public void HeaderPage_Savepoint()
{
var data = new byte[Constants.PAGE_SIZE];
var buffer = new PageBuffer(data, 0, 1);
// mark buffer as writable (debug propose)
buffer.ShareCounter = Constants.BUFFER_WRITABLE;
// create new header page
var header = new HeaderPage(buffer, 0);
header.InsertCollection("my-col1", 1);
header.InsertCollection("my-col2", 2);
header.GetCollections().Count().Should().Be(2);
// savepoint alse execute UpdateBuffer
var sp = header.Savepoint();
header.DeleteCollection("my-col1");
header.DeleteCollection("my-col2");
header.UpdateBuffer();
header.GetCollections().Count().Should().Be(0);
// now, restore header
header.Restore(sp);
header.GetCollections().Count().Should().Be(2);
buffer.ShareCounter = 0;
}
public void HeaderPage_Collections()
{
var data = new byte[Constants.PAGE_SIZE];
var buffer = new PageBuffer(data, 0, 1);
// mark buffer as writable (debug propose)
buffer.ShareCounter = Constants.BUFFER_WRITABLE;
// create new header page
var header = new HeaderPage(buffer, 0);
header.InsertCollection("my-col1", 1);
header.InsertCollection("my-col2", 2);
header.GetCollections().Count().Should().Be(2);
((int)header.GetCollectionPageID("my-col1")).Should().Be(1);
((int)header.GetCollectionPageID("my-col2")).Should().Be(2);
header.GetAvaiableCollectionSpace().Should().Be(7981);
header.UpdateBuffer();
// read header
var h2 = new HeaderPage(buffer);
h2.GetCollections().Count().Should().Be(2);
((int)h2.GetCollectionPageID("my-col1")).Should().Be(1);
((int)h2.GetCollectionPageID("my-col2")).Should().Be(2);
h2.GetAvaiableCollectionSpace().Should().Be(7981);
buffer.ShareCounter = 0;
}
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);
}
