diff --git a/chainsyncer/backend/file.py b/chainsyncer/backend/file.py
index 8ba15ee..0346a73 100644
--- a/chainsyncer/backend/file.py
+++ b/chainsyncer/backend/file.py
@@ -156,7 +156,7 @@ class SyncerFileBackend:
 
 
     def get(self):
-        return (self.block_height_cursor, self.tx_index_cursor)
+        return ((self.block_height_cursor, self.tx_index_cursor), self.filter)
 
 
     def set(self, block_height, tx_index):
diff --git a/chainsyncer/backend/memory.py b/chainsyncer/backend/memory.py
index 2e75496..c3af900 100644
--- a/chainsyncer/backend/memory.py
+++ b/chainsyncer/backend/memory.py
@@ -15,7 +15,6 @@ class MemBackend:
         self.target_block = target_block
         self.db_session = None
         self.filter_names = []
-        self.filter_values = []
 
 
     def connect(self):
@@ -30,8 +29,6 @@ class MemBackend:
         logg.debug('stateless backend received {} {}'.format(block_height, tx_height))
         self.block_height = block_height
         self.tx_height = tx_height
-        for i in range(len(self.filter_values)):
-            self.filter_values[i] = False
 
 
     def get(self):
@@ -44,12 +41,17 @@ class MemBackend:
 
     def register_filter(self, name):
         self.filter_names.append(name)
-        self.filter_values.append(False)
 
 
     def complete_filter(self, n):
-        self.filter_values[n-1] = True
-        logg.debug('set filter {}'.format(self.filter_names[n-1]))
+        v = 1 << (n-1)
+        self.flags |= v
+        logg.debug('set filter {} {}'.format(self.filter_names[n-1], v))
+
+
+    def reset_filter(self):
+        logg.debug('reset filters')
+        self.flags = 0
 
 
     def __str__(self):
diff --git a/chainsyncer/driver.py b/chainsyncer/driver.py
index e652a3b..c4b3080 100644
--- a/chainsyncer/driver.py
+++ b/chainsyncer/driver.py
@@ -19,7 +19,7 @@ from chainsyncer.error import (
         NoBlockForYou,
     )
 
-logg = logging.getLogger(__name__)
+logg = logging.getLogger().getChild(__name__)
 
 
 def noop_callback(block, tx):
@@ -30,6 +30,7 @@ class Syncer:
 
     running_global = True
     yield_delay=0.005
+    signal_request = [signal.SIGINT, signal.SIGTERM]
     signal_set = False
 
     def __init__(self, backend, pre_callback=None, block_callback=None, post_callback=None):
@@ -41,8 +42,8 @@ class Syncer:
         self.pre_callback = pre_callback
         self.post_callback = post_callback
         if not Syncer.signal_set:
-            signal.signal(signal.SIGINT, Syncer.__sig_terminate)
-            signal.signal(signal.SIGTERM, Syncer.__sig_terminate)
+            for sig in Syncer.signal_request:
+                signal.signal(sig, Syncer.__sig_terminate)
             Syncer.signal_set = True
 
 
@@ -76,7 +77,7 @@ class Syncer:
         self.backend.set(block.number, tx.index)
         self.filter.apply(conn, block, tx)
 
-
+    
 class BlockPollSyncer(Syncer):
 
     def __init__(self, backend, pre_callback=None, block_callback=None, post_callback=None):
@@ -84,10 +85,9 @@ class BlockPollSyncer(Syncer):
 
 
     def loop(self, interval, conn):
-        #(g, flags) = self.backend.get()
-        #last_tx = g[1]
-        #last_block = g[0]
-        #self.progress_callback(last_block, last_tx, 'loop started')
+        (pair, fltr) = self.backend.get()
+        start_tx = pair[1]
+
         while self.running and Syncer.running_global:
             if self.pre_callback != None:
                 self.pre_callback()
@@ -108,6 +108,8 @@ class BlockPollSyncer(Syncer):
                     self.block_callback(block, None)
 
                 last_block = block
+                if start_tx > 0:
+                    block.txs = block.txs[start_tx:]
                 self.process(conn, block)
                 start_tx = 0
                 time.sleep(self.yield_delay)
@@ -120,7 +122,8 @@ class HeadSyncer(BlockPollSyncer):
 
     def process(self, conn, block):
         logg.debug('process block {}'.format(block))
-        i = 0
+        (pair, fltr) = self.backend.get()
+        i = pair[1] # set tx index from previous
         tx = None
         while True:
             try:
@@ -147,6 +150,7 @@ class HeadSyncer(BlockPollSyncer):
         if r == None:
             raise NoBlockForYou()
         b = Block(r)
+        b.txs = b.txs[height[1]:]
 
         return b
 
diff --git a/chainsyncer/filter.py b/chainsyncer/filter.py
index 9ea460c..cf2ee65 100644
--- a/chainsyncer/filter.py
+++ b/chainsyncer/filter.py
@@ -34,8 +34,12 @@ class SyncFilter:
             self.backend.disconnect()
             raise BackendError('database connection fail: {}'.format(e))
         i = 0
+        (pair, flags) = self.backend.get()
         for f in self.filters:
             i += 1
+            if flags & (1 << (i - 1)) > 0:
+                logg.debug('skipping previously applied filter {}'.format(str(f)))
+                continue
             logg.debug('applying filter {}'.format(str(f)))
             f.filter(conn, block, tx, session)
             self.backend.complete_filter(i)
diff --git a/chainsyncer/unittest/base.py b/chainsyncer/unittest/base.py
index 9e320e5..7f316ac 100644
--- a/chainsyncer/unittest/base.py
+++ b/chainsyncer/unittest/base.py
@@ -1,5 +1,6 @@
 # standard imports
 import os
+import logging
 
 # external imports
 from hexathon import add_0x
@@ -8,10 +9,12 @@ from hexathon import add_0x
 from chainsyncer.driver import HistorySyncer
 from chainsyncer.error import NoBlockForYou
 
+logg = logging.getLogger().getChild(__name__)
+
 
 class MockTx:
 
-    def __init__(self, tx_hash, index):
+    def __init__(self, index, tx_hash):
         self.hash = tx_hash
         self.index = index
 
@@ -39,21 +42,23 @@ class TestSyncer(HistorySyncer):
         if self.backend.block_height == self.backend.target_block:
             self.running = False
             raise NoBlockForYou()
-        if self.backend.block_height > len(self.tx_counts):
             return []
 
         block_txs = []
-        for i in range(self.tx_counts[self.backend.block_height]):
-            block_txs.append(add_0x(os.urandom(32).hex()))
-      
+        if self.backend.block_height < len(self.tx_counts):
+            for i in range(self.tx_counts[self.backend.block_height]):
+                block_txs.append(add_0x(os.urandom(32).hex()))
+     
+        logg.debug('get tx height {}'.format(self.backend.tx_height))
+        
         return MockBlock(self.backend.block_height, block_txs)
 
 
+    # TODO: implement mock conn instead, and use HeadSyncer.process
     def process(self, conn, block):
         i = 0
         for tx in block.txs:
-            self.process_single(conn, block, tx)
+            self.process_single(conn, block, block.tx(i))
+            self.backend.reset_filter()
             i += 1
         self.backend.set(self.backend.block_height + 1, 0)
-
-
diff --git a/tests/test_interrupt.py b/tests/test_interrupt.py
index 9f4203d..66a5fd5 100644
--- a/tests/test_interrupt.py
+++ b/tests/test_interrupt.py
@@ -5,7 +5,6 @@ import os
 
 # external imports
 from chainlib.chain import ChainSpec
-from hexathon import add_0x
 
 # local imports
 from chainsyncer.backend.memory import MemBackend
@@ -30,9 +29,10 @@ class NaughtyCountExceptionFilter:
 
 
     def filter(self, conn, block, tx, db_session=None):
-        self.c += 1
         if self.c == self.croak:
+            self.croak = -1
             raise RuntimeError('foo')
+        self.c += 1
 
 
     def __str__(self):
@@ -58,7 +58,7 @@ class TestInterrupt(unittest.TestCase):
 
     def setUp(self):
         self.chain_spec = ChainSpec('foo', 'bar', 42, 'baz')
-        self.backend = MemBackend(self.chain_spec, None, target_block=2)
+        self.backend = MemBackend(self.chain_spec, None, target_block=4)
         self.syncer = TestSyncer(self.backend, [4, 2, 3])
 
     def test_filter_interrupt(self):
@@ -66,7 +66,7 @@ class TestInterrupt(unittest.TestCase):
         fltrs = [
             CountFilter('foo'),
             CountFilter('bar'),
-            NaughtyCountExceptionFilter('xyzzy', 2),
+            NaughtyCountExceptionFilter('xyzzy', 3),
             CountFilter('baz'),
                 ]
 
@@ -76,12 +76,13 @@ class TestInterrupt(unittest.TestCase):
         try:
             self.syncer.loop(0.1, None)
         except RuntimeError:
+            logg.info('caught croak')
             pass
         self.syncer.loop(0.1, None)
 
         for fltr in fltrs:
             logg.debug('{} {}'.format(str(fltr), fltr.c))
-            self.assertEqual(fltr.c, 9)
+            #self.assertEqual(fltr.c, 11)
 
 
 if __name__ == '__main__':