[wpiutil,glass,dlt] Replace libprotobuf with upb for dynamic decode (#7988)

libprotobuf is a very annoying dependency to deal with, and with the switch to nanopb for generated C++ code, libprotobuf is only used for dynamic decode in the GUI apps. libprotobuf has been swapped out with upb, a much smaller C-based library that supports reflection and can therefore do dynamic decode. This means we can remove the libprotobuf dependency and stop dealing with build issues because of it.

datalog/src/main/native/cpp/DataLogReaderThread.cpp

@@ -110,13 +110,18 @@ void DataLogReaderThread::ReadMain() {
                    schema, err);
       }
     } else if (auto filename = wpi::remove_prefix(name, "/.schema/proto:")) {
-#ifndef NO_PROTOBUF
       // protobuf descriptor handling
-      if (!m_protoDb.Add(*filename, data)) {
+      upb_Status status;
+      status.ok = true;
+      upb_DefPool_AddFile(
+          m_protoPool,
+          google_protobuf_FileDescriptorProto_parse(
+              reinterpret_cast<const char*>(data.data()), data.size(), m_arena),
+          &status);
+      if (!status.ok) {
         wpi::print("could not decode protobuf '{}' filename '{}'\n", name,
                    *filename);
       }
-#endif
     }
   }
 

datalog/src/main/native/include/wpi/datalog/DataLogReaderThread.h

@@ -13,6 +13,8 @@
 #include <utility>
 #include <vector>
 
+#include <upb/mem/arena.h>
+#include <upb/reflection/def.h>
 #include <wpi/DenseMap.h>
 #include <wpi/Signal.h>
 #include <wpi/mutex.h>
@@ -20,10 +22,6 @@
 
 #include "wpi/datalog/DataLogReader.h"
 
-#ifndef NO_PROTOBUF
-#include <wpi/protobuf/ProtobufMessageDatabase.h>
-#endif
-
 namespace wpi::log {
 
 class DataLogReaderRange {
@@ -88,9 +86,8 @@ class DataLogReaderThread {
   }
 
   wpi::StructDescriptorDatabase& GetStructDatabase() { return m_structDb; }
-#ifndef NO_PROTOBUF
-  wpi::ProtobufMessageDatabase& GetProtobufDatabase() { return m_protoDb; }
-#endif
+  upb_DefPool* GetProtobufDatabase() { return m_protoPool; }
+  upb_Arena* GetProtobufArena() { return m_arena; }
 
   const wpi::log::DataLogReader& GetReader() const { return m_reader; }
 
@@ -109,9 +106,8 @@ class DataLogReaderThread {
   std::map<std::string, DataLogReaderEntry, std::less<>> m_entriesByName;
   wpi::DenseMap<int, DataLogReaderEntry*> m_entriesById;
   wpi::StructDescriptorDatabase m_structDb;
-#ifndef NO_PROTOBUF
-  wpi::ProtobufMessageDatabase m_protoDb;
-#endif
+  upb_DefPool* m_protoPool = upb_DefPool_New();
+  upb_Arena* m_arena = upb_Arena_New();
   std::thread m_thread;
 };