Check that advisory lock prefixes fit in 32 bits (#16)

We only reserve 32 bits for an advisory lock prefix, and since Python
doesn't have a specific `int32` type, do a preflight check on the client
to make sure that a given prefix is valid and will fit.

Author: brandur

src/riverqueue/client.py

@@ -49,7 +49,9 @@ def __init__(
         self, driver: AsyncDriverProtocol, advisory_lock_prefix: Optional[int] = None
     ):
         self.driver = driver
-        self.advisory_lock_prefix = advisory_lock_prefix
+        self.advisory_lock_prefix = _check_advisory_lock_prefix_bounds(
+            advisory_lock_prefix
+        )
 
     async def insert(
         self, args: Args, insert_opts: Optional[InsertOpts] = None
@@ -122,7 +124,9 @@ def __init__(
         self, driver: DriverProtocol, advisory_lock_prefix: Optional[int] = None
     ):
         self.driver = driver
-        self.advisory_lock_prefix = advisory_lock_prefix
+        self.advisory_lock_prefix = _check_advisory_lock_prefix_bounds(
+            advisory_lock_prefix
+        )
 
     def insert(
         self, args: Args, insert_opts: Optional[InsertOpts] = None
@@ -247,6 +251,17 @@ def _build_unique_get_params_and_lock_key(
     return (get_params, _uint64_to_int64(lock_key))
 
 
+def _check_advisory_lock_prefix_bounds(
+    advisory_lock_prefix: Optional[int],
+) -> Optional[int]:
+    if advisory_lock_prefix:
+        print("in_bytes", advisory_lock_prefix.to_bytes(4))
+        # We only reserve 4 bytes for the prefix, so make sure the given one
+        # properly fits. This will error in case that's not the case.
+        advisory_lock_prefix.to_bytes(4)
+    return advisory_lock_prefix
+
+
 def _make_insert_params(
     args: Args,
     insert_opts: InsertOpts,

tests/client_test.py

@@ -147,3 +147,19 @@ def test_insert_with_unique_opts_by_state(client, mock_exec):
     # Check that the UniqueOpts were correctly processed
     call_args = mock_exec.job_insert.call_args[0][0]
     assert call_args.kind == "simple"
+
+
+def test_check_advisory_lock_prefix_bounds():
+    Client(mock_driver, advisory_lock_prefix=123)
+
+    with pytest.raises(OverflowError) as ex:
+        Client(mock_driver, advisory_lock_prefix=-1)
+    assert "can't convert negative int to unsigned" == str(ex.value)
+
+    # 2^32-1 is 0xffffffff (1s for 32 bits) which fits
+    Client(mock_driver, advisory_lock_prefix=2**32 - 1)
+
+    # 2^32 is 0x100000000, which does not
+    with pytest.raises(OverflowError) as ex:
+        Client(mock_driver, advisory_lock_prefix=2**32)
+    assert "int too big to convert" == str(ex.value)