Previously, the PeerFinder manager constructed with a Callback object
provided by the owner which was used to perform operations like connecting,
disconnecting, and sending messages. This made it difficult to change the
overlay code because a single call into the PeerFinder could cause both
OverlayImpl and PeerImp to be re-entered one or more times, sometimes while
holding a recursive mutex. This change eliminates the callback by changing
PeerFinder functions to return values indicating the action the caller should
take.
As a result of this change the PeerFinder no longer needs its own dedicated
thread. OverlayImpl is changed to call into PeerFinder on a timer to perform
periodic activities. Furthermore the Checker class used to perform connectivity
checks has been refactored. It no longer uses an abstract base class, in order
to not type-erase the handler passed to async_connect (ensuring compatibility
with coroutines). To allow unit tests that don't need a network, the Logic
class is now templated on the Checker type. Currently the Manager provides its
own io_service. However, this can easily be changed so that the io_service is
provided upon construction.
Summary
* Remove unused SiteFiles dependency injection
* Remove Callback and update signatures for public APIs
* Remove obsolete functions
* Move timer to overlay
* Steps toward a shared io_service
* Templated, simplified Checker
* Tidy up Checker declaration
* New ripple container aliases use hardened_hash
* Use std::tuple instead of boost::tuple
* Use std unordered containers instead of boost
* Fix Destroyer for new containers
* Fix warning for fnv1a on 32-bit arch
* Validator fixes for new containers
* Revise documentation in README.md
* Inject abstract_clock in Manager
* Introduce the Slot object as a replacement for Peer
* New bullet-proof method for slot accounting
* Replace Peer with Slot for tracking connections
* Prevent duplicate outbound connection attempts
* Improved connection and bootstrap business logic
* Refactor PeerImp, PeersImp private interfaces
* Give PeersImp access to the PeerImp interface
* Handle errors retrieving endpoints from asio sockets
* Use weak_ptr to manage PeerImp lifetime
* Better handling of socket closure in PeerImp
* Improve the orderly shutdown logic of PeersImp
* Implement PeerFinder business logic.
* Support fixed peers (including DNS support).
* Add journal support to Peer and Peers.
* Refactor PeerDoor support.
* Tidy up Peers and eliminate connection functionality and timers.
* Refactor Peer interface and add journal support.
* Allow construction of incoming Peer using an existing socket.
* Remove TESTNET support.
* Allow connections from/to cluster peers without consuming slots
* Misc. cleanups.
