Improve codec error reporting and use Protobuf type parsers directly

Errors during (de-)serialization will now be logged, alongside the
message type in question. Due to differences in internal wiring, the
Java version logs the Document API type whereas C++ logs the protobuf
message type (and also has throttled logging).

3 files changed, 93 insertions, 52 deletions

diff --git a/documentapi/src/main/java/com/yahoo/documentapi/messagebus/protocol/RoutableFactories80.java b/documentapi/src/main/java/com/yahoo/documentapi/messagebus/protocol/RoutableFactories80.java
index e03a7a05a4b..a4dcd660ab8 100644
--- a/documentapi/src/main/java/com/yahoo/documentapi/messagebus/protocol/RoutableFactories80.java
+++ b/documentapi/src/main/java/com/yahoo/documentapi/messagebus/protocol/RoutableFactories80.java
@@ -7,6 +7,7 @@ import ai.vespa.documentapi.protobuf.DocapiVisiting;
 import com.google.protobuf.AbstractMessage;
 import com.google.protobuf.ByteString;
 import com.google.protobuf.CodedOutputStream;
+import com.google.protobuf.Parser;
 import com.yahoo.document.BucketId;
 import com.yahoo.document.Document;
 import com.yahoo.document.DocumentId;
@@ -31,12 +32,15 @@ import java.nio.charset.StandardCharsets;
 import java.util.Objects;
 import java.util.function.BiFunction;
 import java.util.function.Function;
+import java.util.logging.Logger;
 
 /**
  * Implementation of MessageBus message request/response serialization built around Protocol Buffers.
  */
 abstract class RoutableFactories80 {
 
+    private static final Logger log = Logger.getLogger(RoutableFactories80.class.getName());
+
     private static class ProtobufCodec<DocApiT extends Routable, ProtoT extends AbstractMessage> implements RoutableFactory {
 
         private final Class<DocApiT>                          apiClass;
@@ -62,6 +66,7 @@ abstract class RoutableFactories80 {
                     protoStream.flush();
                 }
             } catch (IOException | UnsupportedOperationException e) {
+                logCodecError("encoding", e);
                 return false;
             }
             return true;
@@ -69,7 +74,19 @@ abstract class RoutableFactories80 {
 
         @Override
         public Routable decode(DocumentDeserializer in) {
-            return decoderFn.apply(in);
+            try {
+                return decoderFn.apply(in);
+            } catch (RuntimeException e) {
+                logCodecError("decoding", e);
+                return null;
+            }
+        }
+
+        private void logCodecError(String op, Throwable t) {
+            // TODO ideally we'd print the peer address here, but that information is Abstracted Away(tm)
+            //  and we can't safely propagate the exception to a lower-level component which _does_ know this
+            //  information, as it's not necessarily exception safe.
+            log.severe("Error during Protobuf %s for message type %s: %s".formatted(op, apiClass.getSimpleName(), t.getMessage()));
         }
     }
 
@@ -98,31 +115,31 @@ abstract class RoutableFactories80 {
             return this;
         }
 
-        ProtobufCodecBuilder<DocApiT, ProtoT> decoder(ProtoT messagePrototype, Function<ProtoT, DocApiT> fn) {
+        ProtobufCodecBuilder<DocApiT, ProtoT> decoder(Parser<ProtoT> parser, Function<ProtoT, DocApiT> fn) {
             if (decoderFn != null) {
                 throw new IllegalArgumentException("Decoder already set");
             }
             decoderFn = (buf) -> {
                 try {
-                    var protoObj = messagePrototype.getParserForType().parseFrom(buf.getBuf().getByteBuffer());
-                    return fn.apply(protoClass.cast(protoObj));
+                    var protoObj = parser.parseFrom(buf.getBuf().getByteBuffer());
+                    return fn.apply(protoObj);
                 } catch (IOException e) {
-                    return null;
+                    throw new RuntimeException(e);
                 }
             };
             return this;
         }
 
-        ProtobufCodecBuilder<DocApiT, ProtoT> decoderWithRepo(ProtoT messagePrototype, BiFunction<ProtoT, DocumentTypeManager, DocApiT> fn) {
+        ProtobufCodecBuilder<DocApiT, ProtoT> decoderWithRepo(Parser<ProtoT> parser, BiFunction<ProtoT, DocumentTypeManager, DocApiT> fn) {
             if (decoderFn != null) {
                 throw new IllegalArgumentException("Decoder already set");
             }
             decoderFn = (buf) -> {
                 try {
-                    var protoObj = messagePrototype.getParserForType().parseFrom(buf.getBuf().getByteBuffer());
-                    return fn.apply(protoClass.cast(protoObj), buf.getTypeRepo());
+                    var protoObj = parser.parseFrom(buf.getBuf().getByteBuffer());
+                    return fn.apply(protoObj, buf.getTypeRepo());
                 } catch (IOException e) {
-                    return null;
+                    throw new RuntimeException(e);
                 }
             };
             return this;
@@ -270,7 +287,7 @@ abstract class RoutableFactories80 {
                             .setDocumentId(toProtoDocId(apiMsg.getDocumentId()))
                             .setFieldSet(toProtoFieldSet(apiMsg.getFieldSet()))
                             .build())
-                .decoder(DocapiFeed.GetDocumentRequest.getDefaultInstance(), (protoMsg) ->
+                .decoder(DocapiFeed.GetDocumentRequest.parser(), (protoMsg) ->
                         new GetDocumentMessage(
                                 fromProtoDocId(protoMsg.getDocumentId()),
                                 fromProtoFieldSet(protoMsg.getFieldSet())))
@@ -289,7 +306,7 @@ abstract class RoutableFactories80 {
                     }
                     return builder.build();
                 })
-                .decoderWithRepo(DocapiFeed.GetDocumentResponse.getDefaultInstance(), (protoReply, repo) -> {
+                .decoderWithRepo(DocapiFeed.GetDocumentResponse.parser(), (protoReply, repo) -> {
                     GetDocumentReply reply;
                     if (protoReply.hasDocument()) {
                         var doc = fromProtoDocument(protoReply.getDocument(), repo);
@@ -321,7 +338,7 @@ abstract class RoutableFactories80 {
                     }
                     return builder.build();
                 })
-                .decoderWithRepo(DocapiFeed.PutDocumentRequest.getDefaultInstance(), (protoMsg, repo) -> {
+                .decoderWithRepo(DocapiFeed.PutDocumentRequest.parser(), (protoMsg, repo) -> {
                     var doc = fromProtoDocument(protoMsg.getDocument(), repo);
                     var msg = new PutDocumentMessage(new DocumentPut(doc));
                     if (protoMsg.hasCondition()) {
@@ -341,7 +358,7 @@ abstract class RoutableFactories80 {
                         DocapiFeed.PutDocumentResponse.newBuilder()
                                 .setModificationTimestamp(apiReply.getHighestModificationTimestamp())
                                 .build())
-                .decoder(DocapiFeed.PutDocumentResponse.getDefaultInstance(), (protoReply) -> {
+                .decoder(DocapiFeed.PutDocumentResponse.parser(), (protoReply) -> {
                     var reply = new WriteDocumentReply(DocumentProtocol.REPLY_PUTDOCUMENT);
                     reply.setHighestModificationTimestamp(protoReply.getModificationTimestamp());
                     return reply;
@@ -366,7 +383,7 @@ abstract class RoutableFactories80 {
                     }
                     return builder.build();
                 })
-                .decoderWithRepo(DocapiFeed.UpdateDocumentRequest.getDefaultInstance(), (protoMsg, repo) -> {
+                .decoderWithRepo(DocapiFeed.UpdateDocumentRequest.parser(), (protoMsg, repo) -> {
                     var msg = new UpdateDocumentMessage(fromProtoUpdate(protoMsg.getUpdate(), repo));
                     msg.setOldTimestamp(protoMsg.getExpectedOldTimestamp());
                     msg.setNewTimestamp(protoMsg.getForceAssignTimestamp());
@@ -386,7 +403,7 @@ abstract class RoutableFactories80 {
                                 .setModificationTimestamp(apiReply.getHighestModificationTimestamp())
                                 .setWasFound(apiReply.wasFound())
                                 .build())
-                .decoder(DocapiFeed.UpdateDocumentResponse.getDefaultInstance(), (protoReply) -> {
+                .decoder(DocapiFeed.UpdateDocumentResponse.parser(), (protoReply) -> {
                     var reply = new UpdateDocumentReply();
                     reply.setHighestModificationTimestamp(protoReply.getModificationTimestamp());
                     reply.setWasFound(protoReply.getWasFound());
@@ -410,7 +427,7 @@ abstract class RoutableFactories80 {
                     }
                     return builder.build();
                 })
-                .decoder(DocapiFeed.RemoveDocumentRequest.getDefaultInstance(), (protoMsg) -> {
+                .decoder(DocapiFeed.RemoveDocumentRequest.parser(), (protoMsg) -> {
                     var msg = new RemoveDocumentMessage(fromProtoDocId(protoMsg.getDocumentId()));
                     if (protoMsg.hasCondition()) {
                         msg.setCondition(fromProtoTasCondition(protoMsg.getCondition()));
@@ -428,7 +445,7 @@ abstract class RoutableFactories80 {
                                 .setWasFound(apiReply.wasFound())
                                 .setModificationTimestamp(apiReply.getHighestModificationTimestamp())
                                 .build())
-                .decoder(DocapiFeed.RemoveDocumentResponse.getDefaultInstance(), (protoReply) -> {
+                .decoder(DocapiFeed.RemoveDocumentResponse.parser(), (protoReply) -> {
                     var reply = new RemoveDocumentReply();
                     reply.setWasFound(protoReply.getWasFound());
                     reply.setHighestModificationTimestamp(protoReply.getModificationTimestamp());
@@ -449,7 +466,7 @@ abstract class RoutableFactories80 {
                                 .setBucketSpace(toProtoBucketSpace(apiMsg.getBucketSpace()))
                                 .setSelection(toProtoDocumentSelection(apiMsg.getDocumentSelection()))
                                 .build())
-                .decoder(DocapiFeed.RemoveLocationRequest.getDefaultInstance(), (protoMsg) ->
+                .decoder(DocapiFeed.RemoveLocationRequest.parser(), (protoMsg) ->
                         new RemoveLocationMessage(
                                 fromProtoDocumentSelection(protoMsg.getSelection()),
                                 fromProtoBucketSpace(protoMsg.getBucketSpace())))
@@ -460,7 +477,7 @@ abstract class RoutableFactories80 {
         return ProtobufCodecBuilder
                 .of(DocumentReply.class, DocapiFeed.RemoveLocationResponse.class)
                 .encoder((apiReply) -> DocapiFeed.RemoveLocationResponse.newBuilder().build())
-                .decoder(DocapiFeed.RemoveLocationResponse.getDefaultInstance(),
+                .decoder(DocapiFeed.RemoveLocationResponse.parser(),
                         (protoReply) -> new DocumentReply(DocumentProtocol.REPLY_REMOVELOCATION))
                 .build();
     }
@@ -502,7 +519,7 @@ abstract class RoutableFactories80 {
                     }
                     return builder.build();
                 })
-                .decoder(DocapiVisiting.CreateVisitorRequest.getDefaultInstance(), (protoMsg) -> {
+                .decoder(DocapiVisiting.CreateVisitorRequest.parser(), (protoMsg) -> {
                     var msg = new CreateVisitorMessage();
                     msg.setBucketSpace(fromProtoBucketSpace(protoMsg.getBucketSpace()));
                     msg.setLibraryName(protoMsg.getVisitorLibraryName());
@@ -544,7 +561,7 @@ abstract class RoutableFactories80 {
                                     .build())
                             .build();
                 })
-                .decoder(DocapiVisiting.CreateVisitorResponse.getDefaultInstance(), (protoReply) -> {
+                .decoder(DocapiVisiting.CreateVisitorResponse.parser(), (protoReply) -> {
                     var reply = new CreateVisitorReply(DocumentProtocol.REPLY_CREATEVISITOR);
                     reply.setLastBucket(fromProtoBucketId(protoReply.getLastBucket()));
                     var protoVs = protoReply.getStatistics();
@@ -571,7 +588,7 @@ abstract class RoutableFactories80 {
                         DocapiVisiting.DestroyVisitorRequest.newBuilder()
                                 .setInstanceId(apiMsg.getInstanceId())
                                 .build())
-                .decoder(DocapiVisiting.DestroyVisitorRequest.getDefaultInstance(),
+                .decoder(DocapiVisiting.DestroyVisitorRequest.parser(),
                         (protoMsg) -> new DestroyVisitorMessage(protoMsg.getInstanceId()))
                 .build();
     }
@@ -580,7 +597,7 @@ abstract class RoutableFactories80 {
         return ProtobufCodecBuilder
                 .of(VisitorReply.class, DocapiVisiting.DestroyVisitorResponse.class)
                 .encoder((apiReply) -> DocapiVisiting.DestroyVisitorResponse.newBuilder().build())
-                .decoder(DocapiVisiting.DestroyVisitorResponse.getDefaultInstance(),
+                .decoder(DocapiVisiting.DestroyVisitorResponse.parser(),
                         (protoReply) -> new VisitorReply(DocumentProtocol.REPLY_DESTROYVISITOR))
                 .build();
     }
@@ -601,7 +618,7 @@ abstract class RoutableFactories80 {
                     }
                     return builder.build();
                 })
-                .decoder(DocapiVisiting.MapVisitorRequest.getDefaultInstance(), (protoMsg) -> {
+                .decoder(DocapiVisiting.MapVisitorRequest.parser(), (protoMsg) -> {
                     var msg = new MapVisitorMessage();
                     for (var param : protoMsg.getDataList()) {
                         msg.getData().put(param.getKey(), param.getValue().toStringUtf8());
@@ -615,7 +632,7 @@ abstract class RoutableFactories80 {
         return ProtobufCodecBuilder
                 .of(VisitorReply.class, DocapiVisiting.MapVisitorResponse.class)
                 .encoder((apiReply) -> DocapiVisiting.MapVisitorResponse.newBuilder().build())
-                .decoder(DocapiVisiting.MapVisitorResponse.getDefaultInstance(),
+                .decoder(DocapiVisiting.MapVisitorResponse.parser(),
                         (protoReply) -> new VisitorReply(DocumentProtocol.REPLY_MAPVISITOR))
                 .build();
     }
@@ -631,7 +648,7 @@ abstract class RoutableFactories80 {
                     // Serialization of QueryResultMessages is not implemented in Java (receive only)
                     throw new UnsupportedOperationException("Serialization of QueryResultMessage instances is not supported");
                 })
-                .decoder(DocapiVisiting.QueryResultRequest.getDefaultInstance(), (protoMsg) -> {
+                .decoder(DocapiVisiting.QueryResultRequest.parser(), (protoMsg) -> {
                     var msg = new QueryResultMessage();
                     // Explicitly enforce presence of result/summary fields, as our object is not necessarily
                     // well-defined if these have not been initialized.
@@ -653,7 +670,7 @@ abstract class RoutableFactories80 {
         return ProtobufCodecBuilder
                 .of(VisitorReply.class, DocapiVisiting.QueryResultResponse.class)
                 .encoder((apiReply) -> DocapiVisiting.QueryResultResponse.newBuilder().build())
-                .decoder(DocapiVisiting.QueryResultResponse.getDefaultInstance(),
+                .decoder(DocapiVisiting.QueryResultResponse.parser(),
                         (protoReply) -> new VisitorReply(DocumentProtocol.REPLY_QUERYRESULT))
                 .build();
     }
@@ -673,7 +690,7 @@ abstract class RoutableFactories80 {
                     }
                     return builder.build();
                 })
-                .decoder(DocapiVisiting.VisitorInfoRequest.getDefaultInstance(), (protoMsg) -> {
+                .decoder(DocapiVisiting.VisitorInfoRequest.parser(), (protoMsg) -> {
                     var msg = new VisitorInfoMessage();
                     msg.setErrorMessage(protoMsg.getErrorMessage());
                     for (var protoId : protoMsg.getFinishedBucketsList()) {
@@ -688,7 +705,7 @@ abstract class RoutableFactories80 {
         return ProtobufCodecBuilder
                 .of(VisitorReply.class, DocapiVisiting.VisitorInfoResponse.class)
                 .encoder((apiReply) -> DocapiVisiting.VisitorInfoResponse.newBuilder().build())
-                .decoder(DocapiVisiting.VisitorInfoResponse.getDefaultInstance(),
+                .decoder(DocapiVisiting.VisitorInfoResponse.parser(),
                         (protoReply) -> new VisitorReply(DocumentProtocol.REPLY_VISITORINFO))
                 .build();
     }
@@ -712,7 +729,7 @@ abstract class RoutableFactories80 {
                     }
                     return builder.build();
                 })
-                .decoderWithRepo(DocapiVisiting.DocumentListRequest.getDefaultInstance(), (protoMsg, repo) -> {
+                .decoderWithRepo(DocapiVisiting.DocumentListRequest.parser(), (protoMsg, repo) -> {
                     var msg = new DocumentListMessage();
                     msg.setBucketId(fromProtoBucketId(protoMsg.getBucketId()));
                     for (var entry : protoMsg.getEntriesList()) {
@@ -730,7 +747,7 @@ abstract class RoutableFactories80 {
         return ProtobufCodecBuilder
                 .of(VisitorReply.class, DocapiVisiting.DocumentListResponse.class)
                 .encoder((apiReply) -> DocapiVisiting.DocumentListResponse.newBuilder().build())
-                .decoder(DocapiVisiting.DocumentListResponse.getDefaultInstance(),
+                .decoder(DocapiVisiting.DocumentListResponse.parser(),
                         (protoReply) -> new VisitorReply(DocumentProtocol.REPLY_DOCUMENTLIST))
                 .build();
     }
@@ -750,7 +767,7 @@ abstract class RoutableFactories80 {
                     }
                     return builder.build();
                 })
-                .decoder(DocapiVisiting.EmptyBucketsRequest.getDefaultInstance(), (protoMsg) -> {
+                .decoder(DocapiVisiting.EmptyBucketsRequest.parser(), (protoMsg) -> {
                     var msg = new EmptyBucketsMessage();
                     for (var protoId : protoMsg.getBucketIdsList()) {
                         msg.getBucketIds().add(fromProtoBucketId(protoId));
@@ -764,7 +781,7 @@ abstract class RoutableFactories80 {
         return ProtobufCodecBuilder
                 .of(VisitorReply.class, DocapiVisiting.EmptyBucketsResponse.class)
                 .encoder((apiReply) -> DocapiVisiting.EmptyBucketsResponse.newBuilder().build())
-                .decoder(DocapiVisiting.EmptyBucketsResponse.getDefaultInstance(),
+                .decoder(DocapiVisiting.EmptyBucketsResponse.parser(),
                         (protoReply) -> new VisitorReply(DocumentProtocol.REPLY_EMPTYBUCKETS))
                 .build();
     }
@@ -781,7 +798,7 @@ abstract class RoutableFactories80 {
                                 .setBucketId(toProtoBucketId(apiMsg.getBucketId()))
                                 .setBucketSpace(toProtoBucketSpace(apiMsg.getBucketSpace()))
                                 .build())
-                .decoder(DocapiInspect.GetBucketListRequest.getDefaultInstance(), (protoMsg) ->
+                .decoder(DocapiInspect.GetBucketListRequest.parser(), (protoMsg) ->
                         new GetBucketListMessage(
                                 fromProtoBucketId(protoMsg.getBucketId()),
                                 fromProtoBucketSpace(protoMsg.getBucketSpace())))
@@ -800,7 +817,7 @@ abstract class RoutableFactories80 {
                     }
                     return builder.build();
                 })
-                .decoder(DocapiInspect.GetBucketListResponse.getDefaultInstance(), (protoReply) -> {
+                .decoder(DocapiInspect.GetBucketListResponse.parser(), (protoReply) -> {
                     var reply = new GetBucketListReply();
                     for (var info : protoReply.getBucketInfoList()) {
                         reply.getBuckets().add(new GetBucketListReply.BucketInfo(
@@ -823,7 +840,7 @@ abstract class RoutableFactories80 {
                         DocapiInspect.GetBucketStateRequest.newBuilder()
                                 .setBucketId(toProtoBucketId(apiMsg.getBucketId()))
                                 .build())
-                .decoder(DocapiInspect.GetBucketStateRequest.getDefaultInstance(), (protoMsg) ->
+                .decoder(DocapiInspect.GetBucketStateRequest.parser(), (protoMsg) ->
                         new GetBucketStateMessage(fromProtoBucketId(protoMsg.getBucketId())))
                 .build();
     }
@@ -846,7 +863,7 @@ abstract class RoutableFactories80 {
                     }
                     return builder.build();
                 })
-                .decoder(DocapiInspect.GetBucketStateResponse.getDefaultInstance(), (protoReply) -> {
+                .decoder(DocapiInspect.GetBucketStateResponse.parser(), (protoReply) -> {
                     var reply = new GetBucketStateReply();
                     for (var state : protoReply.getStatesList()) {
                         if (state.hasDocumentId()) {
@@ -879,7 +896,7 @@ abstract class RoutableFactories80 {
                                 .setBucketSpace(toProtoBucketSpace(apiMsg.getBucketSpace()))
                                 .setSelection(toProtoDocumentSelection(apiMsg.getDocumentSelection()))
                                 .build())
-                .decoder(DocapiInspect.StatBucketRequest.getDefaultInstance(), (protoMsg) ->
+                .decoder(DocapiInspect.StatBucketRequest.parser(), (protoMsg) ->
                         new StatBucketMessage(
                                 fromProtoBucketId(protoMsg.getBucketId()),
                                 fromProtoBucketSpace(protoMsg.getBucketSpace()),
@@ -894,7 +911,7 @@ abstract class RoutableFactories80 {
                         DocapiInspect.StatBucketResponse.newBuilder()
                                 .setResults(apiReply.getResults())
                                 .build())
-                .decoder(DocapiInspect.StatBucketResponse.getDefaultInstance(), (protoReply) ->
+                .decoder(DocapiInspect.StatBucketResponse.parser(), (protoReply) ->
                         new StatBucketReply(protoReply.getResults()))
                 .build();
     }
@@ -910,7 +927,7 @@ abstract class RoutableFactories80 {
                         DocapiCommon.WrongDistributionResponse.newBuilder()
                                 .setClusterState(toProtoClusterState(apiReply.getSystemState()))
                                 .build())
-                .decoder(DocapiCommon.WrongDistributionResponse.getDefaultInstance(), (protoReply) ->
+                .decoder(DocapiCommon.WrongDistributionResponse.parser(), (protoReply) ->
                         new WrongDistributionReply(fromProtoClusterState(protoReply.getClusterState())))
                 .build();
     }
@@ -923,7 +940,7 @@ abstract class RoutableFactories80 {
         return ProtobufCodecBuilder
                 .of(DocumentIgnoredReply.class, DocapiCommon.DocumentIgnoredResponse.class)
                 .encoder((apiReply) -> DocapiCommon.DocumentIgnoredResponse.newBuilder().build())
-                .decoder(DocapiCommon.DocumentIgnoredResponse.getDefaultInstance(),
+                .decoder(DocapiCommon.DocumentIgnoredResponse.parser(),
                         (protoReply) -> new DocumentIgnoredReply())
                 .build();
     }
diff --git a/documentapi/src/vespa/documentapi/messagebus/routable_factories_8.cpp b/documentapi/src/vespa/documentapi/messagebus/routable_factories_8.cpp
index 399801526ba..c707d8bb9fc 100644
--- a/documentapi/src/vespa/documentapi/messagebus/routable_factories_8.cpp
+++ b/documentapi/src/vespa/documentapi/messagebus/routable_factories_8.cpp
@@ -11,6 +11,10 @@
 #include <vespa/documentapi/messagebus/docapi_visiting.pb.h>
 #include <vespa/documentapi/messagebus/docapi_inspect.pb.h>
 #include <vespa/vespalib/objects/nbostream.h>
+#include <vespa/vespalib/util/stringfmt.h>
+
+#include <vespa/log/bufferedlogger.h>
+LOG_SETUP(".documentapi.messagebus.routable_factories_8");
 
 namespace documentapi::messagebus {
 
@@ -70,8 +74,10 @@ void set_global_id(protobuf::GlobalId& dest, const document::GlobalId& src) {
 }
 
 document::GlobalId get_global_id(const protobuf::GlobalId& src) {
-    if (src.raw_gid().size() != document::GlobalId::LENGTH) {
-        throw document::DeserializeException("Unexpected serialized protobuf GlobalId size");
+    if (src.raw_gid().size() != document::GlobalId::LENGTH) [[unlikely]] {
+        throw document::DeserializeException(
+                vespalib::make_string("Unexpected serialized protobuf GlobalId size (expected %u, was %zu)",
+                                      document::GlobalId::LENGTH, src.raw_gid().size()));
     }
     return document::GlobalId(src.raw_gid().data()); // By copy
 }
@@ -136,6 +142,11 @@ std::shared_ptr<document::DocumentUpdate> get_update_or_throw(const protobuf::Do
     return upd;
 }
 
+void log_codec_error(const char* op, const char* type, const char* msg) noexcept __attribute__((noinline));
+void log_codec_error(const char* op, const char* type, const char* msg) noexcept {
+    LOGBM(error, "Error during Protobuf %s for message type %s: %s", op, type, msg);
+}
+
 template <typename DocApiType, typename ProtobufType, typename EncodeFn, typename DecodeFn>
 requires std::is_invocable_r_v<void, EncodeFn, const DocApiType&, ProtobufType&> &&
          std::is_invocable_r_v<std::unique_ptr<DocApiType>, DecodeFn, const ProtobufType&>
@@ -154,7 +165,12 @@ public:
         ::google::protobuf::Arena arena;
         auto* proto_obj = ::google::protobuf::Arena::Create<ProtobufType>(&arena);
 
-        _encode_fn(dynamic_cast<const DocApiType&>(obj), *proto_obj);
+        try {
+            _encode_fn(dynamic_cast<const DocApiType&>(obj), *proto_obj);
+        } catch (std::exception& e) {
+            log_codec_error("encode", ProtobufType::descriptor()->name().c_str(), e.what());
+            return false;
+        }
 
         const auto sz = proto_obj->ByteSizeLong();
         assert(sz <= INT32_MAX);
@@ -168,14 +184,19 @@ public:
         const auto buf_size = in.getRemaining();
         assert(buf_size <= INT_MAX);
         bool ok = proto_obj->ParseFromArray(in.getBufferAtPos(), buf_size);
-        if (!ok) {
-            return {}; // Malformed protobuf payload
+        if (!ok) [[unlikely]] {
+            return {}; // Malformed protobuf payload. Caller is expected to log an error.
         }
-        auto msg = _decode_fn(*proto_obj);
-        if constexpr (std::is_base_of_v<DocumentMessage, DocApiType>) {
-            msg->setApproxSize(buf_size); // Wire size is a proxy for in-memory size
+        try {
+            auto msg = _decode_fn(*proto_obj);
+            if constexpr (std::is_base_of_v<DocumentMessage, DocApiType>) {
+                msg->setApproxSize(buf_size); // Wire size is a proxy for in-memory size
+            }
+            return msg;
+        } catch (std::exception& e) {
+            log_codec_error("decode", ProtobufType::descriptor()->name().c_str(), e.what());
+            return {};
         }
-        return msg;
     }
 };
 
@@ -235,7 +256,7 @@ std::shared_ptr<IRoutableFactory> RoutableFactories80::put_document_message_fact
             if (src.getCondition().isPresent()) {
                 set_tas_condition(*dest.mutable_condition(), src.getCondition());
             }
-            if (src.getDocumentSP()) { // This should always be present in practice
+            if (src.getDocumentSP()) [[likely]] { // This should always be present in practice
                 set_document(*dest.mutable_document(), src.getDocument());
             }
             dest.set_create_if_missing(src.get_create_if_non_existent());
@@ -594,7 +615,7 @@ std::shared_ptr<IRoutableFactory> RoutableFactories80::query_result_message_fact
             auto msg = std::make_unique<QueryResultMessage>();
             // Explicitly enforce presence of result/summary fields, as our object is not necessarily
             // well-defined if these have not been initialized.
-            if (!src.has_search_result() || !src.has_document_summary()) {
+            if (!src.has_search_result() || !src.has_document_summary()) [[unlikely]] {
                 throw document::DeserializeException("Query result does not have all required fields set", VESPA_STRLOC);
             }
             {
diff --git a/documentapi/src/vespa/documentapi/messagebus/routable_factories_8.h b/documentapi/src/vespa/documentapi/messagebus/routable_factories_8.h
index 76da2f7dc9f..7bd275800c9 100644
--- a/documentapi/src/vespa/documentapi/messagebus/routable_factories_8.h
+++ b/documentapi/src/vespa/documentapi/messagebus/routable_factories_8.h
@@ -7,6 +7,9 @@ namespace document { class DocumentTypeRepo; }
 
 namespace documentapi::messagebus {
 
+/**
+ * Implementation of MessageBus message request/response serialization built around Protocol Buffers.
+ */
 class RoutableFactories80 {
 public:
     RoutableFactories80() = delete;