Make cleanup functions return 'void' (#19870)
Destructors, Shutdown functions, and other cleanup code should be
declared with a 'void' return type as typically there is nothing that
can be done in the caller when an error is returned.
This removes the error return from such functions throughought Matter.
This transformation is straightforward in every case, and semantic
preserving in almost every case (broken semantics such as leaking memory
or leaving objects in an inconsistent state are not necessarily
preserved); it's rare for shutdown functions to actually return errors,
and also rare for callers to check for them.
Removing the threat of errors from cleanup functions simplifies control
flow in shutdown paths. It also facilitates shutdown from destructors
which is the typical C++ resource management paradigm ("RAII"), as
destructors have no return type.
Some functions had error cases that only occured when there was nothing
to do (e.g. not fully initialized returning 'invalid state'); these are
removed. The postcondition already holds in these cases, and maintaining
a precondition regarding the state would impose duplicative bookkeeping
in client code to track it without any real upside.
This changes a fair number of APIs, but the changes are easy to
accomodate as it is simply a matter of removing dead code (much of
which was already dead; one class even included the note
@return #CHIP_NO_ERROR unconditionally.
as documentation that an error was not actually possible).diff --git a/src/messaging/ExchangeMgr.cpp b/src/messaging/ExchangeMgr.cpp
index b6ce6a9..410183e 100644
--- a/src/messaging/ExchangeMgr.cpp
+++ b/src/messaging/ExchangeMgr.cpp
@@ -92,9 +92,9 @@
return err;
}
-CHIP_ERROR ExchangeManager::Shutdown()
+void ExchangeManager::Shutdown()
{
- VerifyOrReturnError(mState == State::kState_Initialized, CHIP_ERROR_INCORRECT_STATE);
+ VerifyOrReturn(mState != State::kState_NotInitialized);
mReliableMessageMgr.Shutdown();
@@ -105,8 +105,6 @@
}
mState = State::kState_NotInitialized;
-
- return CHIP_NO_ERROR;
}
ExchangeContext * ExchangeManager::NewContext(const SessionHandle & session, ExchangeDelegate * delegate)
