feat: new clipboard manager module

src/clients/clipboard.rs

@@ -0,0 +1,245 @@
+use super::wayland::{self, ClipboardItem};
+use crate::{lock, try_send};
+use indexmap::map::Iter;
+use indexmap::IndexMap;
+use lazy_static::lazy_static;
+use std::sync::{Arc, Mutex};
+use tokio::spawn;
+use tokio::sync::mpsc;
+use tracing::debug;
+
+#[derive(Debug)]
+pub enum ClipboardEvent {
+    Add(Arc<ClipboardItem>),
+    Remove(usize),
+    Activate(usize),
+}
+
+type EventSender = mpsc::Sender<ClipboardEvent>;
+
+/// Clipboard client singleton,
+/// to ensure bars don't duplicate requests to the compositor.
+pub struct ClipboardClient {
+    senders: Arc<Mutex<Vec<(EventSender, usize)>>>,
+    cache: Arc<Mutex<ClipboardCache>>,
+}
+
+impl ClipboardClient {
+    fn new() -> Self {
+        let senders = Arc::new(Mutex::new(Vec::<(EventSender, usize)>::new()));
+
+        let cache = Arc::new(Mutex::new(ClipboardCache::new()));
+
+        {
+            let senders = senders.clone();
+            let cache = cache.clone();
+
+            spawn(async move {
+                let mut rx = {
+                    let wl = wayland::get_client().await;
+                    wl.subscribe_clipboard()
+                };
+
+                while let Ok(item) = rx.recv().await {
+                    debug!("Received clipboard item (ID: {})", item.id);
+
+                    let (existing_id, cache_size) = {
+                        let cache = lock!(cache);
+                        (cache.contains(&item), cache.len())
+                    };
+
+                    existing_id.map_or_else(
+                        || {
+                            {
+                                let mut cache = lock!(cache);
+                                let senders = lock!(senders);
+                                cache.insert(item.clone(), senders.len());
+                            }
+                            let senders = lock!(senders);
+                            let iter = senders.iter();
+                            for (tx, sender_cache_size) in iter {
+                                if cache_size == *sender_cache_size {
+                                    let mut cache = lock!(cache);
+                                    let removed_id = cache
+                                        .remove_ref_first()
+                                        .expect("Clipboard cache unexpectedly empty");
+                                    try_send!(tx, ClipboardEvent::Remove(removed_id));
+                                }
+                                try_send!(tx, ClipboardEvent::Add(item.clone()));
+                            }
+                        },
+                        |existing_id| {
+                            let senders = lock!(senders);
+                            let iter = senders.iter();
+                            for (tx, _) in iter {
+                                try_send!(tx, ClipboardEvent::Activate(existing_id));
+                            }
+                        },
+                    );
+                }
+            });
+        }
+
+        Self { senders, cache }
+    }
+
+    pub async fn subscribe(&self, cache_size: usize) -> mpsc::Receiver<ClipboardEvent> {
+        let (tx, rx) = mpsc::channel(16);
+
+        let wl = wayland::get_client().await;
+        wl.roundtrip();
+
+        {
+            let mut cache = lock!(self.cache);
+
+            if let Some(item) = wl.get_clipboard() {
+                cache.insert_or_inc_ref(item);
+            }
+
+            let iter = cache.iter();
+            for (id, (item, _)) in iter {
+                println!("Initialising value with id {id}");
+                try_send!(tx, ClipboardEvent::Add(item.clone()));
+            }
+        }
+
+        {
+            let mut senders = lock!(self.senders);
+            senders.push((tx, cache_size));
+        }
+
+        rx
+    }
+
+    pub async fn copy(&self, id: usize) {
+        debug!("Copying item with id {id}");
+
+        let item = {
+            let cache = lock!(self.cache);
+            cache.get(id)
+        };
+
+        if let Some(item) = item {
+            let wl = wayland::get_client().await;
+            wl.copy_to_clipboard(item);
+        }
+
+        let senders = lock!(self.senders);
+        let iter = senders.iter();
+        for (tx, _) in iter {
+            try_send!(tx, ClipboardEvent::Activate(id));
+        }
+    }
+
+    pub fn remove(&self, id: usize) {
+        let mut cache = lock!(self.cache);
+        cache.remove(id);
+
+        let senders = lock!(self.senders);
+        let iter = senders.iter();
+        for (tx, _) in iter {
+            try_send!(tx, ClipboardEvent::Remove(id));
+        }
+    }
+}
+
+/// Shared clipboard item cache.
+///
+/// Items are stored with a number of references,
+/// allowing different consumers to 'remove' cached items
+/// at different times.
+#[derive(Debug)]
+struct ClipboardCache {
+    cache: IndexMap<usize, (Arc<ClipboardItem>, usize)>,
+}
+
+impl ClipboardCache {
+    /// Creates a new empty cache.
+    fn new() -> Self {
+        Self {
+            cache: IndexMap::new(),
+        }
+    }
+
+    /// Gets the entry with key `id` from the cache.
+    fn get(&self, id: usize) -> Option<Arc<ClipboardItem>> {
+        self.cache.get(&id).map(|(item, _)| item).cloned()
+    }
+
+    /// Inserts an entry with `ref_count` initial references.
+    fn insert(&mut self, item: Arc<ClipboardItem>, ref_count: usize) -> Option<Arc<ClipboardItem>> {
+        self.cache
+            .insert(item.id, (item, ref_count))
+            .map(|(item, _)| item)
+    }
+
+    /// Inserts an entry with `ref_count` initial references,
+    /// or increments the `ref_count` by 1 if it already exists.
+    fn insert_or_inc_ref(&mut self, item: Arc<ClipboardItem>) {
+        let mut item = self.cache.entry(item.id).or_insert((item, 0));
+        item.1 += 1;
+    }
+
+    /// Removes the entry with key `id`.
+    /// This ignores references.
+    fn remove(&mut self, id: usize) -> Option<Arc<ClipboardItem>> {
+        self.cache.shift_remove(&id).map(|(item, _)| item)
+    }
+
+    /// Removes a reference to the entry with key `id`.
+    ///
+    /// If the reference count reaches zero, the entry
+    /// is removed from the cache.
+    fn remove_ref(&mut self, id: usize) {
+        if let Some(entry) = self.cache.get_mut(&id) {
+            entry.1 -= 1;
+
+            if entry.1 == 0 {
+                self.cache.shift_remove(&id);
+            }
+        }
+    }
+
+    /// Removes a reference to the first entry.
+    ///
+    /// If the reference count reaches zero, the entry
+    /// is removed from the cache.
+    fn remove_ref_first(&mut self) -> Option<usize> {
+        if let Some((id, _)) = self.cache.first() {
+            let id = *id;
+            self.remove_ref(id);
+            Some(id)
+        } else {
+            None
+        }
+    }
+
+    /// Checks if an item with matching mime type and value
+    /// already exists in the cache.
+    fn contains(&self, item: &ClipboardItem) -> Option<usize> {
+        self.cache.values().find_map(|(it, _)| {
+            if it.mime_type == item.mime_type && it.value == item.value {
+                Some(it.id)
+            } else {
+                None
+            }
+        })
+    }
+
+    /// Gets the current number of items in the cache.
+    fn len(&self) -> usize {
+        self.cache.len()
+    }
+
+    fn iter(&self) -> Iter<'_, usize, (Arc<ClipboardItem>, usize)> {
+        self.cache.iter()
+    }
+}
+
+lazy_static! {
+    static ref CLIENT: ClipboardClient = ClipboardClient::new();
+}
+
+pub fn get_client() -> &'static ClipboardClient {
+    &CLIENT
+}