[lldb] [Core] Split read thread support into ThreadedCommunication

Split the read thread support from Communication into a dedicated
ThreadedCommunication subclass.  The read thread support is used only
by a subset of Communication consumers, and it adds a lot of complexity
to the base class.  Furthermore, having a dedicated subclass makes it
clear whether a particular consumer needs to account for the possibility
of read thread being running or not.

The modules currently calling `StartReadThread()` are updated to use
`ThreadedCommunication`.  The remaining modules use the simplified
`Communication` class.

`SBCommunication` is changed to use `ThreadedCommunication` in order
to avoid changing the public API.

`CommunicationKDP` is updated in order to (hopefully) compile with
the new code.  However, I do not have a Darwin box to test it, so I've
limited the changes to the bare minimum.

`GDBRemoteCommunication` is updated to become a `Broadcaster` directly.
Since it does not inherit from `ThreadedCommunication`, its event
support no longer collides with the one used for read thread and can
be implemented cleanly.  The support for
`eBroadcastBitReadThreadDidExit` is removed from the code -- since
the read thread was not used, this event was never reported.

Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.llvm.org/D133251

1 files changed, 1 insertions, 1 deletions

diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp
index 616de51..33e041b 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp
@@ -60,7 +60,7 @@ using namespace lldb_private::process_gdb_remote;
 // GDBRemoteCommunication constructor
 GDBRemoteCommunication::GDBRemoteCommunication(const char *comm_name,
                                                const char *listener_name)
-    : Communication(comm_name),
+    : Communication(), Broadcaster(nullptr, comm_name),
 #ifdef LLDB_CONFIGURATION_DEBUG
       m_packet_timeout(1000),
 #else