[bitbake-devel][PATCH v2 08/10] hashserv: server: Use streaming and queue API for upstream exist queries

[Joshua Watt <jpewhacker@gmail.com>]

Reworks the "unihash-exists" handler to use the new server queue API and
client streaming API to efficiently stream requests to the upstream
server instead of having to wait for a roundtrip on the requests.

Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>
---
 lib/hashserv/server.py | 31 ++++++++++++++++++++++++++-----
 lib/hashserv/tests.py  |  5 +++++
 2 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/lib/hashserv/server.py b/lib/hashserv/server.py
index d0e6f23fc..0153730fa 100644
--- a/lib/hashserv/server.py
+++ b/lib/hashserv/server.py
@@ -522,17 +522,38 @@ class ServerClient(bb.asyncrpc.AsyncServerConnection):
 
     @permissions(READ_PERM)
     async def handle_exists_stream(self, request):
-        async def handler(l):
+        async def exists_handler(l):
             if await self.db.unihash_exists(l):
                 return "true"
+            return "false"
+
+        if not self.upstream_client:
+            return await self._stream_handler(exists_handler)
 
-            if self.upstream_client is not None:
-                if await self.upstream_client.unihash_exists(l):
+        async with self.upstream_client.unihash_exists_stream() as stream:
+
+            async def get_local_result(m):
+                if await self.db.unihash_exists(m):
                     return "true"
+                return None
 
-            return "false"
+            async def get_upstream_result(m):
+                exists = await stream.get_result()
+                return "true" if exists else "false"
 
-        return await self._stream_handler(handler)
+            queue = asyncio.Queue()
+            upstream = UpstreamQueue(
+                queue,
+                get_local_result,
+                stream.send_query,
+                get_upstream_result,
+            )
+
+            await bb.asyncrpc.TaskGroup.run(
+                self._stream_queue_handler(upstream.handler, queue),
+                upstream.process_results(),
+            )
+        return self.NO_RESPONSE
 
     async def report_readonly(self, data):
         method = data["method"]
diff --git a/lib/hashserv/tests.py b/lib/hashserv/tests.py
index e24bdcacb..a7ce7425e 100644
--- a/lib/hashserv/tests.py
+++ b/lib/hashserv/tests.py
@@ -374,20 +374,25 @@ class HashEquivalenceCommonTests(object):
             nonlocal side_client
 
             # check upstream server
+            self.assertTrue(self.client.unihash_exists(unihash))
             self.assertClientGetHash(self.client, taskhash, unihash)
 
             # Hash should *not* be present on the side server
+            if old_sidehash and unihash != old_sidehash:
+                self.assertFalse(side_client.unihash_exists(unihash))
             self.assertClientGetHash(side_client, taskhash, old_sidehash)
 
             # Hash should be present on the downstream server, since it
             # will defer to the upstream server. This will trigger
             # the backfill in the downstream server
+            self.assertTrue(down_client.unihash_exists(unihash))
             self.assertClientGetHash(down_client, taskhash, unihash)
 
             # After waiting for the downstream client to finish backfilling the
             # task from the upstream server, it should appear in the side server
             # since the database is populated
             down_client.backfill_wait()
+            self.assertTrue(side_client.unihash_exists(unihash))
             self.assertClientGetHash(side_client, taskhash, unihash)
 
         # Basic report
-- 
2.54.0