Replace filter execution control with bools instead of exceptions

chainsyncer/session.py

@@ -26,16 +26,10 @@ class SyncSession:
     def filter(self, conn, block, tx):
         self.session_store.connect()
         for fltr in self.filters:
-            try:
-                self.item.advance()
-            except FilterDone:
-                break
-            interrupt = fltr.filter(conn, block, tx)
-            self.item.release(interrupt=interrupt)
-        try:
             self.item.advance()
-            raise BackendError('filter state inconsitent with filter list')
-        except FilterDone:
-            self.item.reset()
+            interrupt = fltr.filter(conn, block, tx)
+            if not self.item.release(interrupt=interrupt):
+                break
+        self.item.reset()
         self.next()
         self.session_store.disconnect()

chainsyncer/state/base.py

@@ -19,12 +19,14 @@ class SyncState:
         self.state_store.add('LOCK')
         self.state_store.add('INTERRUPT')
         self.state_store.add('RESET')
+
         self.state = self.state_store.state
         self.put = self.state_store.put
         self.set = self.state_store.set
         self.next = self.state_store.next
         self.move = self.state_store.move
         self.unset = self.state_store.unset
+        self.peek = self.state_store.peek
         self.from_name = self.state_store.from_name
         self.state_store.sync()
         self.all = self.state_store.all

chainsyncer/store/fs.py

@@ -82,6 +82,10 @@ class SyncFsItem:
         self.sync_state.replace(self.state_key, v)
 
 
+    def __find_advance(self):
+        v = self.filter_state.state(self.state_key)
+
+
     def advance(self):
         if self.skip_filter:
             raise FilterDone()
@@ -95,24 +99,30 @@ class SyncFsItem:
         except StateInvalid:
             done = True
         if done:
-            self.filter_state.set(self.state_key, self.filter_state.from_name('DONE'))
             raise FilterDone()
         self.filter_state.set(self.state_key, self.filter_state.from_name('LOCK'))
        
 
     def release(self, interrupt=False):
         if self.skip_filter:
-            raise FilterDone()
+            return False
         if interrupt:
             self.filter_state.unset(self.state_key, self.filter_state.from_name('LOCK'))
             self.filter_state.set(self.state_key, self.filter_state.from_name('INTERRUPT'))
             self.filter_state.set(self.state_key, self.filter_state.from_name('DONE'))
-            return
+            return False
 
         state = self.filter_state.state(self.state_key)
         if state & self.filter_state.from_name('LOCK') == 0:
             raise LockError('release attempt on {} when state unlocked'.format(self.state_key))
         self.filter_state.unset(self.state_key, self.filter_state.from_name('LOCK'))
+        try:
+            c = self.filter_state.peek(self.state_key)
+            logg.debug('peeked {}'.format(c))
+        except StateInvalid:
+            self.filter_state.set(self.state_key, self.filter_state.from_name('DONE'))
+            return False
+        return True
         
 
     def __str__(self):

tests/test_filter.py

@@ -31,7 +31,6 @@ class TestFilter(unittest.TestCase):
         self.path = tempfile.mkdtemp()
         self.store = SyncFsStore(self.path)
         self.session = SyncSession(self.store)
-        self.session.start()
         self.conn = MockConn()
 
 
@@ -45,6 +44,8 @@ class TestFilter(unittest.TestCase):
         fltr_two = MockFilter('bar')
         self.store.register(fltr_two)
 
+        self.session.start()
+
         tx_hash = os.urandom(32).hex()
         tx = MockTx(42, tx_hash)
         block = MockBlock(13, [tx_hash])
@@ -61,6 +62,8 @@ class TestFilter(unittest.TestCase):
         fltr_two = MockFilter('bar')
         self.store.register(fltr_two)
 
+        self.session.start()
+
         tx_hash = os.urandom(32).hex()
         tx = MockTx(42, tx_hash)
         block = MockBlock(13, [tx_hash])