[#18771, #21352] docdb: Fix LightweightMessage max size when parsing

Summary:
LightweightMessage currently sets a maximum size for reading to `rpc_max_message_size`
(default 255 MB), but Preparer batches based on `protobuf_message_total_bytes_limit` (default
511 MB). This results in cases where under default settings, we may have protobufs between 255 MB
and 511 MB, which `LightweightMessage::ParseFromSlice` is unable to read.

This diff changes the limit to use `protobuf_message_total_bytes_limit`, so that protobufs between
`rpc_max_message_size` and `protobuf_message_total_bytes_limit` can be parsed properly.

This addresses errors such as:
```
Found a corruption in a closed log segment: OK
Error: Corruption (yb/consensus/log_util.cc:965): Log file corruption detected.: Failed to parse PB at offset: 26013423, length: 303149529. Cause: Corruption (yb/rpc/lightweight_message.cc:376): Failed to parse ‘entry’: Failed trying to read batch #5 at offset 26013423 for log segment /mnt/d0/yb-data/tserver/wals/table-12345678901234567890123456789012/tablet-12345678901234567890123456789012/wal-000003000: ...
```
(length larger than 255 MB) when such protobufs are written to WALs.

This also fixes cause of flakiness for TabletPeerTest.MaxRaftBatchProtobufLimit in TSAN builds.

Jira: DB-7654, DB-10251

Test Plan:
Jenkins.

Added test:
```
yb_build.sh --cxx-test rpc_lwproto-test --gtest_filter LWProtoTest.BigMessage
```

Also ran TabletPeerTest.MaxRaftBatchProtobufLimit 100x on Jenkins.

Reviewers: sergei, qhu

Reviewed By: qhu

Subscribers: yyan, bogdan, rthallam, ybase

Differential Revision: https://phorge.dev.yugabyte.com/D33041

src/yb/rpc/lightweight_message.cc

@@ -31,6 +31,8 @@ DEFINE_UNKNOWN_uint64(rpc_max_message_size, 255_MB,
     "The maximum size of a message of any RPC that the server will accept. The sum of "
     "consensus_max_batch_size_bytes and 1KB should be less than rpc_max_message_size");
 
+DECLARE_int32(protobuf_message_total_bytes_limit);
+
 using google::protobuf::internal::WireFormatLite;
 using google::protobuf::io::CodedOutputStream;
 
@@ -378,8 +380,7 @@ Status ParseFailed(const char* field_name) {
 }
 
 void SetupLimit(google::protobuf::io::CodedInputStream* in) {
-  in->SetTotalBytesLimit(narrow_cast<int>(FLAGS_rpc_max_message_size),
-                         narrow_cast<int>(FLAGS_rpc_max_message_size * 3 / 4));
+  in->SetTotalBytesLimit(FLAGS_protobuf_message_total_bytes_limit, 0 /* unused */);
 }
 
 ThreadSafeArena& empty_arena() {

src/yb/rpc/lwproto-test.cc

@@ -19,11 +19,33 @@
 
 #include "yb/util/faststring.h"
 #include "yb/util/logging.h"
+#include "yb/util/random_util.h"
+#include "yb/util/size_literals.h"
 #include "yb/util/test_macros.h"
 
+DECLARE_int32(protobuf_message_total_bytes_limit);
+DECLARE_uint64(rpc_max_message_size);
+
 namespace yb {
 namespace rpc {
 
+namespace {
+
+template <typename PB>
+Status SerializePB(PB& pb, faststring& buf) {
+  LOG(INFO) << "Source proto: " << pb.ShortDebugString();
+
+  AnyMessageConstPtr ptr(&pb);
+  buf.resize(ptr.SerializedSize());
+  RETURN_NOT_OK(ptr.SerializeToArray(buf.data()));
+
+  LOG(INFO) << "Binary dump: " << Slice(buf).ToDebugHexString();
+
+  return Status::OK();
+}
+
+} // namespace
+
 // Make sure LW protobuf skips unknown fields.
 TEST(LWProtoTest, SkipsUnknownFields) {
   rpc_test::TestObjectPB pb;
@@ -37,13 +59,7 @@ TEST(LWProtoTest, SkipsUnknownFields) {
     pb.set_int32_2(15);
     pb.mutable_record2()->set_text("record2");
 
-    LOG(INFO) << "Source proto: " << pb.ShortDebugString();
-
-    AnyMessageConstPtr ptr(&pb);
-    buf.resize(ptr.SerializedSize());
-    ASSERT_OK(ptr.SerializeToArray(buf.data()));
-
-    LOG(INFO) << "Binary dump: " << Slice(buf).ToDebugHexString();
+    ASSERT_OK(SerializePB(pb, buf));
   }
 
   {
@@ -82,5 +98,29 @@ TEST(LWProtoTest, SkipsUnknownFields) {
   }
 }
 
+// Test a very large proto (rpc_max_message_size < proto size < protobuf_message_total_bytes_limit).
+TEST(LWProtoTest, BigMessage) {
+  faststring buf;
+  rpc_test::TestObjectPB pb;
+
+  ANNOTATE_UNPROTECTED_WRITE(FLAGS_rpc_max_message_size) = 4_MB;
+  ANNOTATE_UNPROTECTED_WRITE(FLAGS_protobuf_message_total_bytes_limit) = 8_MB;
+
+  constexpr auto kPBSize = 6_MB;
+
+  pb.set_string1(RandomHumanReadableString(kPBSize));
+  ASSERT_OK(SerializePB(pb, buf));
+
+  ThreadSafeArena arena;
+  rpc_test::LWTestObjectPBv2 lwpb2(&arena);
+  AnyMessagePtr ptr(&lwpb2);
+
+  ASSERT_OK(ptr.ParseFromSlice(Slice(buf)));
+  LOG(INFO) << "Read lightweight proto: " << lwpb2.ShortDebugString();
+
+  ASSERT_TRUE(lwpb2.has_string1());
+  ASSERT_EQ(pb.string1(), lwpb2.string1());
+}
+
 } // namespace rpc
 } // namespace yb