Adding upstream version 115.7.0esr.upstream/115.7.0esr

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 690 insertions, 0 deletions

diff --git a/third_party/rust/tokio-stream/src/stream_map.rs b/third_party/rust/tokio-stream/src/stream_map.rs
new file mode 100644
index 0000000000..215980474b
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+++ b/third_party/rust/tokio-stream/src/stream_map.rs
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+use crate::Stream;
+
+use std::borrow::Borrow;
+use std::hash::Hash;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+
+/// Combine many streams into one, indexing each source stream with a unique
+/// key.
+///
+/// `StreamMap` is similar to [`StreamExt::merge`] in that it combines source
+/// streams into a single merged stream that yields values in the order that
+/// they arrive from the source streams. However, `StreamMap` has a lot more
+/// flexibility in usage patterns.
+///
+/// `StreamMap` can:
+///
+/// * Merge an arbitrary number of streams.
+/// * Track which source stream the value was received from.
+/// * Handle inserting and removing streams from the set of managed streams at
+///   any point during iteration.
+///
+/// All source streams held by `StreamMap` are indexed using a key. This key is
+/// included with the value when a source stream yields a value. The key is also
+/// used to remove the stream from the `StreamMap` before the stream has
+/// completed streaming.
+///
+/// # `Unpin`
+///
+/// Because the `StreamMap` API moves streams during runtime, both streams and
+/// keys must be `Unpin`. In order to insert a `!Unpin` stream into a
+/// `StreamMap`, use [`pin!`] to pin the stream to the stack or [`Box::pin`] to
+/// pin the stream in the heap.
+///
+/// # Implementation
+///
+/// `StreamMap` is backed by a `Vec<(K, V)>`. There is no guarantee that this
+/// internal implementation detail will persist in future versions, but it is
+/// important to know the runtime implications. In general, `StreamMap` works
+/// best with a "smallish" number of streams as all entries are scanned on
+/// insert, remove, and polling. In cases where a large number of streams need
+/// to be merged, it may be advisable to use tasks sending values on a shared
+/// [`mpsc`] channel.
+///
+/// [`StreamExt::merge`]: crate::StreamExt::merge
+/// [`mpsc`]: https://docs.rs/tokio/1.0/tokio/sync/mpsc/index.html
+/// [`pin!`]: https://docs.rs/tokio/1.0/tokio/macro.pin.html
+/// [`Box::pin`]: std::boxed::Box::pin
+///
+/// # Examples
+///
+/// Merging two streams, then remove them after receiving the first value
+///
+/// ```
+/// use tokio_stream::{StreamExt, StreamMap, Stream};
+/// use tokio::sync::mpsc;
+/// use std::pin::Pin;
+///
+/// #[tokio::main]
+/// async fn main() {
+///     let (tx1, mut rx1) = mpsc::channel::<usize>(10);
+///     let (tx2, mut rx2) = mpsc::channel::<usize>(10);
+///
+///     // Convert the channels to a `Stream`.
+///     let rx1 = Box::pin(async_stream::stream! {
+///           while let Some(item) = rx1.recv().await {
+///               yield item;
+///           }
+///     }) as Pin<Box<dyn Stream<Item = usize> + Send>>;
+///
+///     let rx2 = Box::pin(async_stream::stream! {
+///           while let Some(item) = rx2.recv().await {
+///               yield item;
+///           }
+///     }) as Pin<Box<dyn Stream<Item = usize> + Send>>;
+///
+///     tokio::spawn(async move {
+///         tx1.send(1).await.unwrap();
+///
+///         // This value will never be received. The send may or may not return
+///         // `Err` depending on if the remote end closed first or not.
+///         let _ = tx1.send(2).await;
+///     });
+///
+///     tokio::spawn(async move {
+///         tx2.send(3).await.unwrap();
+///         let _ = tx2.send(4).await;
+///     });
+///
+///     let mut map = StreamMap::new();
+///
+///     // Insert both streams
+///     map.insert("one", rx1);
+///     map.insert("two", rx2);
+///
+///     // Read twice
+///     for _ in 0..2 {
+///         let (key, val) = map.next().await.unwrap();
+///
+///         if key == "one" {
+///             assert_eq!(val, 1);
+///         } else {
+///             assert_eq!(val, 3);
+///         }
+///
+///         // Remove the stream to prevent reading the next value
+///         map.remove(key);
+///     }
+/// }
+/// ```
+///
+/// This example models a read-only client to a chat system with channels. The
+/// client sends commands to join and leave channels. `StreamMap` is used to
+/// manage active channel subscriptions.
+///
+/// For simplicity, messages are displayed with `println!`, but they could be
+/// sent to the client over a socket.
+///
+/// ```no_run
+/// use tokio_stream::{Stream, StreamExt, StreamMap};
+///
+/// enum Command {
+///     Join(String),
+///     Leave(String),
+/// }
+///
+/// fn commands() -> impl Stream<Item = Command> {
+///     // Streams in user commands by parsing `stdin`.
+/// # tokio_stream::pending()
+/// }
+///
+/// // Join a channel, returns a stream of messages received on the channel.
+/// fn join(channel: &str) -> impl Stream<Item = String> + Unpin {
+///     // left as an exercise to the reader
+/// # tokio_stream::pending()
+/// }
+///
+/// #[tokio::main]
+/// async fn main() {
+///     let mut channels = StreamMap::new();
+///
+///     // Input commands (join / leave channels).
+///     let cmds = commands();
+///     tokio::pin!(cmds);
+///
+///     loop {
+///         tokio::select! {
+///             Some(cmd) = cmds.next() => {
+///                 match cmd {
+///                     Command::Join(chan) => {
+///                         // Join the channel and add it to the `channels`
+///                         // stream map
+///                         let msgs = join(&chan);
+///                         channels.insert(chan, msgs);
+///                     }
+///                     Command::Leave(chan) => {
+///                         channels.remove(&chan);
+///                     }
+///                 }
+///             }
+///             Some((chan, msg)) = channels.next() => {
+///                 // Received a message, display it on stdout with the channel
+///                 // it originated from.
+///                 println!("{}: {}", chan, msg);
+///             }
+///             // Both the `commands` stream and the `channels` stream are
+///             // complete. There is no more work to do, so leave the loop.
+///             else => break,
+///         }
+///     }
+/// }
+/// ```
+#[derive(Debug)]
+pub struct StreamMap<K, V> {
+    /// Streams stored in the map
+    entries: Vec<(K, V)>,
+}
+
+impl<K, V> StreamMap<K, V> {
+    /// An iterator visiting all key-value pairs in arbitrary order.
+    ///
+    /// The iterator element type is &'a (K, V).
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio_stream::{StreamMap, pending};
+    ///
+    /// let mut map = StreamMap::new();
+    ///
+    /// map.insert("a", pending::<i32>());
+    /// map.insert("b", pending());
+    /// map.insert("c", pending());
+    ///
+    /// for (key, stream) in map.iter() {
+    ///     println!("({}, {:?})", key, stream);
+    /// }
+    /// ```
+    pub fn iter(&self) -> impl Iterator<Item = &(K, V)> {
+        self.entries.iter()
+    }
+
+    /// An iterator visiting all key-value pairs mutably in arbitrary order.
+    ///
+    /// The iterator element type is &'a mut (K, V).
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio_stream::{StreamMap, pending};
+    ///
+    /// let mut map = StreamMap::new();
+    ///
+    /// map.insert("a", pending::<i32>());
+    /// map.insert("b", pending());
+    /// map.insert("c", pending());
+    ///
+    /// for (key, stream) in map.iter_mut() {
+    ///     println!("({}, {:?})", key, stream);
+    /// }
+    /// ```
+    pub fn iter_mut(&mut self) -> impl Iterator<Item = &mut (K, V)> {
+        self.entries.iter_mut()
+    }
+
+    /// Creates an empty `StreamMap`.
+    ///
+    /// The stream map is initially created with a capacity of `0`, so it will
+    /// not allocate until it is first inserted into.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio_stream::{StreamMap, Pending};
+    ///
+    /// let map: StreamMap<&str, Pending<()>> = StreamMap::new();
+    /// ```
+    pub fn new() -> StreamMap<K, V> {
+        StreamMap { entries: vec![] }
+    }
+
+    /// Creates an empty `StreamMap` with the specified capacity.
+    ///
+    /// The stream map will be able to hold at least `capacity` elements without
+    /// reallocating. If `capacity` is 0, the stream map will not allocate.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio_stream::{StreamMap, Pending};
+    ///
+    /// let map: StreamMap<&str, Pending<()>> = StreamMap::with_capacity(10);
+    /// ```
+    pub fn with_capacity(capacity: usize) -> StreamMap<K, V> {
+        StreamMap {
+            entries: Vec::with_capacity(capacity),
+        }
+    }
+
+    /// Returns an iterator visiting all keys in arbitrary order.
+    ///
+    /// The iterator element type is &'a K.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio_stream::{StreamMap, pending};
+    ///
+    /// let mut map = StreamMap::new();
+    ///
+    /// map.insert("a", pending::<i32>());
+    /// map.insert("b", pending());
+    /// map.insert("c", pending());
+    ///
+    /// for key in map.keys() {
+    ///     println!("{}", key);
+    /// }
+    /// ```
+    pub fn keys(&self) -> impl Iterator<Item = &K> {
+        self.iter().map(|(k, _)| k)
+    }
+
+    /// An iterator visiting all values in arbitrary order.
+    ///
+    /// The iterator element type is &'a V.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio_stream::{StreamMap, pending};
+    ///
+    /// let mut map = StreamMap::new();
+    ///
+    /// map.insert("a", pending::<i32>());
+    /// map.insert("b", pending());
+    /// map.insert("c", pending());
+    ///
+    /// for stream in map.values() {
+    ///     println!("{:?}", stream);
+    /// }
+    /// ```
+    pub fn values(&self) -> impl Iterator<Item = &V> {
+        self.iter().map(|(_, v)| v)
+    }
+
+    /// An iterator visiting all values mutably in arbitrary order.
+    ///
+    /// The iterator element type is &'a mut V.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio_stream::{StreamMap, pending};
+    ///
+    /// let mut map = StreamMap::new();
+    ///
+    /// map.insert("a", pending::<i32>());
+    /// map.insert("b", pending());
+    /// map.insert("c", pending());
+    ///
+    /// for stream in map.values_mut() {
+    ///     println!("{:?}", stream);
+    /// }
+    /// ```
+    pub fn values_mut(&mut self) -> impl Iterator<Item = &mut V> {
+        self.iter_mut().map(|(_, v)| v)
+    }
+
+    /// Returns the number of streams the map can hold without reallocating.
+    ///
+    /// This number is a lower bound; the `StreamMap` might be able to hold
+    /// more, but is guaranteed to be able to hold at least this many.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio_stream::{StreamMap, Pending};
+    ///
+    /// let map: StreamMap<i32, Pending<()>> = StreamMap::with_capacity(100);
+    /// assert!(map.capacity() >= 100);
+    /// ```
+    pub fn capacity(&self) -> usize {
+        self.entries.capacity()
+    }
+
+    /// Returns the number of streams in the map.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio_stream::{StreamMap, pending};
+    ///
+    /// let mut a = StreamMap::new();
+    /// assert_eq!(a.len(), 0);
+    /// a.insert(1, pending::<i32>());
+    /// assert_eq!(a.len(), 1);
+    /// ```
+    pub fn len(&self) -> usize {
+        self.entries.len()
+    }
+
+    /// Returns `true` if the map contains no elements.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio_stream::{StreamMap, pending};
+    ///
+    /// let mut a = StreamMap::new();
+    /// assert!(a.is_empty());
+    /// a.insert(1, pending::<i32>());
+    /// assert!(!a.is_empty());
+    /// ```
+    pub fn is_empty(&self) -> bool {
+        self.entries.is_empty()
+    }
+
+    /// Clears the map, removing all key-stream pairs. Keeps the allocated
+    /// memory for reuse.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio_stream::{StreamMap, pending};
+    ///
+    /// let mut a = StreamMap::new();
+    /// a.insert(1, pending::<i32>());
+    /// a.clear();
+    /// assert!(a.is_empty());
+    /// ```
+    pub fn clear(&mut self) {
+        self.entries.clear();
+    }
+
+    /// Insert a key-stream pair into the map.
+    ///
+    /// If the map did not have this key present, `None` is returned.
+    ///
+    /// If the map did have this key present, the new `stream` replaces the old
+    /// one and the old stream is returned.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio_stream::{StreamMap, pending};
+    ///
+    /// let mut map = StreamMap::new();
+    ///
+    /// assert!(map.insert(37, pending::<i32>()).is_none());
+    /// assert!(!map.is_empty());
+    ///
+    /// map.insert(37, pending());
+    /// assert!(map.insert(37, pending()).is_some());
+    /// ```
+    pub fn insert(&mut self, k: K, stream: V) -> Option<V>
+    where
+        K: Hash + Eq,
+    {
+        let ret = self.remove(&k);
+        self.entries.push((k, stream));
+
+        ret
+    }
+
+    /// Removes a key from the map, returning the stream at the key if the key was previously in the map.
+    ///
+    /// The key may be any borrowed form of the map's key type, but `Hash` and
+    /// `Eq` on the borrowed form must match those for the key type.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio_stream::{StreamMap, pending};
+    ///
+    /// let mut map = StreamMap::new();
+    /// map.insert(1, pending::<i32>());
+    /// assert!(map.remove(&1).is_some());
+    /// assert!(map.remove(&1).is_none());
+    /// ```
+    pub fn remove<Q: ?Sized>(&mut self, k: &Q) -> Option<V>
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq,
+    {
+        for i in 0..self.entries.len() {
+            if self.entries[i].0.borrow() == k {
+                return Some(self.entries.swap_remove(i).1);
+            }
+        }
+
+        None
+    }
+
+    /// Returns `true` if the map contains a stream for the specified key.
+    ///
+    /// The key may be any borrowed form of the map's key type, but `Hash` and
+    /// `Eq` on the borrowed form must match those for the key type.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio_stream::{StreamMap, pending};
+    ///
+    /// let mut map = StreamMap::new();
+    /// map.insert(1, pending::<i32>());
+    /// assert_eq!(map.contains_key(&1), true);
+    /// assert_eq!(map.contains_key(&2), false);
+    /// ```
+    pub fn contains_key<Q: ?Sized>(&self, k: &Q) -> bool
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq,
+    {
+        for i in 0..self.entries.len() {
+            if self.entries[i].0.borrow() == k {
+                return true;
+            }
+        }
+
+        false
+    }
+}
+
+impl<K, V> StreamMap<K, V>
+where
+    K: Unpin,
+    V: Stream + Unpin,
+{
+    /// Polls the next value, includes the vec entry index
+    fn poll_next_entry(&mut self, cx: &mut Context<'_>) -> Poll<Option<(usize, V::Item)>> {
+        use Poll::*;
+
+        let start = self::rand::thread_rng_n(self.entries.len() as u32) as usize;
+        let mut idx = start;
+
+        for _ in 0..self.entries.len() {
+            let (_, stream) = &mut self.entries[idx];
+
+            match Pin::new(stream).poll_next(cx) {
+                Ready(Some(val)) => return Ready(Some((idx, val))),
+                Ready(None) => {
+                    // Remove the entry
+                    self.entries.swap_remove(idx);
+
+                    // Check if this was the last entry, if so the cursor needs
+                    // to wrap
+                    if idx == self.entries.len() {
+                        idx = 0;
+                    } else if idx < start && start <= self.entries.len() {
+                        // The stream being swapped into the current index has
+                        // already been polled, so skip it.
+                        idx = idx.wrapping_add(1) % self.entries.len();
+                    }
+                }
+                Pending => {
+                    idx = idx.wrapping_add(1) % self.entries.len();
+                }
+            }
+        }
+
+        // If the map is empty, then the stream is complete.
+        if self.entries.is_empty() {
+            Ready(None)
+        } else {
+            Pending
+        }
+    }
+}
+
+impl<K, V> Default for StreamMap<K, V> {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl<K, V> Stream for StreamMap<K, V>
+where
+    K: Clone + Unpin,
+    V: Stream + Unpin,
+{
+    type Item = (K, V::Item);
+
+    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+        if let Some((idx, val)) = ready!(self.poll_next_entry(cx)) {
+            let key = self.entries[idx].0.clone();
+            Poll::Ready(Some((key, val)))
+        } else {
+            Poll::Ready(None)
+        }
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let mut ret = (0, Some(0));
+
+        for (_, stream) in &self.entries {
+            let hint = stream.size_hint();
+
+            ret.0 += hint.0;
+
+            match (ret.1, hint.1) {
+                (Some(a), Some(b)) => ret.1 = Some(a + b),
+                (Some(_), None) => ret.1 = None,
+                _ => {}
+            }
+        }
+
+        ret
+    }
+}
+
+impl<K, V> std::iter::FromIterator<(K, V)> for StreamMap<K, V>
+where
+    K: Hash + Eq,
+{
+    fn from_iter<T: IntoIterator<Item = (K, V)>>(iter: T) -> Self {
+        let iterator = iter.into_iter();
+        let (lower_bound, _) = iterator.size_hint();
+        let mut stream_map = Self::with_capacity(lower_bound);
+
+        for (key, value) in iterator {
+            stream_map.insert(key, value);
+        }
+
+        stream_map
+    }
+}
+
+impl<K, V> Extend<(K, V)> for StreamMap<K, V> {
+    fn extend<T>(&mut self, iter: T)
+    where
+        T: IntoIterator<Item = (K, V)>,
+    {
+        self.entries.extend(iter);
+    }
+}
+
+mod rand {
+    use std::cell::Cell;
+
+    mod loom {
+        #[cfg(not(loom))]
+        pub(crate) mod rand {
+            use std::collections::hash_map::RandomState;
+            use std::hash::{BuildHasher, Hash, Hasher};
+            use std::sync::atomic::AtomicU32;
+            use std::sync::atomic::Ordering::Relaxed;
+
+            static COUNTER: AtomicU32 = AtomicU32::new(1);
+
+            pub(crate) fn seed() -> u64 {
+                let rand_state = RandomState::new();
+
+                let mut hasher = rand_state.build_hasher();
+
+                // Hash some unique-ish data to generate some new state
+                COUNTER.fetch_add(1, Relaxed).hash(&mut hasher);
+
+                // Get the seed
+                hasher.finish()
+            }
+        }
+
+        #[cfg(loom)]
+        pub(crate) mod rand {
+            pub(crate) fn seed() -> u64 {
+                1
+            }
+        }
+    }
+
+    /// Fast random number generate
+    ///
+    /// Implement xorshift64+: 2 32-bit xorshift sequences added together.
+    /// Shift triplet `[17,7,16]` was calculated as indicated in Marsaglia's
+    /// Xorshift paper: <https://www.jstatsoft.org/article/view/v008i14/xorshift.pdf>
+    /// This generator passes the SmallCrush suite, part of TestU01 framework:
+    /// <http://simul.iro.umontreal.ca/testu01/tu01.html>
+    #[derive(Debug)]
+    pub(crate) struct FastRand {
+        one: Cell<u32>,
+        two: Cell<u32>,
+    }
+
+    impl FastRand {
+        /// Initialize a new, thread-local, fast random number generator.
+        pub(crate) fn new(seed: u64) -> FastRand {
+            let one = (seed >> 32) as u32;
+            let mut two = seed as u32;
+
+            if two == 0 {
+                // This value cannot be zero
+                two = 1;
+            }
+
+            FastRand {
+                one: Cell::new(one),
+                two: Cell::new(two),
+            }
+        }
+
+        pub(crate) fn fastrand_n(&self, n: u32) -> u32 {
+            // This is similar to fastrand() % n, but faster.
+            // See https://lemire.me/blog/2016/06/27/a-fast-alternative-to-the-modulo-reduction/
+            let mul = (self.fastrand() as u64).wrapping_mul(n as u64);
+            (mul >> 32) as u32
+        }
+
+        fn fastrand(&self) -> u32 {
+            let mut s1 = self.one.get();
+            let s0 = self.two.get();
+
+            s1 ^= s1 << 17;
+            s1 = s1 ^ s0 ^ s1 >> 7 ^ s0 >> 16;
+
+            self.one.set(s0);
+            self.two.set(s1);
+
+            s0.wrapping_add(s1)
+        }
+    }
+
+    // Used by `StreamMap`
+    pub(crate) fn thread_rng_n(n: u32) -> u32 {
+        thread_local! {
+            static THREAD_RNG: FastRand = FastRand::new(loom::rand::seed());
+        }
+
+        THREAD_RNG.with(|rng| rng.fastrand_n(n))
+    }
+}