| Return the best available mutex for the given session:
that is, an object to synchronize on for the given session.
Returns the session mutex attribute if available; usually,
this means that the HttpSessionMutexListener needs to be defined
in web.xml. Falls back to the Session reference itself
if no mutex attribute found.
The session mutex is guaranteed to be the same object during
the entire lifetime of the session, available under the key defined
by the SESSION_MUTEX_ATTRIBUTE constant. It serves as a
safe reference to synchronize on for locking on the current session.
In many cases, the Session reference itself is a safe mutex
as well, since it will always be the same object reference for the
same active logical session. However, this is not guaranteed across
different servlet containers; the only 100% safe way is a session mutex.
Parameters:
fc - the FacesContext to find the session mutex for the mutex object (never null)
See Also: org.springframework.web.util.WebUtils.SESSION_MUTEX_ATTRIBUTE
See Also: org.springframework.web.util.HttpSessionMutexListener | 