Save chunks in db

One of the changes introduced for this is that multiple chunks and
diffs are now represented by dicts, not lists.

dbchunkpool.py

@@ -2,8 +2,8 @@ import sqlite3
 import time
 import threading
 
-from chunks import ChunkPool
-from utils import Position
+from chunks import ChunkPool, Chunk
+from utils import Position, CHUNK_WIDTH, CHUNK_HEIGHT
 
 class ChunkDB():
 	"""
@@ -12,6 +12,8 @@ class ChunkDB():
 	
 	def __init__(self, filename):
 		self.dbfilename = filename
+		
+		self._create_table()
 	
 	def transaction(func):
 		def wrapper(self, *args, **kwargs):
@@ -24,14 +26,56 @@ class ChunkDB():
 		
 		return wrapper
 	
+	@transaction
+	def _create_table(self, con):
+		cur = con.cursor()
+		cur.execute(("CREATE TABLE IF NOT EXISTS chunks ("
+		             "x INTEGER NOT NULL, "
+		             "y INTEGER NOT NULL, "
+		             "content TEXT, "
+		             "PRIMARY KEY (x, y)"
+		             ")"))
+	
 	@transaction
 	def save_many(self, con, chunks):
-		print("save_many")
+		lchunks = ChunkDB.chunks_to_list(chunks)
+		con.executemany("INSERT OR REPLACE INTO chunks VALUES (?, ?, ?)", lchunks)
 	
 	@transaction
 	def load_many(self, con, coords):
-		print("load_many")
-		return [(coor, None) for coor in coords]
+		cur = con.cursor()
+		results = []
+		
+		for pos in coords:
+			cur.execute("SELECT * FROM chunks WHERE x=? AND y=?", pos)
+			results.extend(cur.fetchall())
+		
+		results = ChunkDB.list_to_chunks(results)
+		return results
+	
+	@transaction
+	def remove_empty(self, con):
+		con.execute("DELETE FROM chunks WHERE content=?", (" "*CHUNK_WIDTH*CHUNK_HEIGHT,))
+	
+	@staticmethod
+	def list_to_chunks(l):
+		chunks = {}
+		
+		for item in l:
+			pos = Position(item[0], item[1])
+			chunk = Chunk.from_string(item[2])
+			chunks[pos] = chunk
+		
+		return chunks
+	
+	@staticmethod
+	def chunks_to_list(chunks):
+		l = []
+		
+		for pos, chunk in chunks.items():
+			l.append((pos[0], pos[1], chunk.to_string()))
+		
+		return l
 
 class DBChunkPool(ChunkPool):
 	"""
@@ -42,8 +86,8 @@ class DBChunkPool(ChunkPool):
 		super().__init__()
 		self._chunkdb = ChunkDB(filename)
 		
-		self.save_period = 10 # save and clean up every minute
-		self.max_age = 20 # ca. one minute until a chunk is unloaded again
+		self.save_period = 60 # save and clean up every minute
+		self.max_age = 60 # ca. one minute until a chunk is unloaded again
 		
 		self.save_thread = threading.Thread(
 			target=self.perodic_save,
@@ -55,27 +99,23 @@ class DBChunkPool(ChunkPool):
 	def save_changes(self):
 		diffs = self.commit_changes()
 		
-		changed_chunks = []
-		for dchunk in diffs:
-			pos = dchunk[0]
+		changed_chunks = {}
+		for pos, diff in diffs.items():
 			chunk = self.get(pos)
-			changed_chunks.append((pos, chunk))
+			changed_chunks[pos] = chunk
 		
 		self._chunkdb.save_many(changed_chunks)
 	
 	def load(self, pos):
-		print("Loading individual chunk...")
 		raise Exception
 	
 	def load_list(self, coords):
-		print("Loading chunk list...")
 		to_load = [pos for pos in coords if pos not in self._chunks]
 		chunks = self._chunkdb.load_many(to_load)
-		for dchunk in chunks:
-			pos = dchunk[0]
-			chunk = dchunk[1]
-			if chunk:
-				self.set(pos, chunk)
+		
+		for pos in to_load:
+			if pos in chunks:
+				self.set(pos, chunks.get(pos))
 			else:
 				self.create(pos)
 	
@@ -84,21 +124,20 @@ class DBChunkPool(ChunkPool):
 			time.sleep(self.save_period)
 			
 			with self:
-				print("BEFORE:::")
-				self.print_chunks()
-				
 				self.save_changes()
 				
 				# unload old chunks
 				now = time.time()
-				for pos, chunk in self._chunks.items():
-					print(f"p{pos} :: t{now} :: m{chunk.last_modified} :: a{chunk.age(now)}")
 				self.clean_up(condition=lambda pos, chunk: chunk.age(now) > self.max_age)
-				
-				print("AFTER:::")
-				self.print_chunks()
 	
-	def get_min_max(self):
+	def remove_empty(self):
+		self._chunkdb.remove_empty()
+	
+	def _get_min_max(self):
+		"""
+		Meant for debugging.
+		"""
+		
 		minx = min(pos.x for pos in self._chunks)
 		maxx = max(pos.x for pos in self._chunks)
 		miny = min(pos.y for pos in self._chunks)
@@ -106,9 +145,13 @@ class DBChunkPool(ChunkPool):
 		
 		return minx, maxx, miny, maxy
 	
-	def print_chunks(self):
+	def _print_chunks(self):
+		"""
+		Meant for debugging.
+		"""
+		
 		if self._chunks:
-			minx, maxx, miny, maxy = self.get_min_max()
+			minx, maxx, miny, maxy = self._get_min_max()
 			sizex, sizey = maxx - minx + 1, maxy - miny + 1
 			print("┌" + "─"*sizex*2 + "┐")
 			for y in range(miny, maxy + 1):