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>> + 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<dyn Sink<Task<Args, Extensions>, Error = SendError> + Send + Sync + Unpin>;
125        Self {
126            sender: MemorySink {
127                inner: Arc::new(futures_util::lock::Mutex::new(sender)),
128            },
129            receiver: receiver.boxed(),
130        }
131    }
132}
133
134impl<Args, Ctx> Sink<Task<Args, Ctx>> for MemoryStorage<Args, Ctx> {
135    type Error = SendError;
136
137    fn poll_ready(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
138        self.as_mut().sender.poll_ready_unpin(cx)
139    }
140
141    fn start_send(mut self: Pin<&mut Self>, item: Task<Args, Ctx>) -> Result<(), Self::Error> {
142        self.as_mut().sender.start_send_unpin(item)
143    }
144
145    fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
146        self.as_mut().sender.poll_flush_unpin(cx)
147    }
148
149    fn poll_close(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
150        self.as_mut().sender.poll_close_unpin(cx)
151    }
152}
153
154type MemorySinkInner<Args, Ctx = Extensions> = Arc<
155    futures_util::lock::Mutex<
156        Box<dyn Sink<Task<Args, Ctx>, Error = SendError> + Send + Sync + Unpin + 'static>,
157    >,
158>;
159
160/// Memory sink for sending tasks to the in-memory backend
161pub struct MemorySink<Args, Ctx = Extensions> {
162    pub(super) inner: MemorySinkInner<Args, Ctx>,
163}
164
165impl<Args, Ctx> std::fmt::Debug for MemorySink<Args, Ctx> {
166    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
167        f.debug_struct("MemorySink")
168            .field("inner", &"<Sink>")
169            .finish()
170    }
171}
172
173impl<Args, Ctx> Clone for MemorySink<Args, Ctx> {
174    fn clone(&self) -> Self {
175        Self {
176            inner: Arc::clone(&self.inner),
177        }
178    }
179}
180
181impl<Args, Ctx> Sink<Task<Args, Ctx>> for MemorySink<Args, Ctx> {
182    type Error = SendError;
183
184    fn poll_ready(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
185        let mut lock = ready!(self.inner.lock().poll_unpin(cx));
186        Pin::new(&mut *lock).poll_ready_unpin(cx)
187    }
188
189    fn start_send(self: Pin<&mut Self>, mut item: Task<Args, Ctx>) -> Result<(), Self::Error> {
190        let mut lock = self.inner.try_lock().unwrap();
191        // Ensure task has id
192        item.parts
193            .task_id
194            .get_or_insert_with(|| TaskId::new(RandomId::default()));
195        Pin::new(&mut *lock).start_send_unpin(item)
196    }
197
198    fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
199        let mut lock = ready!(self.inner.lock().poll_unpin(cx));
200        Pin::new(&mut *lock).poll_flush_unpin(cx)
201    }
202
203    fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
204        let mut lock = ready!(self.inner.lock().poll_unpin(cx));
205        Pin::new(&mut *lock).poll_close_unpin(cx)
206    }
207}
208
209impl<Args, Ctx> std::fmt::Debug for MemoryStorage<Args, Ctx> {
210    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
211        f.debug_struct("MemoryStorage")
212            .field("sender", &self.sender)
213            .field("receiver", &"<Stream>")
214            .finish()
215    }
216}
217
218impl<Args, Ctx> Stream for MemoryStorage<Args, Ctx> {
219    type Item = Task<Args, Ctx>;
220
221    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
222        self.receiver.poll_next_unpin(cx)
223    }
224}
225
226// MemoryStorage as a Backend
227impl<Args: 'static + Clone + Send, Ctx: 'static + Default> Backend for MemoryStorage<Args, Ctx> {
228    type Args = Args;
229    type IdType = RandomId;
230
231    type Context = Ctx;
232
233    type Error = SendError;
234    type Stream = TaskStream<Task<Args, Ctx>, SendError>;
235    type Layer = Identity;
236    type Beat = BoxStream<'static, Result<(), Self::Error>>;
237
238    fn heartbeat(&self, _: &WorkerContext) -> Self::Beat {
239        stream::once(async { Ok(()) }).boxed()
240    }
241    fn middleware(&self) -> Self::Layer {
242        Identity::new()
243    }
244
245    fn poll(self, _worker: &WorkerContext) -> Self::Stream {
246        (self.receiver.boxed().map(|r| Ok(Some(r))).boxed()) as _
247    }
248}
249
250impl<Args: Clone + Send + 'static, Ctx: Default + 'static> BackendExt for MemoryStorage<Args, Ctx> {
251    type Codec = IdentityCodec;
252    type Compact = Args;
253    type CompactStream = TaskStream<Task<Args, Self::Context>, Self::Error>;
254
255    fn poll_compact(self, _worker: &WorkerContext) -> Self::CompactStream {
256        (self.receiver.map(|task| Ok(Some(task))).boxed()) as _
257    }
258}
apalis_core/backend/impls/memory.rs

apalis_core/backend/impls/
memory.rs
