apalis_core/backend/impls/
memory.rs

1//! # In-memory backend based on channels
2//!
3//! An in-memory backend suitable for testing, prototyping, or lightweight task processing scenarios where persistence is not required.
4//!
5//! ## Features
6//! - Generic in-memory queue for any task type.
7//! - Implements [`Backend`] for integration with workers.
8//! - Sink support: Ability to push new tasks.
9//!
10//! A detailed feature list can be found in the [capabilities](crate::backend::memory::MemoryStorage#capabilities) section.
11//!
12//! ## Example
13//!
14//! ```rust
15//! # use apalis_core::backend::memory::MemoryStorage;
16//! # use apalis_core::worker::context::WorkerContext;
17//! # use apalis_core::worker::builder::WorkerBuilder;
18//! # use apalis_core::backend::TaskSink;
19//! # async fn task(_: u32, ctx: WorkerContext) { ctx.stop().unwrap();}
20//! #[tokio::main]
21//! async fn main() {
22//!     let mut store = MemoryStorage::new();
23//!     store.push(42).await.unwrap();
24//!
25//!     let worker = WorkerBuilder::new("int-worker")
26//!         .backend(store)
27//!         .build(task);
28//!
29//!     worker.run().await.unwrap();
30//! }
31//! ```
32//!
33//! ## Note
34//! This backend is not persistent and is intended for use cases where durability is not required.
35//! For production workloads, consider using a persistent backend such as PostgreSQL or Redis.
36//!
37//! ## See Also
38//! - [`Backend`]
39//! - [`WorkerContext`]
40use crate::backend::BackendExt;
41use crate::backend::codec::IdentityCodec;
42use crate::features_table;
43use crate::task::extensions::Extensions;
44use crate::{
45    backend::{Backend, TaskStream},
46    task::{
47        Task,
48        task_id::{RandomId, TaskId},
49    },
50    worker::context::WorkerContext,
51};
52use futures_channel::mpsc::{SendError, unbounded};
53use futures_core::ready;
54use futures_sink::Sink;
55use futures_util::{
56    FutureExt, SinkExt, Stream, StreamExt,
57    stream::{self, BoxStream},
58};
59use std::{
60    pin::Pin,
61    sync::Arc,
62    task::{Context, Poll},
63};
64use tower_layer::Identity;
65
66/// In-memory queue that is based on channels
67///
68///
69/// ## Example
70/// ```rust
71/// # use apalis_core::backend::memory::MemoryStorage;
72/// # fn setup() -> MemoryStorage<u32> {
73/// let mut backend = MemoryStorage::new();
74/// # backend
75/// # }
76/// ```
77///
78#[doc = features_table! {
79    setup = r#"
80        # {
81        #   use apalis_core::backend::memory::MemoryStorage;
82        #   MemoryStorage::new()
83        # };
84    "#,
85    Backend => supported("Basic Backend functionality", true),
86    TaskSink => supported("Ability to push new tasks", true),
87    Serialization => not_supported("Serialization support for arguments"),
88
89    PipeExt => not_implemented("Allow other backends to pipe to this backend"),
90    MakeShared => not_supported("Share the same storage across multiple workers"),
91
92    Update => not_supported("Allow updating a task"),
93    FetchById => not_supported("Allow fetching a task by its ID"),
94    Reschedule => not_supported("Reschedule a task"),
95
96    ResumeById => not_supported("Resume a task by its ID"),
97    ResumeAbandoned => not_supported("Resume abandoned tasks"),
98    Vacuum => not_supported("Vacuum the task storage"),
99
100    Workflow => not_implemented("Flexible enough to support workflows"),
101    WaitForCompletion => not_implemented("Wait for tasks to complete without blocking"), // Requires Clone
102
103    RegisterWorker => not_supported("Allow registering a worker with the backend"),
104    ListWorkers => not_supported("List all workers registered with the backend"),
105    ListTasks => not_supported("List all tasks in the backend"),
106}]
107pub struct MemoryStorage<Args, Ctx = Extensions> {
108    pub(super) sender: MemorySink<Args, Ctx>,
109    pub(super) receiver: Pin<Box<dyn Stream<Item = Task<Args, Ctx, RandomId>> + Send>>,
110}
111
112impl<Args: Send + 'static> Default for MemoryStorage<Args, Extensions> {
113    fn default() -> Self {
114        Self::new()
115    }
116}
117
118impl<Args: Send + 'static> MemoryStorage<Args, Extensions> {
119    /// Create a new in-memory storage
120    #[must_use]
121    pub fn new() -> Self {
122        let (sender, receiver) = unbounded();
123        let sender = Box::new(sender)
124            as Box<
125                dyn Sink<Task<Args, Extensions, RandomId>, Error = SendError> + Send + Sync + Unpin,
126            >;
127        Self {
128            sender: MemorySink {
129                inner: Arc::new(futures_util::lock::Mutex::new(sender)),
130            },
131            receiver: receiver.boxed(),
132        }
133    }
134}
135
136impl<Args, Ctx> Sink<Task<Args, Ctx, RandomId>> for MemoryStorage<Args, Ctx> {
137    type Error = SendError;
138
139    fn poll_ready(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
140        self.as_mut().sender.poll_ready_unpin(cx)
141    }
142
143    fn start_send(
144        mut self: Pin<&mut Self>,
145        item: Task<Args, Ctx, RandomId>,
146    ) -> Result<(), Self::Error> {
147        self.as_mut().sender.start_send_unpin(item)
148    }
149
150    fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
151        self.as_mut().sender.poll_flush_unpin(cx)
152    }
153
154    fn poll_close(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
155        self.as_mut().sender.poll_close_unpin(cx)
156    }
157}
158
159type MemorySinkInner<Args, Ctx = Extensions> = Arc<
160    futures_util::lock::Mutex<
161        Box<dyn Sink<Task<Args, Ctx, RandomId>, Error = SendError> + Send + Sync + Unpin + 'static>,
162    >,
163>;
164
165/// Memory sink for sending tasks to the in-memory backend
166pub struct MemorySink<Args, Ctx = Extensions> {
167    pub(super) inner: MemorySinkInner<Args, Ctx>,
168}
169
170impl<Args, Ctx> std::fmt::Debug for MemorySink<Args, Ctx> {
171    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
172        f.debug_struct("MemorySink")
173            .field("inner", &"<Sink>")
174            .finish()
175    }
176}
177
178impl<Args, Ctx> Clone for MemorySink<Args, Ctx> {
179    fn clone(&self) -> Self {
180        Self {
181            inner: Arc::clone(&self.inner),
182        }
183    }
184}
185
186impl<Args, Ctx> Sink<Task<Args, Ctx, RandomId>> for MemorySink<Args, Ctx> {
187    type Error = SendError;
188
189    fn poll_ready(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
190        let mut lock = ready!(self.inner.lock().poll_unpin(cx));
191        Pin::new(&mut *lock).poll_ready_unpin(cx)
192    }
193
194    fn start_send(
195        self: Pin<&mut Self>,
196        mut item: Task<Args, Ctx, RandomId>,
197    ) -> Result<(), Self::Error> {
198        let mut lock = self.inner.try_lock().unwrap();
199        // Ensure task has id
200        item.parts
201            .task_id
202            .get_or_insert_with(|| TaskId::new(RandomId::default()));
203        Pin::new(&mut *lock).start_send_unpin(item)
204    }
205
206    fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
207        let mut lock = ready!(self.inner.lock().poll_unpin(cx));
208        Pin::new(&mut *lock).poll_flush_unpin(cx)
209    }
210
211    fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
212        let mut lock = ready!(self.inner.lock().poll_unpin(cx));
213        Pin::new(&mut *lock).poll_close_unpin(cx)
214    }
215}
216
217impl<Args, Ctx> std::fmt::Debug for MemoryStorage<Args, Ctx> {
218    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
219        f.debug_struct("MemoryStorage")
220            .field("sender", &self.sender)
221            .field("receiver", &"<Stream>")
222            .finish()
223    }
224}
225
226impl<Args, Ctx> Stream for MemoryStorage<Args, Ctx> {
227    type Item = Task<Args, Ctx, RandomId>;
228
229    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
230        self.receiver.poll_next_unpin(cx)
231    }
232}
233
234// MemoryStorage as a Backend
235impl<Args: 'static + Clone + Send, Ctx: 'static + Default> Backend for MemoryStorage<Args, Ctx> {
236    type Args = Args;
237    type IdType = RandomId;
238
239    type Context = Ctx;
240
241    type Error = SendError;
242    type Stream = TaskStream<Task<Args, Ctx, RandomId>, SendError>;
243    type Layer = Identity;
244    type Beat = BoxStream<'static, Result<(), Self::Error>>;
245
246    fn heartbeat(&self, _: &WorkerContext) -> Self::Beat {
247        stream::once(async { Ok(()) }).boxed()
248    }
249    fn middleware(&self) -> Self::Layer {
250        Identity::new()
251    }
252
253    fn poll(self, _worker: &WorkerContext) -> Self::Stream {
254        (self.receiver.boxed().map(|r| Ok(Some(r))).boxed()) as _
255    }
256}
257
258impl<Args: Clone + Send + 'static, Ctx: Default + 'static> BackendExt for MemoryStorage<Args, Ctx> {
259    type Codec = IdentityCodec;
260    type Compact = Args;
261    type CompactStream = TaskStream<Task<Args, Self::Context, RandomId>, Self::Error>;
262
263    fn poll_compact(self, _worker: &WorkerContext) -> Self::CompactStream {
264        (self.receiver.map(|task| Ok(Some(task))).boxed()) as _
265    }
266}
apalis_core/backend/impls/memory.rs

apalis_core/backend/impls/
memory.rs
