public void ReadOnlySnapshot()
{
var blob = NewBlob();
var writer = new CloudBlobBacked <string>(
blob,
writeToCloudFrequency: ShortInterval);
writer.Object = "hello";
PauseForReplication();
var snapshot = new CloudBlobBacked <string>(blob);
Assert.AreEqual("hello", snapshot.Object);
writer.Object = "changed";
PauseForReplication();
Assert.AreEqual("hello", snapshot.Object);
var snapshot2 = new CloudBlobBacked <string>(blob);
Assert.AreEqual("changed", snapshot2.Object);
writer.Shutdown();
}
public void ReaderWriterWithoutLease()
{
var blob = NewBlob();
var writer = new CloudBlobBacked <string>(
blob,
leaseDuration: null,
writeToCloudFrequency: ShortInterval);
var reader = new CloudBlobBacked <string>(
blob,
readFromCloudFrequency: ShortInterval);
writer.Object = "Hello world!";
int attempts = 0;
while (!writer.Object.Equals(reader.Object) && (attempts < 10))
{
PauseForReplication();
attempts++;
}
Assert.AreEqual(writer.Object, "Hello world!");
Assert.AreEqual(reader.Object, "Hello world!");
reader.Shutdown();
writer.Shutdown();
}
public void LockBlocksWrites()
{
var blob = NewBlob();
var writer1 = new CloudBlobBacked <string>(
blob,
writeToCloudFrequency: ShortInterval);
var writer2 = new CloudBlobBacked <string>(
blob,
writeToCloudFrequency: ShortInterval);
writer1.Object = "hello";
PauseForReplication();
var reader = new CloudBlobBacked <string>(
blob,
readFromCloudFrequency: ShortInterval);
Assert.AreEqual("hello", reader.Object);
lock (writer1.SyncRoot)
{
Assert.AreEqual("hello", reader.Object);
writer1.Object = "1";
writer2.Object = "2";
PauseForReplication();
Assert.AreEqual("2", reader.Object);
writer2.Shutdown();
}
PauseForReplication();
Assert.AreEqual("1", reader.Object);
reader.Shutdown();
writer1.Shutdown();
writer2.Shutdown();
}
public void Lease()
{
var blob = NewBlob();
// Take a lease out on a new blob
var exclusiveWriter = new CloudBlobBacked <string>(
blob,
writeToCloudFrequency: ShortInterval,
leaseDuration: LeaseDuration);
exclusiveWriter.Object = "Hello";
// Verify that no one else can take the lease
try
{
new CloudBlobBacked <string>(blob, leaseDuration: LeaseDuration);
Assert.Fail("I managed to take a lease on this object form elsewhere");
}
catch (InvalidOperationException)
{
}
// A reader is ok though
PauseForReplication();
var reader = new CloudBlobBacked <string>(blob, readFromCloudFrequency: ShortInterval);
Assert.AreEqual("Hello", reader.Object);
// Someone else can try and update it, but updates will not be made while the lease is active...
var otherWriter = new CloudBlobBacked <string>(blob, writeToCloudFrequency: ShortInterval);
otherWriter.Object = "I changed";
PauseForReplication();
Assert.AreNotEqual("I changed", reader.Object);
Assert.AreEqual("I changed", otherWriter.Object);
// The write will eventually be made after the lease is given up though
exclusiveWriter.Shutdown();
PauseForReplication();
Assert.AreEqual("I changed", reader.Object);
Assert.AreEqual("I changed", otherWriter.Object);
reader.Shutdown();
otherWriter.Shutdown();
}
public void MultipleWritersStress()
{
var blob = NewBlob();
// Two instances fighting over the value of an object and a witness
// that ensures they each win at least 'Difficulty' times.
const int Difficulty = 4;
var witness = new CloudBlobBacked <string>(
blob,
readFromCloudFrequency: ShortInterval);
var writer1 = new CloudBlobBacked <string>(
blob,
readFromCloudFrequency: ShortInterval,
writeToCloudFrequency: TimeSpan.FromSeconds(0.3));
var writer2 = new CloudBlobBacked <string>(
blob,
readFromCloudFrequency: ShortInterval,
writeToCloudFrequency: TimeSpan.FromSeconds(0.7));
int writer1SuccessCount = 0;
int writer2SuccessCount = 0;
witness.OnUpdate += (s, e) =>
{
writer1SuccessCount += "1".Equals(witness.Object) ? 1 : 0;
writer2SuccessCount += "2".Equals(witness.Object) ? 1 : 0;
};
while ((writer1SuccessCount < Difficulty) || (writer2SuccessCount < Difficulty))
{
writer1.Object = "1";
writer2.Object = "2";
Thread.Sleep(TimeSpan.FromSeconds(0.5));
}
witness.Shutdown();
writer1.Shutdown();
writer2.Shutdown();
}
public void ReaderWriterWithLease()
{
var blob = NewBlob();
var writer = new CloudBlobBacked <string>(
blob,
leaseDuration: LeaseDuration,
writeToCloudFrequency: ShortInterval);
var reader = new CloudBlobBacked <string>(
blob,
readFromCloudFrequency: ShortInterval);
writer.Object = "Hello world!";
PauseForReplication();
Assert.AreEqual(writer.Object, reader.Object);
reader.Shutdown();
writer.Shutdown();
}
private void AllVariations <T>(Action <CloudBlobBacked <T> > test) where T : class
{
Trace.TraceInformation("readOnce");
var readOnce =
new CloudBlobBacked <T>(NewBlob());
test(readOnce);
readOnce.Shutdown();
Trace.TraceInformation("readOnceUnderLease");
var readOnceUnderLease =
new CloudBlobBacked <T>(NewBlob(), leaseDuration: LeaseDuration);
test(readOnceUnderLease);
readOnceUnderLease.Shutdown();
Trace.TraceInformation("readContinually");
var readContinually =
new CloudBlobBacked <T>(NewBlob(), readFromCloudFrequency: ShortInterval);
test(readContinually);
readContinually.Shutdown();
Trace.TraceInformation("readContinuallyUnderLease");
var readContinuallyUnderLease = new CloudBlobBacked <T>(
NewBlob(),
readFromCloudFrequency: ShortInterval,
leaseDuration: LeaseDuration);
test(readContinuallyUnderLease);
readContinuallyUnderLease.Shutdown();
Trace.TraceInformation("writeContinually");
var writeContinually =
new CloudBlobBacked <T>(NewBlob(), writeToCloudFrequency: ShortInterval);
test(writeContinually);
writeContinually.Shutdown();
Trace.TraceInformation("writeContinuallyUnderLease");
var writeContinuallyUnderLease = new CloudBlobBacked <T>(
NewBlob(),
writeToCloudFrequency: ShortInterval,
leaseDuration: LeaseDuration);
test(writeContinuallyUnderLease);
writeContinuallyUnderLease.Shutdown();
Trace.TraceInformation("readWriteContinually");
var readWriteContinually = new CloudBlobBacked <T>(
NewBlob(),
readFromCloudFrequency: ShortInterval,
writeToCloudFrequency: ShortInterval);
test(readWriteContinually);
readWriteContinually.Shutdown();
Trace.TraceInformation("readWriteContinuallyUnderLease");
var readWriteContinuallyUnderLease = new CloudBlobBacked <T>(
NewBlob(),
readFromCloudFrequency: ShortInterval,
writeToCloudFrequency: ShortInterval,
leaseDuration: LeaseDuration);
test(readWriteContinuallyUnderLease);
readWriteContinuallyUnderLease.Shutdown();
}