Work around strange error with atomic and swift under Xcode 8.3.3.
Haven't been able to make a repo case, but this should "fix" the problem
by avoid it completely.
- Move readOnlySemaphore_ into the .m file so it isn't exposed in any
header.
- Move GPBGetObjectIvarWithField() also to go with the new limited
visibility on the readOnlySemaphore_.
diff --git a/objectivec/GPBMessage.m b/objectivec/GPBMessage.m
index 2e9fd7c..db5d3b6 100644
--- a/objectivec/GPBMessage.m
+++ b/objectivec/GPBMessage.m
@@ -78,6 +78,20 @@
GPBMessage *autocreator_;
GPBFieldDescriptor *autocreatorField_;
GPBExtensionDescriptor *autocreatorExtension_;
+
+ // A lock to provide mutual exclusion from internal data that can be modified
+ // by *read* operations such as getters (autocreation of message fields and
+ // message extensions, not setting of values). Used to guarantee thread safety
+ // for concurrent reads on the message.
+ // NOTE: OSSpinLock may seem like a good fit here but Apple engineers have
+ // pointed out that they are vulnerable to live locking on iOS in cases of
+ // priority inversion:
+ // http://mjtsai.com/blog/2015/12/16/osspinlock-is-unsafe/
+ // https://lists.swift.org/pipermail/swift-dev/Week-of-Mon-20151214/000372.html
+ // Use of readOnlySemaphore_ must be prefaced by a call to
+ // GPBPrepareReadOnlySemaphore to ensure it has been created. This allows
+ // readOnlySemaphore_ to be only created when actually needed.
+ _Atomic(dispatch_semaphore_t) readOnlySemaphore_;
}
@end
@@ -3272,4 +3286,32 @@
return GetOrCreateMapIvarWithField(self, field, syntax);
}
+id GPBGetObjectIvarWithField(GPBMessage *self, GPBFieldDescriptor *field) {
+ NSCAssert(!GPBFieldIsMapOrArray(field), @"Shouldn't get here");
+ if (GPBGetHasIvarField(self, field)) {
+ uint8_t *storage = (uint8_t *)self->messageStorage_;
+ id *typePtr = (id *)&storage[field->description_->offset];
+ return *typePtr;
+ }
+ // Not set...
+
+ // Non messages (string/data), get their default.
+ if (!GPBFieldDataTypeIsMessage(field)) {
+ return field.defaultValue.valueMessage;
+ }
+
+ GPBPrepareReadOnlySemaphore(self);
+ dispatch_semaphore_wait(self->readOnlySemaphore_, DISPATCH_TIME_FOREVER);
+ GPBMessage *result = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
+ if (!result) {
+ // For non repeated messages, create the object, set it and return it.
+ // This object will not initially be visible via GPBGetHasIvar, so
+ // we save its creator so it can become visible if it's mutated later.
+ result = GPBCreateMessageWithAutocreator(field.msgClass, self, field);
+ GPBSetAutocreatedRetainedObjectIvarWithField(self, field, result);
+ }
+ dispatch_semaphore_signal(self->readOnlySemaphore_);
+ return result;
+}
+
#pragma clang diagnostic pop
diff --git a/objectivec/GPBMessage_PackagePrivate.h b/objectivec/GPBMessage_PackagePrivate.h
index 366e5bb..ca10983 100644
--- a/objectivec/GPBMessage_PackagePrivate.h
+++ b/objectivec/GPBMessage_PackagePrivate.h
@@ -61,20 +61,6 @@
// GPBMessage_Storage with _has_storage__ as the first field.
// Kept public because static functions need to access it.
GPBMessage_StoragePtr messageStorage_;
-
- // A lock to provide mutual exclusion from internal data that can be modified
- // by *read* operations such as getters (autocreation of message fields and
- // message extensions, not setting of values). Used to guarantee thread safety
- // for concurrent reads on the message.
- // NOTE: OSSpinLock may seem like a good fit here but Apple engineers have
- // pointed out that they are vulnerable to live locking on iOS in cases of
- // priority inversion:
- // http://mjtsai.com/blog/2015/12/16/osspinlock-is-unsafe/
- // https://lists.swift.org/pipermail/swift-dev/Week-of-Mon-20151214/000372.html
- // Use of readOnlySemaphore_ must be prefaced by a call to
- // GPBPrepareReadOnlySemaphore to ensure it has been created. This allows
- // readOnlySemaphore_ to be only created when actually needed.
- _Atomic(dispatch_semaphore_t) readOnlySemaphore_;
}
// Gets an extension value without autocreating the result if not found. (i.e.
diff --git a/objectivec/GPBUtilities.m b/objectivec/GPBUtilities.m
index 2574656..e2a12ca 100644
--- a/objectivec/GPBUtilities.m
+++ b/objectivec/GPBUtilities.m
@@ -628,34 +628,6 @@
return *typePtr;
}
-id GPBGetObjectIvarWithField(GPBMessage *self, GPBFieldDescriptor *field) {
- NSCAssert(!GPBFieldIsMapOrArray(field), @"Shouldn't get here");
- if (GPBGetHasIvarField(self, field)) {
- uint8_t *storage = (uint8_t *)self->messageStorage_;
- id *typePtr = (id *)&storage[field->description_->offset];
- return *typePtr;
- }
- // Not set...
-
- // Non messages (string/data), get their default.
- if (!GPBFieldDataTypeIsMessage(field)) {
- return field.defaultValue.valueMessage;
- }
-
- GPBPrepareReadOnlySemaphore(self);
- dispatch_semaphore_wait(self->readOnlySemaphore_, DISPATCH_TIME_FOREVER);
- GPBMessage *result = GPBGetObjectIvarWithFieldNoAutocreate(self, field);
- if (!result) {
- // For non repeated messages, create the object, set it and return it.
- // This object will not initially be visible via GPBGetHasIvar, so
- // we save its creator so it can become visible if it's mutated later.
- result = GPBCreateMessageWithAutocreator(field.msgClass, self, field);
- GPBSetAutocreatedRetainedObjectIvarWithField(self, field, result);
- }
- dispatch_semaphore_signal(self->readOnlySemaphore_);
- return result;
-}
-
// Only exists for public api, no core code should use this.
int32_t GPBGetMessageEnumField(GPBMessage *self, GPBFieldDescriptor *field) {
GPBFileSyntax syntax = [self descriptor].file.syntax;
