save.v

1//! Creating saves.2//!3//! A save is a full snapshot: every tracked path with its object hash and4//! executable bit, plus the message, time, machine and optional agent and5//! session. Its ID is the first 12 hex characters of the Blake3 hash of the6//! canonical record, computed once, at creation, and never recomputed — which7//! is why `strip` can change a save's files and keep its ID.89module history1011import strings12import time13import src.machine14import src.snapshot15import src.storage1617pub struct SaveInput {18pub mut:19	message       string20	agent         string21	session       string22	is_checkpoint bool23	restores      string24	replayed_from string25	created_at    i6426	machine       string27}2829pub const nothing_changed = 'nothing has changed since the last save'3031// save_worktree walks the working tree and records it. A plain save refuses32// when the tree matches head; a checkpoint always records. The walk runs33// before the lock, so other commands are not held up by the hashing.34pub fn save_worktree(store &storage.Store, root string, ig snapshot.Ignore, input SaveInput) !Save {35	walked_head := head_id(store)36	files := snapshot.walk(store, root, ig)!37	store.begin()!38	save := save_walk(store, root, input, walked_head, files) or {39		store.rollback()40		return err41	}42	store.commit()!43	refresh_log_md(store)44	return save45}4647// save_walk records a walk inside the caller's transaction. A restore still48// writing its files is refused: the tree is half one save and half another.49// When another command moved head after the walk, the walk is stale, and50// recording it on the new head would quietly undo that command, so the tree51// (and its ignore rules, which may have changed too) is read again under the52// lock.53fn save_walk(store &storage.Store, root string, input SaveInput, walked_head string, walked []snapshot.FileEntry) !Save {54	if snapshot.restore_pending(store) {55		return error(snapshot.restore_unfinished)56	}57	mut files := walked.clone()58	moved := head_id(store) != walked_head59	if moved {60		files = snapshot.walk(store, root, snapshot.load(root))!61	}62	if input.restores == '' && !input.is_checkpoint {63		if previous := head(store) {64			if snapshot.same_tree(files, files_of(store, previous.id)!) {65				if moved {66					// Another agent's save, made while this one waited for the67					// lock, already holds these changes.68					return error('${nothing_changed} — [${previous.id}] "${previous.message}" was saved a moment ago and already holds this tree')69				}70				return error(nothing_changed)71			}72		}73	}74	return record_save(store, root, files, input)!75}7677// save_tree records an already-known tree. `root` is '' when the objects are78// already in the store — a restore, or a replay during a steal.79pub fn save_tree(store &storage.Store, root string, files []snapshot.FileEntry, input SaveInput) !Save {80	store.begin()!81	save := record_save(store, root, files, input) or {82		store.rollback()83		return err84	}85	store.commit()!86	refresh_log_md(store)87	return save88}8990// record_save writes one save inside the caller's transaction. A steal uses it91// to land a whole replay — several saves, fetched objects and fetched events —92// in a single step, so a failure leaves no half-combined line behind.93pub fn record_save(store &storage.Store, root string, files []snapshot.FileEntry, input SaveInput) !Save {94	if root != '' {95		snapshot.store_objects(store, root, files)!96	}97	return write_save(store, files, input)!98}99100fn write_save(store &storage.Store, files []snapshot.FileEntry, input SaveInput) !Save {101	created_at := if input.created_at > 0 { input.created_at } else { time.now().unix() }102	mut save := Save{103		parent:        head_id(store)104		message:       input.message105		created_at:    created_at106		machine:       if input.machine != '' { input.machine } else { machine.name() }107		is_checkpoint: input.is_checkpoint108		size_bytes:    tree_size(store, files)109		agent:         input.agent110		session:       input.session111		restores:      input.restores112		replayed_from: input.replayed_from113	}114	// Two saves made in the same second with the same record would collide.115	// Bumping the clock keeps one line of history and keeps the ID unique.116	for {117		save.id = save_id(save, files)118		if by_id(store, save.id) == none {119			break120		}121		save.created_at++122	}123	insert_save(store, save, files)!124	store.set_state(storage.head_key, save.id)!125	return save126}127128// import_save records a save exactly as another machine made it: same ID, same129// parent, same time, same files. `steal` and `migrate` use it; a save made here130// goes through write_save instead, which mints the ID.131pub fn import_save(store &storage.Store, save Save, files []snapshot.FileEntry) ! {132	insert_save(store, save, files)!133}134135// set_head moves the line's head without creating a save. Only fetching another136// machine's saves does that: nothing is erased and nothing is re-recorded,137// because those saves are already on the line.138pub fn set_head(store &storage.Store, id string) ! {139	store.set_state(storage.head_key, id)!140}141142fn insert_save(store &storage.Store, save Save, files []snapshot.FileEntry) ! {143	mut stmt := store.db.prepare('INSERT INTO saves (id, parent, message, created_at, machine,144		is_checkpoint, size_bytes, agent, session, restores, replayed_from)145		VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)')!146	stmt.bind_text(1, save.id)!147	if save.parent == '' {148		stmt.bind_null(2)!149	} else {150		stmt.bind_text(2, save.parent)!151	}152	stmt.bind_text(3, save.message)!153	stmt.bind_int(4, save.created_at)!154	stmt.bind_text(5, save.machine)!155	stmt.bind_int(6, if save.is_checkpoint { 1 } else { 0 })!156	stmt.bind_int(7, save.size_bytes)!157	bind_optional(stmt, 8, save.agent)!158	bind_optional(stmt, 9, save.session)!159	bind_optional(stmt, 10, save.restores)!160	bind_optional(stmt, 11, save.replayed_from)!161	stmt.step()!162	stmt.finalize()163164	mut files_stmt :=165		store.db.prepare('INSERT INTO save_files (save_id, path, hash, executable) VALUES (?, ?, ?, ?)')!166	defer {167		files_stmt.finalize()168	}169	for file in files {170		files_stmt.bind_text(1, save.id)!171		files_stmt.bind_text(2, file.path)!172		files_stmt.bind_text(3, file.hash)!173		files_stmt.bind_int(4, if file.executable { 1 } else { 0 })!174		files_stmt.step()!175		// A statement that has returned DONE must be reset before rebinding.176		files_stmt.reset()177	}178}179180fn bind_optional(stmt &storage.Stmt, index int, value string) ! {181	if value == '' {182		stmt.bind_null(index)!183	} else {184		stmt.bind_text(index, value)!185	}186}187188// save_id is the first 12 hex characters of the Blake3 hash of the canonical189// record: parent, message, time, machine, checkpoint mark, agent, session and190// the sorted file list.191pub fn save_id(save Save, files []snapshot.FileEntry) string {192	return storage.hash_hex(canonical(save, files).bytes())[..12]193}194195fn canonical(save Save, files []snapshot.FileEntry) string {196	mut sb := strings.Builder{}197	sb.write_string('koh3-save-v1\n')198	put_field(mut sb, 'parent', save.parent)199	put_field(mut sb, 'message', save.message)200	put_field(mut sb, 'created', save.created_at.str())201	put_field(mut sb, 'machine', save.machine)202	put_field(mut sb, 'checkpoint', if save.is_checkpoint { '1' } else { '0' })203	put_field(mut sb, 'agent', save.agent)204	put_field(mut sb, 'session', save.session)205	put_field(mut sb, 'files', files.len.str())206	for file in files {207		mark := if file.executable { 'x' } else { '-' }208		put_field(mut sb, 'file', '${mark}${file.hash} ${file.path}')209	}210	return sb.str()211}212213// Length-prefixed fields keep the record unambiguous whatever a message or a214// path contains.215fn put_field(mut sb strings.Builder, name string, value string) {216	sb.write_string('${name}:${value.len}:')217	sb.write_string(value)218	sb.write_string('\n')219}220221fn tree_size(store &storage.Store, files []snapshot.FileEntry) i64 {222	mut total := i64(0)223	for file in files {224		total += store.object_size(file.hash) or { 0 }225	}226	return total227}