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import collection._
import collection.concurrent.TrieMap
object SnapshotSpec extends Spec {
def test() {
"support snapshots" in {
val ctn = new TrieMap
ctn.snapshot()
ctn.readOnlySnapshot()
val ct = new TrieMap[Int, Int]
for (i <- 0 until 100) ct.put(i, i)
ct.snapshot()
ct.readOnlySnapshot()
}
"empty 2 quiescent snapshots in isolation" in {
val sz = 4000
class Worker(trie: TrieMap[Wrap, Int]) extends Thread {
override def run() {
for (i <- 0 until sz) {
assert(trie.remove(new Wrap(i)) == Some(i))
for (j <- 0 until sz)
if (j <= i) assert(trie.get(new Wrap(j)) == None)
else assert(trie.get(new Wrap(j)) == Some(j))
}
}
}
val ct = new TrieMap[Wrap, Int]
for (i <- 0 until sz) ct.put(new Wrap(i), i)
val snapt = ct.snapshot()
val original = new Worker(ct)
val snapshot = new Worker(snapt)
original.start()
snapshot.start()
original.join()
snapshot.join()
for (i <- 0 until sz) {
assert(ct.get(new Wrap(i)) == None)
assert(snapt.get(new Wrap(i)) == None)
}
}
def consistentReadOnly(name: String, readonly: Map[Wrap, Int], sz: Int, N: Int) {
@volatile var e: Exception = null
// reads possible entries once and stores them
// then reads all these N more times to check if the
// state stayed the same
class Reader(trie: Map[Wrap, Int]) extends Thread {
setName("Reader " + name)
override def run() =
try check()
catch {
case ex: Exception => e = ex
}
def check() {
val initial = mutable.Map[Wrap, Int]()
for (i <- 0 until sz) trie.get(new Wrap(i)) match {
case Some(i) => initial.put(new Wrap(i), i)
case None => // do nothing
}
for (k <- 0 until N) {
for (i <- 0 until sz) {
val tres = trie.get(new Wrap(i))
val ires = initial.get(new Wrap(i))
if (tres != ires) println(i, "initially: " + ires, "traversal %d: %s".format(k, tres))
assert(tres == ires)
}
}
}
}
val reader = new Reader(readonly)
reader.start()
reader.join()
if (e ne null) {
e.printStackTrace()
throw e
}
}
// traverses the trie `rep` times and modifies each entry
class Modifier(trie: TrieMap[Wrap, Int], index: Int, rep: Int, sz: Int) extends Thread {
setName("Modifier %d".format(index))
override def run() {
for (k <- 0 until rep) {
for (i <- 0 until sz) trie.putIfAbsent(new Wrap(i), i) match {
case Some(_) => trie.remove(new Wrap(i))
case None => // do nothing
}
}
}
}
// removes all the elements from the trie
class Remover(trie: TrieMap[Wrap, Int], index: Int, totremovers: Int, sz: Int) extends Thread {
setName("Remover %d".format(index))
override def run() {
for (i <- 0 until sz) trie.remove(new Wrap((i + sz / totremovers * index) % sz))
}
}
"have a consistent quiescent read-only snapshot" in {
val sz = 10000
val N = 100
val W = 10
val ct = new TrieMap[Wrap, Int]
for (i <- 0 until sz) ct(new Wrap(i)) = i
val readonly = ct.readOnlySnapshot()
val threads = for (i <- 0 until W) yield new Modifier(ct, i, N, sz)
threads.foreach(_.start())
consistentReadOnly("qm", readonly, sz, N)
threads.foreach(_.join())
}
// now, we check non-quiescent snapshots, as these permit situations
// where a thread is caught in the middle of the update when a snapshot is taken
"have a consistent non-quiescent read-only snapshot, concurrent with removes only" in {
val sz = 1250
val W = 100
val S = 5000
val ct = new TrieMap[Wrap, Int]
for (i <- 0 until sz) ct(new Wrap(i)) = i
val threads = for (i <- 0 until W) yield new Remover(ct, i, W, sz)
threads.foreach(_.start())
for (i <- 0 until S) consistentReadOnly("non-qr", ct.readOnlySnapshot(), sz, 5)
threads.foreach(_.join())
}
"have a consistent non-quiescent read-only snapshot, concurrent with modifications" in {
val sz = 1000
val N = 7000
val W = 10
val S = 7000
val ct = new TrieMap[Wrap, Int]
for (i <- 0 until sz) ct(new Wrap(i)) = i
val threads = for (i <- 0 until W) yield new Modifier(ct, i, N, sz)
threads.foreach(_.start())
for (i <- 0 until S) consistentReadOnly("non-qm", ct.readOnlySnapshot(), sz, 5)
threads.foreach(_.join())
}
def consistentNonReadOnly(name: String, trie: TrieMap[Wrap, Int], sz: Int, N: Int) {
@volatile var e: Exception = null
// reads possible entries once and stores them
// then reads all these N more times to check if the
// state stayed the same
class Worker extends Thread {
setName("Worker " + name)
override def run() =
try check()
catch {
case ex: Exception => e = ex
}
def check() {
val initial = mutable.Map[Wrap, Int]()
for (i <- 0 until sz) trie.get(new Wrap(i)) match {
case Some(i) => initial.put(new Wrap(i), i)
case None => // do nothing
}
for (k <- 0 until N) {
// modify
for ((key, value) <- initial) {
val oldv = if (k % 2 == 0) value else -value
val newv = -oldv
trie.replace(key, oldv, newv)
}
// check
for (i <- 0 until sz) if (initial.contains(new Wrap(i))) {
val expected = if (k % 2 == 0) -i else i
//println(trie.get(new Wrap(i)))
assert(trie.get(new Wrap(i)) == Some(expected))
} else {
assert(trie.get(new Wrap(i)) == None)
}
}
}
}
val worker = new Worker
worker.start()
worker.join()
if (e ne null) {
e.printStackTrace()
throw e
}
}
"have a consistent non-quiescent snapshot, concurrent with modifications" in {
val sz = 9000
val N = 1000
val W = 10
val S = 400
val ct = new TrieMap[Wrap, Int]
for (i <- 0 until sz) ct(new Wrap(i)) = i
val threads = for (i <- 0 until W) yield new Modifier(ct, i, N, sz)
threads.foreach(_.start())
for (i <- 0 until S) {
consistentReadOnly("non-qm", ct.snapshot(), sz, 5)
consistentNonReadOnly("non-qsnap", ct.snapshot(), sz, 5)
}
threads.foreach(_.join())
}
"work when many concurrent snapshots are taken, concurrent with modifications" in {
val sz = 12000
val W = 10
val S = 10
val modifytimes = 1200
val snaptimes = 600
val ct = new TrieMap[Wrap, Int]
for (i <- 0 until sz) ct(new Wrap(i)) = i
class Snapshooter extends Thread {
setName("Snapshooter")
override def run() {
for (k <- 0 until snaptimes) {
val snap = ct.snapshot()
for (i <- 0 until sz) snap.remove(new Wrap(i))
for (i <- 0 until sz) assert(!snap.contains(new Wrap(i)))
}
}
}
val mods = for (i <- 0 until W) yield new Modifier(ct, i, modifytimes, sz)
val shooters = for (i <- 0 until S) yield new Snapshooter
val threads = mods ++ shooters
threads.foreach(_.start())
threads.foreach(_.join())
}
}
}
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