Added methods to create utilize a lock table for managing access to the database during a multi-threaded import. Currently, only MySQL is supported

pyfpdb/Database.py

@@ -273,6 +273,7 @@ class Database:
         self.db_path = ''
         gen = c.get_general_params()
         self.day_start = 0
+        self._has_lock = False
         
         if 'day_start' in gen:
             self.day_start = float(gen['day_start'])
@@ -1719,6 +1720,34 @@ class Database:
 # however the calling prog requires. Main aims:
 # - existing static routines from fpdb_simple just modified
 
+    def setThreadId(self, threadid):
+        self.threadId = threadid
+    
+    def acquireLock(self, wait=True, retry_time=.01):
+        while not self._has_lock:
+            cursor = self.get_cursor()
+            cursor.execute(self.sql.query['selectLock'])
+            record = cursor.fetchall()
+            self.commit()
+            if not len(record):
+                cursor.execute(self.sql.query['switchLock'], (True, self.threadId))
+                self.commit()
+                self._has_lock = True
+                return True
+            else:
+                cursor.execute(self.sql.query['missedLock'], (1, self.threadId))
+                self.commit()
+                if not wait:
+                    return False
+                sleep(retry_time)
+    
+    def releaseLock(self):
+        if self._has_lock:
+            cursor = self.get_cursor()
+            num = cursor.execute(self.sql.query['switchLock'], (False, self.threadId))
+            self.commit()
+            self._has_lock = False
+
     def lock_for_insert(self):
         """Lock tables in MySQL to try to speed inserts up"""
         try:

pyfpdb/SQL.py

@@ -108,6 +108,15 @@ class Sql:
             self.query['createSettingsTable'] = """CREATE TABLE Settings
             (version INTEGER NOT NULL) """
             
+        ################################
+        # Create InsertLock
+        ################################
+        if db_server == 'mysql':
+            self.query['createLockTable'] = """CREATE TABLE InsertLock (
+                        id BIGINT UNSIGNED AUTO_INCREMENT NOT NULL, PRIMARY KEY (id),
+                        locked BOOLEAN NOT NULL DEFAULT FALSE)
+                        ENGINE=INNODB"""
+
         ################################
         # Create RawHands (this table is all but identical with RawTourneys)
         ################################
@@ -4502,6 +4511,25 @@ class Sql:
         elif db_server == 'sqlite':
             self.query['analyze'] = "analyze"
             
+        if db_server == 'mysql':
+            self.query['selectLock'] = """
+                        SELECT locked 
+                        FROM InsertLock 
+                        WHERE locked=True 
+                        LOCK IN SHARE MODE"""
+            
+        if db_server == 'mysql':
+            self.query['switchLock'] = """
+                        UPDATE InsertLock SET
+                        locked=%s
+                        WHERE id=%s"""
+                        
+        if db_server == 'mysql':               
+            self.query['missedLock'] = """
+                        UPDATE InsertLock SET
+                        missed=missed+%s
+                        WHERE id=%s"""
+
         if db_server == 'mysql':
             self.query['lockForInsert'] = """
                 lock tables Hands write, HandsPlayers write, HandsActions write, Players write