Forcing Persist Service to Finish

[Khalid Latif]

I have developed an extension for TBird for archiving messages to my own
repository. Because I don't know how to read the message source into a
buffer, I write it into a temporary file using nsIWebBrowserPersist
service and then read the file into a buffer.

The nsIWebBrowserPersist service seems to be asynchronous as immediately
reading the file causes error as the saveURI method might not have done
its work. As a way out I repeatedly display alert showing "currentState"
until its value is PERSIST_STATE_FINISHED. After one or at most two
alerts it proceeds to the next code.

My question is, Is there any elegant way of forcing nsWebBrowserPersist
service to finish its job? Alternatively a method to read the message
source directly into a buffer will be appreciated.

Currently the code looks like this:

const nsIWBP = Components.interfaces.nsIWebBrowserPersist;
var persist =
Components.classes["@mozilla.org/embedding/browser/nsWebBrowserPersist;1"].createInstance(nsIWBP);
persist.persistFlags = nsIWBP.PERSIST_FLAGS_REPLACE_EXISTING_FILES
| nsIWBP.PERSIST_FLAGS_FROM_CACHE;

persist.saveURI(msgURI, null, null, null, null, localFile);

// force to complete
while(persist.currentState != persist.PERSIST_STATE_FINISHED)
alert(persist.currentState);

// further work

Regards,
Khalid