From a5c117b542d21db94d16677663a84e7f352ffe73 Mon Sep 17 00:00:00 2001
From: Victor Shyba <victor.shyba@gmail.com>
Date: Mon, 7 Sep 2020 17:17:51 -0300
Subject: [PATCH] wait for lbrycrd on start

---
 lbry/blockchain/lbrycrd.py                      |  2 ++
 lbry/blockchain/sync/synchronizer.py            | 12 +++++++++++-
 tests/integration/blockchain/test_blockchain.py |  8 ++++++++
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/lbry/blockchain/lbrycrd.py b/lbry/blockchain/lbrycrd.py
index 11aa79ba2..a43d5f600 100644
--- a/lbry/blockchain/lbrycrd.py
+++ b/lbry/blockchain/lbrycrd.py
@@ -243,6 +243,8 @@ class Lbrycrd:
             self.subscription = None
 
     async def rpc(self, method, params=None):
+        if self.session.closed:
+            raise Exception("session is closed! We are shutting down.")
         message = {
             "jsonrpc": "1.0",
             "id": "1",
diff --git a/lbry/blockchain/sync/synchronizer.py b/lbry/blockchain/sync/synchronizer.py
index 003b24efa..95a68aea2 100644
--- a/lbry/blockchain/sync/synchronizer.py
+++ b/lbry/blockchain/sync/synchronizer.py
@@ -43,9 +43,19 @@ class BlockchainSync(Sync):
         self.advance_loop_task: Optional[asyncio.Task] = None
         self.advance_loop_event = asyncio.Event()
 
+    async def wait_for_chain_ready(self):
+        while True:
+            try:
+                return await self.chain.ensure_subscribable()
+            except asyncio.CancelledError:
+                raise
+            except Exception as e:
+                log.warning("Blockchain not ready, waiting for it: %s", str(e))
+                await asyncio.sleep(1)
+
     async def start(self):
         self.db.stop_event.clear()
-        await self.chain.ensure_subscribable()
+        await self.wait_for_chain_ready()
         self.advance_loop_task = asyncio.create_task(self.advance())
         await self.advance_loop_task
         await self.chain.subscribe()
diff --git a/tests/integration/blockchain/test_blockchain.py b/tests/integration/blockchain/test_blockchain.py
index 7804dfc34..a706e079e 100644
--- a/tests/integration/blockchain/test_blockchain.py
+++ b/tests/integration/blockchain/test_blockchain.py
@@ -613,6 +613,14 @@ class TestMultiBlockFileSyncing(BasicBlockchainTestCase):
 
 
 class TestGeneralBlockchainSync(SyncingBlockchainTestCase):
+    async def test_sync_waits_for_lbrycrd_to_start(self):
+        await self.sync.stop()
+        await self.chain.stop()
+        sync_start = asyncio.ensure_future(self.sync.start())
+        await asyncio.sleep(0)
+        await self.chain.start()
+        await sync_start
+        self.assertTrue(sync_start.done())  # test goal is to get here without exceptions
 
     async def test_sync_advances(self):
         blocks = []