Diff: CallbackMessage

Your trail:
Search SINQ Wiki:
SINQ LIN

SINQ Wiki
- Main Page
- Search SINQ Wiki
- Sample Environment
- Probenumg. Intern
- Troubleshooting SICS

This Page
- Page Info
- Printer Friendly

Referenced by
...nobody

Wiki Info
- Unused pages
- Undefined pages
- RecentChanges
- Page Index
- System Info
- JSPWiki Docu
- SandBox
- OneMinuteWiki
- Create a New Page




JSPWiki v2.0.52


Difference between version 11 and version 1:
Lines 5-8 were replaced by lines 5-8
- typedef struct {
- char *class;
- /* ... message data ... */
- } <message class>;
+ typedef struct {
+ char *class;
+ /* ... message data ... */
+ } <message class>;
Line 12 was replaced by line 12
- Example:
+ Given the following functions dealing with callbacks:
Line 14 was replaced by lines 14-49
- static char *setCallbackClass="set callback";
+ typedef void KillFunc(void *);
+ typedef int CallbackFunction(Hdb *node, void *msg, void *data);
+ typedef struct Callback Callback;
+
+ InvokeCallback(Hdb *node, void *msg);
+ Callback *MakeCallback(CallbackFunction *cbFunc, void *data, KillFunc *killFunc);
+ AppendCallback(Hdb *node, Callback *cb);
+ PrependCallback(Hdb *node, Callback *cb);
+ }}}
+ The callbacks are stored as one list per node.
+
+ Extract from (sics)hipadaba.h:
+ {{{
+ typedef struct {
+ char *class;
+ SConnection *pCon;
+ ValueStruct *value;
+ } SetCallbackMsg;
+
+ SetCallbackMsg *SetCallbackCast(void *msg);
+ }}}
+
+ The members of callback message contain the additional arguments needed for the handling of
+ the callback. SetCallbackCast reveals if an anonymous message is a SetCallbackMsg. It returns
+ NULL otherwise.
+
+ Extract from (sics)hipadaba.c:
+ {{{
+ static char *setCallbackClass="set callback";
+
+ SetCallbackMsg *SetCallbackCast(void *msg) {
+ if (((SetCallbackMsg *)msg)->class == setCallbackClass) {
+ return msg;
+ }
+ return NULL;
+ }
Lines 16-21 were replaced by line 51
- typedef struct {
- char *class;
- SConnection *pCon;
- Hdb *node;
- ValueStruct *value;
- } SetCallbackMsg;
+ ...
Line 23 was replaced by line 53
- ...
+ /* calling the callback */
Removed lines 25-26
- /* calling the callback */
- {
Removed line 30
- setMsg.node = node;
Line 32 was replaced by lines 59-114
- CallCallback(callbacklist, &setMsg);
+ InvokeCallback(node, &setMsg);
+ }}}
+
+ The text content of setCallbackClass is not very important, it may be used
+ for logging purposes. The check for a particular class is done by comparing
+ the pointers, not the contents.
+
+ Extract from a module implementing a callback:
+ {{{
+ int MySetCallback(Hdb *node, void *msg, void *data) {
+ SetCallbackMsg *setMsg = SetCallbackCast(msg);
+ MyData *mydata;
+
+ if (! setMsg) return 0; /* not handled */
+
+ mydata = data;
+ /* do the set */
+
+ return 1;
+ }
+
+ ...
+
+ void KillMyData(MyData *data) {
+ /* free resources */
+ }
+ ...
+
+ MyData *data;
+ Callback *cb;
+
+ cb = MakeCallback(MySetCallback, data, (KillFunc *)KillMyData);
+ AppendCallback(node, cb);
+ }}}
+
+ An implementation may use the same callback function for handling different
+ callback messages, with the same user data:
+ {{{
+ int CombinedCallback(Hdb *node, void *msg, void *data) {
+ SetCallbackMsg *setMsg;
+ UpdateCallbackMsg *updateMsg;
+ MyData *mydata = data;
+
+ setMsg = SetCallbackCast(msg);
+ if (setMsg) {
+ /* handle setMsg */
+ return 1;
+ }
+
+ updateMsg= UpdateCallbackCast(msg);
+ if (updateMsg) {
+ /* handle updateMsg */
+ return 1;
+ }
+
+ return 0; /* not handled */
At line 33 added 10 lines.
+ }}}
+
+ For the implementation of Hipadaba at least the following callbacks have
+ to be implemented:
+
+ * SetCallback
+ * ReadCallback
+ * UpdateCallback
+ * KillForIDCallback
+ * KillForInternalIDCallback

Back to CallbackMessage, or to the Page History.