From b1441d424713c8a37c532c87f0a95f35ff179c49 Mon Sep 17 00:00:00 2001
From: Jack Robison <jackrobison@lbry.io>
Date: Wed, 19 Jan 2022 10:10:03 -0500
Subject: [PATCH] wait for writing to finish before closing the db

---
 lbry/wallet/server/block_processor.py | 59 +++++++++++++++------------
 1 file changed, 34 insertions(+), 25 deletions(-)

diff --git a/lbry/wallet/server/block_processor.py b/lbry/wallet/server/block_processor.py
index bd11e3d4e..a8190e827 100644
--- a/lbry/wallet/server/block_processor.py
+++ b/lbry/wallet/server/block_processor.py
@@ -180,6 +180,9 @@ class BlockProcessor:
         self.pending_transaction_num_mapping: Dict[bytes, int] = {}
         self.pending_transactions: Dict[int, bytes] = {}
 
+        self._stopping = False
+        self._ready_to_stop = asyncio.Event()
+
     async def run_in_thread_with_lock(self, func, *args):
         # Run in a thread to prevent blocking.  Shielded so that
         # cancellations from shutdown don't lose work - when the task
@@ -197,8 +200,6 @@ class BlockProcessor:
         return await asyncio.shield(run_in_thread())
 
     async def check_mempool(self):
-        if self.db.prefix_db.closed:
-            return
         current_mempool = {
             k.tx_hash: v.raw_tx for (k, v) in self.db.prefix_db.mempool_tx.iterate()
         }
@@ -1552,30 +1553,35 @@ class BlockProcessor:
 
     async def process_blocks_and_mempool_forever(self):
         """Loop forever processing blocks as they arrive."""
-        while True:
-            if self.height == self.daemon.cached_height():
-                if not self._caught_up_event.is_set():
-                    await self._first_caught_up()
-                    self._caught_up_event.set()
-            try:
-                await asyncio.wait_for(self.blocks_event.wait(), 0.1)
-            except asyncio.TimeoutError:
-                pass
-            self.blocks_event.clear()
-            blocks = self.prefetcher.get_prefetched_blocks()
-            if not blocks:
+        try:
+            while not self._stopping:
+                if self.height == self.daemon.cached_height():
+                    if not self._caught_up_event.is_set():
+                        await self._first_caught_up()
+                        self._caught_up_event.set()
                 try:
-                    await self.check_mempool()
-                    self.db.prefix_db.unsafe_commit()
-                except Exception:
-                    self.logger.exception("error while updating mempool txs")
-                    raise
-            else:
-                try:
-                    await self.check_and_advance_blocks(blocks)
-                except Exception:
-                    self.logger.exception("error while processing txs")
-                    raise
+                    await asyncio.wait_for(self.blocks_event.wait(), 0.1)
+                except asyncio.TimeoutError:
+                    pass
+                self.blocks_event.clear()
+                blocks = self.prefetcher.get_prefetched_blocks()
+                if self._stopping:
+                    break
+                if not blocks:
+                    try:
+                        await self.check_mempool()
+                        self.db.prefix_db.unsafe_commit()
+                    except Exception:
+                        self.logger.exception("error while updating mempool txs")
+                        raise
+                else:
+                    try:
+                        await self.check_and_advance_blocks(blocks)
+                    except Exception:
+                        self.logger.exception("error while processing txs")
+                        raise
+        finally:
+            self._ready_to_stop.set()
 
     async def _es_caught_up(self):
         self.db.es_sync_height = self.height
@@ -1645,6 +1651,7 @@ class BlockProcessor:
             self.db.close()
 
     async def start(self):
+        self._stopping = False
         env = self.env
         min_str, max_str = env.coin.SESSIONCLS.protocol_min_max_strings()
         self.logger.info(f'software version: {lbry.__version__}')
@@ -1662,6 +1669,8 @@ class BlockProcessor:
         await _start_cancellable(self.fetch_and_process_blocks)
 
     async def stop(self):
+        self._stopping = True
+        await self._ready_to_stop.wait()
         for task in reversed(self.cancellable_tasks):
             task.cancel()
         await asyncio.wait(self.cancellable_tasks)