feat: add retry functionality

Author: c-git

Cargo.lock

@@ -21,6 +21,7 @@ anyhow = "1.0.95"
 document-features = "0.2.10"
 egui = { version = "0.30.0", default-features = false, optional = true }
 futures = "0.3.28"
+rand = "0.8.5"
 reqwest = { version = "0.12.12", default-features = false }
 thiserror = "2.0.9"
 tracing = "0.1.41"

Cargo.toml

@@ -1,27 +1,29 @@
-use crate::{DataState, ErrorBounds};
+use tracing::{error, warn};
+
+use crate::{data_state::CanMakeProgress, Awaiting, DataState, ErrorBounds};
+use std::fmt::Debug;
 use std::ops::Range;
-use std::time::Instant;
+use std::time::{Duration, Instant};
 
 /// Automatically retries with a delay on failure until attempts are exhausted
 #[derive(Debug)]
 pub struct DataStateRetry<T, E: ErrorBounds = anyhow::Error> {
-    /// The wrapped [`DataState`]
-    pub inner: DataState<T, E>,
     /// Number of attempts that the retries get reset to
     pub max_attempts: u8,
     /// The range of milliseconds to select a random value from to set the delay
     /// to retry
-    pub retry_delay_ms: Range<u16>,
+    pub retry_delay_millis: Range<u16>,
     attempts_left: u8,
-    last_attempt: Option<Instant>,
+    inner: DataState<T, E>, // Not public to ensure resets happen as they should
+    next_allowed_attempt: Instant,
 }
 
 impl<T, E: ErrorBounds> DataStateRetry<T, E> {
     /// Creates a new instance of [DataStateRetry]
-    pub fn new(max_attempts: u8, retry_delay_ms: Range<u16>) -> Self {
+    pub fn new(max_attempts: u8, retry_delay_millis: Range<u16>) -> Self {
         Self {
             max_attempts,
-            retry_delay_ms,
+            retry_delay_millis,
             ..Default::default()
         }
     }
@@ -31,9 +33,170 @@ impl<T, E: ErrorBounds> DataStateRetry<T, E> {
         self.attempts_left
     }
 
-    /// If an attempt was made the instant that it happened at
-    pub fn last_attempt(&self) -> Option<Instant> {
-        self.last_attempt
+    /// The instant that needs to be waited for before another attempt is
+    /// allowed
+    pub fn next_allowed_attempt(&self) -> Instant {
+        self.next_allowed_attempt
+    }
+
+    /// Provides access to the inner [`DataState`]
+    pub fn inner(&self) -> &DataState<T, E> {
+        &self.inner
+    }
+
+    /// Consumes self and returns the unwrapped inner
+    pub fn into_inner(self) -> DataState<T, E> {
+        self.inner
+    }
+
+    /// Provides access to the stored data if available (returns Some if
+    /// self.inner is `Data::Present(_)`)
+    pub fn present(&self) -> Option<&T> {
+        if let DataState::Present(data) = self.inner.as_ref() {
+            Some(data)
+        } else {
+            None
+        }
+    }
+
+    /// Provides mutable access to the stored data if available (returns Some if
+    /// self.inner is `Data::Present(_)`)
+    pub fn present_mut(&mut self) -> Option<&mut T> {
+        if let DataState::Present(data) = self.inner.as_mut() {
+            Some(data)
+        } else {
+            None
+        }
+    }
+
+    #[cfg(feature = "egui")]
+    /// Attempts to load the data and displays appropriate UI if applicable.
+    ///
+    /// Note see [`DataState::egui_get`] for more info.
+    #[must_use]
+    pub fn egui_get<F>(
+        &mut self,
+        ui: &mut egui::Ui,
+        retry_msg: Option<&str>,
+        fetch_fn: F,
+    ) -> CanMakeProgress
+    where
+        F: FnOnce() -> Awaiting<T, E>,
+    {
+        match self.inner.as_ref() {
+            DataState::None | DataState::AwaitingResponse(_) => {
+                self.ui_spinner_with_attempt_count(ui);
+                self.get(fetch_fn)
+            }
+            DataState::Present(_data) => {
+                // Does nothing as data is already present
+                CanMakeProgress::UnableToMakeProgress
+            }
+            DataState::Failed(e) => {
+                ui.colored_label(
+                    ui.visuals().error_fg_color,
+                    format!("{} attempts exhausted. {e}", self.max_attempts),
+                );
+                if ui.button(retry_msg.unwrap_or("Restart Requests")).clicked() {
+                    self.reset_attempts();
+                    self.inner = DataState::default();
+                }
+                CanMakeProgress::AbleToMakeProgress
+            }
+        }
+    }
+
+    /// Attempts to load the data and returns if it is able to make progress.
+    ///
+    /// See [`DataState::get`] for more info.
+    #[must_use]
+    pub fn get<F>(&mut self, fetch_fn: F) -> CanMakeProgress
+    where
+        F: FnOnce() -> Awaiting<T, E>,
+    {
+        match self.inner.as_mut() {
+            DataState::None => {
+                // Going to make an attempt, set when the next attempt is allowed
+                use rand::Rng;
+                let wait_time_in_millis = rand::thread_rng()
+                    .gen_range(self.retry_delay_millis.clone())
+                    .into();
+                self.next_allowed_attempt = Instant::now()
+                    .checked_add(Duration::from_millis(wait_time_in_millis))
+                    .expect("failed to get random delay, value was out of range");
+
+                self.inner.get(fetch_fn)
+            }
+            DataState::AwaitingResponse(rx) => {
+                if let Some(new_state) = DataState::await_data(rx) {
+                    // TODO 4: Add some tests to ensure await_data work as this function assumes
+                    self.inner = match new_state.as_ref() {
+                        DataState::None => {
+                            error!("Unexpected new state received of DataState::None");
+                            unreachable!("Only expect Failed or Present variants to be returned but got None")
+                        }
+                        DataState::AwaitingResponse(_) => {
+                            error!("Unexpected new state received of AwaitingResponse");
+                            unreachable!("Only expect Failed or Present variants to be returned bug got AwaitingResponse")
+                        }
+                        DataState::Present(_) => {
+                            // Data was successfully received
+                            self.reset_attempts();
+                            new_state
+                        }
+                        DataState::Failed(_) => new_state,
+                    };
+                }
+                CanMakeProgress::AbleToMakeProgress
+            }
+            DataState::Present(_) => self.inner.get(fetch_fn),
+            DataState::Failed(err_msg) => {
+                if self.attempts_left == 0 {
+                    self.inner.get(fetch_fn)
+                } else {
+                    let wait_duration_left = self
+                        .next_allowed_attempt
+                        .saturating_duration_since(Instant::now());
+                    if wait_duration_left.is_zero() {
+                        warn!(?err_msg, ?self.attempts_left, "retrying request");
+                        self.attempts_left -= 1;
+                        self.inner = DataState::None;
+                    }
+                    CanMakeProgress::AbleToMakeProgress
+                }
+            }
+        }
+    }
+
+    /// Resets the attempts taken
+    pub fn reset_attempts(&mut self) {
+        self.attempts_left = self.max_attempts;
+        self.next_allowed_attempt = Instant::now();
+    }
+
+    /// Clear stored data
+    pub fn clear(&mut self) {
+        self.inner = DataState::default();
+    }
+
+    /// Returns `true` if the internal data state is [`DataState::Present`].
+    #[must_use]
+    pub fn is_present(&self) -> bool {
+        self.inner.is_present()
+    }
+
+    /// Returns `true` if the internal data state is [`DataState::None`].
+    #[must_use]
+    pub fn is_none(&self) -> bool {
+        self.inner.is_none()
+    }
+
+    fn ui_spinner_with_attempt_count(&self, ui: &mut egui::Ui) {
+        ui.horizontal(|ui| {
+            ui.spinner();
+            ui.separator();
+            ui.label(format!("{} attempts left", self.attempts_left))
+        });
     }
 }
 
@@ -42,9 +205,9 @@ impl<T, E: ErrorBounds> Default for DataStateRetry<T, E> {
         Self {
             inner: Default::default(),
             max_attempts: 3,
-            retry_delay_ms: 1000..5000,
+            retry_delay_millis: 1000..5000,
             attempts_left: 3,
-            last_attempt: Default::default(),
+            next_allowed_attempt: Instant::now(),
         }
     }
 }