The current adjusttimers does an O(n) loop and then queues
a bunch of reinsertions, each of which is O(log n), for a worst
case of O(n log n) time plus an allocation of n elements.
Reestablishing the heap invariant from an arbitrarily ordered
slice can be done in O(n) time, so it is both simpler and faster
to avoid the allocated temporary queue and just re-init the
heap if we have damaged it. The cost of doing so is no worse
than the O(n) loop we already did.
This change also avoids holding multiple timers locked (status
set to timerMoving) at any given moment, as well as holding
individual timers locked for unbounded amounts of time,
as opposed to fixed-size critical sections.
[This is one CL in a refactoring stack making very small changes
in each step, so that any subtle bugs that we miss can be more
easily pinpointed to a small change.]
Change-Id: If966c1d1e66db797f4b19e7b1abbc06ab651764d
Reviewed-on: https://go-review.googlesource.com/c/go/+/564115 Reviewed-by: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>