Merge pull request #335 from nats-io/reqid-nuid

Add couple of extra unique token characters to requests

nats/aio/client.py

@@ -20,6 +20,7 @@
 import ssl
 import sys
 import time
+from secrets import token_hex
 from dataclasses import dataclass
 from email.parser import BytesParser
 from random import shuffle
@@ -56,7 +57,7 @@
     Subscription,
 )
 
-__version__ = '2.1.6'
+__version__ = '2.1.7'
 __lang__ = 'python3'
 _logger = logging.getLogger(__name__)
 PROTOCOL = 1
@@ -168,12 +169,8 @@ def __init__(self) -> None:
         self._reconnection_task: Union[asyncio.Task[None], None] = None
         self._reconnection_task_future: Optional[asyncio.Future] = None
         self._max_payload: int = DEFAULT_MAX_PAYLOAD_SIZE
-        # This is the client id that the NATS server knows
-        # about. Useful in debugging application errors
-        # when logged with this identifier along
-        # with nats server log.
-        # This would make more sense if we log the server
-        # connected to as well in case of cluster setup.
+
+        # client id that the NATS server knows about.
         self._client_id: Optional[str] = None
         self._sid: int = 0
         self._subs: Dict[int, Subscription] = {}
@@ -929,8 +926,10 @@ async def _request_new_style(
             await self._init_request_sub()
         assert self._resp_sub_prefix
 
-        # Use a new NUID for the token inbox and then use the future.
+        # Use a new NUID + couple of unique token bytes to identify the request,
+        # then use the future to get the response.
         token = self._nuid.next()
+        token.extend(token_hex(2).encode())
         inbox = self._resp_sub_prefix[:]
         inbox.extend(token)
         future: asyncio.Future = asyncio.Future()

nats/nuid.py

@@ -12,8 +12,9 @@
 # limitations under the License.
 #
 
-from random import Random, SystemRandom
+from random import Random
 from sys import maxsize as MaxInt
+from secrets import token_bytes, randbelow
 
 DIGITS = b'0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'
 BASE = 62
@@ -33,8 +34,7 @@ class NUID:
     """
 
     def __init__(self) -> None:
-        self._srand = SystemRandom()
-        self._prand = Random(self._srand.randint(0, MaxInt))
+        self._prand = Random(randbelow(MaxInt))
         self._seq = self._prand.randint(0, MAX_SEQ)
         self._inc = MIN_INC + self._prand.randint(BASE + 1, INC)
         self._prefix = bytearray()
@@ -60,9 +60,7 @@ def next(self) -> bytearray:
         return prefix
 
     def randomize_prefix(self) -> None:
-        random_bytes = (
-            self._srand.getrandbits(8) for i in range(PREFIX_LENGTH)
-        )
+        random_bytes = token_bytes(PREFIX_LENGTH)
         self._prefix = bytearray(DIGITS[c % BASE] for c in random_bytes)
 
     def reset_sequential(self) -> None:

tests/test_js.py

@@ -700,6 +700,22 @@ async def error_cb(err):
         assert len(msgs) <= 100
         assert sub.pending_msgs == 0
         assert sub.pending_bytes == 0
+
+        # Consumer has a single message pending but none in buffer.
+        await js.publish("a3", b'last message')
+        info = await sub.consumer_info()
+        assert info.num_pending == 1
+        assert sub.pending_msgs == 0
+
+        # Remove interest
+        await sub.unsubscribe()
+        with pytest.raises(TimeoutError):
+            await sub.fetch(1, timeout=1)
+
+        # The pending message is still there, but not possible to consume.
+        info = await sub.consumer_info()
+        assert info.num_pending == 1
+
         await nc.close()
 
 

todo.md

@@ -20,7 +20,7 @@
 - [X] io_loop becomes loop parameter
 - [X] Drain Mode
 - [X] Connect timeout
+- [X] Adopt async/await in client
+- [X] Subscription object on subscribe
+- [X] Error handler yields the subscription
 - [ ] Use asyncio.Protocol
-- [ ] Adopt async/await in client
-- [ ] Subscription object on subscribe
-- [ ] Error handler yields the subscription