1 files changed, 152 insertions, 0 deletions
diff --git a/osdep/mac/precise_timer.swift b/osdep/mac/precise_timer.swift
new file mode 100644
index 0000000000..6d5f0b43d0
--- /dev/null
+++ b/osdep/mac/precise_timer.swift
@@ -0,0 +1,152 @@
+/*
+ * This file is part of mpv.
+ *
+ * mpv is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * mpv is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with mpv.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+import Cocoa
+
+struct Timing {
+    let time: UInt64
+    let closure: () -> Void
+}
+
+class PreciseTimer {
+    unowned var common: Common
+
+    let nanoPerSecond: Double = 1e+9
+    let machToNano: Double = {
+        var timebase: mach_timebase_info = mach_timebase_info()
+        mach_timebase_info(&timebase)
+        return Double(timebase.numer) / Double(timebase.denom)
+    }()
+
+    let condition = NSCondition()
+    var events: [Timing] = []
+    var isRunning: Bool = true
+    var isHighPrecision: Bool = false
+
+    var thread: pthread_t!
+    var threadPort: thread_port_t = thread_port_t()
+    let policyFlavor = thread_policy_flavor_t(THREAD_TIME_CONSTRAINT_POLICY)
+    let policyCount = MemoryLayout<thread_time_constraint_policy>.size /
+                          MemoryLayout<integer_t>.size
+    var typeNumber: mach_msg_type_number_t {
+        return mach_msg_type_number_t(policyCount)
+    }
+    var threadAttr: pthread_attr_t = {
+        var attr = pthread_attr_t()
+        var param = sched_param()
+        pthread_attr_init(&attr)
+        param.sched_priority = sched_get_priority_max(SCHED_FIFO)
+        pthread_attr_setschedparam(&attr, &param)
+        pthread_attr_setschedpolicy(&attr, SCHED_FIFO)
+        return attr
+    }()
+
+    init?(common com: Common) {
+        common = com
+
+        pthread_create(&thread, &threadAttr, entryC, TypeHelper.bridge(obj: self))
+        if thread == nil {
+            common.log.warning("Couldn't create pthread for high precision timer")
+            return nil
+        }
+
+        threadPort = pthread_mach_thread_np(thread)
+    }
+
+    func updatePolicy(periodSeconds: Double = 1 / 60.0) {
+        let period = periodSeconds * nanoPerSecond / machToNano
+        var policy = thread_time_constraint_policy(
+            period: UInt32(period),
+            computation: UInt32(0.75 * period),
+            constraint: UInt32(0.85 * period),
+            preemptible: 1
+        )
+
+        let success = withUnsafeMutablePointer(to: &policy) {
+            $0.withMemoryRebound(to: integer_t.self, capacity: policyCount) {
+                thread_policy_set(threadPort, policyFlavor, $0, typeNumber)
+            }
+        }
+
+        isHighPrecision = success == KERN_SUCCESS
+        if !isHighPrecision {
+            common.log.warning("Couldn't create a high precision timer")
+        }
+    }
+
+    func terminate() {
+        condition.lock()
+        isRunning = false
+        condition.signal()
+        condition.unlock()
+        pthread_kill(thread, SIGALRM)
+        pthread_join(thread, nil)
+    }
+
+    func scheduleAt(time: UInt64, closure: @escaping () -> Void) {
+        condition.lock()
+        let firstEventTime = events.first?.time ?? 0
+        let lastEventTime = events.last?.time ?? 0
+        events.append(Timing(time: time, closure: closure))
+
+        if lastEventTime > time {
+            events.sort { $0.time < $1.time }
+        }
+
+        condition.signal()
+        condition.unlock()
+
+        if firstEventTime > time {
+            pthread_kill(thread, SIGALRM)
+        }
+    }
+
+    let threadSignal: @convention(c) (Int32) -> Void = { (_ sig: Int32) in }
+
+    let entryC: @convention(c) (UnsafeMutableRawPointer) -> UnsafeMutableRawPointer? = { (ptr: UnsafeMutableRawPointer) in
+        let ptimer: PreciseTimer = TypeHelper.bridge(ptr: ptr)
+        ptimer.entry()
+        return nil
+    }
+
+    func entry() {
+        signal(SIGALRM, threadSignal)
+
+        while isRunning {
+            condition.lock()
+            while events.count == 0 && isRunning {
+                condition.wait()
+            }
+
+            if !isRunning { break }
+
+            guard let event = events.first else {
+                continue
+            }
+            condition.unlock()
+
+            mach_wait_until(event.time)
+
+            condition.lock()
+            if events.first?.time == event.time && isRunning {
+                event.closure()
+                events.removeFirst()
+            }
+            condition.unlock()
+        }
+    }
+}