commit 5b2e7a62b4f31d8d2b3ef28092a8323ed2295107
Author: Bùi Thành Nhân <hi@imnhan.com>
Date:   Sat Aug 8 02:30:44 2020 +0700

    implement scheduled task that updates titles
    
    And potentially other things.
    Usage: just run `pytaku-scheduler`.

diff --git a/README.md b/README.md
index c45f7c9..c21953a 100644
--- a/README.md
+++ b/README.md
@@ -9,4 +9,8 @@
 
 pytaku-generate-config > pytaku.conf.json
 # fill stuff as needed
+
+# run 2 processes:
+gunicorn pytaku.main:app -w 7 -b 0.0.0.0:5001  # web server
+pytaku-scheduler  # scheduled tasks e.g. update titles
 ```
diff --git a/pyproject.toml b/pyproject.toml
index da4e8cf..680d4a2 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "pytaku"
-version = "0.1.7"
+version = "0.1.8"
 description = ""
 authors = ["Bùi Thành Nhân <hi@imnhan.com>"]
 license = "AGPL-3.0-only"
@@ -12,6 +12,7 @@ packages = [
 [tool.poetry.scripts]
 pytaku-migrate = "pytaku:migrate"
 pytaku-generate-config = "pytaku:generate_config"
+pytaku-scheduler = "pytaku:scheduler"
 
 [tool.poetry.dependencies]
 python = "^3.7"
diff --git a/src/pytaku/__init__.py b/src/pytaku/__init__.py
index bd3e1b9..fca72ae 100644
--- a/src/pytaku/__init__.py
+++ b/src/pytaku/__init__.py
@@ -19,3 +19,9 @@ def migrate():
 
 def generate_config():
     print(config.generate_json(DEBUG=True))
+
+
+def scheduler():
+    from .scheduler import main_loop
+
+    main_loop()
diff --git a/src/pytaku/persistence.py b/src/pytaku/persistence.py
index a03efbd..32e16a7 100644
--- a/src/pytaku/persistence.py
+++ b/src/pytaku/persistence.py
@@ -277,3 +277,9 @@ def unread(user_id, site, chapter_id):
         "DELETE FROM read WHERE user_id=? AND site=? AND chapter_id=?;",
         (user_id, site, chapter_id),
     )
+
+
+def find_outdated_titles(since="-6 hours"):
+    return run_sql(
+        "SELECT id, site FROM title WHERE updated_at <= datetime('now', ?);", (since,)
+    )
diff --git a/src/pytaku/scheduler.py b/src/pytaku/scheduler.py
new file mode 100644
index 0000000..5c7176d
--- /dev/null
+++ b/src/pytaku/scheduler.py
@@ -0,0 +1,47 @@
+import time
+from datetime import datetime, timedelta
+
+from mangoapi import get_title
+
+from .persistence import find_outdated_titles, save_title
+
+now = datetime.now
+
+
+def main_loop():
+    workers = [UpdateOutdatedSeries()]
+
+    while True:
+        for worker in workers:
+            if worker.should_run():
+                print("Running", worker.__class__.__name__)
+                worker.run()
+                worker.after_run()
+        time.sleep(5)
+
+
+class Worker:
+    interval = timedelta(days=1)
+
+    def __init__(self):
+        self.last_run = datetime(1, 1, 1)
+
+    def should_run(self):
+        return now() - self.last_run >= self.interval
+
+    def run(self):
+        raise NotImplementedError()
+
+    def after_run(self):
+        self.last_run = now()
+
+
+class UpdateOutdatedSeries(Worker):
+    interval = timedelta(seconds=9)
+
+    def run(self):
+        for title in find_outdated_titles():
+            print(f"Updating title {title['id']} from {title['site']}...", end="")
+            updated_title = get_title(title["id"])
+            save_title(updated_title)
+            print(" done")