Feature #2989
Updated by Junxiao Shi over 8 years ago
Implement a minimal UDP **permanent face**.
In this minimal implementation,
* `UdpFace` constructor accepts `FacePersistency persistency` parameter in place of `bool isOnDemand`.
* If `persistency == FacePersistency::PERMANENT`, the face ignores all socket errors after successful creation.
Errors during the initial face creation should be reported as usual.
* There is no UP/DOWN state transitions.
An operator who decides to use a permanent face must take care to choose a strategy that is able to try multiple faces (ie. not `best-route`).
This Feature also includes the following changes:
* `Face::isOnDemand` and `Face::setOnDemand` are replaced with `Face::getPersistency` and `Face::setPersistency` (also, `bool m_isOnDemand` is replaced with `FacePersistency m_persistency`); all usages of those methods shall be replaced
* `ProtocolFactory::createFace` needs a `FacePersistency persistency` parameter.
If a `ProtocolFactory` subclass does not support the specified `persistency`, throw `ProtocolFactory::Error`.
* `UdpFactory::createFace` should support `FacePersistency::PERSISTENT` and `FacePersistency::PERMANENT`.
* `FaceManager::createFace` passes `FacePersistency::PERSISTENT` to `ProtocolFactory::createFace`.
**NFD Developer Guide** "Face Abstraction" section should be updated as part of this issue.
To allow an operator to use UDP permanent faces, management and `nfdc` changes are needed, but they are not part of this issue.