electrum

commit 4346d2fc765f40a9388108c06cf1ee132d663923
parent 83750a861fb594c0316cac3c36c53b28bbb4485a
Author: SomberNight <somber.night@protonmail.com>
Date:   Fri, 12 Feb 2021 21:31:18 +0100

synchronizer: ensure fairness between wallets

Scenario (prior to change):
User opens wallet1 with 10k addresses, and then immediately opens wallet2
with 100 addresses.
wallet1 will synchronise first, fully, and only then will wallet2 start syncing.

Now, wallet1 and wallet2 will sync concurrently (and wallet2 will finish much
sooner as expected).

Diffstat:
M
electrum/synchronizer.py
 | 
13
++++++++++---

1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/electrum/synchronizer.py b/electrum/synchronizer.py
@@ -61,6 +61,10 @@ class SynchronizerBase(NetworkJobOnDefaultServer):
     def __init__(self, network: 'Network'):
         self.asyncio_loop = network.asyncio_loop
         self._reset_request_counters()
+        # Ensure fairness between Synchronizers. e.g. if multiple wallets
+        # are open, a large wallet should not starve the small wallets:
+        self._network_request_semaphore = asyncio.Semaphore(100)
+
         NetworkJobOnDefaultServer.__init__(self, network)
 
     def _reset(self):
@@ -106,7 +110,8 @@ class SynchronizerBase(NetworkJobOnDefaultServer):
             self.scripthash_to_address[h] = addr
             self._requests_sent += 1
             try:
-                await self.session.subscribe('blockchain.scripthash.subscribe', [h], self.status_queue)
+                async with self._network_request_semaphore:
+                    await self.session.subscribe('blockchain.scripthash.subscribe', [h], self.status_queue)
             except RPCError as e:
                 if e.message == 'history too large':  # no unique error code
                     raise GracefulDisconnect(e, log_level=logging.ERROR) from e
@@ -167,7 +172,8 @@ class Synchronizer(SynchronizerBase):
         self.requested_histories.add((addr, status))
         h = address_to_scripthash(addr)
         self._requests_sent += 1
-        result = await self.interface.get_history_for_scripthash(h)
+        async with self._network_request_semaphore:
+            result = await self.interface.get_history_for_scripthash(h)
         self._requests_answered += 1
         self.logger.info(f"receiving history {addr} {len(result)}")
         hashes = set(map(lambda item: item['tx_hash'], result))
@@ -210,7 +216,8 @@ class Synchronizer(SynchronizerBase):
     async def _get_transaction(self, tx_hash, *, allow_server_not_finding_tx=False):
         self._requests_sent += 1
         try:
-            raw_tx = await self.interface.get_transaction(tx_hash)
+            async with self._network_request_semaphore:
+                raw_tx = await self.interface.get_transaction(tx_hash)
         except RPCError as e:
             # most likely, "No such mempool or blockchain transaction"
             if allow_server_not_finding_tx: