Introduce create_triggers()

scrapyd/sqlite.py

@@ -98,8 +98,8 @@ def __init__(self, database=None, table="queue"):
         q = "create table if not exists %s (id integer primary key, " \
             "priority real key, message blob, insert_time TIMESTAMP)" % table
         self.conn.execute(q)
-        # Backward compatibility for scrapyd<1.3.0
-        self.ensure_insert_time_column()
+        self.ensure_insert_time_column()  # Backward compatibility for scrapyd<1.3.0
+        self.create_triggers()
         self.update_project_priority_map()
 
     def put(self, message, priority=0.0):
@@ -108,14 +108,12 @@ def put(self, message, priority=0.0):
             % self.table
         self.conn.execute(q, args)
         self.conn.commit()
-        self.update_project_priority_map()
 
     def pop(self):
         q = "select id, message from %s order by priority desc limit 1" \
             % self.table
         idmsg = self.conn.execute(q).fetchone()
         if idmsg is None:
-            self.update_project_priority_map()
             return
         id, msg = idmsg
         q = "delete from %s where id=?" % self.table
@@ -124,7 +122,6 @@ def pop(self):
             self.conn.rollback()
             return self.pop()
         self.conn.commit()
-        self.update_project_priority_map()
         return self.decode(msg)
 
     def remove(self, func):
@@ -139,13 +136,11 @@ def remove(self, func):
                     return self.remove(func)
                 n += 1
         self.conn.commit()
-        self.update_project_priority_map()
         return n
 
     def clear(self):
         self.conn.execute("delete from %s" % self.table)
         self.conn.commit()
-        self.update_project_priority_map()
 
     def ensure_insert_time_column(self):
         q = "SELECT sql FROM sqlite_master WHERE type='table' AND name='%s'" % self.table
@@ -156,6 +151,17 @@ def ensure_insert_time_column(self):
             self.conn.execute(q)
             self.conn.commit()
 
+    def create_triggers(self):
+        self.conn.create_function("update_project_priority_map", 0, self.update_project_priority_map)
+        for action in ['INSERT', 'UPDATE', 'DELETE']:
+            name = 'trigger_on_%s' % action.lower()
+            self.conn.execute("""
+                CREATE TRIGGER IF NOT EXISTS %s AFTER %s ON %s
+                BEGIN
+                    SELECT update_project_priority_map();
+                END;
+            """ % (name, action, self.table))
+
     def update_project_priority_map(self):
         q = "select priority, strftime('%%s', insert_time) from %s order by priority desc limit 1" \
             % self.table