diff options
Diffstat (limited to 'packages/meshbay-cli/src/meshbay_cli')
5 files changed, 214 insertions, 1 deletions
diff --git a/packages/meshbay-cli/src/meshbay_cli/client/sctp_fix.py b/packages/meshbay-cli/src/meshbay_cli/client/sctp_fix.py new file mode 100644 index 0000000..62835d3 --- /dev/null +++ b/packages/meshbay-cli/src/meshbay_cli/client/sctp_fix.py @@ -0,0 +1,126 @@ +"""Fixes to aiortc's SCTP stack, applied on import (aiortc 1.15). + +The first two are the node's (`meshbay_node/transport/webrtc/sctp_fix.py`, where +why each is needed is written down); this is a copy because the client does not +depend on the node, and `meshbay-common` does not depend on aiortc (the hub uses +it without). `test_sctp_fix.py` in each package holds its copy to aiortc itself. + +In a download this side is the receiver of the node's 1 MiB `file_chunk` +messages, about 870 SCTP packets each, and two receiver costs set the ceiling. +Measured on loopback, 400 MB, one connection: + +- aiortc walked every fragment of the message in progress after each one + arrived, 153 million steps: two thirds of the client's CPU. Fixed by the + reassembly fix below — 20 MB/s became 28; +- it acknowledged every packet. RFC 4960 §6.2 asks for one SACK every second + packet (Chromium does that), and each SACK costs the node a DTLS decryption + and a parse on the one core that also sends: more of its time than sending + the data. One every second packet — 28 MB/s became 39, the node's own figure + for the transfer 49. + +A SACK still goes at once when something is out of order or duplicated (that is +the loss signal the sender is waiting for) or the packet carried anything other +than data; a lone packet is acknowledged within `SACK_DELAY_S`. +""" + +import asyncio +import contextlib + +from aiortc.rtcsctptransport import ( + SCTP_DATA_LAST_FRAG, + DataChunk, + InboundStream, + InitChunk, + RTCSctpTransport, + parse_packet, +) + +# RFC 4960 §6.2: at most 500 ms; 200 is what implementations use. +SACK_DELAY_S = 0.2 + + +def _flight_size_increase(self, chunk) -> None: + chunk._acked = False + self._flight_size += chunk._book_size + + +RTCSctpTransport._flight_size_increase = _flight_size_increase + + +_add_chunk = InboundStream.add_chunk +_pop_messages = InboundStream.pop_messages +_prune_chunks = InboundStream.prune_chunks + + +def add_chunk(self, chunk) -> None: + _add_chunk(self, chunk) + if chunk.flags & SCTP_DATA_LAST_FRAG: + self._last_frags = getattr(self, "_last_frags", 0) + 1 + + +def pop_messages(self): + # Only ever too high (a pruned last fragment), never too low: a message + # leaves the reassembly with exactly one last fragment, and only here. + if not getattr(self, "_last_frags", 0): + return + for message in _pop_messages(self): + self._last_frags -= 1 + yield message + + +def prune_chunks(self, tsn: int) -> int: + size = _prune_chunks(self, tsn) + self._last_frags = sum(1 for c in self.reassembly if c.flags & SCTP_DATA_LAST_FRAG) + return size + + +InboundStream.add_chunk = add_chunk +InboundStream.pop_messages = pop_messages +InboundStream.prune_chunks = prune_chunks + + +async def _handle_data(self, data: bytes) -> None: + """aiortc's own, down to the SACK at the end: that one may wait for a + second packet.""" + try: + _, _, verification_tag, chunks = parse_packet(data) + except ValueError: + return + if any(isinstance(x, InitChunk) for x in chunks): + assert len(chunks) == 1 + expected_tag = 0 + else: + expected_tag = self._local_verification_tag + if verification_tag != expected_tag: + return + for chunk in chunks: + await self._receive_chunk(chunk) + if not self._sack_needed: + return + self._sack_packets = getattr(self, "_sack_packets", 0) + 1 + if (self._sack_packets >= 2 or self._sack_misordered or self._sack_duplicates + or not all(isinstance(c, DataChunk) for c in chunks)): + await _sack_now(self) + elif getattr(self, "_sack_timer", None) is None: + self._sack_timer = self._loop.call_later(SACK_DELAY_S, _sack_later, self) + + +async def _sack_now(self) -> None: + timer = getattr(self, "_sack_timer", None) + if timer is not None: + timer.cancel() + self._sack_timer = None + self._sack_packets = 0 + if self._sack_needed and self._association_state != self.State.CLOSED: + # The DTLS transport may be gone under a timer that fired late. + with contextlib.suppress(ConnectionError): + await self._send_sack() + + +def _sack_later(self) -> None: + self._sack_timer = None + # Held: a task nobody references can be collected before it runs. + self._sack_task = asyncio.ensure_future(_sack_now(self)) + + +RTCSctpTransport._handle_data = _handle_data diff --git a/packages/meshbay-cli/src/meshbay_cli/client/session.py b/packages/meshbay-cli/src/meshbay_cli/client/session.py index d10acc8..b6fc9e2 100644 --- a/packages/meshbay-cli/src/meshbay_cli/client/session.py +++ b/packages/meshbay-cli/src/meshbay_cli/client/session.py @@ -63,6 +63,7 @@ from meshbay_common.handshake import ( from meshbay_common.join import join_transcript from ..errors import NODE, NODE_KEY, VERSION, CliError +from . import sctp_fix, udp_buffer # noqa: F401 (patch aiortc and aioice on import) from .account import Account from .keys import ( LEGACY_MAGIC, @@ -250,6 +251,13 @@ class GroupSession: raise CliError(NODE, "The group's index does not open under the group key; " "the session is ended.") from e + def open_delta(self, msg: dict) -> dict: + """A pushed `index_delta`, opened under the group key.""" + try: + return unseal(self.gek, PURPOSE_INDEX, "index_delta", self.group_id, msg) + except Exception as e: + raise CliError(NODE, "An index update does not open under the group key.") from e + async def close(self) -> None: with contextlib.suppress(Exception): await self.pc.close() diff --git a/packages/meshbay-cli/src/meshbay_cli/client/tree.py b/packages/meshbay-cli/src/meshbay_cli/client/tree.py index 6e537ef..dd3acc8 100644 --- a/packages/meshbay-cli/src/meshbay_cli/client/tree.py +++ b/packages/meshbay-cli/src/meshbay_cli/client/tree.py @@ -57,6 +57,39 @@ class Tree: dirs |= set(roots) return cls(roots, dirs, files) + def apply_delta(self, delta: dict) -> bool: + """ + Bring the tree up to an `index_delta`, in place. True when the delta + changed what the tree holds — a file added or removed, a root's state — + rather than only the fields of files already there. + + A delta carries no `dirs`, so an empty folder made elsewhere is not in + it: a structural change is where the caller asks for the whole index + again, once. The common delta is enrichment filling in a file's fields, + about one a second while a library is being enriched, and asking for + the whole index on each of those took the download's own event loop: + 67 full indexes in the 80 s of one download. + """ + updates = {e["id"]: e for e in delta.get("updates", [])} + gone = set(delta.get("deletions", [])) + for parent, entries in self.files.items(): + if gone or any(e["id"] in updates for e in entries): + self.files[parent] = [updates.get(e["id"], e) for e in entries + if e["id"] not in gone] + known = {e["id"] for entries in self.files.values() for e in entries} + added = [e for e in delta.get("additions", []) if e["id"] not in known] + for e in added: + self.files.setdefault(e["path"], []).append(e) + parts = e["path"].split("/") + for i in range(1, len(parts) + 1): + self.dirs.add("/".join(parts[:i])) + roots = {r["name"]: r for r in delta.get("roots", [])} + moved_roots = bool(roots) and roots != self.roots + if moved_roots: + self.roots = roots + self.dirs |= set(roots) + return bool(gone or added or moved_roots) + def root_available(self, path: str) -> bool: root = self.roots.get(path.split("/", 1)[0]) return bool(root.get("available", True)) if root else True diff --git a/packages/meshbay-cli/src/meshbay_cli/client/udp_buffer.py b/packages/meshbay-cli/src/meshbay_cli/client/udp_buffer.py new file mode 100644 index 0000000..c0045d8 --- /dev/null +++ b/packages/meshbay-cli/src/meshbay_cli/client/udp_buffer.py @@ -0,0 +1,18 @@ +"""A larger receive buffer on the client's ICE sockets, applied on import. + +In a download the client is the receiver, and it reads its socket from Python +— on the same event loop as the terminal interface — more slowly than a node +sends in bursts. aioice asks the kernel for 256 KB per socket; what does not fit +is dropped by this machine's kernel (`UdpRcvbufErrors`), the node's SCTP sender +takes each drop for congestion and halves its window. Measured on loopback, 400 +MB: 3245 drops and 19 MB/s with 256 KB. The node does the same for the same +reason in the other direction (`meshbay_node/transport/webrtc/udp_buffer.py`). + +Linux grants no more than `net.core.rmem_max`; Windows grants what is asked. +""" + +import aioice.turn + +WANTED = 4 * 1024 * 1024 + +aioice.turn.UDP_SOCKET_BUFFER_SIZE = WANTED diff --git a/packages/meshbay-cli/src/meshbay_cli/tui/screens.py b/packages/meshbay-cli/src/meshbay_cli/tui/screens.py index 39b5df3..b6fd347 100644 --- a/packages/meshbay-cli/src/meshbay_cli/tui/screens.py +++ b/packages/meshbay-cli/src/meshbay_cli/tui/screens.py @@ -41,6 +41,9 @@ from .panes import LocalPane, RemotePane from .widgets import Choice, TransferStrip PER_GROUP = 2 +# A burst of index updates that added or removed files is answered by one full +# index, this long after the last of them. +REFRESH_AFTER_DELTA_S = 2.0 class SignInScreen(Screen): @@ -118,6 +121,7 @@ class MainScreen(Screen): self._trees: dict[str, Tree] = {} self._gates: dict[str, asyncio.Semaphore] = {} self._watching: set[str] = set() + self._refreshes: dict[str, asyncio.TimerHandle] = {} def compose(self) -> ComposeResult: with Horizontal(): @@ -150,12 +154,36 @@ class MainScreen(Screen): self._trees[group["id"]] = Tree.from_index(await session.index()) if group["id"] not in self._watching: self._watching.add(group["id"]) - session.ch.on_push("index_delta", lambda _msg, g=group: self._changed(g)) + session.ch.on_push( + "index_delta", lambda msg, g=group, s=session: self._delta(g, s, msg)) return self._trees[group["id"]] def forget_tree(self, group: dict) -> None: self._trees.pop(group["id"], None) + def _delta(self, group: dict, session, msg: dict) -> None: + """A pushed index update, applied to the tree in place. Only one that + adds or removes something is drawn, and asks for the whole index — once + for a burst, not once per message.""" + tree = self._trees.get(group["id"]) + if tree is None: + return # the next look asks for the whole index anyway + try: + structural = tree.apply_delta(session.open_delta(msg)) + except CliError: + structural = True + if not structural: + return + pending = self._refreshes.pop(group["id"], None) + if pending is not None: + pending.cancel() + self._refreshes[group["id"]] = asyncio.get_running_loop().call_later( + REFRESH_AFTER_DELTA_S, self._refreshed, group) + + def _refreshed(self, group: dict) -> None: + self._refreshes.pop(group["id"], None) + self._changed(group) + def _changed(self, group: dict) -> None: """Something changed in the group: the index is asked for again, and the pane redrawn if it is showing that group.""" |