diff --git a/mercurial/help/internals/wireprotocolrpc.txt b/mercurial/help/internals/wireprotocolrpc.txt
--- a/mercurial/help/internals/wireprotocolrpc.txt
+++ b/mercurial/help/internals/wireprotocolrpc.txt
@@ -336,7 +336,53 @@
validate that received data conforms to UTF-8. The topic name
SHOULD be ASCII.
-Stream Encoding Settings (``0x08``)
+Sender Protocol Settings (``0x08``)
+-----------------------------------
+
+This frame type advertises the sender's support for various protocol and
+stream level features. The data advertised in this frame is used to influence
+subsequent behavior of the current frame exchange channel.
+
+The frame payload consists of a CBOR map. It may contain the following
+bytestring keys:
+
+contentencodings
+ (array of bytestring) A list of content encodings supported by the
+ sender, in order of most to least preferred.
+
+ Peers are allowed to encode stream data using any of the listed
+ encodings.
+
+ See the ``Content Encoding Profiles`` section for an enumeration
+ of supported content encodings.
+
+ If not defined, the value is assumed to be a list with the single value
+ ``identity``, meaning only the no-op encoding is supported.
+
+ Senders MAY filter the set of advertised encodings against what it
+ knows the receiver supports (e.g. if the receiver advertised encodings
+ via the capabilities descriptor). However, doing so will prevent
+ servers from gaining an understanding of the aggregate capabilities
+ of clients. So clients are discouraged from doing so.
+
+When this frame is not sent/received, the receiver assumes default values
+for all keys.
+
+If encountered, this frame type MUST be sent before any other frame type
+in a channel.
+
+The following flag values are defined for this frame type:
+
+0x01
+ Data continuation. When set, an additional frame containing more protocol
+ settings immediately follows.
+0x02
+ End of data. When set, the protocol settings data has been completely
+ sent.
+
+The ``0x01`` flag is mutually exclusive with the ``0x02`` flag.
+
+Stream Encoding Settings (``0x09``)
-----------------------------------
This frame type holds information defining the content encoding
@@ -351,11 +397,25 @@
The payload of this frame defines what content encoding has (possibly)
been applied to the payloads of subsequent frames in this stream.
-The payload begins with an 8-bit integer defining the length of the
-encoding *profile*, followed by the string name of that profile, which
-must be an ASCII string. All bytes that follow can be used by that
-profile for supplemental settings definitions. See the section below
-on defined encoding profiles.
+The payload consists of a series of CBOR values. The first value is a
+bytestring denoting the content encoding profile of the data in this
+stream. Subsequent CBOR values supplement this simple value in a
+profile-specific manner. See the ``Content Encoding Profiles`` section
+for more.
+
+In the absence of this frame on a stream, it is assumed the stream is
+using the ``identity`` content encoding.
+
+The following flag values are defined for this frame type:
+
+0x01
+ Data continuation. When set, an additional frame containing more encoding
+ settings immediately follows.
+0x02
+ End of data. When set, the encoding settings data has been completely
+ sent.
+
+The ``0x01`` flag is mutually exclusive with the ``0x02`` flag.
Stream States and Flags
=======================
@@ -387,6 +447,11 @@
defined by the stream should be applied when attempting to read
the frame. When not set, the frame payload isn't encoded.
+TODO consider making stream opening and closing communicated via
+explicit frame types (e.g. a "stream state change" frame) rather than
+flags on all frames. This would make stream state changes more explicit,
+as they could only occur on specific frame types.
+
Streams
=======
@@ -452,9 +517,35 @@
them. A profile defines a shared understanding of content encoding
settings and behavior.
-The following profiles are defined:
+Profiles are described in the following sections.
+
+identity
+--------
+
+The ``identity`` profile is a no-op encoding: the encoded bytes are
+exactly the input bytes.
+
+This profile MUST be supported by all peers.
+
+In the absence of an identified profile, the ``identity`` profile is
+assumed.
-TBD
+zstd-8mb
+--------
+
+Zstandard encoding (RFC 8478). Zstandard is a fast and effective lossless
+compression format.
+
+This profile allows decompressor window sizes of up to 8 MB.
+
+zlib
+----
+
+zlib compressed data (RFC 1950). zlib is a widely-used and supported
+lossless compression format.
+
+It isn't as fast as zstandard and it is recommended to use zstandard instead,
+if possible.
Command Protocol
================
diff --git a/mercurial/wireprotoframing.py b/mercurial/wireprotoframing.py
--- a/mercurial/wireprotoframing.py
+++ b/mercurial/wireprotoframing.py
@@ -49,7 +49,8 @@
FRAME_TYPE_ERROR_RESPONSE = 0x05
FRAME_TYPE_TEXT_OUTPUT = 0x06
FRAME_TYPE_PROGRESS = 0x07
-FRAME_TYPE_STREAM_SETTINGS = 0x08
+FRAME_TYPE_SENDER_PROTOCOL_SETTINGS = 0x08
+FRAME_TYPE_STREAM_SETTINGS = 0x09
FRAME_TYPES = {
b'command-request': FRAME_TYPE_COMMAND_REQUEST,
@@ -58,6 +59,7 @@
b'error-response': FRAME_TYPE_ERROR_RESPONSE,
b'text-output': FRAME_TYPE_TEXT_OUTPUT,
b'progress': FRAME_TYPE_PROGRESS,
+ b'sender-protocol-settings': FRAME_TYPE_SENDER_PROTOCOL_SETTINGS,
b'stream-settings': FRAME_TYPE_STREAM_SETTINGS,
}
@@ -89,6 +91,22 @@
b'eos': FLAG_COMMAND_RESPONSE_EOS,
}
+FLAG_SENDER_PROTOCOL_SETTINGS_CONTINUATION = 0x01
+FLAG_SENDER_PROTOCOL_SETTINGS_EOS = 0x02
+
+FLAGS_SENDER_PROTOCOL_SETTINGS = {
+ b'continuation': FLAG_SENDER_PROTOCOL_SETTINGS_CONTINUATION,
+ b'eos': FLAG_SENDER_PROTOCOL_SETTINGS_EOS,
+}
+
+FLAG_STREAM_ENCODING_SETTINGS_CONTINUATION = 0x01
+FLAG_STREAM_ENCODING_SETTINGS_EOS = 0x02
+
+FLAGS_STREAM_ENCODING_SETTINGS = {
+ b'continuation': FLAG_STREAM_ENCODING_SETTINGS_CONTINUATION,
+ b'eos': FLAG_STREAM_ENCODING_SETTINGS_EOS,
+}
+
# Maps frame types to their available flags.
FRAME_TYPE_FLAGS = {
FRAME_TYPE_COMMAND_REQUEST: FLAGS_COMMAND_REQUEST,
@@ -97,7 +115,8 @@
FRAME_TYPE_ERROR_RESPONSE: {},
FRAME_TYPE_TEXT_OUTPUT: {},
FRAME_TYPE_PROGRESS: {},
- FRAME_TYPE_STREAM_SETTINGS: {},
+ FRAME_TYPE_SENDER_PROTOCOL_SETTINGS: FLAGS_SENDER_PROTOCOL_SETTINGS,
+ FRAME_TYPE_STREAM_SETTINGS: FLAGS_STREAM_ENCODING_SETTINGS,
}
ARGUMENT_RECORD_HEADER = struct.Struct(r'<HH')