Use Abseil logging for gRPC v1.65.0 and above.

Original logging method is now deprecated and results in error message
on Nginx startup.

src/grpc_log.cpp

@@ -2,8 +2,8 @@
 
 #include "grpc_log.hpp"
 
-#include <grpc/support/log.h>
 #include <google/protobuf/stubs/common.h>
+#include <grpcpp/grpcpp.h>
 
 #if GOOGLE_PROTOBUF_VERSION < 4022000
 
@@ -36,17 +36,17 @@ class ProtobufLog {
 #include <absl/log/initialize.h>
 #include <absl/log/log_sink_registry.h>
 
-class ProtobufLog : absl::LogSink {
+class NgxLogSink : absl::LogSink {
 public:
-    ProtobufLog()
+    NgxLogSink()
     {
         absl::InitializeLog();
         absl::AddLogSink(this);
         // Disable logging to stderr
         absl::SetStderrThreshold(static_cast<absl::LogSeverity>(100));
     }
 
-    ~ProtobufLog() override { absl::RemoveLogSink(this); }
+    ~NgxLogSink() override { absl::RemoveLogSink(this); }
 
     void Send(const absl::LogEntry& entry) override
     {
@@ -61,12 +61,19 @@ class ProtobufLog : absl::LogSink {
         ngx_str_t message { entry.text_message().size(),
                             (u_char*)entry.text_message().data() };
 
-        ngx_log_error(level, ngx_cycle->log, 0, "OTel/protobuf: %V", &message);
+        ngx_log_error(level, ngx_cycle->log, 0, "OTel/grpc: %V", &message);
     }
 };
 
+typedef NgxLogSink ProtobufLog;
+
 #endif
 
+#if (GRPC_CPP_VERSION_MAJOR < 1) || \
+    (GRPC_CPP_VERSION_MAJOR == 1 && GRPC_CPP_VERSION_MINOR < 65)
+
+#include <grpc/support/log.h>
+
 class GrpcLog {
 public:
     GrpcLog() { gpr_set_log_function(grpcLogHandler); }
@@ -87,6 +94,13 @@ class GrpcLog {
     ProtobufLog protoLog;
 };
 
+#else
+
+// newer gRPC implies newer protobuf, and both use Abseil for logging
+typedef NgxLogSink GrpcLog;
+
+#endif
+
 void initGrpcLog()
 {
     static GrpcLog init;