Feedback infrastructure

src/provider/mod.rs

@@ -14,6 +14,7 @@ use crate::calendar::CalendarId;
 
 mod sync_progress;
 use sync_progress::SyncProgress;
+pub use sync_progress::FeedbackSender;
 
 /// A data source that combines two `CalDavSource`s, which is able to sync both sources.
 ///
@@ -64,22 +65,34 @@ where
     /// To be sure `local` accurately mirrors the `remote` source, you can run [`Provider::sync`]
     pub fn remote(&self) -> &R { &self.remote }
 
-    /// Performs a synchronisation between `local` and `remote`.
+    /// Performs a synchronisation between `local` and `remote`, and provide feeedback to the user about the progress.
     ///
     /// This bidirectional sync applies additions/deletions made on a source to the other source.
     /// In case of conflicts (the same item has been modified on both ends since the last sync, `remote` always wins)
     ///
     /// It returns whether the sync was totally successful (details about errors are logged using the `log::*` macros).
     /// In case errors happened, the sync might have been partially executed, and you can safely run this function again, since it has been designed to gracefully recover from errors.
-    pub async fn sync(&mut self) -> bool {
-        let mut result = SyncProgress::new();
-        if let Err(err) = self.run_sync(&mut result).await {
-            result.error(&format!("Sync terminated because of an error: {}", err));
-        }
-        result.is_success()
+    pub async fn sync_with_feedback(&mut self, feedback_sender: FeedbackSender) -> bool {
+        let mut progress = SyncProgress::new_with_feedback_channel(feedback_sender);
+        self.run_sync(&mut progress).await
     }
 
-    async fn run_sync(&mut self, progress: &mut SyncProgress) -> Result<(), Box<dyn Error>> {
+    /// Performs a synchronisation between `local` and `remote`, without giving any feedback.
+    ///
+    /// See [sync_with_feedback]
+    pub async fn sync(&mut self) -> bool {
+        let mut progress = SyncProgress::new();
+        self.run_sync(&mut progress).await
+    }
+
+    async fn run_sync(&mut self, progress: &mut SyncProgress) -> bool {
+        if let Err(err) = self.run_sync_inner(progress).await {
+            progress.error(&format!("Sync terminated because of an error: {}", err));
+        }
+        progress.is_success()
+    }
+
+    async fn run_sync_inner(&mut self, progress: &mut SyncProgress) -> Result<(), Box<dyn Error>> {
         progress.info("Starting a sync.");
 
         let mut handled_calendars = HashSet::new();

src/provider/sync_progress.rs

@@ -1,11 +1,65 @@
-/// A counter of errors that happen during a sync
+//! Utilities to track the progression of a sync
+
+use std::fmt::{Display, Error, Formatter};
+
+/// An event that happens during a sync
+pub enum SyncEvent {
+    /// Sync has not started
+    NotStarted,
+    /// Sync has just started but no calendar is handled yet
+    Started,
+    /// Sync is in progress.
+    InProgress{ calendar: String, details: String},
+    /// Sync is finished
+    Finished{ success: bool },
+}
+
+impl Display for SyncEvent {
+    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
+        match self {
+            SyncEvent::NotStarted => write!(f, "Not started"),
+            SyncEvent::Started => write!(f, "Sync has started"),
+            SyncEvent::InProgress{calendar, details} => write!(f, "[{}] {}", calendar, details),
+            SyncEvent::Finished{success} => match success {
+                true => write!(f, "Sync successfully finished"),
+                false => write!(f, "Sync finished with errors"),
+            }
+        }
+    }
+}
+
+impl Default for SyncEvent {
+    fn default() -> Self {
+        Self::NotStarted
+    }
+}
+
+
+
+pub type FeedbackSender = tokio::sync::watch::Sender<SyncEvent>;
+pub type FeedbackReceiver = tokio::sync::watch::Receiver<SyncEvent>;
+
+pub fn feedback_channel() -> (FeedbackSender, FeedbackReceiver) {
+    tokio::sync::watch::channel(SyncEvent::default())
+}
+
+
+
+
+/// A structure that tracks the progression and the errors that happen during a sync
 pub struct SyncProgress {
     n_errors: u32,
+    feedback_channel: Option<FeedbackSender>
 }
 impl SyncProgress {
     pub fn new() -> Self {
-        Self { n_errors: 0 }
+        Self { n_errors: 0, feedback_channel: None }
     }
+    pub fn new_with_feedback_channel(channel: FeedbackSender) -> Self {
+        Self { n_errors: 0, feedback_channel: Some(channel) }
+    }
+
+
     pub fn is_success(&self) -> bool {
         self.n_errors == 0
     }