adb: fdevent: add fdevent_context_epoll.
Implement an epoll-backed fdevent_context, that reduces overhead when
we're polling many file descriptors. FdeventTest.smoke goes from ~5.2s
to ~3.3s when run on the host (after this patch's modification to change
it from chaining 10 file descriptors together to 512).
Test: adb_test on host
Test: adbd_test on blueline
Test: test_adb.py
Test: test_device.py
Change-Id: Iacf0093aa7bebea31e447c2cb012af72d8c3297e
diff --git a/adb/fdevent/fdevent.h b/adb/fdevent/fdevent.h
index 3d30d49..86814d7 100644
--- a/adb/fdevent/fdevent.h
+++ b/adb/fdevent/fdevent.h
@@ -60,6 +60,8 @@
fdevent* Create(unique_fd fd, std::variant<fd_func, fd_func2> func, void* arg);
// Deallocate an fdevent object, returning the file descriptor that was owned by it.
+ // Note that this calls Set, which is a virtual method, so destructors that call this must be
+ // final.
unique_fd Destroy(fdevent* fde);
protected: