public void EditWhileIteratingThreaded()
{
var d = new ConcurrentDictionary <string, string>();
Assert.IsTrue(d.TryAdd("0", "1"));
Assert.IsTrue(d.TryAdd("a", "b"));
int[] expectedCount = { 2 };
Assert.AreEqual(expectedCount[0], d.Count);
string a = null;
var foundCount = 0;
var didAdd = 0;
var didRemove = 0;
var found = new CircularBucket <string>(16);
ThreadStart remover = () =>
{
var removed = d.TryRemove("a", out a);
if (Thread.VolatileRead(ref didRemove) == 0 && removed)
{
expectedCount[0]--;
}
if (removed)
{
Interlocked.CompareExchange(ref didRemove, 1, 0);
}
};
ThreadStart adder = () =>
{
var added = d.TryAdd("c", "d");
if (Thread.VolatileRead(ref didAdd) == 0 && added)
{
expectedCount[0]++;
}
if (added)
{
Interlocked.CompareExchange(ref didAdd, 1, 0);
}
};
// MSDN says: "it does not represent a moment-in-time snapshot of the dictionary."
// And also "The contents exposed through the enumerator may contain modifications made to the dictionary after GetEnumerator was called."
foreach (var item in d)
{
found.Add(item.Key);
foundCount++;
var old = expectedCount[0];
Assert.AreEqual(expectedCount[0], d.Count);
{
var t = new Thread(remover);
t.Start();
t.Join();
}
if (foundCount == 1)
{
Assert.AreNotEqual(old, expectedCount[0]);
}
else
{
Assert.AreEqual(old, expectedCount[0]);
}
Assert.AreEqual(expectedCount[0], d.Count);
old = expectedCount[0];
{
var t = new Thread(adder);
t.Start();
t.Join();
}
if (foundCount == 1)
{
Assert.AreNotEqual(old, expectedCount[0]);
}
else
{
Assert.AreEqual(old, expectedCount[0]);
}
Assert.AreEqual(expectedCount[0], d.Count);
}
Assert.IsNull(a);
var array = found.ToArray();
if (!array.IsSupersetOf(new[] { "0", "c" }))
{
foreach (var item in array)
{
Console.WriteLine(item);
}
Assert.Fail();
}
Assert.AreEqual(2, expectedCount[0]);
Assert.AreEqual(1, didAdd);
Assert.AreEqual(1, didRemove);
Assert.IsTrue(foundCount - expectedCount[0] < 2, "foundCount: {0}, expectedCount:{1}", foundCount, expectedCount[0]);
Assert.AreEqual(expectedCount[0], d.Count);
}
public void EditWhileIterating()
{
var d = new ConcurrentDictionary <string, string>();
Assert.IsTrue(d.TryAdd("0", "1"));
Assert.IsTrue(d.TryAdd("a", "b"));
var expectedCount = 2;
Assert.AreEqual(expectedCount, d.Count);
string a = null;
var foundCount = 0;
var didAdd = false;
var didRemove = false;
var found = new CircularBucket <string>(16);
// MSDN says: "it does not represent a moment-in-time snapshot of the dictionary."
// And also "The contents exposed through the enumerator may contain modifications made to the dictionary after GetEnumerator was called."
// Note: There is no guarantee the items are in insert order
foreach (var item in d)
{
found.Add(item.Key);
foundCount++;
Assert.AreEqual(expectedCount, d.Count);
var removed = d.TryRemove("a", out a);
if (didRemove)
{
Assert.IsFalse(removed);
}
else
{
Assert.IsTrue(removed);
expectedCount--;
}
didRemove = didRemove | removed;
Assert.IsTrue(didRemove);
Assert.AreEqual(expectedCount, d.Count);
var added = d.TryAdd("c", "d");
if (didAdd)
{
Assert.IsFalse(added);
}
else
{
Assert.IsTrue(added);
expectedCount++;
}
didAdd = didAdd | added;
Assert.IsTrue(didAdd);
Assert.AreEqual(expectedCount, d.Count);
}
Assert.IsNull(a);
var array = found.ToArray();
if (!array.IsSupersetOf(new[] { "0", "c" }))
{
foreach (var item in array)
{
Console.WriteLine(item);
}
Assert.Fail();
}
Assert.AreEqual(2, expectedCount);
Assert.AreEqual(true, didAdd);
Assert.AreEqual(true, didRemove);
Assert.IsTrue(foundCount - expectedCount < 2, "foundCount: {0}, expectedCount:{1}", foundCount, expectedCount);
Assert.AreEqual(expectedCount, d.Count);
}