Start move to Tokio

src/port_pool.rs

@@ -0,0 +1,31 @@
+use std::ops::Range;
+
+use anyhow::Context;
+
+const MIN_PORT: u16 = 32768;
+const MAX_PORT: u16 = 60999;
+const PORT_RANGE: Range<u16> = MIN_PORT..MAX_PORT;
+
+pub struct PortPool {
+    inner: lockfree::queue::Queue<u16>,
+}
+
+impl PortPool {
+    pub fn new() -> Self {
+        let inner = lockfree::queue::Queue::default();
+        PORT_RANGE.for_each(|p| inner.push(p) as ());
+        Self {
+            inner,
+        }
+    }
+
+    pub fn next(&self) -> anyhow::Result<u16> {
+        self.inner
+            .pop()
+            .with_context(|| "Virtual port pool is exhausted")
+    }
+
+    pub fn release(&self, port: u16) {
+        self.inner.push(port);
+    }
+}