Start documenting the project (#96)

* Start documenting the project

* Add AsyncQueue implementation

* Documenting Async runnable

* By default value in uniq function

* Fix errors and warnings async runnable docs

* Update src/asynk/async_queue.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_queue.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_queue.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_queue.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_queue.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_runnable.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_runnable.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_runnable.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_runnable.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_runnable.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* format something

* Update src/asynk/async_queue.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_queue.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_queue.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_queue.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_queue.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_queue.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_queue.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_queue.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_queue.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_queue.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_queue.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_queue.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_queue.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_queue.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_runnable.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_runnable.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_runnable.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_runnable.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_runnable.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_runnable.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_runnable.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_runnable.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_runnable.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* uniq documentation

* Update src/asynk/async_runnable.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_queue.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_queue.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_queue.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_queue.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_runnable.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

* Update src/asynk/async_runnable.rs

Co-authored-by: Ayrat Badykov <ayratin555@gmail.com>

Co-authored-by: pxp9 <pepe.marquezromero@gmail.com>
Co-authored-by: Pmarquez <48651252+pxp9@users.noreply.github.com>

README.md

@@ -6,7 +6,7 @@
 
 Background task processing library for Rust. It uses Postgres DB as a task queue.
 
-## Features
+## Key Features
 
  Here are some of the fang's key features:
 

src/asynk/async_queue.rs

@@ -113,39 +113,59 @@ impl From<cron::error::Error> for AsyncQueueError {
     }
 }
 
+/// This trait defines operations for an asynchronous queue.
+/// The trait can be implemented for different storage backends.
+/// For now, the trait is only implemented for PostgreSQL. More backends are planned to be implemented in the future.
+
 #[async_trait]
 pub trait AsyncQueueable: Send {
+    /// This method should retrieve one task of the `task_type` type. If `task_type` is `None` it will try to
+    /// fetch a task of the type `common`. After fetching it should update the state of the task to
+    /// `FangTaskState::InProgress`.
+    ///
     async fn fetch_and_touch_task(
         &mut self,
         task_type: Option<String>,
     ) -> Result<Option<Task>, AsyncQueueError>;
 
+    /// Enqueue a task to the queue, The task will be executed as soon as possible by the worker of the same type
+    /// created by an AsyncWorkerPool.
     async fn insert_task(&mut self, task: &dyn AsyncRunnable) -> Result<Task, AsyncQueueError>;
 
+    /// The method will remove all tasks from the queue
     async fn remove_all_tasks(&mut self) -> Result<u64, AsyncQueueError>;
 
+    /// Remove all tasks that are scheduled in the future.
     async fn remove_all_scheduled_tasks(&mut self) -> Result<u64, AsyncQueueError>;
 
+    /// Remove a task by its id.
     async fn remove_task(&mut self, id: Uuid) -> Result<u64, AsyncQueueError>;
 
+    /// Remove a task by its metadata (struct fields values)
     async fn remove_task_by_metadata(
         &mut self,
         task: &dyn AsyncRunnable,
     ) -> Result<u64, AsyncQueueError>;
 
+    /// Removes all tasks that have the specified `task_type`.
     async fn remove_tasks_type(&mut self, task_type: &str) -> Result<u64, AsyncQueueError>;
 
+    /// Retrieve a task from storage by its `id`.
     async fn find_task_by_id(&mut self, id: Uuid) -> Result<Task, AsyncQueueError>;
 
+    /// Update the state field of the specified task
+    /// See the `FangTaskState` enum for possible states.
     async fn update_task_state(
         &mut self,
         task: Task,
         state: FangTaskState,
     ) -> Result<Task, AsyncQueueError>;
 
+    /// Update the state of a task to `FangTaskState::Failed` and set an error_message.
     async fn fail_task(&mut self, task: Task, error_message: &str)
         -> Result<Task, AsyncQueueError>;
 
+    /// Schedule a task.
     async fn schedule_task(&mut self, task: &dyn AsyncRunnable) -> Result<Task, AsyncQueueError>;
 
     async fn schedule_retry(
@@ -156,6 +176,19 @@ pub trait AsyncQueueable: Send {
     ) -> Result<Task, AsyncQueueError>;
 }
 
+/// An async queue that can be used to enqueue tasks.
+/// It uses a PostgreSQL storage. It must be connected to perform any operation.
+/// To connect an `AsyncQueue` to PostgreSQL database call the `connect` method.
+/// A Queue can be created with the TypedBuilder.
+///
+///    ```rust
+///         let mut queue = AsyncQueue::builder()
+///             .uri("postgres://postgres:postgres@localhost/fang")
+///             .max_pool_size(max_pool_size)
+///             .build();
+///     ```
+///
+
 #[derive(TypedBuilder, Debug, Clone)]
 pub struct AsyncQueue<Tls>
 where
@@ -344,6 +377,7 @@ where
     <Tls as MakeTlsConnect<Socket>>::TlsConnect: Send,
     <<Tls as MakeTlsConnect<Socket>>::TlsConnect as TlsConnect<Socket>>::Future: Send,
 {
+    /// Check if the connection with db is established
     pub fn check_if_connection(&self) -> Result<(), AsyncQueueError> {
         if self.connected {
             Ok(())
@@ -351,6 +385,8 @@ where
             Err(AsyncQueueError::NotConnectedError)
         }
     }
+
+    /// Connect to the db if not connected
     pub async fn connect(&mut self, tls: Tls) -> Result<(), AsyncQueueError> {
         let manager = PostgresConnectionManager::new_from_stringlike(self.uri.clone(), tls)?;
 
@@ -363,6 +399,7 @@ where
         self.connected = true;
         Ok(())
     }
+
     async fn remove_all_tasks_query(
         transaction: &mut Transaction<'_>,
     ) -> Result<u64, AsyncQueueError> {

src/asynk/async_runnable.rs

@@ -37,27 +37,55 @@ impl From<SerdeError> for FangError {
     }
 }
 
+/// Implement this trait to run your custom tasks.
 #[typetag::serde(tag = "type")]
 #[async_trait]
 pub trait AsyncRunnable: Send + Sync {
+    /// Execute the task. This method should define its logic
     async fn run(&self, client: &mut dyn AsyncQueueable) -> Result<(), FangError>;
 
+    /// Define the type of the task.
+    /// The `common` task type is used by default
     fn task_type(&self) -> String {
         COMMON_TYPE.to_string()
     }
 
+    /// If set to true, no new tasks with the same metadata will be inserted
+    /// By default it is set to false.
     fn uniq(&self) -> bool {
         false
     }
 
+    /// This method defines if a task is periodic or it should be executed once in the future.
+    ///
+    /// Be careful it works only with the UTC timezone.
+    ///
+    ///
+    /// Example:
+    ///
+    ///
+    /**
+    ```rust
+     fn cron(&self) -> Option<Scheduled> {
+         let expression = "0/20 * * * Aug-Sep * 2022/1";
+         Some(Scheduled::CronPattern(expression.to_string()))
+     }
+    ```
+    */
+
+    /// In order to schedule  a task once, use the `Scheduled::ScheduleOnce` enum variant.
     fn cron(&self) -> Option<Scheduled> {
         None
     }
 
+    /// Define the maximum number of retries the task will be retried.
+    /// By default the number of retries is 20.
     fn max_retries(&self) -> i32 {
         RETRIES_NUMBER
     }
 
+    /// Define the backoff mode
+    /// By default, it is exponential,  2^(attempt)
     fn backoff(&self, attempt: u32) -> u32 {
         u32::pow(2, attempt)
     }

src/blocking.rs

@@ -1,4 +1,4 @@
-pub mod error;
+mod error;
 pub mod fang_task_state;
 pub mod queue;
 pub mod runnable;

src/blocking/fang_task_state.rs

@@ -1,9 +1,18 @@
+/// Possible states of the task
 #[derive(diesel_derive_enum::DbEnum, Debug, Eq, PartialEq, Clone)]
 #[DieselTypePath = "crate::schema::sql_types::FangTaskState"]
 pub enum FangTaskState {
+    /// The task is ready to be executed
     New,
+    /// The task is being executing.
+    ///
+    /// The task may stay in this state forever
+    /// if an unexpected error happened
     InProgress,
+    /// The task failed
     Failed,
+    /// The task finished successfully
     Finished,
+    /// The task is being retried. It means it failed but it's scheduled to be executed again
     Retried,
 }

src/lib.rs

@@ -2,49 +2,80 @@
 
 use std::time::Duration;
 use thiserror::Error;
+use typed_builder::TypedBuilder;
 
+/// Represents a schedule for scheduled tasks.
+///
+/// It's used in the [`AsyncRunnable::cron`] and [`Runnable::cron`]
+#[derive(Debug, Clone)]
 pub enum Scheduled {
+    /// A cron pattern for a periodic task
+    ///
+    /// For example, `Scheduled::CronPattern("0/20 * * * * * *")`
     CronPattern(String),
+    /// A datetime for a scheduled task that will be executed once
+    ///
+    /// For example, `Scheduled::ScheduleOnce(chrono::Utc::now() + std::time::Duration::seconds(7i64))`
     ScheduleOnce(DateTime<Utc>),
 }
 
+/// List of error types that can occur while working with cron schedules.
 #[derive(Debug, Error)]
 pub enum CronError {
+    /// A problem occured during cron schedule parsing.
     #[error(transparent)]
     LibraryError(#[from] cron::error::Error),
+    /// [`Scheduled`] enum variant is not provided
     #[error("You have to implement method `cron()` in your AsyncRunnable")]
     TaskNotSchedulableError,
+    /// The next execution can not be determined using the current [`Scheduled::CronPattern`]
     #[error("No timestamps match with this cron pattern")]
     NoTimestampsError,
 }
 
+/// All possible options for retaining tasks in the db after their execution.
+///
+/// The default mode is [`RetentionMode::RemoveAll`]
 #[derive(Clone, Debug)]
 pub enum RetentionMode {
+    /// Keep all tasks
     KeepAll,
+    /// Remove all tasks
     RemoveAll,
+    /// Remove only successfully finished tasks
     RemoveFinished,
 }
+
 impl Default for RetentionMode {
     fn default() -> Self {
         RetentionMode::RemoveAll
     }
 }
 
-#[derive(Clone, Debug)]
+/// Configuration parameters for putting workers to sleep
+/// while they don't have any tasks to execute
+#[derive(Clone, Debug, TypedBuilder)]
 pub struct SleepParams {
+    /// the current sleep period
     pub sleep_period: Duration,
+    /// the maximum period a worker is allowed to sleep.
+    /// After this value is reached, `sleep_period` is not increased anymore
     pub max_sleep_period: Duration,
+    /// the initial value of the `sleep_period`
     pub min_sleep_period: Duration,
+    /// the step that `sleep_period` is increased by on every iteration
     pub sleep_step: Duration,
 }
 
 impl SleepParams {
+    /// Reset the `sleep_period` if `sleep_period` > `min_sleep_period`
     pub fn maybe_reset_sleep_period(&mut self) {
         if self.sleep_period != self.min_sleep_period {
             self.sleep_period = self.min_sleep_period;
         }
     }
 
+    /// Increase the `sleep_period` by the `sleep_step` if the `max_sleep_period` is not reached
     pub fn maybe_increase_sleep_period(&mut self) {
         if self.sleep_period < self.max_sleep_period {
             self.sleep_period += self.sleep_step;
@@ -63,11 +94,14 @@ impl Default for SleepParams {
     }
 }
 
+/// An error that can happen during executing of tasks
 #[derive(Debug)]
 pub struct FangError {
+    /// A description of an error
     pub description: String,
 }
 
+#[doc(hidden)]
 #[cfg(feature = "blocking")]
 extern crate diesel;
 
@@ -94,6 +128,7 @@ pub use chrono::Utc;
 
 #[cfg(feature = "blocking")]
 pub mod blocking;
+
 #[cfg(feature = "blocking")]
 pub use blocking::*;