CDRIVER-4220 simplify and test obsolete bson_sync_synchronize API (#1766)

The bson_sync_synchronize() macro in bson_compat has long been superseded by bson_atomic_thread_fence(), and all of bson_atomic is now deprecated. This change replaces bson_sync_synchronize with a deprecated inline function, preparing for its removal in the next major version.

* bson-compat: replace bson_sync_synchronize macro with deprecated inline
* tests: trivial test for bson_sync_synchronize

Author: Micah Scott @ MongoDB

src/libbson/src/bson/bson-compat.h

@@ -169,19 +169,6 @@ typedef signed char bool;
 #endif
 
 
-#if defined(__GNUC__)
-#if (__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ >= 1)
-#define bson_sync_synchronize() __sync_synchronize ()
-#elif defined(__i386__) || defined(__i486__) || defined(__i586__) || defined(__i686__) || defined(__x86_64__)
-#define bson_sync_synchronize() asm volatile ("mfence" ::: "memory")
-#else
-#define bson_sync_synchronize() asm volatile ("sync" ::: "memory")
-#endif
-#elif defined(_MSC_VER)
-#define bson_sync_synchronize() MemoryBarrier ()
-#endif
-
-
 #if !defined(va_copy) && defined(__va_copy)
 #define va_copy(dst, src) __va_copy (dst, src)
 #endif
@@ -216,6 +203,13 @@ typedef signed char bool;
 #define BSON_IF_POSIX(...) __VA_ARGS__
 #endif
 
+static BSON_INLINE void BSON_GNUC_DEPRECATED
+bson_sync_synchronize (void)
+{
+   BSON_IF_MSVC (MemoryBarrier ();)
+   BSON_IF_GNU_LIKE (__sync_synchronize ();)
+}
+
 
 BSON_END_DECLS
 

src/libbson/tests/test-bson-sync.c

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2009-present MongoDB, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+
+#include <bson/bson.h>
+#include <common-macros-private.h> // BEGIN_IGNORE_DEPRECATIONS
+
+#include "TestSuite.h"
+
+static void
+test_bson_sync_synchronize (void)
+{
+   BEGIN_IGNORE_DEPRECATIONS
+
+   // This doesn't test for correct functionality, only that it exists and can be called
+   bson_sync_synchronize ();
+
+   END_IGNORE_DEPRECATIONS
+}
+
+void
+test_bson_sync_install (TestSuite *suite)
+{
+   TestSuite_Add (suite, "/bson/sync/synchronize", test_bson_sync_synchronize);
+}

src/libmongoc/CMakeLists.txt

@@ -1040,6 +1040,7 @@ set (test-libmongoc-sources
    ${mongo-c-driver_SOURCE_DIR}/src/libbson/tests/test-bson-cmp.c
    ${mongo-c-driver_SOURCE_DIR}/src/libbson/tests/test-bson-corpus.c
    ${mongo-c-driver_SOURCE_DIR}/src/libbson/tests/test-bson-error.c
+   ${mongo-c-driver_SOURCE_DIR}/src/libbson/tests/test-bson-sync.c
    ${mongo-c-driver_SOURCE_DIR}/src/libbson/tests/test-bson-version.c
    ${mongo-c-driver_SOURCE_DIR}/src/libbson/tests/test-bson.c
    ${mongo-c-driver_SOURCE_DIR}/src/libbson/tests/test-clock.c

src/libmongoc/tests/test-libmongoc-main.c

@@ -30,6 +30,7 @@ main (int argc, char *argv[])
    TEST_INSTALL (test_bson_corpus_install);
    TEST_INSTALL (test_bson_error_install);
    TEST_INSTALL (test_bson_install);
+   TEST_INSTALL (test_bson_sync_install);
    TEST_INSTALL (test_bson_version_install);
    TEST_INSTALL (test_clock_install);
    TEST_INSTALL (test_decimal128_install);