class Message

The ctor is deliberately a no-op to avoid forwarding args from all

subclasses. The real initialization is performed by Reset().

Nested messages are allocated via placement new by MessageArena and

implictly destroyed when the RootMessage's arena goes away. This is

fine as long as all the fields are PODs, which is checked by the

static_assert()s in the Reset() method.

Clears up the state, allowing the message to be reused as a fresh one.

Commits all the changes to the buffer (backfills the size field of this and

all nested messages) and seals the message. Returns the size of the message

(and all nested sub-messages), without taking into account any chunking.

Finalize is idempotent and can be called several times w/o side effects.

Short messages may be compacted in memory into the size field, since their

size can be represented with fewer than

proto_utils::kMessageLengthFieldSize bytes.

Optional. If is_valid() == true, the corresponding memory region (its

length == proto_utils::kMessageLengthFieldSize) is backfilled with the size

of this message. This is the mechanism used by messages to backfill their

corresponding size field in the parent message. In most cases this is only

used for nested messages and the ScatteredStreamWriter::Delegate (e.g.

TraceWriterImpl), takes case of the outer message.

Proto types: uint64, uint32, int64, int32, bool, enum.

Proto types: sint64, sint32.

Proto types: bool, enum (small).

Faster version of AppendVarInt for tiny numbers.

Proto types: fixed64, sfixed64, fixed32, sfixed32, double, float.

Append raw bytes for a field, using the supplied |ranges| to

copy from |num_ranges| individual buffers.

Begins a nested message. The returned object is owned by the MessageArena

of the root message. The nested message ends either when Finalize() is

called or when any other Append* method is called in the parent class.

The template argument T is supposed to be a stub class auto generated from

a .proto, hence a subclass of Message.

Gives read-only access to the underlying stream_writer. This is used only

by few internals to query the state of the underlying buffer. It is almost

always a bad idea to poke at the stream_writer() internals.

Appends some raw bytes to the message. The use-case for this is preserving

unknown fields in the decode -> re-encode path of xxx.gen.cc classes

generated by the cppgen_plugin.cc.

The caller needs to guarantee that the appended data is properly

proto-encoded and each field has a proto preamble.