public void Disk_Read_Write()
{
var settings = new EngineSettings
{
MemorySegmentSize = 10,
DataStream = new MemoryStream(),
LogStream = new MemoryStream()
};
var disk = new DiskService(settings);
var pages = new List <PageBuffer>();
// let's create 100 pages with 0-99 full data
for (var i = 0; i < 100; i++)
{
var p = disk.NewPage();
p.Fill((byte)i); // fills with 0 - 99
pages.Add(p);
}
// page will be saved in LOG file in PagePosition order (0-99)
disk.WriteAsync(pages);
// wait for async queue writes
disk.Queue.Wait();
// after release, no page can be read/write
pages.Clear();
// lets do some read tests
var reader = disk.GetReader();
for (var i = 0; i < 100; i++)
{
var p = reader.ReadPage(i * 8192, false, FileOrigin.Log);
p.All((byte)i).Should().BeTrue();
p.Release();
}
// test cache in use
disk.Cache.PagesInUse.Should().Be(0);
// wait all async threads
disk.Dispose();
}
public void CacheAsync_Thread_ShareCounter()
{
// Set() - Seta true - Se estiver bloqueado, vai liberar
// Reset() - Seta false - Quando chegar no proximo Wait() vai aguardar
// Wait() - Trava a thread SE estiver false (Reset) - Passa reto se estiver true (Set)
var wa = new ManualResetEventSlim(true);
var wb = new ManualResetEventSlim(false);
// serialize 2 threads
void serialize(ManualResetEventSlim toBlock, ManualResetEventSlim toFree)
{
toBlock?.Reset();
toFree.Set();
toBlock?.Wait();
}
;
var disk = new DiskService(new EngineSettings {
DataStream = new MemoryStream(), MemorySegmentSize = 10
});
var ta = new Task(() =>
{
var r = disk.GetReader();
wa.Wait();
// test starts here!!!
var p0 = new HeaderPage(r.NewPage(), 0);
p0.UserVersion = 25;
disk.WriteAsync(new PageBuffer[] { p0.UpdateBuffer() });
// (1 ->) jump to thread B
serialize(wa, wb);
// (2 <-) continue from thread B
disk.Queue.Wait();
// (3 ->) jump to thread B
serialize(wa, wb);
});
var tb = new Task(() =>
{
var r = disk.GetReader();
wb.Wait();
// (1 <-) continue from thread A
var p0 = r.ReadPage(0, false, FileOrigin.Log);
// share counter can be 2 or 3
// - if 2, page was not persisted yet on disk (async)
// - if 1, page already persisted on disk
var share = p0.ShareCounter;
(share >= 1 && share <= 2).Should().BeTrue();
// (2 ->) jump to thread A
serialize(wb, wa);
// (3 <-) continue from thread B
// but now, I'm sure this page was saved and thread A release
p0.ShareCounter.Should().Be(1);
// let's release my page
p0.Release();
p0.ShareCounter.Should().Be(0);
// release thread A
serialize(null, wa);
});
ta.Start();
tb.Start();
Task.WaitAll(ta, tb);
}