Add import queue and worker system

TODO.md

@@ -94,10 +94,10 @@
 
 ### 🎯 Milestone 10: **"Import Infrastructure" Release** – Queue & Worker Setup
 
-* [ ] Implement import queue system
-* [ ] Add background worker process for playlist imports
-* [ ] Support multiple concurrent import jobs
-* [ ] Implement priority handling for import jobs
+* [x] Implement import queue system
+* [x] Add background worker process for playlist imports
+* [x] Support multiple concurrent import jobs
+* [x] Implement priority handling for import jobs
 
 ### 🎯 Milestone 11: **"Progress Pulse" Release** – Import Status Tracking
 

musicround/__init__.py

@@ -335,6 +335,16 @@ def create_app(config=None):
     # Register error handlers
     from musicround.errors import register_error_handlers
     register_error_handlers(app)
+
+    # Initialize import queue and background workers
+    from musicround.helpers.import_queue import ImportQueue, ImportWorker
+    worker_count = int(os.environ.get('IMPORT_WORKER_COUNT', '2'))
+    import_queue = ImportQueue()
+    workers = [ImportWorker(app, import_queue) for _ in range(worker_count)]
+    for w in workers:
+        w.start()
+    app.config['import_queue'] = import_queue
+    app.config['import_workers'] = workers
     
     # Try to create database tables if they don't exist
     with app.app_context():

musicround/helpers/import_queue.py

@@ -0,0 +1,98 @@
+"""Import queue and worker implementation for asynchronous playlist imports."""
+
+from __future__ import annotations
+
+import threading
+from dataclasses import dataclass, field
+from queue import PriorityQueue, Empty
+from typing import Optional
+from flask import current_app
+from flask_login import login_user, logout_user
+
+from musicround.models import User, db
+from musicround.helpers.import_helper import ImportHelper
+
+
+@dataclass(order=True)
+class ImportJob:
+    """Represents a single import job."""
+
+    priority: int
+    service_name: str = field(compare=False)
+    item_type: str = field(compare=False)
+    item_id: str = field(compare=False)
+    user_id: int = field(compare=False)
+
+
+class ImportQueue:
+    """Priority queue for import jobs."""
+
+    def __init__(self) -> None:
+        self._queue: PriorityQueue[tuple[int, int, ImportJob]] = PriorityQueue()
+        self._counter = 0
+        self._lock = threading.Lock()
+
+    def add_job(self, job: ImportJob) -> None:
+        """Add a job to the queue."""
+        with self._lock:
+            self._counter += 1
+            self._queue.put((job.priority, self._counter, job))
+
+    def get_job(self, timeout: Optional[float] = None) -> Optional[ImportJob]:
+        """Retrieve the next job from the queue."""
+        try:
+            _, _, job = self._queue.get(timeout=timeout)
+            return job
+        except Empty:
+            return None
+
+    def task_done(self) -> None:
+        """Signal that a previously fetched job is complete."""
+        self._queue.task_done()
+
+
+class ImportWorker(threading.Thread):
+    """Background worker thread for processing import jobs."""
+
+    def __init__(self, app, queue: ImportQueue) -> None:
+        super().__init__(daemon=True)
+        self.app = app
+        self.queue = queue
+        self._stop_event = threading.Event()
+
+    def stop(self) -> None:
+        """Stop the worker loop."""
+        self._stop_event.set()
+
+    def run(self) -> None:
+        with self.app.app_context():
+            while not self._stop_event.is_set():
+                job = self.queue.get_job(timeout=1.0)
+                if job is None:
+                    continue
+                self._process_job(job)
+                self.queue.task_done()
+
+    def _process_job(self, job: ImportJob) -> None:
+        user = User.query.get(job.user_id)
+        if not user:
+            current_app.logger.error("Import job for unknown user %s", job.user_id)
+            return
+        with self.app.test_request_context():
+            login_user(user)
+            try:
+                current_app.logger.info(
+                    "Processing import job: service=%s type=%s id=%s user=%s priority=%s",
+                    job.service_name,
+                    job.item_type,
+                    job.item_id,
+                    job.user_id,
+                    job.priority,
+                )
+                ImportHelper.import_item(job.service_name, job.item_type, job.item_id)
+                db.session.commit()
+            except Exception as exc:  # pylint: disable=broad-except
+                current_app.logger.error("Import job failed: %s", exc, exc_info=True)
+                db.session.rollback()
+            finally:
+                logout_user()

musicround/routes/import_songs.py

@@ -85,22 +85,23 @@ def import_playlist():
             flash("No playlist ID provided for import.", "danger")
             return redirect(request.referrer or url_for('core.search'))
 
-        result = ImportHelper.import_item(service_name='spotify', item_type='playlist', item_id=playlist_id, oauth_spotify=oauth.spotify)
-        
-        imported_count = result.get('imported_count', 0)
-        skipped_count = result.get('skipped_count', 0)
-        error_count = result.get('error_count', 0)
-        errors = result.get("errors", [])
+        priority = int(request.form.get('priority', 10))
+        queue = current_app.config.get('import_queue')
+        if not queue:
+            flash("Import queue not initialized.", "danger")
+            return redirect(url_for('core.view_songs'))
 
-        if imported_count > 0:
-            flash(f'Successfully imported {imported_count} songs from playlist! ({skipped_count} skipped, {error_count} errors).', 'success')
-        elif skipped_count > 0 and error_count == 0:
-            flash(f'All {skipped_count} songs were already in the database.', 'info')
-        elif error_count > 0:
-            flash(f'Playlist import: {imported_count} new, {skipped_count} skipped, {error_count} errors. Errors: {", ".join(errors)}', 'warning')
-        else:
-            flash(f'Error importing playlist: {", ".join(errors) if errors else "No songs imported, playlist might be empty or an unknown issue occurred."}', 'danger')
-            
+        from musicround.helpers.import_queue import ImportJob
+
+        job = ImportJob(
+            priority=priority,
+            service_name='spotify',
+            item_type='playlist',
+            item_id=playlist_id,
+            user_id=current_user.id,
+        )
+        queue.add_job(job)
+        flash('Playlist import queued.', 'info')
         return redirect(url_for('core.view_songs'))
         
     return render_template('service_import.html',

musicround/version.py

@@ -5,10 +5,10 @@ This module provides version details that can be displayed in both CLI and UI.
 
 # Version information
 VERSION_INFO = {
-    "version": "1.9.0",
-    "release_name": "Documentation Dynamo",
-    "release_date": "2025-05-12",
-    "build_number": "20250512001"
+    "version": "1.10.0",
+    "release_name": "Import Infrastructure",
+    "release_date": "2025-05-27",
+    "build_number": "20250527001"
 }
 
 def get_version_str(include_build=False):