Add idle callback to poller

chainsyncer/driver/poll.py

@@ -12,6 +12,7 @@ from chainsyncer.error import (
 logg = logging.getLogger(__name__)
 
 
+NS_DIV = 1000000000
 
 class BlockPollSyncer(Syncer):
     """Syncer driver implementation of chainsyncer.driver.base.Syncer that retrieves new blocks through polling.
@@ -19,6 +20,40 @@ class BlockPollSyncer(Syncer):
 
     name = 'blockpoll'
 
+
+    def __init__(self, backend, chain_interface, pre_callback=None, block_callback=None, post_callback=None, idle_callback=None):
+        super(BlockPollSyncer, self).__init__(backend, chain_interface, pre_callback=pre_callback, block_callback=block_callback, post_callback=post_callback)
+        self.idle_callback = idle_callback
+        self.last_start = 0
+        self.clock_id = time.CLOCK_MONOTONIC_RAW
+
+
+    def idle(self, interval):
+        interval *= NS_DIV
+        idle_start = time.clock_gettime_ns(self.clock_id)
+        delta = idle_start - self.last_start
+        if delta > interval:
+            interval /= NS_DIV
+            time.sleep(interval)
+            return
+
+        if self.idle_callback != None:
+            r = True
+            while r:
+                before = time.clock_gettime_ns(self.clock_id)
+                r = self.idle_callback(interval)
+                after = time.clock_gettime_ns(self.clock_id)
+                delta = after - before
+                if delta < 0:
+                    return
+                interval -= delta
+                if interval < 0:
+                    return
+
+        interval /= NS_DIV
+        time.sleep(interval)
+
+
     def loop(self, interval, conn):
         """Indefinite loop polling the given RPC connection for new blocks in the given interval.
 
@@ -34,9 +69,9 @@ class BlockPollSyncer(Syncer):
 
 
         while self.running and Syncer.running_global:
+            self.last_start = time.clock_gettime_ns(self.clock_id)
             if self.pre_callback != None:
                 self.pre_callback()
-            #while True and Syncer.running_global:
             while True and self.running:
                 if start_tx > 0:
                     start_tx -= 1
@@ -48,11 +83,6 @@ class BlockPollSyncer(Syncer):
                     return self.backend.get()
                 except NoBlockForYou as e:
                     break
-# TODO: To properly handle this, ensure that previous request is rolled back
-#                except sqlalchemy.exc.OperationalError as e:
-#                    logg.error('database error: {}'.format(e))
-#                    break
-
                 if self.block_callback != None:
                     self.block_callback(block, None)
 
@@ -65,4 +95,5 @@ class BlockPollSyncer(Syncer):
                 time.sleep(self.yield_delay)
             if self.post_callback != None:
                 self.post_callback()
-            time.sleep(interval)
+
+            self.idle(interval)

setup.cfg

@@ -1,6 +1,6 @@
 [metadata]
 name = chainsyncer
-version = 0.0.7
+version = 0.1.0
 description = Generic blockchain syncer driver
 author = Louis Holbrook
 author_email = dev@holbrook.no