(""))
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}
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"take" in {
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ByteString1.empty.take(-1) should ===(ByteString(""))
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ByteString1.empty.take(0) should ===(ByteString(""))
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@ -323,18 +324,22 @@ class ByteStringSpec extends WordSpec with Matchers with Checkers {
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}
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}
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"ByteString1C" must {
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"drop(0)" in {
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ByteString1C.fromString("").drop(0) should ===(ByteString.empty)
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ByteString1C.fromString("a").drop(0) should ===(ByteString("a"))
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}
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"drop(1)" in {
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"drop" in {
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ByteString1C.fromString("").drop(-1) should ===(ByteString(""))
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ByteString1C.fromString("").drop(0) should ===(ByteString(""))
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ByteString1C.fromString("").drop(1) should ===(ByteString(""))
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ByteString1C.fromString("a").drop(-1) should ===(ByteString("a"))
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ByteString1C.fromString("a").drop(0) should ===(ByteString("a"))
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ByteString1C.fromString("a").drop(1) should ===(ByteString(""))
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ByteString1C.fromString("ab").drop(1) should ===(ByteString("b"))
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}
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"drop(n)" in {
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ByteString1C.fromString("ab").drop(2) should ===(ByteString(""))
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ByteString1C.fromString("ab").drop(3) should ===(ByteString(""))
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ByteString1C.fromString("a").drop(2) should ===(ByteString(""))
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ByteString1C.fromString("abc").drop(-1) should ===(ByteString("abc"))
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ByteString1C.fromString("abc").drop(0) should ===(ByteString("abc"))
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ByteString1C.fromString("abc").drop(1) should ===(ByteString("bc"))
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ByteString1C.fromString("abc").drop(2) should ===(ByteString("c"))
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ByteString1C.fromString("abc").drop(3) should ===(ByteString(""))
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ByteString1C.fromString("abc").drop(4) should ===(ByteString(""))
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ByteString1C.fromString("0123456789").drop(1).take(2) should ===(ByteString("12"))
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ByteString1C.fromString("0123456789").drop(5).take(4).drop(1).take(2) should ===(ByteString("67"))
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}
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"take" in {
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ByteString1.fromString("abcdefg").drop(1).take(0) should ===(ByteString(""))
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@ -345,33 +350,47 @@ class ByteStringSpec extends WordSpec with Matchers with Checkers {
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}
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}
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"ByteStrings" must {
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"drop(0)" in {
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ByteStrings(ByteString1.fromString(""), ByteString1.fromString("")).drop(0) should ===(ByteString.empty)
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ByteStrings(ByteString1.fromString(""), ByteString1.fromString("a")).drop(0) should ===(ByteString("a"))
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(ByteString1C.fromString("") ++ ByteString1.fromString("a")).drop(0) should ===(ByteString("a"))
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ByteStrings(ByteString1.fromString("a"), ByteString1.fromString("")).drop(0) should ===(ByteString("a"))
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ByteStrings(ByteString1.fromString("a"), ByteString1.fromString("a")).drop(0) should ===(ByteString("aa"))
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"drop" in {
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ByteStrings(ByteString1.fromString(""), ByteString1.fromString("")).drop(Int.MinValue) should ===(ByteString(""))
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ByteStrings(ByteString1.fromString(""), ByteString1.fromString("")).drop(-1) should ===(ByteString(""))
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ByteStrings(ByteString1.fromString(""), ByteString1.fromString("")).drop(0) should ===(ByteString(""))
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}
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"drop(1)" in {
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ByteStrings(ByteString1.fromString(""), ByteString1.fromString("")).drop(1) should ===(ByteString(""))
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ByteStrings(ByteString1.fromString("a"), ByteString1.fromString("")).drop(1) should ===(ByteString(""))
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ByteStrings(ByteString1.fromString(""), ByteString1.fromString("a")).drop(1) should ===(ByteString(""))
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ByteStrings(ByteString1.fromString("ab"), ByteString1.fromString("cd")).drop(1) should ===(ByteString("bcd"))
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ByteStrings(Vector(ByteString1.fromString("xaaa"))).drop(1) should ===(ByteString("aaa"))
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}
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"drop(n)" in {
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ByteStrings(ByteString1.fromString("a"), ByteString1.fromString("")).drop(1) should ===(ByteString(""))
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ByteStrings(ByteString1.fromString(""), ByteString1.fromString("a")).drop(1) should ===(ByteString(""))
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ByteStrings(ByteString1.fromString("ab"), ByteString1.fromString("cd")).drop(3) should ===(ByteString("d"))
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ByteStrings(ByteString1.fromString("ab"), ByteString1.fromString("cd")).drop(4) should ===(ByteString(""))
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ByteStrings(ByteString1.fromString("ab"), ByteString1.fromString("cd")).drop(5) should ===(ByteString(""))
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ByteStrings(ByteString1.fromString("ab"), ByteString1.fromString("cd")).drop(10) should ===(ByteString(""))
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ByteStrings(ByteString1.fromString(""), ByteString1.fromString("")).drop(Int.MaxValue) should ===(ByteString(""))
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ByteStrings(ByteString1.fromString("ab"), ByteString1.fromString("cd")).drop(-2) should ===(ByteString("abcd"))
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ByteStrings(ByteString1.fromString(""), ByteString1.fromString("")).drop(-2) should ===(ByteString(""))
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ByteStrings(ByteString1.fromString("ab"), ByteString1.fromString("")).drop(Int.MinValue) should ===(ByteString("ab"))
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ByteStrings(ByteString1.fromString(""), ByteString1.fromString("ab")).dropRight(Int.MinValue) should ===(ByteString("ab"))
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ByteStrings(ByteString1.fromString("a"), ByteString1.fromString("")).drop(Int.MinValue) should ===(ByteString("a"))
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ByteStrings(ByteString1.fromString("a"), ByteString1.fromString("")).drop(-1) should ===(ByteString("a"))
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ByteStrings(ByteString1.fromString("a"), ByteString1.fromString("")).drop(0) should ===(ByteString("a"))
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ByteStrings(ByteString1.fromString("a"), ByteString1.fromString("")).drop(1) should ===(ByteString(""))
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ByteStrings(ByteString1.fromString("a"), ByteString1.fromString("")).drop(2) should ===(ByteString(""))
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ByteStrings(ByteString1.fromString("a"), ByteString1.fromString("")).drop(Int.MaxValue) should ===(ByteString(""))
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ByteStrings(ByteString1.fromString(""), ByteString1.fromString("a")).drop(Int.MinValue) should ===(ByteString("a"))
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ByteStrings(ByteString1.fromString(""), ByteString1.fromString("a")).drop(-1) should ===(ByteString("a"))
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ByteStrings(ByteString1.fromString(""), ByteString1.fromString("a")).drop(0) should ===(ByteString("a"))
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ByteStrings(ByteString1.fromString(""), ByteString1.fromString("a")).drop(1) should ===(ByteString(""))
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ByteStrings(ByteString1.fromString(""), ByteString1.fromString("a")).drop(2) should ===(ByteString(""))
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ByteStrings(ByteString1.fromString(""), ByteString1.fromString("a")).drop(Int.MaxValue) should ===(ByteString(""))
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val bss = ByteStrings(Vector(
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ByteString1.fromString("a"),
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ByteString1.fromString("bc"),
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ByteString1.fromString("def")))
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bss.drop(Int.MinValue) should ===(ByteString("abcdef"))
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bss.drop(-1) should ===(ByteString("abcdef"))
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bss.drop(0) should ===(ByteString("abcdef"))
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bss.drop(1) should ===(ByteString("bcdef"))
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bss.drop(2) should ===(ByteString("cdef"))
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bss.drop(3) should ===(ByteString("def"))
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bss.drop(4) should ===(ByteString("ef"))
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bss.drop(5) should ===(ByteString("f"))
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bss.drop(6) should ===(ByteString(""))
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bss.drop(7) should ===(ByteString(""))
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bss.drop(Int.MaxValue) should ===(ByteString(""))
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ByteString("0123456789").drop(5).take(2) should ===(ByteString("56"))
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ByteString("0123456789").drop(5).drop(3).take(1) should ===(ByteString("8"))
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(ByteString1C.fromString("a") ++ ByteString1.fromString("bc")).drop(2) should ===(ByteString("c"))
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}
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"slice" in {
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ByteStrings(ByteString1.fromString(""), ByteString1.fromString("a")).slice(1, 1) should ===(ByteString(""))
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@ -485,32 +485,24 @@ object ByteString {
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else drop0(n)
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private def drop0(n: Int): ByteString = {
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var continue = true
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var fullDrops = 0
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var remainingToDrop = n
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do {
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// impl note: could be optimised a bit by using VectorIterator instead,
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// however then we're forced to call .toVector which halfs performance
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// We can work around that, as there's a Scala private method "remainingVector" which is fast,
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// but let's not go into calling private APIs here just yet.
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val currentLength = bytestrings(fullDrops).length
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if (remainingToDrop >= currentLength) {
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fullDrops += 1
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remainingToDrop -= currentLength
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} else continue = false
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} while (remainingToDrop > 0 && continue)
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// impl note: could be optimised a bit by using VectorIterator instead,
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// however then we're forced to call .toVector which halfs performance
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// We can work around that, as there's a Scala private method "remainingVector" which is fast,
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// but let's not go into calling private APIs here just yet.
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@tailrec def findSplit(fullDrops: Int, remainingToDrop: Int): (Int, Int) = {
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val bs = bytestrings(fullDrops)
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if (bs.length > remainingToDrop) (fullDrops, remainingToDrop)
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else findSplit(fullDrops + 1, remainingToDrop - bs.length)
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}
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val remainingByteStrings = bytestrings.drop(fullDrops)
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if (remainingByteStrings.isEmpty) ByteString.empty
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else if (remainingToDrop > 0) {
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val h: ByteString1 = remainingByteStrings.head.drop1(remainingToDrop)
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val bs = remainingByteStrings.tail
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val (fullDrops, remainingToDrop) = findSplit(0, n)
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if (h.isEmpty)
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if (bs.isEmpty) ByteString.empty
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else new ByteStrings(bs, length - n)
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else new ByteStrings(h +: bs, length - n)
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} else ByteStrings(remainingByteStrings, length - n)
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if (remainingToDrop == 0)
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new ByteStrings(bytestrings.drop(fullDrops), length - n)
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else if (fullDrops == bytestrings.length - 1)
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bytestrings(fullDrops).drop(remainingToDrop)
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else
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new ByteStrings(bytestrings(fullDrops).drop1(remainingToDrop) +: bytestrings.drop(fullDrops + 1), length - n)
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}
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protected def writeReplace(): AnyRef = new SerializationProxy(this)
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@ -0,0 +1,69 @@
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/**
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* Copyright (C) 2014-2016 Lightbend Inc. <http://www.lightbend.com>
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*/
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package akka.util
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import java.util.concurrent.TimeUnit
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import akka.util.ByteString.{ ByteString1, ByteStrings }
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import org.openjdk.jmh.annotations._
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import scala.util.Random
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@State(Scope.Benchmark)
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@Measurement(timeUnit = TimeUnit.MILLISECONDS)
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class ByteString_drop_Benchmark {
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val str = List.fill[Byte](4)(0).mkString
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val numVec = 1024
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val bss = ByteStrings(Vector.fill(numVec)(ByteString1.fromString(str)))
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val rand = new Random()
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val len = str.size * numVec
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val n_greater_or_eq_to_len = len + rand.nextInt(Int.MaxValue - len)
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val n_neg = rand.nextInt(Int.MaxValue) * -1
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val n_avg = len / 2
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val n_best = 1
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val n_worst = len - 1
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/*
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--------------------------------- BASELINE ------------------------------------------------------------------
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[info] Benchmark Mode Cnt Score Error Units
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[info] ByteString_drop_Benchmark.bss_avg thrpt 40 544841.222 ± 12917.565 ops/s
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[info] ByteString_drop_Benchmark.bss_best thrpt 40 10141204.609 ± 415441.925 ops/s
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[info] ByteString_drop_Benchmark.bss_greater_or_eq_to_len thrpt 40 902173327.723 ± 9921650.983 ops/s
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[info] ByteString_drop_Benchmark.bss_negative thrpt 40 1179430602.793 ± 12193702.247 ops/s
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[info] ByteString_drop_Benchmark.bss_worst thrpt 40 297489.038 ± 5534.801 ops/s
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*/
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@Benchmark
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def bss_negative(): Unit = {
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@volatile var m: ByteString = null
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m = bss.drop(n_neg)
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}
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@Benchmark
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def bss_greater_or_eq_to_len(): Unit = {
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@volatile var m: ByteString = null
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m = bss.drop(n_greater_or_eq_to_len)
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}
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@Benchmark
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def bss_avg(): Unit = {
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@volatile var m: ByteString = null
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m = bss.drop(n_avg)
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}
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@Benchmark
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def bss_best(): Unit = {
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@volatile var m: ByteString = null
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m = bss.drop(n_best)
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}
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@Benchmark
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def bss_worst(): Unit = {
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@volatile var m: ByteString = null
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m = bss.drop(n_worst)
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}
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}
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