Fix bug in detailed wallet sync relating to gap addrs.

Prior to this commit, addresses imported on tx creation
were at the tip of the index only, but detailed sync
requires all address gap-forwards to be imported, else
it requires a restart.
The particular fix approach taken her is aggression
because import is cheap; we import wallet.gaplimit forwards
on all branches, taking advantage of the bci's function
_collect_addresses_gap, thus ensuring that unless the gap
limit changes, we will definitely not need a restart.
Fast sync did not suffer from this and is unchanged.

jmclient/jmclient/blockchaininterface.py

@@ -504,10 +504,20 @@ def get_address_usages(self, wallet):
         # overall performance gain is probably negligible
         used_indices = self._get_used_indices(wallet, used_addresses)
         self._rewind_wallet_indices(wallet, used_indices, saved_indices)
+        # Now that we have finalized the wallet indices, update:
+        wallet.save()
         self.wallet_synced = True
 
     def sync_addresses(self, wallet, restart_cb=None):
+        # This more detailed version of wallet syncing must cover situations
+        # where the user has used the wallet on other Bitcoin Core instances
+        # and therefore the wallet label either does not have addresses
+        # imported, and/or, after the addresses are imported, they may not
+        # have the full history, since a rescan is required to discover
+        # the history of addresses before they were imported.
+
         log.debug("requesting detailed wallet history")
+
         wallet_name = self.get_wallet_name(wallet)
 
         addresses, saved_indices = self._collect_addresses_init(wallet)
@@ -529,7 +539,6 @@ def sync_addresses(self, wallet, restart_cb=None):
         used_addresses_gen = (tx['address']
                               for tx in self._yield_transactions(wallet_name)
                               if tx['category'] == 'receive')
-
         used_indices = self._get_used_indices(wallet, used_addresses_gen)
         log.debug("got used indices: {}".format(used_indices))
         gap_limit_used = not self._check_gap_indices(wallet, used_indices)
@@ -547,6 +556,8 @@ def sync_addresses(self, wallet, restart_cb=None):
         else:
             log.debug("Wallet successfully synced")
             self._rewind_wallet_indices(wallet, used_indices, saved_indices)
+            # Now that we have finalized the wallet indices, update:
+            wallet.save()
             self.wallet_synced = True
 
     @staticmethod

jmclient/jmclient/wallet.py

@@ -426,12 +426,18 @@ def get_key_from_addr(self, addr):
         privkey = self._get_priv_from_path(path)[0]
         return hexlify(privkey).decode('ascii')
 
-    def _get_addr_int_ext(self, get_script_func, mixdepth, bci=None):
-        script = get_script_func(mixdepth)
+    def _get_addr_int_ext(self, internal, mixdepth, bci=None):
+        script = self.get_internal_script(mixdepth) if internal else \
+            self.get_external_script(mixdepth)
         addr = self.script_to_addr(script)
         if bci is not None and hasattr(bci, 'import_addresses'):
             assert hasattr(bci, 'get_wallet_name')
-            bci.import_addresses([addr], bci.get_wallet_name(self))
+            # we aggressively import ahead of our index, so that when
+            # detailed sync is needed in future, it will not find
+            # imports missing (and this operation costs nothing).
+            addrs_to_import = list(bci._collect_addresses_gap(
+                self, self.gaplimit))
+            bci.import_addresses(addrs_to_import, bci.get_wallet_name(self))
         return addr
 
     def get_external_addr(self, mixdepth, bci=None):
@@ -443,8 +449,7 @@ def get_external_addr(self, mixdepth, bci=None):
         address into this blockchaininterface instance
         (based on Bitcoin Core's model).
         """
-        return self._get_addr_int_ext(self.get_external_script, mixdepth,
-                                      bci=bci)
+        return self._get_addr_int_ext(False, mixdepth, bci=bci)
 
     def get_internal_addr(self, mixdepth, bci=None):
         """
@@ -454,8 +459,7 @@ def get_internal_addr(self, mixdepth, bci=None):
         address into this blockchaininterface instance
         (based on Bitcoin Core's model).
         """
-        return self._get_addr_int_ext(self.get_internal_script, mixdepth,
-                                      bci=bci)
+        return self._get_addr_int_ext(True, mixdepth, bci=bci)
 
     def get_external_script(self, mixdepth):
         return self.get_new_script(mixdepth, False)