Add filtering

chainsyncer/db/models/filter.py

@@ -0,0 +1,40 @@
+# standard imports
+import hashlib
+
+# third-party imports
+from sqlalchemy import Column, String, Integer, BLOB
+from sqlalchemy.ext.hybrid import hybrid_property, hybrid_method
+
+# local imports
+from .base import SessionBase
+
+
+zero_digest = '{:<064s'.format('0')
+
+
+class BlockchainSyncFilter(SessionBase):
+
+    __tablename__ = 'chain_sync_filter'
+
+    chain_sync_id = Column(Integer, ForeignKey='chain_sync.id')
+    flags = Column(BLOB)
+    digest = Column(String)
+    count = Column(Integer)
+
+    @staticmethod
+    def set(self, names):
+
+
+    def __init__(self, names, chain_sync, digest=None):
+        if len(names) == 0:
+            digest = zero_digest
+        elif digest == None:
+            h = hashlib.new('sha256')
+            for n in names:
+                h.update(n.encode('utf-8') + b'\x00')
+            z = h.digest()
+            digest = z.hex()
+        self.digest = digest
+        self.count = len(names)
+        self.flags = bytearray((len(names) -1 ) / 8 + 1)
+        self.chain_sync_id = chain_sync.id