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| 1 | //! `ore sync` -- two repositories on one filesystem, brought into agreement. |
| 2 | //! |
| 3 | //! The engine's `oxedyne_fe2o3_ore::sync` is a state machine over four messages |
| 4 | //! and nothing else: it opens no file and holds no connection, so what carries |
| 5 | //! the bytes is decided here. Version zero carries them the shortest distance |
| 6 | //! there is. The other repository is a path this machine can already read and |
| 7 | //! write -- a second checkout, a directory a file synchroniser mirrors, a |
| 8 | //! mounted drive, a memory stick -- and this process runs both ends of the |
| 9 | //! conversation. |
| 10 | //! |
| 11 | //! That is legitimate rather than a shortcut, because the protocol is |
| 12 | //! peer-symmetric: there is no client and no server, no message one side may |
| 13 | //! send that the other may not, and no state either session keeps that the |
| 14 | //! other's bytes do not put there. Two sessions in one process therefore compute |
| 15 | //! exactly what two sessions on two machines would. The messages are encoded to |
| 16 | //! bytes and decoded back even so, so that what is exercised here is the wire |
| 17 | //! format and not a shortcut around it, and so that the byte counts this verb |
| 18 | //! reports are the bytes a network transport would carry. |
| 19 | //! |
| 20 | //! # Both ends converge, and both ends say so |
| 21 | //! |
| 22 | //! A sync is not a fetch and not a push. Each side sends what the other lacks, |
| 23 | //! each absorbs what arrives, and both logs end holding the same operations, |
| 24 | //! written to both sets of segments before the command returns. |
| 25 | //! |
| 26 | //! # One working copy is written |
| 27 | //! |
| 28 | //! The repository the command was run from is rendered and materialised at the |
| 29 | //! merged state. The other one is not: it may be somebody else's checkout, and |
| 30 | //! writing into it uninvited is not this tool's business. What is left there |
| 31 | //! instead is [`Pending`], the marker that lets the next verb run there write the |
| 32 | //! working copy forward safely -- see [`settle`], and see [`crate::repo`] for why |
| 33 | //! the marker is needed at all. |
| 34 | //! |
| 35 | //! # Both ends can afterwards say what arrived |
| 36 | //! |
| 37 | //! Each end writes down where its log stood either side of the exchange, which |
| 38 | //! is what `ore log --arrived` reads. It is bookkeeping of the tool's own and |
| 39 | //! not history -- see [`crate::arrived`] -- and it is written at both ends for |
| 40 | //! the reason the operations reach both: an exchange that only one end could |
| 41 | //! account for would be a fetch. |
| 42 | //! |
| 43 | //! # Provenance crosses with the operations |
| 44 | //! |
| 45 | //! Two things travel besides the operations. The public keys each end knows are |
| 46 | //! written into the other's configuration first, which is what lets a signature |
| 47 | //! that arrives a moment later be checked; and the operations themselves cross |
| 48 | //! sealed, this being the substitution the engine's sync module leaves to its |
| 49 | //! caller -- see [`Party::seal_outgoing`]. What arrives is verified before a |
| 50 | //! session is allowed to absorb any of it, and a batch holding one operation |
| 51 | //! whose signature does not hold is refused whole, by name. |
| 52 | //! |
| 53 | //! Keys cross by the same route the operations do, which here is a filesystem |
| 54 | //! both ends can read: each side reads the other's configuration and writes down |
| 55 | //! what it has not seen. A transport that is not a shared filesystem would need |
| 56 | //! the bindings in a message of their own, and that is the one part of this verb |
| 57 | //! a network version would not inherit unchanged. |
| 58 | //! |
| 59 | //! # Choosing a mode |
| 60 | //! |
| 61 | //! Neither peer knows the difference before it has spoken, so the sketch is |
| 62 | //! sized from a guess and the protocol is built to survive a bad one: an |
| 63 | //! undersized table stalls, says so, and the frontier walk answers in the same |
| 64 | //! turn without losing a round trip. [`choose`] makes the guess. |
| 65 | //! |
| 66 | //! # The other transport |
| 67 | //! |
| 68 | //! An argument beginning `http://` or `https://` is a relay rather than a path, |
| 69 | //! and [`crate::relay`] carries the same exchange there. The capture below |
| 70 | //! happens either way and first, so a network that is not there costs nothing |
| 71 | //! but the attempt. |
| 72 | |
| 73 | use crate::arrived as delta; |
| 74 | use crate::capture; |
| 75 | use crate::collisions; |
| 76 | use crate::keys::{ |
| 77 | self, |
| 78 | Prov, |
| 79 | Trust, |
| 80 | }; |
| 81 | use crate::relay; |
| 82 | use crate::repo::{ |
| 83 | Lock, |
| 84 | Pending, |
| 85 | Repo, |
| 86 | CONFIG_FILE, |
| 87 | ORE_DIR, |
| 88 | }; |
| 89 | use crate::tree; |
| 90 | use crate::verbs; |
| 91 | |
| 92 | use ore_store::store::Keep; |
| 93 | use ore_store::store::{ |
| 94 | arrived, |
| 95 | sealed, |
| 96 | }; |
| 97 | |
| 98 | use oxedyne_fe2o3_core::prelude::*; |
| 99 | use oxedyne_fe2o3_ore::envelope::Envelope; |
| 100 | use oxedyne_fe2o3_ore::id::OpId; |
| 101 | use oxedyne_fe2o3_ore::log::OpLog; |
| 102 | use oxedyne_fe2o3_ore::sync::{ |
| 103 | Fallback, |
| 104 | Message, |
| 105 | Mode, |
| 106 | Session, |
| 107 | Step, |
| 108 | }; |
| 109 | |
| 110 | use std::collections::{ |
| 111 | BTreeMap, |
| 112 | BTreeSet, |
| 113 | VecDeque, |
| 114 | }; |
| 115 | use std::path::PathBuf; |
| 116 | |
| 117 | |
| 118 | /// How many messages one exchange may carry before it is called a fault. |
| 119 | /// |
| 120 | /// A sync is four messages each way at most. The bound is far above that and is |
| 121 | /// there so that a session that somehow never converges stops rather than |
| 122 | /// looping. |
| 123 | pub const MESSAGE_LIMIT: usize = 64; |
| 124 | |
| 125 | |
| 126 | /// What one exchange did. |
| 127 | pub struct Exchange { |
| 128 | /// The mode the sessions ran in. |
| 129 | pub mode: Mode, |
| 130 | /// Operations the other end did not hold and now does. |
| 131 | pub sent: usize, |
| 132 | /// Operations this end did not hold and now does. |
| 133 | pub received: usize, |
| 134 | /// Operations both ends already held. |
| 135 | pub shared: usize, |
| 136 | /// Messages carried, both directions. |
| 137 | pub messages: usize, |
| 138 | /// Bytes those messages came to, encoded as they would cross a wire. |
| 139 | pub bytes: usize, |
| 140 | /// The first fallback either end made, if either made one. |
| 141 | pub fell_back: Option<Fallback>, |
| 142 | } |
| 143 | |
| 144 | impl Exchange { |
| 145 | /// Reports whether the two logs already agreed. |
| 146 | pub fn is_empty(&self) -> bool { |
| 147 | self.sent == 0 && self.received == 0 |
| 148 | } |
| 149 | |
| 150 | /// Writes the mode as a line of text, saying what it was sized for and |
| 151 | /// whether it held. |
| 152 | pub fn mode_line(&self, held: usize) -> String { |
| 153 | let opened = match self.mode { |
| 154 | Mode::Walk => fmt!("frontier walk"), |
| 155 | Mode::Sketch { estimate, .. } => fmt!( |
| 156 | "sketch, sized for {} operation{} of difference over {} held", |
| 157 | estimate, if estimate == 1 { "" } else { "s" }, held, |
| 158 | ), |
| 159 | }; |
| 160 | match self.fell_back { |
| 161 | None => opened, |
| 162 | Some(why) => fmt!( |
| 163 | "{}, which fell back to the frontier walk: {}", opened, why.why()), |
| 164 | } |
| 165 | } |
| 166 | } |
| 167 | |
| 168 | |
| 169 | /// What settling a pending marker did. |
| 170 | pub enum Settled { |
| 171 | /// There was no marker: the working copy and the log agree about who is |
| 172 | /// ahead. |
| 173 | Nothing, |
| 174 | /// The working copy was written forward to the state the log now holds. |
| 175 | Written, |
| 176 | /// The marker was dropped without writing anything, because the working copy |
| 177 | /// had been edited since the sync left it. |
| 178 | Overtaken, |
| 179 | /// The marker stands, because this is not the working copy's own command. |
| 180 | Held(Pending), |
| 181 | } |
| 182 | |
| 183 | |
| 184 | /// Returns the mode two logs on this machine should open in. |
| 185 | /// |
| 186 | /// The rule is the engine's, because a relay running the same session asks the |
| 187 | /// same question of the same two shapes; see [`Mode::between`]. |
| 188 | pub fn choose(local: &OpLog, remote: &OpLog) -> Mode { |
| 189 | Mode::between( |
| 190 | local.len(), |
| 191 | local.frontier().len(), |
| 192 | remote.len(), |
| 193 | remote.frontier().len(), |
| 194 | ) |
| 195 | } |
| 196 | |
| 197 | |
| 198 | /// One end of an exchange: the log being brought up to date, and everything the |
| 199 | /// provenance of what crosses depends on. |
| 200 | /// |
| 201 | /// It is a borrow of the parts of a [`Repo`] a sync touches rather than the |
| 202 | /// repository itself, because both ends are open at once and only one of them |
| 203 | /// is this working copy. |
| 204 | pub struct Party<'a> { |
| 205 | /// What this end is called, in a message about it. |
| 206 | pub name: String, |
| 207 | /// The log being brought up to date. |
| 208 | pub log: &'a mut OpLog, |
| 209 | /// The envelope each sealed operation is held in, read for what this end |
| 210 | /// sends and written for what arrives. |
| 211 | pub envelopes: &'a mut BTreeMap<OpId, Envelope>, |
| 212 | /// What is known about who wrote each operation, extended as they arrive. |
| 213 | pub prov: &'a mut BTreeMap<OpId, Prov>, |
| 214 | /// The keys this end will accept a signature from, as they stand after the |
| 215 | /// two ends have taught each other. |
| 216 | pub trust: Trust, |
| 217 | /// Whether this end refuses an unsigned operation from the other. |
| 218 | pub require_signed: bool, |
| 219 | } |
| 220 | |
| 221 | impl<'a> Party<'a> { |
| 222 | |
| 223 | /// Replaces the bare entries of an outgoing message with the envelopes this |
| 224 | /// end holds for them. |
| 225 | /// |
| 226 | /// The session builds a send set out of the log, and a log holds records |
| 227 | /// rather than envelopes, so what it produces is bare. This is the |
| 228 | /// substitution the engine's sync module leaves to its caller: provenance |
| 229 | /// crosses as provenance, and an operation that was signed when it was |
| 230 | /// written is signed when it is sent on. |
| 231 | pub fn seal_outgoing(&self, msg: Message) |
| 232 | -> Outcome<Message> |
| 233 | { |
| 234 | let entries = match msg { |
| 235 | Message::Send { entries } => entries, |
| 236 | other => return Ok(other), |
| 237 | }; |
| 238 | Ok(Message::Send { entries: res!(sealed(entries, self.envelopes)) }) |
| 239 | } |
| 240 | |
| 241 | /// Checks everything an arriving message carries before a session sees it. |
| 242 | /// |
| 243 | /// Three things happen here and all of them before anything is absorbed: a |
| 244 | /// sealed entry whose signature does not verify is refused by name, a bare |
| 245 | /// entry is refused where this end requires signatures, and the envelope of |
| 246 | /// everything that passes is kept so it can be written to the segments and |
| 247 | /// handed on. |
| 248 | pub fn check_incoming(&mut self, msg: &Message, from: &str) |
| 249 | -> Outcome<()> |
| 250 | { |
| 251 | let entries = msg.entries(); |
| 252 | if entries.is_empty() { |
| 253 | return Ok(()); |
| 254 | } |
| 255 | let whence = fmt!("what {} sent", from); |
| 256 | let mut bare: Vec<OpId> = Vec::new(); |
| 257 | // Checked together, and refused one at a time by name if the set does not |
| 258 | // hold; see `keys::check_all`. |
| 259 | let checked = res!(keys::check_all(entries, &self.trust, &whence, Keep::Envelopes)); |
| 260 | for got in &checked { |
| 261 | if got.prov == Prov::Bare { |
| 262 | bare.push(got.rec.id()); |
| 263 | } |
| 264 | } |
| 265 | if self.require_signed && !bare.is_empty() { |
| 266 | let shown: Vec<String> = bare.iter().take(3).map(|id| fmt!("{}", id)).collect(); |
| 267 | return Err(err!( |
| 268 | "{} requires signed operations, and {} of the {} {} sent are unsigned \ |
| 269 | ({}{}). Nothing was absorbed. Either that repository signs its work with \ |
| 270 | `ore key`, or this one stops requiring it.", |
| 271 | self.name, bare.len(), entries.len(), from, |
| 272 | shown.join(", "), |
| 273 | if bare.len() > shown.len() { fmt!(" and {} more", bare.len() - shown.len()) } |
| 274 | else { fmt!("") }; |
| 275 | Invalid, Input, Security, Missing)); |
| 276 | } |
| 277 | // What is written down is what is about to be absorbed. An operation this |
| 278 | // end already holds keeps the form it was written in here: upgrading a |
| 279 | // bare copy to a sealed one would mean rewriting a segment that is already |
| 280 | // on disk, and a log that only ever grows is worth more than that. |
| 281 | for got in checked { |
| 282 | let id = got.rec.id(); |
| 283 | if self.log.contains(&id) { |
| 284 | continue; |
| 285 | } |
| 286 | if let Some(env) = got.env { |
| 287 | self.envelopes.insert(id, env); |
| 288 | } |
| 289 | self.prov.insert(id, got.prov); |
| 290 | } |
| 291 | Ok(()) |
| 292 | } |
| 293 | } |
| 294 | |
| 295 | |
| 296 | /// Runs both ends of an exchange until each has said everything it owes. |
| 297 | /// |
| 298 | /// The two sessions are handed nothing but encoded messages, in the order a |
| 299 | /// transport would deliver them. Neither reads the other's log and neither reads |
| 300 | /// the other's session; that they are in one process is a fact about this |
| 301 | /// transport and about nothing above it. |
| 302 | /// |
| 303 | /// Provenance rides along with the operations. What one end sends is sealed with |
| 304 | /// whatever envelopes it holds, and what the other end receives is verified |
| 305 | /// against the keys it knows before a session is allowed to absorb any of it. |
| 306 | pub fn exchange(here: &mut Party, there: &mut Party, mode: Mode) |
| 307 | -> Outcome<Exchange> |
| 308 | { |
| 309 | let here_len = here.log.len(); |
| 310 | let there_len = there.log.len(); |
| 311 | let mut here_sess = Session::new(mode); |
| 312 | let mut there_sess = Session::new(mode); |
| 313 | let mut to_there: VecDeque<Vec<u8>> = VecDeque::new(); |
| 314 | let mut to_here: VecDeque<Vec<u8>> = VecDeque::new(); |
| 315 | let mut messages = 0usize; |
| 316 | let mut bytes = 0usize; |
| 317 | let mut fell_back: Option<Fallback> = None; |
| 318 | let opening = res!(here_sess.open(here.log)); |
| 319 | to_there.push_back(res!(res!(here.seal_outgoing(opening)).encode())); |
| 320 | loop { |
| 321 | if messages > MESSAGE_LIMIT { |
| 322 | return Err(err!( |
| 323 | "An exchange carried {} messages without converging, which no sync \ |
| 324 | needs; the sessions are not making progress.", messages; |
| 325 | Bug, Excessive)); |
| 326 | } |
| 327 | // Whichever queue holds something, oldest first. Which of the two is |
| 328 | // drained first decides nothing: a session answers what it is given. |
| 329 | let (buf, to) = match to_there.pop_front() { |
| 330 | Some(buf) => (buf, true), |
| 331 | None => match to_here.pop_front() { |
| 332 | Some(buf) => (buf, false), |
| 333 | None => break, |
| 334 | }, |
| 335 | }; |
| 336 | messages += 1; |
| 337 | bytes += buf.len(); |
| 338 | let msg = res!(Message::decode(&buf)); |
| 339 | // Verified by the end it arrived at, under the keys that end knows, before |
| 340 | // the session is given the chance to absorb anything. |
| 341 | let turn = if to { |
| 342 | res!(there.check_incoming(&msg, &here.name)); |
| 343 | res!(there_sess.receive(there.log, msg)) |
| 344 | } else { |
| 345 | res!(here.check_incoming(&msg, &there.name)); |
| 346 | res!(here_sess.receive(here.log, msg)) |
| 347 | }; |
| 348 | if let Step::FellBack(why) = turn.step { |
| 349 | if fell_back.is_none() { |
| 350 | fell_back = Some(why); |
| 351 | } |
| 352 | } |
| 353 | for m in turn.send { |
| 354 | if to { |
| 355 | // The other end spoke, so the other end's envelopes are what its |
| 356 | // words are sealed with. |
| 357 | to_here.push_back(res!(res!(there.seal_outgoing(m)).encode())); |
| 358 | } else { |
| 359 | to_there.push_back(res!(res!(here.seal_outgoing(m)).encode())); |
| 360 | } |
| 361 | } |
| 362 | } |
| 363 | if !here_sess.is_converged() || !there_sess.is_converged() { |
| 364 | return Err(err!( |
| 365 | "An exchange ran out of messages with one end unfinished: this end {}, \ |
| 366 | the other {}.", |
| 367 | if here_sess.is_converged() { "converged" } else { "did not" }, |
| 368 | if there_sess.is_converged() { "converged" } else { "did not" }; |
| 369 | Bug, Missing)); |
| 370 | } |
| 371 | // What each end absorbed is what the other end genuinely owed it, whatever |
| 372 | // the send set was: the walk is loose and a receiver drops what it holds. |
| 373 | let sent = there_sess.ops_absorbed(); |
| 374 | let received = here_sess.ops_absorbed(); |
| 375 | if sent > here_len || received > there_len { |
| 376 | return Err(err!( |
| 377 | "An exchange handed over {} of {} operations one way and {} of {} the \ |
| 378 | other, which is more than either log held.", |
| 379 | sent, here_len, received, there_len; |
| 380 | Bug, Range)); |
| 381 | } |
| 382 | // Both ends compute the same intersection from opposite sides, so the two |
| 383 | // answers disagreeing means one of the counts is wrong. |
| 384 | let shared = here_len - sent; |
| 385 | if there_len - received != shared { |
| 386 | return Err(err!( |
| 387 | "An exchange makes the operations both ends held {} counted from here \ |
| 388 | and {} counted from the other end.", shared, there_len - received; |
| 389 | Bug, Mismatch)); |
| 390 | } |
| 391 | Ok(Exchange { |
| 392 | mode, |
| 393 | sent, |
| 394 | received, |
| 395 | shared, |
| 396 | messages, |
| 397 | bytes, |
| 398 | fell_back, |
| 399 | }) |
| 400 | } |
| 401 | |
| 402 | |
| 403 | /// Deals with the marker a sync left in a repository it was not run from. |
| 404 | /// |
| 405 | /// `write` says whether this is that working copy's own command. A verb run |
| 406 | /// there may write the working copy forward; a peer syncing with it from |
| 407 | /// somewhere else may not, and leaves the marker where it is. |
| 408 | /// |
| 409 | /// Writing forward is conditional in either case. The marker records the state |
| 410 | /// the working copy was left standing at, so a working copy that still renders |
| 411 | /// that state exactly is one nobody has touched and nothing is lost by writing |
| 412 | /// it forward. One that does not render it has been edited since, and those |
| 413 | /// edits are the reader's own work: the marker is dropped, nothing is written, |
| 414 | /// and the capture that follows records what is there. |
| 415 | pub fn settle(repo: &mut Repo, write: bool) |
| 416 | -> Outcome<Settled> |
| 417 | { |
| 418 | let pending = match res!(repo.read_pending()) { |
| 419 | Some(p) => p, |
| 420 | None => return Ok(Settled::Nothing), |
| 421 | }; |
| 422 | let standing = res!(tree::at(&repo.log, &pending.frontier)); |
| 423 | let ignore = res!(capture::Ignore::read(&repo.root)); |
| 424 | let want = res!(standing.contents()); |
| 425 | let (disk, _) = res!(capture::scan(&repo.root, &ignore, want.keys())); |
| 426 | if disk != want { |
| 427 | println!("this working copy was edited after a sync with {} brought operations \ |
| 428 | into its history, so it is left exactly as it stands", pending.from); |
| 429 | res!(repo.clear_pending()); |
| 430 | return Ok(Settled::Overtaken); |
| 431 | } |
| 432 | if !write { |
| 433 | return Ok(Settled::Held(pending)); |
| 434 | } |
| 435 | let tree = res!(tree::whole(&repo.log)); |
| 436 | let moved = res!(tree::materialise(&repo.root, &tree, tree::Surplus::Remove)); |
| 437 | println!("a sync with {} brought operations into this history; the working copy is \ |
| 438 | now the merged state", pending.from); |
| 439 | verbs::report_moved_files(&moved); |
| 440 | // The spill goes forward with the working copy. A state written here without |
| 441 | // it would leave the buried side of a collision missing at one end of a sync |
| 442 | // and present at the other, which is the one asymmetry the whole exchange |
| 443 | // exists to remove. |
| 444 | collisions::report(&res!(collisions::spill(repo, &tree))); |
| 445 | res!(repo.clear_pending()); |
| 446 | println!(); |
| 447 | Ok(Settled::Written) |
| 448 | } |
| 449 | |
| 450 | |
| 451 | /// Resolves the argument to the root of another Ore repository. |
| 452 | /// |
| 453 | /// The path must be the root itself rather than somewhere inside it. A search up |
| 454 | /// the ancestors is what [`Repo::find_root`] does for the working copy a person |
| 455 | /// is standing in, where the intent is unmistakable; for an argument naming |
| 456 | /// somebody else's repository it would mean a mistyped path quietly syncing with |
| 457 | /// whatever repository happened to be above it. |
| 458 | fn remote_root(path: &str) |
| 459 | -> Outcome<PathBuf> |
| 460 | { |
| 461 | let root = match std::fs::canonicalize(path) { |
| 462 | Ok(p) => p, |
| 463 | Err(e) => return Err(err!(e, |
| 464 | "The path {:?} could not be resolved. `ore sync` takes the root of another \ |
| 465 | Ore repository this machine can reach: a second checkout, a directory a \ |
| 466 | file synchroniser mirrors, or a mounted drive.", path; |
| 467 | IO, File, Read)), |
| 468 | }; |
| 469 | if !root.join(ORE_DIR).join(CONFIG_FILE).is_file() { |
| 470 | return Err(err!( |
| 471 | "{:?} is not an Ore repository: it holds no {}/{}. `ore sync` takes the \ |
| 472 | root of another repository, not a directory within one and not a directory \ |
| 473 | above one.", root.display(), ORE_DIR, CONFIG_FILE; |
| 474 | Invalid, Input, Missing)); |
| 475 | } |
| 476 | Ok(root) |
| 477 | } |
| 478 | |
| 479 | |
| 480 | /// `ore sync` -- exchanges operations with another repository, and leaves both |
| 481 | /// holding the same history. |
| 482 | /// |
| 483 | /// `taking` is `--pull-only`: take what the other end has and hand over nothing. |
| 484 | /// The exchange is otherwise the same one, and only this end moves, so the two |
| 485 | /// are left agreeing only if this end was the only one behind. |
| 486 | /// |
| 487 | /// It exists for two reasons. A relay classifies a request that hands nothing |
| 488 | /// over as a read, so a `pull` grant is usable only by a caller offering |
| 489 | /// nothing: without this a replica holding any work of its own is refused |
| 490 | /// outright, the whole request and not its push half. And a sync over a local |
| 491 | /// path writes to the other repository -- it captures that working copy and |
| 492 | /// absorbs into its log -- which is not what somebody reading a contribution |
| 493 | /// intends. |
| 494 | pub fn sync(repo: &mut Repo, path: &str, taking: bool, dry: bool) |
| 495 | -> Outcome<()> |
| 496 | { |
| 497 | // Capture first, as every verb does. Whatever this working copy holds is in |
| 498 | // the history before anything arrives, so nothing here can be lost by what |
| 499 | // does. |
| 500 | println!("here:"); |
| 501 | let what = res!(capture::capture(repo)); |
| 502 | verbs::report(&what); |
| 503 | |
| 504 | // A relay is the other carrier of the same exchange, and it is reached after |
| 505 | // the capture for the reason the capture is first: whatever is here is in the |
| 506 | // history before anything else happens, network or no network. |
| 507 | if relay::Remote::is_url(path) { |
| 508 | // A rehearsal hands nothing over, whatever was asked: offering is a write, |
| 509 | // and a question that writes is not a question. |
| 510 | return relay::sync(repo, path, taking || dry, dry); |
| 511 | } |
| 512 | |
| 513 | let root = res!(remote_root(path)); |
| 514 | println!(); |
| 515 | if root == repo.root { |
| 516 | println!("{} is this repository, so there is nothing to sync with; a sync \ |
| 517 | needs two", root.display()); |
| 518 | return Ok(()); |
| 519 | } |
| 520 | // Taken for the whole command, and released however it ends. This end's lock |
| 521 | // was taken before the repository was opened, in main. |
| 522 | let _lock = res!(Lock::take(&root.join(ORE_DIR))); |
| 523 | // The far end of a path sync hands its operations over as surely as this end |
| 524 | // does, so its envelopes are wanted. |
| 525 | let mut remote = res!(Repo::open_at(&root, Keep::Envelopes)); |
| 526 | // How much the other end held before this command touched it, which is what |
| 527 | // says at the end whether it owes itself a mark. Taken before its capture and |
| 528 | // not after, since a capture is one of the ways this command makes its log |
| 529 | // grow. |
| 530 | let there_held = remote.log.len(); |
| 531 | if remote.cfg.replica == repo.cfg.replica { |
| 532 | return Err(err!( |
| 533 | "{:?} and this repository are both replica {}, which is what copying a \ |
| 534 | working copy's {} directory leaves behind. Two repositories of one replica \ |
| 535 | name mint the same operation identifiers for different operations, and \ |
| 536 | nothing afterwards can tell those apart. Make the second one with `ore \ |
| 537 | init` and bring this history into it with `ore sync`.", |
| 538 | root.display(), repo.cfg.replica, ORE_DIR; |
| 539 | Invalid, Data, Conflict)); |
| 540 | } |
| 541 | |
| 542 | println!("{}:", root.display()); |
| 543 | // Whether the other end is to be touched at all. Taking without giving and |
| 544 | // asking what would arrive are both promises about that repository, and the |
| 545 | // first thing an ordinary sync does to it is the loudest: it captures its |
| 546 | // working copy, which turns whatever that person had deliberately not |
| 547 | // recorded into history under their own name. A relay has no working copy and |
| 548 | // needed no such care; a path does. |
| 549 | let shy = taking || dry; |
| 550 | let standing = if shy { |
| 551 | println!("left alone: nothing here is captured, written or recorded"); |
| 552 | remote.log.frontier() |
| 553 | } else { |
| 554 | // The other end is captured too, so that its working copy is in its history |
| 555 | // before anything arrives there either. The exception is a working copy still |
| 556 | // standing where an earlier sync left it: it holds no work of its own to |
| 557 | // record, and capturing it would record the difference from the merged state |
| 558 | // as an edit. |
| 559 | let settled = res!(settle(&mut remote, false)); |
| 560 | match &settled { |
| 561 | Settled::Held(pending) => { |
| 562 | println!("captured nothing; its working copy stands at the state an \ |
| 563 | earlier sync left it at"); |
| 564 | pending.frontier.clone() |
| 565 | }, |
| 566 | _ => { |
| 567 | let theirs = res!(capture::capture(&mut remote)); |
| 568 | verbs::report(&theirs); |
| 569 | remote.log.frontier() |
| 570 | }, |
| 571 | } |
| 572 | }; |
| 573 | |
| 574 | // The keys cross before the operations do, in both directions, because what |
| 575 | // arrives is verified against what is known and a key learned afterwards |
| 576 | // would be learned too late. This is trust on first use: each end writes down |
| 577 | // what the other says its keys are, and nothing here asks for more than that. |
| 578 | // The two configurations are the channel, this transport being a filesystem |
| 579 | // both ends can read. |
| 580 | println!(); |
| 581 | let learned_here = repo.learn_keys(&remote.cfg); |
| 582 | let learned_there = if shy { 0 } else { remote.learn_keys(&repo.cfg) }; |
| 583 | // A rehearsal writes nothing at all, the learned keys included: a question |
| 584 | // that changed the configuration would be a poor question. |
| 585 | if !dry { |
| 586 | res!(repo.save_config()); |
| 587 | } |
| 588 | if !shy { |
| 589 | res!(remote.save_config()); |
| 590 | } |
| 591 | println!("keys {} known here ({} learned now), {} known there ({} learned now)", |
| 592 | repo.cfg.keys.len(), learned_here, remote.cfg.keys.len(), learned_there); |
| 593 | |
| 594 | let here_before: BTreeSet<OpId> = repo.log.iter().map(|rec| rec.id()).collect(); |
| 595 | let there_before: BTreeSet<OpId> = remote.log.iter().map(|rec| rec.id()).collect(); |
| 596 | let here_was = repo.log.frontier(); |
| 597 | let there_was = remote.log.frontier(); |
| 598 | let here_held = repo.log.len(); |
| 599 | let mode = choose(&repo.log, &remote.log); |
| 600 | // What must not be written is exchanged into copies instead. Both flags are |
| 601 | // this one mechanism aimed at different sides: taking without giving spares |
| 602 | // the other end, and a rehearsal spares both. The exchange itself is the |
| 603 | // exchange, so what is learned is what a real sync would have learned. |
| 604 | let mut spare_here = if dry { repo.log.clone() } else { OpLog::default() }; |
| 605 | let mut spare_here_env = if dry { repo.envelopes.clone() } else { BTreeMap::new() }; |
| 606 | let mut spare_here_prov = if dry { repo.prov.clone() } else { BTreeMap::new() }; |
| 607 | let mut spare_there = if shy { remote.log.clone() } else { OpLog::default() }; |
| 608 | let mut spare_there_env = if shy { remote.envelopes.clone() } else { BTreeMap::new() }; |
| 609 | let mut spare_there_prov = if shy { remote.prov.clone() } else { BTreeMap::new() }; |
| 610 | let done = { |
| 611 | let (h_log, h_env, h_prov) = if dry { |
| 612 | (&mut spare_here, &mut spare_here_env, &mut spare_here_prov) |
| 613 | } else { |
| 614 | (&mut repo.log, &mut repo.envelopes, &mut repo.prov) |
| 615 | }; |
| 616 | let (t_log, t_env, t_prov) = if shy { |
| 617 | (&mut spare_there, &mut spare_there_env, &mut spare_there_prov) |
| 618 | } else { |
| 619 | (&mut remote.log, &mut remote.envelopes, &mut remote.prov) |
| 620 | }; |
| 621 | let mut here = Party { |
| 622 | name: fmt!("{}", repo.root.display()), |
| 623 | trust: repo.cfg.trust(), |
| 624 | require_signed: repo.cfg.require_signed, |
| 625 | log: h_log, |
| 626 | envelopes: h_env, |
| 627 | prov: h_prov, |
| 628 | }; |
| 629 | let mut there = Party { |
| 630 | name: fmt!("{}", remote.root.display()), |
| 631 | trust: remote.cfg.trust(), |
| 632 | require_signed: remote.cfg.require_signed, |
| 633 | log: t_log, |
| 634 | envelopes: t_env, |
| 635 | prov: t_prov, |
| 636 | }; |
| 637 | res!(exchange(&mut here, &mut there, mode)) |
| 638 | }; |
| 639 | |
| 640 | // Everything that arrived reaches the segments before the command says a word |
| 641 | // about what it did, at both ends. |
| 642 | let mine = if dry { |
| 643 | Vec::new() |
| 644 | } else { |
| 645 | let mine = arrived(&repo.log, &here_before, &repo.envelopes, &BTreeMap::new()); |
| 646 | res!(repo.write_entries_from(&mine, None)); |
| 647 | mine |
| 648 | }; |
| 649 | let _ = &mine; |
| 650 | let theirs = if shy { |
| 651 | Vec::new() |
| 652 | } else { |
| 653 | let theirs = arrived(&remote.log, &there_before, &remote.envelopes, &BTreeMap::new()); |
| 654 | res!(remote.write_entries_from(&theirs, None)); |
| 655 | theirs |
| 656 | }; |
| 657 | // What each end can afterwards be asked about this exchange. Both ends absorb, |
| 658 | // so both ends get a record, and it is written whether anything crossed or |
| 659 | // not: a sync that brought nothing is an answer to "what arrived" as much as |
| 660 | // one that brought everything. |
| 661 | if !dry { |
| 662 | res!(delta::record(&repo.root, &fmt!("{}", root.display()), |
| 663 | here_was.clone(), repo.log.frontier())); |
| 664 | } |
| 665 | if !shy { |
| 666 | res!(delta::record(&remote.root, &fmt!("{}", repo.root.display()), |
| 667 | there_was.clone(), remote.log.frontier())); |
| 668 | } |
| 669 | // The mark naming where the exchange left the two of them: one operation, |
| 670 | // authored here, written into both logs. |
| 671 | // |
| 672 | // After the exchange rather than before it. A mark written before the |
| 673 | // hand-over has only this end's frontier as its parents, so the operations |
| 674 | // arriving a moment later are concurrent with it and the frontier becomes two |
| 675 | // heads -- the same expensive mirror path, one step later. |
| 676 | // |
| 677 | // One mark rather than one per end, which was tried and does not converge. If |
| 678 | // each end names its own frontier, each ends holding a mark the other has not |
| 679 | // got; the next sync carries those two across and each end then writes another |
| 680 | // one, so the two logs differ by two operations after every sync there will |
| 681 | // ever be and `ore sync` run twice never says it has nothing to carry. It was |
| 682 | // measured going 7, 9, 11, 13 operations over four syncs of a repository |
| 683 | // nobody was editing. Both ends hold the same operations by this point, so |
| 684 | // this end's frontier is also that end's, and one mark parented on it leaves |
| 685 | // both standing at the same single mark -- which is the invariant, and a fixed |
| 686 | // point: the next sync exchanges nothing and writes nothing. |
| 687 | // |
| 688 | // Writing into somebody else's repository is not a new liberty here: an |
| 689 | // ordinary sync already captures their working copy, which is a far larger |
| 690 | // thing to do to it, and every operation this end sends is written there |
| 691 | // already. `--pull-only` and `--dry-run` both leave that end alone, which is |
| 692 | // what `shy` says, and then this end's mark is the ordinary one every command |
| 693 | // ends with. |
| 694 | let mut named: Option<OpId> = None; |
| 695 | if !shy && remote.log.len() > there_held { |
| 696 | if let Some(id) = res!(verbs::auto_mark(repo)) { |
| 697 | res!(remote.take(res!(repo.entry_of(&id)))); |
| 698 | named = Some(id); |
| 699 | } |
| 700 | } |
| 701 | if !theirs.is_empty() { |
| 702 | // The other end's own memory of what was done to it, in the manner of the |
| 703 | // batch record every command keeps here. |
| 704 | res!(remote.record(&fmt!("sync {}", repo.root.display()), there_was)); |
| 705 | res!(remote.save_pending(&Pending { |
| 706 | frontier: standing, |
| 707 | from: fmt!("{}", repo.root.display()), |
| 708 | })); |
| 709 | } |
| 710 | |
| 711 | println!(); |
| 712 | println!("mode {}", done.mode_line(here_held)); |
| 713 | if dry { |
| 714 | println!("offered nothing: a rehearsal hands nothing over"); |
| 715 | println!("would take {} operation{} this repository does not hold", |
| 716 | done.received, if done.received == 1 { "" } else { "s" }); |
| 717 | } else if taking { |
| 718 | println!("offered nothing, by request"); |
| 719 | if done.sent > 0 { |
| 720 | println!("kept back {} operation{} {} does not hold, which stay here until \ |
| 721 | a sync offers them", |
| 722 | done.sent, if done.sent == 1 { "" } else { "s" }, root.display()); |
| 723 | } |
| 724 | println!("received {} operation{} from replica {}", |
| 725 | done.received, if done.received == 1 { "" } else { "s" }, remote.cfg.replica); |
| 726 | } else if done.is_empty() { |
| 727 | println!("nothing to exchange: both repositories already held the same {} \ |
| 728 | operation{}", done.shared, if done.shared == 1 { "" } else { "s" }); |
| 729 | } else { |
| 730 | println!("sent {} operation{} to replica {}", |
| 731 | done.sent, if done.sent == 1 { "" } else { "s" }, remote.cfg.replica); |
| 732 | println!("received {} operation{} from replica {}", |
| 733 | done.received, if done.received == 1 { "" } else { "s" }, remote.cfg.replica); |
| 734 | println!("shared {} operation{} both already held", |
| 735 | done.shared, if done.shared == 1 { "" } else { "s" }); |
| 736 | } |
| 737 | println!("traffic {} message{}, {} byte{}", |
| 738 | done.messages, if done.messages == 1 { "" } else { "s" }, |
| 739 | done.bytes, if done.bytes == 1 { "" } else { "s" }); |
| 740 | if shy { |
| 741 | println!("this repository {} {} operation{}, and {} is as it was", |
| 742 | if dry { "holds" } else { "now holds" }, |
| 743 | if dry { spare_here.len() } else { repo.log.len() }, |
| 744 | if repo.log.len() == 1 { "" } else { "s" }, |
| 745 | root.display()); |
| 746 | } else { |
| 747 | println!("both repositories now hold {} operation{}", |
| 748 | repo.log.len(), if repo.log.len() == 1 { "" } else { "s" }); |
| 749 | } |
| 750 | // Said out loud, because it is the one operation this command wrote that the |
| 751 | // exchange did not carry, and it accounts for the difference between what was |
| 752 | // sent, received and shared and what both ends now hold. |
| 753 | if let Some(id) = named { |
| 754 | println!("named both ends at {}, so each stands at one point rather than \ |
| 755 | at a frontier the git mirror would have to render whole", id); |
| 756 | } |
| 757 | println!("frontier {}", verbs::frontier_of(&repo.log.frontier())); |
| 758 | |
| 759 | // A rehearsal stops here: nothing was written, so there is no working copy to |
| 760 | // bring forward, and what would have arrived is described from the copies |
| 761 | // before they are let go of. |
| 762 | if dry { |
| 763 | println!(); |
| 764 | println!("nothing was written: this was a rehearsal, and {} was not touched", |
| 765 | root.display()); |
| 766 | res!(delta::describe(&spare_here, &repo.root, &spare_here_prov, |
| 767 | repo.cfg.replica, &here_was, &spare_here.frontier(), "it would bring")); |
| 768 | println!(); |
| 769 | println!("`ore sync {}` takes it", root.display()); |
| 770 | return Ok(()); |
| 771 | } |
| 772 | |
| 773 | // This working copy is written to the merged state. The other one is not, |
| 774 | // and the marker left there is what lets the next verb run there write it |
| 775 | // forward without treading on anything done in the meantime. |
| 776 | let tree = res!(tree::whole(&repo.log)); |
| 777 | let moved = res!(tree::materialise(&repo.root, &tree, tree::Surplus::Remove)); |
| 778 | println!(); |
| 779 | println!("the working copy here is now the merged state"); |
| 780 | verbs::report_moved_files(&moved); |
| 781 | if !theirs.is_empty() { |
| 782 | println!("{} holds them in its log; its working copy is written the next time \ |
| 783 | a verb runs there", root.display()); |
| 784 | } |
| 785 | println!(); |
| 786 | verbs::summarise(repo, &tree) |
| 787 | } |