add README

README.md

@@ -0,0 +1,97 @@
+<p align="center"><img src="logo.png" alt="fang" height="300px"></p>
+
+# Fang
+
+Background job processing library for Rust.
+
+Currently, it uses postgres to store state. But in the future, more backends will be supported.
+
+## Installation
+
+1. Add this to your Cargo.toml
+
+
+```toml
+[dependencies]
+fang = "0.1"
+typetag = "0.1"
+serde = { version = "1.0", features = ["derive"] }
+```
+
+2. Create `fang_tasks` table in the postgres database. The migration can be found in [the migrations directory](https://github.com/ayrat555/fang/blob/master/migrations/2021-06-05-112912_create_fang_tasks/up.sql).
+
+## Usage
+
+### Defining a job
+
+Every job should implement `fang::Runnable` trait which is used by `fang` to execut it.
+
+
+```rust
+    use fang::Error;
+    use fang::Runnable;
+    use serde::{Deserialize, Serialize};
+
+
+    #[derive(Serialize, Deserialize)]
+    struct Job {
+        pub number: u16,
+    }
+
+    #[typetag::serde]
+    impl Runnable for Job {
+        fn run(&self) -> Result<(), Error> {
+            println!("the number is {}", self.number);
+
+            Ok(())
+        }
+    }
+```
+
+As you can see from the example above, trait implementation has `#[typetag::serde]` which is used to deserialize the job.
+
+### Enqueuing a job
+
+To enqueue a job use `Postgres::enqueue_task`
+
+
+```rust
+use fang::Postgres;
+
+...
+
+Postgres::enqueue_task(&Job { number: 10 }).unwrap();
+
+```
+
+
+### Starting workers
+
+Every worker is executed in a separate thread. In case of panic, they are always restarted.
+
+Use `WorkerPool::new` to start workers. It accepts two parameters - the number of workers and the prefix for worker thread name.
+
+
+```rust
+use fang::WorkerPool;
+
+WorkerPool::new(10, "sync".to_string()).start();
+```
+
+## Potential/future features
+
+  * Extendable/new backends
+  * Workers for specific types of tasks. Currently, each workers execute all types of tasks
+  * Configurable db records retention. Currently, fang doesn't remove tasks from the db.
+
+## Contributing
+
+1. [Fork it!](https://github.com/ayrat555/fang/fork)
+2. Create your feature branch (`git checkout -b my-new-feature`)
+3. Commit your changes (`git commit -am 'Add some feature'`)
+4. Push to the branch (`git push origin my-new-feature`)
+5. Create new Pull Request
+
+## Author
+
+Ayrat Badykov (@ayrat555)

src/postgres.rs

@@ -27,26 +27,14 @@ pub struct NewTask {
 }
 
 pub struct Postgres {
-    pub database_url: String,
     pub connection: PgConnection,
 }
 
 impl Postgres {
     pub fn new(database_url: Option<String>) -> Self {
-        dotenv().ok();
+        let connection = Self::pg_connection(database_url);
 
-        let url = match database_url {
-            Some(string_url) => string_url,
-            None => env::var("DATABASE_URL").expect("DATABASE_URL must be set"),
-        };
-
-        let connection =
-            PgConnection::establish(&url).unwrap_or_else(|_| panic!("Error connecting to {}", url));
-
-        Self {
-            connection,
-            database_url: url,
-        }
+        Self { connection }
     }
 
     pub fn push_task(&self, job: &dyn Runnable) -> Result<Task, Error> {
@@ -57,6 +45,10 @@ impl Postgres {
         self.insert(&new_task)
     }
 
+    pub fn enqueue_task(job: &dyn Runnable) -> Result<Task, Error> {
+        Self::new(None).push_task(job)
+    }
+
     pub fn insert(&self, params: &NewTask) -> Result<Task, Error> {
         diesel::insert_into(fang_tasks::table)
             .values(params)
@@ -130,9 +122,20 @@ impl Postgres {
             .get_result::<Task>(&self.connection)
     }
 
-    pub fn current_time() -> DateTime<Utc> {
+    fn current_time() -> DateTime<Utc> {
         Utc::now()
     }
+
+    fn pg_connection(database_url: Option<String>) -> PgConnection {
+        dotenv().ok();
+
+        let url = match database_url {
+            Some(string_url) => string_url,
+            None => env::var("DATABASE_URL").expect("DATABASE_URL must be set"),
+        };
+
+        PgConnection::establish(&url).unwrap_or_else(|_| panic!("Error connecting to {}", url))
+    }
 }
 
 #[cfg(test)]