1 files changed, 50 insertions, 0 deletions
diff --git a/src/model/k2v/poll.rs b/src/model/k2v/poll.rs
new file mode 100644
index 00000000..93105207
--- /dev/null
+++ b/src/model/k2v/poll.rs
@@ -0,0 +1,50 @@
+use std::collections::HashMap;
+use std::sync::Mutex;
+
+use serde::{Deserialize, Serialize};
+use tokio::sync::broadcast;
+
+use crate::k2v::item_table::*;
+
+#[derive(Debug, Hash, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct PollKey {
+	pub partition: K2VItemPartition,
+	pub sort_key: String,
+}
+
+#[derive(Default)]
+pub struct SubscriptionManager {
+	subscriptions: Mutex<HashMap<PollKey, broadcast::Sender<K2VItem>>>,
+}
+
+impl SubscriptionManager {
+	pub fn new() -> Self {
+		Self::default()
+	}
+
+	pub fn subscribe(&self, key: &PollKey) -> broadcast::Receiver<K2VItem> {
+		let mut subs = self.subscriptions.lock().unwrap();
+		if let Some(s) = subs.get(key) {
+			s.subscribe()
+		} else {
+			let (tx, rx) = broadcast::channel(8);
+			subs.insert(key.clone(), tx);
+			rx
+		}
+	}
+
+	pub fn notify(&self, item: &K2VItem) {
+		let key = PollKey {
+			partition: item.partition.clone(),
+			sort_key: item.sort_key.clone(),
+		};
+		let mut subs = self.subscriptions.lock().unwrap();
+		if let Some(s) = subs.get(&key) {
+			if s.send(item.clone()).is_err() {
+				// no more subscribers, remove channel from here
+				// (we will re-create it later if we need to subscribe again)
+				subs.remove(&key);
+			}
+		}
+	}
+}