@Test(timeout = 1000)
public void readers_and_writers_must_block_on_evicting_page() throws Exception {
// If we have a loaded page ...
PageSwapper io = new BufferPageSwapper(ByteBuffer.allocate(TEST_PAGE_SIZE));
long pageId = 12;
PinnablePage page = table.load(io, pageId, PageLock.EXCLUSIVE);
monitor.observe(Fault.class);
// ... a page that will take a long time to evict
CountDownLatch latch = monitor.trap(is(new Evict(io, pageId)));
// ... and a page that is soon up for eviction
page.unpin(PageLock.EXCLUSIVE);
// ... then when we observe the eviction taking place
monitor.observe(Evict.class);
// ... other threads should not be able to pin that page
Thread pinForShared = fork($pinUnpin(page, io, pageId, PageLock.SHARED));
Thread pinForExclusive = fork($pinUnpin(page, io, pageId, PageLock.EXCLUSIVE));
awaitThreadState(pinForShared, Thread.State.WAITING);
awaitThreadState(pinForExclusive, Thread.State.WAITING);
// ... until the eviction finishes
latch.countDown();
pinForShared.join();
pinForExclusive.join();
}
@Test
public void must_notify_monitor_of_evicted_pages() throws Exception {
// If we load a page ...
PageSwapper io = new BufferPageSwapper(ByteBuffer.allocate(TEST_PAGE_SIZE));
long pageId = 12;
PinnablePage page = table.load(io, pageId, PageLock.EXCLUSIVE);
page.unpin(PageLock.EXCLUSIVE);
// ... then we should observe its page fault
assertThat(monitor.observe(Fault.class), is(new Fault(io, pageId)));
// ... and when it sits idle for long enough, we should observe its eviction
assertThat(monitor.observe(Evict.class), is(new Evict(io, pageId)));
}
@Test
public void flushing_pages_with_specific_pageio_must_not_race_with_eviction() throws Exception {
// The idea is that we repeatedly load a page with an EXCLUSIVE lock, and unpin it so it can
// be evicted. As soon as we have unpinned, we repeatedly try to flush it with our given
// PageIO. If this causes an exception to be thrown, then we've raced with the eviction
// where we shouldn't.
PageSwapper io = new BufferPageSwapper(ByteBuffer.allocate(TEST_PAGE_SIZE));
long pageId = 12;
PinnablePage page = table.load(io, pageId, PageLock.EXCLUSIVE);
monitor.observe(Fault.class);
page.unpin(PageLock.EXCLUSIVE); // eviction is now possible
LockSupport.unpark(sweeperThread);
while (monitor.tryObserve(Evict.class) == null) {
table.flush(io);
}
}
