bufferstreams: Present times are no longer Instants.

We need to be able to read these over the wire and send them as
timestamps to C++ code. Replace the instants with a more compatible i64
timestamp nanos timestamp.

Test: atest
Change-Id: Ia63685ac406855b4a9257c661839640ab74a555c

Author: James Shargo

libs/bufferstreams/rust/src/lib.rs

@@ -23,8 +23,6 @@ pub mod subscriptions;
 use buffers::Buffer;
 pub use stream_config::*;
 
-use std::time::Instant;
-
 /// This function will print Hello World.
 #[no_mangle]
 pub extern "C" fn hello() -> bool {
@@ -106,7 +104,8 @@ pub trait BufferSubscriber {
 /// BufferSubscriptions serve as the bridge between BufferPublishers and
 /// BufferSubscribers. BufferSubscribers receive a BufferSubscription when they
 /// subscribe to a BufferPublisher via on_subscribe.
-/// This object is to be used by the BufferSubscriber to cancel its subscription
+///
+/// This object is used by the BufferSubscriber to cancel its subscription
 /// or request more buffers.
 ///
 /// BufferSubcriptions are required to adhere to the following, based on the
@@ -147,7 +146,7 @@ pub trait BufferSubscriber {
 /// no other Subscription exists at this point.
 /// * Calling Subscription.cancel MUST return normally.
 /// * Calling Subscription.request MUST return normally.
-pub trait BufferSubscription {
+pub trait BufferSubscription: Send + Sync + 'static {
     /// request
     fn request(&self, n: u64);
     /// cancel
@@ -161,8 +160,8 @@ pub type BufferError = anyhow::Error;
 pub struct Frame {
     /// A buffer to be used this frame.
     pub buffer: Buffer,
-    /// The time at which the buffer was dispatched.
-    pub present_time: Instant,
+    /// The time at which this buffer is expected to be displayed.
+    pub present_time: i64,
     /// A fence used for reading/writing safely.
     pub fence: i32,
 }
@@ -175,14 +174,12 @@ mod test {
     use anyhow::anyhow;
     use buffers::Buffer;
     use nativewindow::{AHardwareBuffer_Format, AHardwareBuffer_UsageFlags};
-    use std::borrow::BorrowMut;
-    use std::error::Error;
-    use std::ops::Add;
-    use std::sync::Arc;
-    use std::time::Duration;
+    use std::{borrow::BorrowMut, error::Error, ops::Add, sync::Arc};
 
-    use crate::publishers::testing::*;
-    use crate::subscribers::{testing::*, SharedSubscriber};
+    use crate::{
+        publishers::testing::*,
+        subscribers::{testing::*, SharedSubscriber},
+    };
 
     const STREAM_CONFIG: StreamConfig = StreamConfig {
         width: 1,
@@ -200,7 +197,7 @@ mod test {
                     .create_hardware_buffer()
                     .expect("Unable to create hardware buffer for test"),
             ),
-            present_time: Instant::now() + Duration::from_secs(1),
+            present_time: 1,
             fence: 0,
         }
     }

libs/bufferstreams/rust/src/publishers/buffer_pool_publisher.rs

@@ -14,8 +14,6 @@
 
 //!
 
-use std::time::Instant;
-
 use crate::{
     buffers::BufferPool, subscriptions::SharedBufferSubscription, BufferPublisher,
     BufferSubscriber, Frame, StreamConfig,
@@ -43,7 +41,7 @@ impl BufferPoolPublisher {
 
     /// If the [SharedBufferSubscription] is ready for a [Frame], a buffer will be requested from
     /// [BufferPool] and sent over to the [BufferSubscriber].
-    pub fn send_next_frame(&mut self, present_time: Instant) -> bool {
+    pub fn send_next_frame(&mut self, present_time: i64) -> bool {
         if let Some(subscriber) = self.subscriber.as_mut() {
             if self.subscription.take_request() {
                 if let Some(buffer) = self.buffer_pool.next_buffer() {
@@ -103,7 +101,7 @@ mod test {
 
         subscriber.map_inner(|s| s.request(1));
 
-        assert!(buffer_pool_publisher.send_next_frame(Instant::now()));
+        assert!(buffer_pool_publisher.send_next_frame(1));
 
         let events = subscriber.map_inner_mut(|s| s.take_events());
         assert!(matches!(events.last().unwrap(), TestingSubscriberEvent::Next(_)));