Add threading test for C extension

We already have some threading coverage in the general reader tests,
but this provides more detailed implementation tests for the extension.

Author: oschwald

tests/threading_test.py

@@ -0,0 +1,274 @@
+"""Tests for thread-safety and free-threading support."""
+
+from __future__ import annotations
+
+import threading
+import time
+import unittest
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from maxminddb.types import Record
+
+try:
+    import maxminddb.extension  # noqa: F401
+
+    HAS_EXTENSION = True
+except ImportError:
+    HAS_EXTENSION = False
+
+from maxminddb import open_database
+from maxminddb.const import MODE_MMAP_EXT
+
+
+@unittest.skipIf(
+    not HAS_EXTENSION,
+    "No C extension module found. Skipping threading tests",
+)
+class TestThreadSafety(unittest.TestCase):
+    """Test thread safety of the C extension."""
+
+    def test_concurrent_reads(self) -> None:
+        """Test multiple threads reading concurrently."""
+        reader = open_database(
+            "tests/data/test-data/MaxMind-DB-test-ipv4-24.mmdb",
+            MODE_MMAP_EXT,
+        )
+
+        results: list[Record | None] = [None] * 100
+        errors: list[Exception] = []
+
+        def lookup(index: int, ip: str) -> None:
+            try:
+                results[index] = reader.get(ip)
+            except Exception as e:  # noqa: BLE001
+                errors.append(e)
+
+        threads = []
+        for i in range(100):
+            ip = f"1.1.1.{(i % 32) + 1}"
+            t = threading.Thread(target=lookup, args=(i, ip))
+            threads.append(t)
+            t.start()
+
+        for t in threads:
+            t.join()
+
+        reader.close()
+
+        self.assertEqual(len(errors), 0, f"Errors during concurrent reads: {errors}")
+        # All lookups should have completed
+        self.assertNotIn(None, results)
+
+    def test_read_during_close(self) -> None:
+        """Test that close is safe when reads are happening concurrently."""
+        reader = open_database(
+            "tests/data/test-data/MaxMind-DB-test-ipv4-24.mmdb",
+            MODE_MMAP_EXT,
+        )
+
+        errors: list[Exception] = []
+        should_stop = threading.Event()
+
+        def continuous_reader() -> None:
+            # Keep reading until signaled to stop or reader is closed
+            while not should_stop.is_set():
+                try:
+                    reader.get("1.1.1.1")
+                except ValueError as e:  # noqa: PERF203
+                    # Expected once close() is called
+                    if "closed MaxMind DB" not in str(e):
+                        errors.append(e)
+                    break
+                except Exception as e:  # noqa: BLE001
+                    errors.append(e)
+                    break
+
+        # Start multiple readers
+        threads = [threading.Thread(target=continuous_reader) for _ in range(10)]
+        for t in threads:
+            t.start()
+
+        # Let readers run for a bit
+        time.sleep(0.05)
+
+        # Close while reads are happening
+        reader.close()
+
+        # Signal threads to stop
+        should_stop.set()
+
+        # Wait for all threads
+        for t in threads:
+            t.join(timeout=1.0)
+
+        self.assertEqual(len(errors), 0, f"Errors during close test: {errors}")
+
+    def test_read_after_close(self) -> None:
+        """Test that reads after close raise appropriate error."""
+        reader = open_database(
+            "tests/data/test-data/MaxMind-DB-test-ipv4-24.mmdb",
+            MODE_MMAP_EXT,
+        )
+        reader.close()
+
+        with self.assertRaisesRegex(
+            ValueError,
+            "Attempt to read from a closed MaxMind DB",
+        ):
+            reader.get("1.1.1.1")
+
+    def test_concurrent_reads_and_metadata(self) -> None:
+        """Test concurrent reads and metadata access."""
+        reader = open_database(
+            "tests/data/test-data/MaxMind-DB-test-ipv4-24.mmdb",
+            MODE_MMAP_EXT,
+        )
+
+        errors: list[Exception] = []
+        results: list[bool] = []
+
+        def do_reads() -> None:
+            try:
+                for _ in range(50):
+                    reader.get("1.1.1.1")
+                results.append(True)
+            except Exception as e:  # noqa: BLE001
+                errors.append(e)
+
+        def do_metadata() -> None:
+            try:
+                for _ in range(50):
+                    reader.metadata()
+                results.append(True)
+            except Exception as e:  # noqa: BLE001
+                errors.append(e)
+
+        threads = []
+        for _ in range(5):
+            threads.append(threading.Thread(target=do_reads))
+            threads.append(threading.Thread(target=do_metadata))
+
+        for t in threads:
+            t.start()
+
+        for t in threads:
+            t.join()
+
+        reader.close()
+
+        self.assertEqual(
+            len(errors), 0, f"Errors during concurrent operations: {errors}"
+        )
+        self.assertEqual(len(results), 10, "All threads should complete")
+
+    def test_concurrent_iteration(self) -> None:
+        """Test that iteration is thread-safe."""
+        reader = open_database(
+            "tests/data/test-data/MaxMind-DB-test-ipv4-24.mmdb",
+            MODE_MMAP_EXT,
+        )
+
+        errors: list[Exception] = []
+        counts: list[int] = []
+
+        def iterate() -> None:
+            try:
+                count = 0
+                for _ in reader:
+                    count += 1
+                counts.append(count)
+            except Exception as e:  # noqa: BLE001
+                errors.append(e)
+
+        threads = [threading.Thread(target=iterate) for _ in range(10)]
+
+        for t in threads:
+            t.start()
+
+        for t in threads:
+            t.join()
+
+        reader.close()
+
+        self.assertEqual(len(errors), 0, f"Errors during iteration: {errors}")
+        # All threads should see the same number of entries
+        self.assertEqual(len(set(counts)), 1, "All threads should see same entry count")
+
+    def test_stress_test(self) -> None:
+        """Stress test with many threads and operations."""
+        reader = open_database(
+            "tests/data/test-data/MaxMind-DB-test-ipv4-24.mmdb",
+            MODE_MMAP_EXT,
+        )
+
+        errors: list[Exception] = []
+        operations_completed = threading.Event()
+
+        def random_operations() -> None:
+            try:
+                for i in range(100):
+                    # Mix different operations
+                    if i % 3 == 0:
+                        reader.get("1.1.1.1")
+                    elif i % 3 == 1:
+                        reader.metadata()
+                    else:
+                        reader.get_with_prefix_len("1.1.1.2")
+            except Exception as e:  # noqa: BLE001
+                errors.append(e)
+
+        threads = [threading.Thread(target=random_operations) for _ in range(20)]
+
+        for t in threads:
+            t.start()
+
+        for t in threads:
+            t.join()
+
+        operations_completed.set()
+        reader.close()
+
+        self.assertEqual(len(errors), 0, f"Errors during stress test: {errors}")
+
+    def test_multiple_readers_different_databases(self) -> None:
+        """Test multiple readers on different databases in parallel."""
+        errors: list[Exception] = []
+
+        def use_reader(filename: str) -> None:
+            try:
+                reader = open_database(filename, MODE_MMAP_EXT)
+                for _ in range(50):
+                    reader.get("1.1.1.1")
+                reader.close()
+            except Exception as e:  # noqa: BLE001
+                errors.append(e)
+
+        threads = [
+            threading.Thread(
+                target=use_reader,
+                args=("tests/data/test-data/MaxMind-DB-test-ipv4-24.mmdb",),
+            )
+            for _ in range(5)
+        ]
+        threads.extend(
+            [
+                threading.Thread(
+                    target=use_reader,
+                    args=("tests/data/test-data/MaxMind-DB-test-ipv6-24.mmdb",),
+                )
+                for _ in range(5)
+            ]
+        )
+
+        for t in threads:
+            t.start()
+
+        for t in threads:
+            t.join()
+
+        self.assertEqual(len(errors), 0, f"Errors with multiple readers: {errors}")
+
+
+if __name__ == "__main__":
+    unittest.main()