PHPC-2470: Vendor bson-atomic as phongo_atomic

libmongoc 1.29.0 deprecated bson-atomic.h, so this vendors the necessary functionality into PHPC.

Author: jmikola

config.m4

@@ -127,6 +127,7 @@ if test "$PHP_MONGODB" != "no"; then
   PHP_MONGODB_SOURCES="\
     php_phongo.c \
     src/phongo_apm.c \
+    src/phongo_atomic.c \
     src/phongo_bson.c \
     src/phongo_bson_encode.c \
     src/phongo_client.c \

config.w32

@@ -114,7 +114,7 @@ if (PHP_MONGODB != "no") {
   var PHP_MONGODB_UTF8PROC_SOURCES="utf8proc.c";
 
   EXTENSION("mongodb", "php_phongo.c", null, PHP_MONGODB_CFLAGS);
-  MONGODB_ADD_SOURCES("/src", "phongo_apm.c phongo_bson.c phongo_bson_encode.c phongo_client.c phongo_compat.c phongo_error.c phongo_execute.c phongo_ini.c phongo_log.c phongo_util.c");
+  MONGODB_ADD_SOURCES("/src", "phongo_apm.c phongo_atomic.c phongo_bson.c phongo_bson_encode.c phongo_client.c phongo_compat.c phongo_error.c phongo_execute.c phongo_ini.c phongo_log.c phongo_util.c");
   MONGODB_ADD_SOURCES("/src/BSON", "Binary.c BinaryInterface.c Document.c Iterator.c DBPointer.c Decimal128.c Decimal128Interface.c Int64.c Javascript.c JavascriptInterface.c MaxKey.c MaxKeyInterface.c MinKey.c MinKeyInterface.c ObjectId.c ObjectIdInterface.c PackedArray.c Persistable.c Regex.c RegexInterface.c Serializable.c Symbol.c Timestamp.c TimestampInterface.c Type.c Undefined.c Unserializable.c UTCDateTime.c UTCDateTimeInterface.c functions.c");
   MONGODB_ADD_SOURCES("/src/MongoDB", "BulkWrite.c ClientEncryption.c Command.c Cursor.c CursorId.c CursorInterface.c Manager.c Query.c ReadConcern.c ReadPreference.c Server.c ServerApi.c ServerDescription.c Session.c TopologyDescription.c WriteConcern.c WriteConcernError.c WriteError.c WriteResult.c");
   MONGODB_ADD_SOURCES("/src/MongoDB/Exception", "AuthenticationException.c BulkWriteException.c CommandException.c ConnectionException.c ConnectionTimeoutException.c EncryptionException.c Exception.c ExecutionTimeoutException.c InvalidArgumentException.c LogicException.c RuntimeException.c ServerException.c SSLConnectionException.c UnexpectedValueException.c WriteException.c");

php_phongo.c

@@ -25,6 +25,7 @@
 #include <ext/standard/info.h>
 
 #include "php_phongo.h"
+#include "src/phongo_atomic.h"
 #include "src/phongo_client.h"
 #include "src/phongo_error.h"
 #include "src/phongo_ini.h"
@@ -130,7 +131,7 @@ PHP_GINIT_FUNCTION(mongodb) /* {{{ */
 #endif
 
 	/* Increment the thread counter. */
-	bson_atomic_int32_fetch_add(&phongo_num_threads, 1, bson_memory_order_seq_cst);
+	phongo_atomic_int32_fetch_add(&phongo_num_threads, 1, phongo_memory_order_seq_cst);
 
 	/* Clear extension globals */
 	memset(mongodb_globals, 0, sizeof(zend_mongodb_globals));
@@ -375,7 +376,7 @@ PHP_GSHUTDOWN_FUNCTION(mongodb) /* {{{ */
 	 * is the last thread, MSHUTDOWN has been called, persistent clients from
 	 * all threads have been destroyed, and it is now safe to shutdown libmongoc
 	 * and restore libbson's original vtable. */
-	if (bson_atomic_int32_fetch_sub(&phongo_num_threads, 1, bson_memory_order_seq_cst) - 1 == 0) {
+	if (phongo_atomic_int32_fetch_sub(&phongo_num_threads, 1, phongo_memory_order_seq_cst) - 1 == 0) {
 		mongoc_cleanup();
 		bson_mem_restore_vtable();
 	}

src/phongo_atomic.c

@@ -0,0 +1,124 @@
+/*
+ * Copyright 2024-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.
+ */
+
+/* Note: this file was derived from libbson's bson-atomic.c */
+
+#include "bson/bson.h"
+
+#include "phongo_atomic.h"
+
+#ifdef BSON_OS_UNIX
+/* For sched_yield() */
+#include <sched.h>
+#endif
+
+static void
+_thrd_yield (void)
+{
+   BSON_IF_WINDOWS (SwitchToThread ();)
+   BSON_IF_POSIX (sched_yield ();)
+}
+
+/**
+ * Some platforms do not support compiler intrinsics for atomic operations.
+ * We emulate that here using a spin lock and regular arithmetic operations
+ */
+static int8_t gEmulAtomicLock = 0;
+
+static void
+_lock_emul_atomic (void)
+{
+   int i;
+   if (phongo_atomic_int8_compare_exchange_weak (&gEmulAtomicLock, 0, 1, phongo_memory_order_acquire) == 0) {
+      /* Successfully took the spinlock */
+      return;
+   }
+   /* Failed. Try taking ten more times, then begin sleeping. */
+   for (i = 0; i < 10; ++i) {
+      if (phongo_atomic_int8_compare_exchange_weak (&gEmulAtomicLock, 0, 1, phongo_memory_order_acquire) == 0) {
+         /* Succeeded in taking the lock */
+         return;
+      }
+   }
+   /* Still don't have the lock. Spin and yield */
+   while (phongo_atomic_int8_compare_exchange_weak (&gEmulAtomicLock, 0, 1, phongo_memory_order_acquire) != 0) {
+      _thrd_yield ();
+   }
+}
+
+static void
+_unlock_emul_atomic (void)
+{
+   int64_t rv = phongo_atomic_int8_exchange (&gEmulAtomicLock, 0, phongo_memory_order_release);
+   BSON_ASSERT (rv == 1 && "Released atomic lock while not holding it");
+}
+
+int32_t
+_phongo_emul_atomic_int32_fetch_add (volatile int32_t *p, int32_t n, enum phongo_memory_order _unused)
+{
+   int32_t ret;
+
+   BSON_UNUSED (_unused);
+
+   _lock_emul_atomic ();
+   ret = *p;
+   *p += n;
+   _unlock_emul_atomic ();
+   return ret;
+}
+
+int32_t
+_phongo_emul_atomic_int32_exchange (volatile int32_t *p, int32_t n, enum phongo_memory_order _unused)
+{
+   int32_t ret;
+
+   BSON_UNUSED (_unused);
+
+   _lock_emul_atomic ();
+   ret = *p;
+   *p = n;
+   _unlock_emul_atomic ();
+   return ret;
+}
+
+int32_t
+_phongo_emul_atomic_int32_compare_exchange_strong (volatile int32_t *p,
+                                                 int32_t expect_value,
+                                                 int32_t new_value,
+                                                 enum phongo_memory_order _unused)
+{
+   int32_t ret;
+
+   BSON_UNUSED (_unused);
+
+   _lock_emul_atomic ();
+   ret = *p;
+   if (ret == expect_value) {
+      *p = new_value;
+   }
+   _unlock_emul_atomic ();
+   return ret;
+}
+
+int32_t
+_phongo_emul_atomic_int32_compare_exchange_weak (volatile int32_t *p,
+                                               int32_t expect_value,
+                                               int32_t new_value,
+                                               enum phongo_memory_order order)
+{
+   /* We're emulating. We can't do a weak version. */
+   return _phongo_emul_atomic_int32_compare_exchange_strong (p, expect_value, new_value, order);
+}