1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
|
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())
}
}
}
|