From eeb5318c25ac8bce5c1d1a14847768715cb68e79 Mon Sep 17 00:00:00 2001
From: Brian Gianforcaro <b.gianfo@gmail.com>
Date: Sun, 26 Apr 2020 12:59:27 -0700
Subject: [PATCH] Kernel: Expose timers via a TimerId type

The public consumers of the timer API shouldn't need to know
the how timer id's are tracked internally. Expose a typedef
instead to allow the internal implementation to be protected
from potential churn in the future.

It's also just good API design.
---
 Kernel/Thread.cpp     |  2 +-
 Kernel/TimerQueue.cpp |  6 +++---
 Kernel/TimerQueue.h   | 10 ++++++----
 3 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/Kernel/Thread.cpp b/Kernel/Thread.cpp
index a15c5c388b..6702d00564 100644
--- a/Kernel/Thread.cpp
+++ b/Kernel/Thread.cpp
@@ -893,7 +893,7 @@ Thread::BlockResult Thread::wait_on(WaitQueue& queue, timeval* timeout, Atomic<b
     set_state(State::Queued);
     queue.enqueue(*current);
 
-    u64 timer_id = 0;
+    TimerId timer_id {};
     if (timeout) {
         timer_id = TimerQueue::the().add_timer(*timeout, [&]() {
             wake_from_queue();
diff --git a/Kernel/TimerQueue.cpp b/Kernel/TimerQueue.cpp
index 4222102b42..2435c31611 100644
--- a/Kernel/TimerQueue.cpp
+++ b/Kernel/TimerQueue.cpp
@@ -47,7 +47,7 @@ TimerQueue::TimerQueue()
     m_ticks_per_second = TimeManagement::the().ticks_per_second();
 }
 
-u64 TimerQueue::add_timer(NonnullOwnPtr<Timer>&& timer)
+TimerId TimerQueue::add_timer(NonnullOwnPtr<Timer>&& timer)
 {
     ASSERT(timer->expires >= g_uptime);
 
@@ -64,7 +64,7 @@ u64 TimerQueue::add_timer(NonnullOwnPtr<Timer>&& timer)
     return m_timer_id_count;
 }
 
-u64 TimerQueue::add_timer(timeval& deadline, Function<void()>&& callback)
+TimerId TimerQueue::add_timer(timeval& deadline, Function<void()>&& callback)
 {
     NonnullOwnPtr timer = make<Timer>();
     timer->expires = g_uptime + seconds_to_ticks(deadline.tv_sec) + microseconds_to_ticks(deadline.tv_usec);
@@ -72,7 +72,7 @@ u64 TimerQueue::add_timer(timeval& deadline, Function<void()>&& callback)
     return add_timer(move(timer));
 }
 
-bool TimerQueue::cancel_timer(u64 id)
+bool TimerQueue::cancel_timer(TimerId id)
 {
     auto it = m_timer_queue.find([id](auto& timer) { return timer->id == id; });
     if (it.is_end())
diff --git a/Kernel/TimerQueue.h b/Kernel/TimerQueue.h
index d0fd9d0381..449609da94 100644
--- a/Kernel/TimerQueue.h
+++ b/Kernel/TimerQueue.h
@@ -34,8 +34,10 @@
 
 namespace Kernel {
 
+typedef u64 TimerId;
+
 struct Timer {
-    u64 id;
+    TimerId id;
     u64 expires;
     Function<void()> callback;
     bool operator<(const Timer& rhs) const
@@ -56,9 +58,9 @@ class TimerQueue {
 public:
     static TimerQueue& the();
 
-    u64 add_timer(NonnullOwnPtr<Timer>&&);
-    u64 add_timer(timeval& timeout, Function<void()>&& callback);
-    bool cancel_timer(u64 id);
+    TimerId add_timer(NonnullOwnPtr<Timer>&&);
+    TimerId add_timer(timeval& timeout, Function<void()>&& callback);
+    bool cancel_timer(TimerId id);
     void fire();
 
 private: