Total queue size in the disk

src/queue/mod.rs

@@ -3,6 +3,7 @@
 mod iter;
 mod receiver;
 mod sender;
+mod size;
 
 pub use iter::QueueIter;
 pub use receiver::{Receiver, ReceiverBuilder, RecvGuard};

src/queue/receiver.rs

@@ -191,6 +191,16 @@ impl Receiver {
         ReceiverBuilder::default().open(base)
     }
 
+    /// Gets the total size of the queue in bytes in disk.
+    /// 
+    /// # Errors
+    /// 
+    /// This function will return an IO error if any errors are encountered while going
+    /// throught the listed files in disk.
+    pub fn get_size(&self) -> io::Result<u64> {
+        super::size::total_directory_size(&self.base)
+    }
+
     /// Starts a transaction in the queue.
     fn begin(&mut self) {
         log::debug!("begin transaction in {:?} at {:?}", self.base, self.state);

src/queue/sender.rs

@@ -202,6 +202,16 @@ impl Sender {
         SenderBuilder::default().open(base)
     }
 
+    /// Gets the total size of the queue in bytes in disk.
+    /// 
+    /// # Errors
+    /// 
+    /// This function will return an IO error if any errors are encountered while going
+    /// throught the listed files in disk.
+    pub fn get_size(&self) -> io::Result<u64> {
+        super::size::total_directory_size(&self.base)
+    }
+
     /// Saves the sender queue state. You do not need to use method in most
     /// circumstances, since it is automatically done on drop (yes, it will be
     /// called eve if your thread panics). However, you can use this function to

src/queue/size.rs

@@ -0,0 +1,25 @@
+//! Utilities for calculating the size of a queue.
+
+use std::path::Path;
+use std::{fs, io};
+
+/// Goes through each file in the given directory _non-recursively_ and adds up all their
+/// sizes.
+pub(crate) fn total_directory_size(dir: &Path) -> Result<u64, io::Error> {
+    let mut size = 0;
+
+    for maybe_entry in fs::read_dir(dir)? {
+        let metadata = maybe_entry?.metadata()?;
+        if !metadata.is_file() {
+            continue;
+        }
+
+        // Here, we will count the size of _all_ files, not only of the queue segment
+        // files `*.q`. This might be useful for wusers with many small queues. So, no
+        // filtering based on extension.
+
+        size += metadata.len();
+    }
+
+    Ok(size)
+}

src/state.rs

@@ -134,6 +134,8 @@ impl QueueStatePersistence {
         QueueStatePersistence::default()
     }
 
+    /// Opens a new file persistence stored inside the _folder_ `base` (i.e., it will
+    /// look for the file `{base}/recv-metadata`).
     pub fn open<P: AsRef<Path>>(&mut self, base: P) -> io::Result<QueueState> {
         let path = recv_persistence_filename(base);
         self.path = Some(path.clone());