On Wed, Nov 19, 2008 at 11:22:31AM -0500, David Lively wrote:
On Wed, 2008-11-19 at 10:35 -0500, David Lively wrote:
The patch already synchronizes operations using virConnect objects with each other. To avoid making illegal EventImpl callbacks from Java for the current libvirt, I have to lock every Connect object known to Java and hold off creating new connections (via open & friends) around an EventImpl callback. This sounds rather appalling to me, but it's starting to sound like the only practical route in the short term (unless it turns out we can rely on pthreads in WIN32 ...).
Hmmm ... maybe the less appalling :-) route is practical. Currently, we require only the Windows equivalent of a simple pthread mutex. We just need to support declaration, initialization, lock, unlock, and destruction, something like the following (thanks to Tom Hazel for pointing me to the Windows Mutex stuff):
#if (defined _WIN32 || defined __WIN32__) #define PTHREAD_MUTEX_T(v) HANDLE v #define pthread_mutex_init(lk,p) ((*(lk)) = CreateMutex(0, FALSE, 0)) #define pthread_mutex_destroy(lk) CloseHandle(*(lk)) #define pthread_mutex_lock(lk) WaitForSingleObject(*(lk), INFINITE) #define pthread_mutex_unlock(lk) ReleaseMutex(*(lk)) #define pthread_sigmask(h, s, o) sigprocmask((h), (s), (o)) #endif
I'm not a Windows guy, so maybe I'm missing something. But this doesn't seem like a Big Deal ...
note that libxml2 that we rely on has a fully ported mutex basic API in libxml/threads.h /* * xmlMutex are a simple mutual exception locks. */ typedef struct _xmlMutex xmlMutex; typedef xmlMutex *xmlMutexPtr; /* * xmlRMutex are reentrant mutual exception locks. */ typedef struct _xmlRMutex xmlRMutex; typedef xmlRMutex *xmlRMutexPtr; XMLPUBFUN xmlMutexPtr XMLCALL xmlNewMutex (void); XMLPUBFUN void XMLCALL xmlMutexLock (xmlMutexPtr tok); XMLPUBFUN void XMLCALL xmlMutexUnlock (xmlMutexPtr tok); XMLPUBFUN void XMLCALL xmlFreeMutex (xmlMutexPtr tok); XMLPUBFUN xmlRMutexPtr XMLCALL xmlNewRMutex (void); XMLPUBFUN void XMLCALL xmlRMutexLock (xmlRMutexPtr tok); XMLPUBFUN void XMLCALL xmlRMutexUnlock (xmlRMutexPtr tok); XMLPUBFUN void XMLCALL xmlFreeRMutex (xmlRMutexPtr tok); in case you really want to do the exclusive locking at the C level while still being portable. Still it's probably better to try to implement most of this at the Java level, at least IMHO, Daniel -- Daniel Veillard | libxml Gnome XML XSLT toolkit http://xmlsoft.org/ daniel@veillard.com | Rpmfind RPM search engine http://rpmfind.net/ http://veillard.com/ | virtualization library http://libvirt.org/