[Development] API review for a new QDnsResolver class

[Jeremy Lainé]

Replying to myself to try and get the discussion going again.

A summary of API decisions so far:

- we only provide an asynchronous API

- we do not want a "manager" object (QNAM-style) to avoid users creating a manager per lookup

- we want a single class to support different types of DNS requests (Q3Dns-style)

- lookups are performed by calling static methods returning a pointer to a QObject-derived class, which emits the "finished()" signal upon completion


What remains to be decided:

- do we want shared pointers or not? My feeling is that using QSharedPointer is going to be awkward for the API user, I cannot find any other example of a Qt API which returns a QSharedPointer to a QObject-derived class.

- finalise the class name (I think QDns was suggested)


In the meantime, I have updated my implementation assuming we use raw pointers, with QDnsReply as the working name for the class:

https://qt.gitorious.org/~sharky/qt/sharkys-qtbase/blobs/8628259746664df7754f7b27d406d7bbd74580b0/src/network/kernel/qdnsreply.h#line154


Some notes about the implementation:

- the actual lookup code is run in a thread, managed by a global threadpool (QHostInfo-style)

- the thread and the QDnsReply both operate on a QSharedPointer<QDnsReplyPrivate>, so it doesn't matter whether the QDnsReply is deleted before or after the thread completes


Cheers,
Jeremy