interface: split up 'step'; binary search of headers

electrum/interface.py

@@ -427,7 +427,7 @@ class Interface(PrintError):
 
         chain = blockchain.check_header(header) if 'mock' not in header else header['mock']['check'](header)
         if chain:
-            self.blockchain = chain
+            self.blockchain = chain if isinstance(chain, Blockchain) else self.blockchain
             return 'catchup', height+1
 
         can_connect = blockchain.can_connect(header) if 'mock' not in header else header['mock']['connect'](height)
@@ -445,32 +445,36 @@ class Interface(PrintError):
                 self.blockchain.save_header(header)
             return 'catchup', height
 
-        # binary
+        good, height, bad, bad_header = await self._search_headers_binary(height, bad, bad_header, chain)
-        if isinstance(chain, Blockchain):  # not when mocking
+        return await self._resolve_potential_chain_fork_given_forkpoint(good, height, bad, bad_header)
-            self.blockchain = chain
+
+    async def _search_headers_binary(self, height, bad, bad_header, chain):
+        self.blockchain = chain if isinstance(chain, Blockchain) else self.blockchain
         good = height
-        height = (bad + good) // 2
-        header = await self.get_block_header(height, 'binary')
         while True:
-            self.print_error("binary step")
+            assert good < bad, (good, bad)
+            height = (good + bad) // 2
+            self.print_error("binary step. good {}, bad {}, height {}".format(good, bad, height))
+            header = await self.get_block_header(height, 'binary')
             chain = blockchain.check_header(header) if 'mock' not in header else header['mock']['check'](header)
             if chain:
+                self.blockchain = chain if isinstance(chain, Blockchain) else self.blockchain
                 good = height
-                self.blockchain = self.blockchain if type(chain) in [bool, int] else chain
             else:
                 bad = height
                 bad_header = header
-            assert good < bad, (good, bad)
+            if good + 1 == bad:
-            if bad != good + 1:
+                break
-                height = (bad + good) // 2
+
-                header = await self.get_block_header(height, 'binary')
-                continue
         mock = bad_header and 'mock' in bad_header and bad_header['mock']['connect'](height)
         real = not mock and self.blockchain.can_connect(bad_header, check_height=False)
         if not real and not mock:
-                raise Exception('unexpected bad header during binary' + str(bad_header)) # line 948 in 8e69174374aee87d73cd2f8005fbbe87c93eee9c's network.py
+            raise Exception('unexpected bad header during binary: {}'.format(bad_header))
-            branch = blockchain.blockchains.get(bad)
         self.print_error("binary search exited. good {}, bad {}".format(good, bad))
+        return good, height, bad, bad_header
+
+    async def _resolve_potential_chain_fork_given_forkpoint(self, good, height, bad, bad_header):
+        branch = blockchain.blockchains.get(bad)
         if branch is not None:
             self.print_error("existing fork found at bad height {}".format(bad))
             ismocking = type(branch) is dict
@@ -516,7 +520,7 @@ class Interface(PrintError):
             else:
                 assert bh == good
                 if bh < self.tip:
-                        self.print_error("catching up from %d"% (bh + 1))
+                    self.print_error("catching up from %d" % (bh + 1))
                     height = bh + 1
                 return 'no_fork', height