add celery example

2023-02-09 10:50:57 -08:00 · 2023-02-09 10:50:57 -08:00 · 3f195248dc
commit 3f195248dc
parent dca8cf013b
9 changed files with 313 additions and 0 deletions
--- a/examples/celery/src/task_app/init.py
+++ b/examples/celery/src/task_app/init.py
@ -0,0 +1,39 @@
+from celery import Celery
+from celery import Task
+from flask import Flask
+from flask import render_template
+
+
+def create_app() -> Flask:
+    app = Flask(__name__)
+    app.config.from_mapping(
+        CELERY=dict(
+            broker_url="redis://localhost",
+            result_backend="redis://localhost",
+            task_ignore_result=True,
+        ),
+    )
+    app.config.from_prefixed_env()
+    celery_init_app(app)
+
+    @app.route("/")
+    def index() -> str:
+        return render_template("index.html")
+
+    from . import views
+
+    app.register_blueprint(views.bp)
+    return app
+
+
+def celery_init_app(app: Flask) -> Celery:
+    class FlaskTask(Task):
+        def __call__(self, *args: object, **kwargs: object) -> object:
+            with app.app_context():
+                return self.run(*args, **kwargs)
+
+    celery_app = Celery(app.name, task_cls=FlaskTask)
+    celery_app.config_from_object(app.config["CELERY"])
+    celery_app.set_default()
+    app.extensions["celery"] = celery_app
+    return celery_app
--- a/examples/celery/src/task_app/tasks.py
+++ b/examples/celery/src/task_app/tasks.py
@ -0,0 +1,23 @@
+import time
+
+from celery import shared_task
+from celery import Task
+
+
+@shared_task(ignore_result=False)
+def add(a: int, b: int) -> int:
+    return a + b
+
+
+@shared_task()
+def block() -> None:
+    time.sleep(5)
+
+
+@shared_task(bind=True, ignore_result=False)
+def process(self: Task, total: int) -> object:
+    for i in range(total):
+        self.update_state(state="PROGRESS", meta={"current": i + 1, "total": total})
+        time.sleep(1)
+
+    return {"current": total, "total": total}
--- a/examples/celery/src/task_app/templates/index.html
+++ b/examples/celery/src/task_app/templates/index.html
@ -0,0 +1,108 @@
+<!doctype html>
+<html>
+<head>
+  <meta charset=UTF-8>
+  <title>Celery Example</title>
+</head>
+<body>
+<h2>Celery Example</h2>
+Execute background tasks with Celery. Submits tasks and shows results using JavaScript.
+
+<hr>
+<h4>Add</h4>
+<p>Start a task to add two numbers, then poll for the result.
+<form id=add method=post action="{{ url_for("tasks.add") }}">
+  <label>A <input type=number name=a value=4></label><br>
+  <label>B <input type=number name=b value=2></label><br>
+  <input type=submit>
+</form>
+<p>Result: <span id=add-result></span></p>
+
+<hr>
+<h4>Block</h4>
+<p>Start a task that takes 5 seconds. However, the response will return immediately.
+<form id=block method=post action="{{ url_for("tasks.block") }}">
+  <input type=submit>
+</form>
+<p id=block-result></p>
+
+<hr>
+<h4>Process</h4>
+<p>Start a task that counts, waiting one second each time, showing progress.
+<form id=process method=post action="{{ url_for("tasks.process") }}">
+  <label>Total <input type=number name=total value="10"></label><br>
+  <input type=submit>
+</form>
+<p id=process-result></p>
+
+<script>
+  const taskForm = (formName, doPoll, report) => {
+    document.forms[formName].addEventListener("submit", (event) => {
+      event.preventDefault()
+      fetch(event.target.action, {
+        method: "POST",
+        body: new FormData(event.target)
+      })
+        .then(response => response.json())
+        .then(data => {
+          report(null)
+
+          const poll = () => {
+            fetch(`/tasks/result/${data["result_id"]}`)
+              .then(response => response.json())
+              .then(data => {
+                report(data)
+
+                if (!data["ready"]) {
+                  setTimeout(poll, 500)
+                } else if (!data["successful"]) {
+                  console.error(formName, data)
+                }
+              })
+          }
+
+          if (doPoll) {
+            poll()
+          }
+        })
+    })
+  }
+
+  taskForm("add", true, data => {
+    const el = document.getElementById("add-result")
+
+    if (data === null) {
+      el.innerText = "submitted"
+    } else if (!data["ready"]) {
+      el.innerText = "waiting"
+    } else if (!data["successful"]) {
+      el.innerText = "error, check console"
+    } else {
+      el.innerText = data["value"]
+    }
+  })
+
+  taskForm("block", false, data => {
+    document.getElementById("block-result").innerText = (
+      "request finished, check celery log to see task finish in 5 seconds"
+    )
+  })
+
+  taskForm("process", true, data => {
+    const el = document.getElementById("process-result")
+
+    if (data === null) {
+      el.innerText = "submitted"
+    } else if (!data["ready"]) {
+      el.innerText = `${data["value"]["current"]} / ${data["value"]["total"]}`
+    } else if (!data["successful"]) {
+      el.innerText = "error, check console"
+    } else {
+      el.innerText = "✅ done"
+    }
+    console.log(data)
+  })
+
+</script>
+</body>
+</html>
--- a/examples/celery/src/task_app/views.py
+++ b/examples/celery/src/task_app/views.py
@ -0,0 +1,38 @@
+from celery.result import AsyncResult
+from flask import Blueprint
+from flask import request
+
+from . import tasks
+
+bp = Blueprint("tasks", __name__, url_prefix="/tasks")
+
+
+@bp.get("/result/<id>")
+def result(id: str) -> dict[str, object]:
+    result = AsyncResult(id)
+    ready = result.ready()
+    return {
+        "ready": ready,
+        "successful": result.successful() if ready else None,
+        "value": result.get() if ready else result.result,
+    }
+
+
+@bp.post("/add")
+def add() -> dict[str, object]:
+    a = request.form.get("a", type=int)
+    b = request.form.get("b", type=int)
+    result = tasks.add.delay(a, b)
+    return {"result_id": result.id}
+
+
+@bp.post("/block")
+def block() -> dict[str, object]:
+    result = tasks.block.delay()
+    return {"result_id": result.id}
+
+
+@bp.post("/process")
+def process() -> dict[str, object]:
+    result = tasks.process.delay(total=request.form.get("total", type=int))
+    return {"result_id": result.id}