Created
November 14, 2014 22:30
-
-
Save williamstein/badf771e50658010d56d to your computer and use it in GitHub Desktop.
BSD-licensed Differential Synchroniziation code with synchronized database built on top.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| ################################################################### | |
| # | |
| # Code to support simultaneous multiple editing | |
| # sessions by different clients of a single object. This uses | |
| # the Differential Synchronization algorithm of Neil Fraser, | |
| # which is the same thing that Google Docs uses. | |
| # | |
| # * "Differential Synchronization" (by Neil Fraser). | |
| # * http://neil.fraser.name/writing/sync/ | |
| # * http://www.youtube.com/watch?v=S2Hp_1jqpY8 | |
| # * http://code.google.com/p/google-diff-match-patch/ | |
| # | |
| # SYMMETRY: The implementation below is completely symmetric. However, | |
| # you *cannot* randomly initiate the synchronization from either the | |
| # "client" or "server" -- if one of the two initiates a sync, then | |
| # that one has to stay the initiater until the sync succeeds. E.g., | |
| # if you run | |
| # client.push_edits( (err) => | |
| # if not err | |
| # server.push_edits() | |
| # ) | |
| # then do not suddenly do "server.push_edits..." until we do not get | |
| # an error above. | |
| ################################################################### | |
| # FOR TESTING: | |
| # coffee -o node_modules -c diffsync.coffee && echo "require('diffsync').test1()" | coffee | |
| SIMULATE_LOSS = false | |
| #SIMULATE_LOSS = true | |
| async = require('async') | |
| {EventEmitter} = require('events') | |
| diff_match_patch = require('googlediff') # TODO: this greatly increases the size of browserify output (unless we compress it) -- watch out. | |
| # maximum time in seconds that diff_main will BLOCK optimizing the diff -- see https://code.google.com/p/google-diff-match-patch/wiki/API | |
| dmp = new diff_match_patch() | |
| dmp.Diff_Timeout = 0.25 | |
| #dmp.Match_Threshold = 0.3 # make matching more conservative | |
| #dmp.Patch_DeleteThreshold = 0.3 # make deleting more conservative | |
| exports.dmp = dmp | |
| misc = require('misc') | |
| {defaults, required, hash_string, len} = misc | |
| # debug = (s) -> | |
| # w = 'winston' | |
| # try | |
| # require(w).debug(s) | |
| # catch e | |
| # # nothing | |
| class DiffSync extends EventEmitter #not used here, but may be in derived classes | |
| constructor: (opts) -> | |
| @init(opts) | |
| # NOTE: We're using init instead of a constructor and super() | |
| # because inheritence doesn't seem to work right across exports in | |
| # coffeescript... this took me 2 hours to figure out :-(. This is used | |
| # in local_hub.coffee :-( | |
| init: (opts) => | |
| opts = defaults opts, | |
| id : undefined | |
| doc : required | |
| if not opts.id? | |
| @id = misc.uuid() | |
| else | |
| @id = opts.id | |
| @live = opts.doc | |
| @shadow = @_copy(@live) | |
| @backup_shadow = @_copy(@shadow) | |
| @shadow_version = 0 | |
| @backup_shadow_version = 0 | |
| @last_version_received = -1 | |
| @edit_stack = [] | |
| # This can be overloaded in a derived class | |
| snapshot: (cb) => # cb(err, snapshot of live document) | |
| cb(false, @_copy(@live)) | |
| # Copy a document; strings are immutable and the default, so we | |
| # just return the object. | |
| _copy: (doc) => | |
| return doc | |
| # Determine array of edits between the two versions of the document | |
| _compute_edits: (version0, version1) => | |
| return dmp.patch_make(version0, version1) | |
| # "Best effort" application of array of edits. | |
| _apply_edits: (edits, doc, cb) => | |
| cb?(false, dmp.patch_apply(edits, doc)[0]) | |
| _apply_edits_to_live: (edits, cb) => | |
| @_apply_edits edits, @live, (err, result) => | |
| if err | |
| cb?(err); return | |
| else | |
| @live = result | |
| cb?() | |
| # Return a checksum of a document | |
| _checksum: (doc) => | |
| return doc.length | |
| ############################################################### | |
| # API: | |
| # | |
| # * connect -- use to connect the client and the remote | |
| # * push_edits -- compute and push collection of edits out | |
| # * recv_edits -- receive edits and apply them, then send ack. | |
| # | |
| ############################################################### | |
| # Connect this client to the other end of the connection, the "server". | |
| connect: (remote) => | |
| @remote = remote | |
| # Do a complete sync cycle; cb() on success and cb(true) if anything goes wrong. | |
| # In case of failure, do *not* initiate a sync from the other side! | |
| # Also, cb('reset') in case of an non-recoverable data corruption error. | |
| sync: (cb) => | |
| @push_edits (err) => | |
| if err | |
| cb(err) | |
| else | |
| @remote.push_edits(cb) | |
| # Create a list of new edits, then send all edits not yet | |
| # processed to @remote, if defined. If @remote, not defined then | |
| # cb(undefined, edit_stack, last_version_received) | |
| # caller, please don't modify edit_stack! | |
| push_edits: (cb) => # | |
| @snapshot (err, snapshot) => | |
| if err | |
| cb?(err); return | |
| if not snapshot? | |
| cb?("snapshot computed in push_edits is undefined"); return | |
| edits = {edits:@_compute_edits(@shadow, snapshot)} | |
| if edits.edits.length > 0 | |
| edits.shadow_version = @shadow_version | |
| edits.shadow_checksum = @_checksum(@shadow) | |
| @edit_stack.push(edits) | |
| @shadow = snapshot | |
| @shadow_version += 1 | |
| if SIMULATE_LOSS and Math.random() < .5 # Simulate packet loss | |
| console.log("Simulating loss!"); cb?(true); return | |
| # Push any remaining edits from the stack, *AND* report the last version we have received so far. | |
| #console.log("DiffSync.push_edits: push any remaining edits from the stack, *AND* report the last version (=#{@last_version_received}) we have received so far.") | |
| if @remote? | |
| @remote.recv_edits(@edit_stack, @last_version_received, cb) | |
| else | |
| cb?() | |
| # Receive and process the edits from the other end of the sync connection. | |
| recv_edits: (edit_stack, last_version_ack, cb) => | |
| if SIMULATE_LOSS and Math.random() < .5 # Simulate packet loss | |
| console.log("Simulating loss!"); cb?(true); return | |
| #console.log("DiffSync.recv_edits: receive and process the edits from the other end of the sync connection", last_version_ack, edit_stack) | |
| # Keep only edits that we still need to send. | |
| @edit_stack = (edits for edits in @edit_stack when edits.shadow_version > last_version_ack) | |
| if edit_stack.length == 0 | |
| cb?() | |
| return | |
| if edit_stack[0].shadow_version != @shadow_version and edit_stack[0].shadow_version == @backup_shadow_version | |
| # Lost return packet | |
| @shadow = @_copy(@backup_shadow) | |
| @shadow_version = @backup_shadow_version | |
| @edit_stack = [] | |
| # Make a backup, just in case it turns out that our message | |
| # back to the client that we applied these changes is lost | |
| # "Lost return packet." | |
| @backup_shadow = @_copy(@shadow) | |
| @backup_shadow_version = @shadow_version | |
| # Process the incoming edits | |
| i = 0 | |
| process_edit = (cb) => | |
| edits = edit_stack[i] | |
| i += 1 | |
| if edits.shadow_version == @shadow_version | |
| if edits.shadow_checksum != @_checksum(@shadow) | |
| # Data corruption in memory or network: we have to just restart everything from scratch. | |
| cb("reset -- checksum mismatch (#{edits.shadow_checksum} != #{@_checksum(@shadow)})") | |
| return | |
| @_apply_edits edits.edits, @shadow, (err, result) => | |
| if err | |
| cb(err) | |
| else | |
| @last_version_received = edits.shadow_version | |
| @shadow = result | |
| @shadow_version += 1 | |
| @_apply_edits_to_live(edits.edits, cb) | |
| else | |
| if edits.shadow_version < @shadow_version | |
| # Packet duplication or loss: ignore -- it will sort itself out later. | |
| cb() | |
| else if edits.shadow_version > @shadow_version | |
| # This should be impossible, unless there is data corruption. | |
| cb("reset -- shadow version from the future #{edits.shadow_version} > #{@shadow_version}") | |
| return | |
| tasks = (process_edit for j in [0...edit_stack.length]) | |
| async.series(tasks, (err) -> cb?(err)) | |
| # This is for debugging. | |
| status: () => {'id':@id, 'live':@live, 'shadow':@shadow, 'shadow_version':@shadow_version, 'edit_stack':@edit_stack} | |
| class CustomDiffSync extends DiffSync | |
| constructor: (opts) -> | |
| #IMPORTANT: (1) None of the custom functions below take callbacks | |
| # as the last argument! | |
| # (2) You really, really want to define patch_in_place. You must if doc0 = doc1 doesn't work. | |
| opts = defaults opts, | |
| id : undefined # anything you want; or leave empty to have a uuid randomly assigned | |
| doc : required # the starting live document | |
| copy : required # copy(doc) --> copy of the doc -- return, not callback! | |
| diff : required # diff(doc0, doc1) --> p such that patch(p, doc0) = doc1 | |
| patch : required # patch(d, doc0) = doc1 | |
| checksum : required # checksum(doc0) -> something simple | |
| patch_in_place : undefined # patch(d, doc0) modified doc0 in place to become doc1. | |
| @opts = opts | |
| @init(id : opts.id, doc : opts.doc) | |
| @_patch = opts.patch | |
| @_patch_in_place = opts.patch_in_place | |
| @_checksum = opts.checksum | |
| _copy: (doc) => | |
| return @opts.copy(doc) | |
| _compute_edits: (version0, version1) => | |
| return @opts.diff(version0, version1) | |
| _apply_edits: (edits, doc, cb) => | |
| cb?(false, @opts.patch(edits, doc)) | |
| _apply_edits_to_live: (edits, cb) => | |
| if @opts.patch_in_place? | |
| @opts.patch_in_place(edits, @live) | |
| cb?() | |
| else | |
| @_apply_edits edits, @live, (err, result) => | |
| if err | |
| cb?(err); return | |
| else | |
| @live = result | |
| cb?() | |
| _checksum: (doc) => | |
| return @opts.checksum(doc) | |
| exports.CustomDiffSync = CustomDiffSync | |
| test0 = (client, server, DocClass, Doc_equal, Doc_str) -> | |
| if DocClass? | |
| client.live = new DocClass("sage") | |
| server.live = new DocClass("my\nsage") | |
| else | |
| client.live = "sage" | |
| server.live = "my\nsage" | |
| if not Doc_equal? | |
| Doc_equal = (s,t) -> s==t | |
| if not Doc_str? | |
| Doc_str = (s) -> s | |
| status = () -> | |
| #console.log("------------------------") | |
| #console.log(misc.to_json(client.status())) | |
| #console.log(misc.to_json(server.status())) | |
| console.log("------------------------") | |
| console.log("'#{Doc_str(client.live)}'") | |
| console.log("'#{Doc_str(server.live)}'") | |
| pusher = undefined | |
| go = () -> | |
| if not pusher? | |
| console.log("SWITCH client/server") | |
| if Math.random() < .5 | |
| pusher = 'client' | |
| else | |
| pusher = 'server' | |
| if pusher == 'client' | |
| client.sync (err) -> | |
| if not err | |
| pusher = undefined | |
| if err.slice(0,5) == 'reset' | |
| throw err | |
| else | |
| server.push_edits (err) -> | |
| if not err | |
| pusher = undefined | |
| if err.slice(0,5) == 'reset' | |
| throw err | |
| go() | |
| if DocClass? | |
| client.live = new DocClass("bar more stuffklajsdf lasdjf lasdj flasdjf lasjdfljas dfaklsdjflkasjd flajsdflkjasdklfj\n" + misc.uuid()) | |
| server.live = new DocClass("bar lkajsdfllkjasdfl jasdlfj alsdkfjasdfjlkasdjflasjdfkljasdf\n" + misc.uuid()) | |
| else | |
| client.live += "more stuffklajsdf lasdjf lasdj flasdjf lasjdfljas dfaklsdjflkasjd flajsdflkjasdklfj\n" + misc.uuid() | |
| server.live = 'bar\n' + server.live + "lkajsdfllkjasdfl jasdlfj alsdkfjas'dfjlkasdjflasjdfkljasdf\n" + misc.uuid() | |
| status() | |
| while not Doc_equal(client.live, server.live) | |
| status() | |
| go() | |
| status() | |
| exports.test1 = () -> | |
| client = new DiffSync(doc:"sage", id:"client") | |
| server = new DiffSync(doc:"sage", id:"server") | |
| client.connect(server) | |
| server.connect(client) | |
| test0(client, server) | |
| exports.test2 = (n) -> | |
| for i in [0...n] | |
| exports.test1() | |
| exports.test3 = () -> | |
| client = new DiffSync(doc:"cat", id:"client") | |
| server = new DiffSync(doc:"cat", id:"server") | |
| client.connect(server) | |
| server.connect(client) | |
| client.live = "cats" | |
| server.live = "my\ncat" | |
| client.sync () => | |
| console.log(misc.to_json(client.status())) | |
| console.log(misc.to_json(server.status())) | |
| exports.test4 = (n=1) -> | |
| # Just use the standard dmp functions on strings again. | |
| copy = (s) -> s | |
| diff = (v0,v1) -> dmp.patch_make(v0,v1) | |
| patch = (d, doc) -> dmp.patch_apply(d, doc)[0] | |
| checksum = (s) -> s.length + 3 # +3 for luck | |
| DS = (id, doc) -> return new CustomDiffSync | |
| id : id | |
| doc : doc | |
| copy : copy | |
| diff : diff | |
| patch : patch | |
| checksum : checksum | |
| for i in [0...n] | |
| client = DS("client", "cat") | |
| server = DS("server", "cat") | |
| client.connect(server) | |
| server.connect(client) | |
| client.live = "cats" | |
| server.live = "my\ncat" | |
| client.sync () => | |
| console.log(misc.to_json(client.status())) | |
| console.log(misc.to_json(server.status())) | |
| test0(client, server) | |
| exports.test5 = (n=1) -> | |
| # | |
| # Make the documents a mutable version of strings (defined via a class) instead. | |
| # | |
| class Doc | |
| constructor: (@doc) -> | |
| if @doc.doc? | |
| console.log("tried to make Doc(Doc)") | |
| traceback() | |
| if @doc == '[object Object]' | |
| console.log("tried to make Doc from obvious mistake") | |
| traceback() | |
| if not @doc? | |
| console.log("tried to make Doc with undefined doc") | |
| traceback() # cause stack trace | |
| if not (typeof @doc == 'string') | |
| console.log("tried to make Doc from non-string '#{misc.to_json(@doc)}'") | |
| traceback() | |
| copy = (s) -> | |
| return new Doc(s.doc) | |
| diff = (v0,v1) -> | |
| return dmp.patch_make(v0.doc, v1.doc) | |
| patch = (d, doc) -> new Doc(dmp.patch_apply(d, doc.doc)[0]) | |
| checksum = (s) -> s.doc.length + 3 # +3 for luck | |
| patch_in_place = (d, s) -> s.doc = dmp.patch_apply(d, s.doc)[0] # modifies s.doc inside object | |
| DS = (id, doc) -> return new CustomDiffSync | |
| id : id | |
| doc : doc | |
| copy : copy | |
| diff : diff | |
| patch : patch | |
| patch_in_place : patch_in_place | |
| checksum : checksum | |
| for i in [0...n] | |
| client = DS("client", new Doc("cat")) | |
| server = DS("server", new Doc("cat")) | |
| client.connect(server) | |
| server.connect(client) | |
| client.live = new Doc("cats") | |
| server.live = new Doc("my\nbat") | |
| client.sync () => | |
| console.log(misc.to_json(client.status())) | |
| console.log(misc.to_json(server.status())) | |
| test0(client, server, Doc, ((s,t) -> s.doc ==t.doc), ((s) -> s.doc)) | |
| exports.test6 = (n=1) -> | |
| # | |
| # Do all diffs at a line level (could be used for a "list of worksheet cells", if followed by a post-processing to remove dups -- see below) | |
| # WARNING: ALL lines must end in \n | |
| # | |
| class Doc | |
| constructor: (@doc) -> | |
| if not (typeof @doc == 'string') | |
| console.log("tried to make Doc from non-string '#{misc.to_json(@doc)}'") | |
| traceback() | |
| copy = (s) -> | |
| return new Doc(s.doc) | |
| # See http://code.google.com/p/google-diff-match-patch/wiki/LineOrWordDiffs | |
| diff = (v0,v1) -> | |
| a = dmp.diff_linesToChars_(v0.doc, v1.doc) | |
| diffs = dmp.diff_main(a.chars1, a.chars2, false) | |
| dmp.diff_charsToLines_(diffs, a.lineArray) | |
| return dmp.patch_make(diffs) | |
| patch = (d, doc) -> new Doc(dmp.patch_apply(d, doc.doc)[0]) | |
| checksum = (s) -> s.doc.length + 3 # +3 for luck | |
| patch_in_place = (d, s) -> s.doc = dmp.patch_apply(d, s.doc)[0] # modifies s.doc inside object | |
| DS = (id, doc) -> return new CustomDiffSync | |
| id : id | |
| doc : doc | |
| copy : copy | |
| diff : diff | |
| patch : patch | |
| patch_in_place : patch_in_place | |
| checksum : checksum | |
| for i in [0...n] | |
| client = DS("client", new Doc("cat")) | |
| server = DS("server", new Doc("cat")) | |
| status = () -> | |
| console.log(client.live.doc) | |
| console.log("-----") | |
| console.log(server.live.doc) | |
| console.log("================") | |
| client.connect(server) | |
| server.connect(client) | |
| status() | |
| client.live = new Doc("cat\nwilliam\nb\nstein\n") | |
| server.live = new Doc("cats\nstein\na\nb\nwilliam\n") | |
| client.sync () => | |
| status() | |
| # test0(client, server, Doc, ((s,t) -> s.doc ==t.doc), ((s) -> s.doc)) | |
| exports.test7 = (n=1) -> | |
| # | |
| # Do all diffs at a line level then delete dup lines (could be used for a "list of worksheet cells") | |
| # WARNING: ALL lines must end in \n | |
| # | |
| dedup = (s) -> | |
| # delete duplicate lines | |
| v = s.split('\n') | |
| lines_so_far = {} | |
| w = [] | |
| for line in v | |
| if not lines_so_far[line]? | |
| w.push(line) | |
| lines_so_far[line] = true | |
| return w.join('\n') | |
| class Doc | |
| constructor: (@doc, dedup_doc) -> | |
| if not (typeof @doc == 'string') | |
| console.log("tried to make Doc from non-string '#{misc.to_json(@doc)}'") | |
| traceback() | |
| if dedup_doc? and dedup_doc | |
| @doc = dedup(@doc) | |
| copy = (s) -> | |
| return new Doc(s.doc, true) | |
| # See http://code.google.com/p/google-diff-match-patch/wiki/LineOrWordDiffs | |
| diff = (v0,v1) -> | |
| a = dmp.diff_linesToChars_(v0.doc, v1.doc) | |
| diffs = dmp.diff_main(a.chars1, a.chars2, false) | |
| dmp.diff_charsToLines_(diffs, a.lineArray) | |
| return dmp.patch_make(diffs) | |
| patch = (d, doc) -> | |
| new Doc(dmp.patch_apply(d, doc.doc)[0], true) | |
| checksum = (s) -> s.doc.length + 3 # +3 for luck | |
| patch_in_place = (d, s) -> | |
| s.doc = dedup(dmp.patch_apply(d, s.doc)[0]) # modifies s.doc inside object | |
| DS = (id, doc) -> return new CustomDiffSync | |
| id : id | |
| doc : doc | |
| copy : copy | |
| diff : diff | |
| patch : patch | |
| patch_in_place : patch_in_place | |
| checksum : checksum | |
| for i in [0...n] | |
| client = DS("client", new Doc("cat")) | |
| server = DS("server", new Doc("cat")) | |
| status = () -> | |
| console.log(client.live.doc) | |
| console.log("-----") | |
| console.log(server.live.doc) | |
| console.log("================") | |
| client.connect(server) | |
| server.connect(client) | |
| status() | |
| # This is like adding a cell at the beginning of both -- one gets added, the other deleted!? | |
| client.live = new Doc("laskdjf\ncat\ncat\nwilliam\nb\nstein\n") | |
| server.live = new Doc("1290384\ncat\ncats\nstein\na\nb\nwilliam\n") | |
| client.sync () => | |
| status() | |
| #test0(client, server, Doc, ((s,t) -> s.doc ==t.doc), ((s) -> s.doc)) | |
| exports.DiffSync = DiffSync | |
| #--------------------------------------------------------------------------------------------------------- | |
| # Support for using synchronized docs to represent Sage Worksheets (i.e., live compute documents) | |
| #--------------------------------------------------------------------------------------------------------- | |
| # WARNING: in Codemirror, to avoid issues with parsing I also set the output marker to be a comment character | |
| # by modifying the python mode as follows: if (ch == "#" || ch == "\uFE21") { | |
| exports.MARKERS = | |
| cell : "\uFE20" | |
| output : "\uFE21" | |
| exports.FLAGS = FLAGS = | |
| execute : "x" # request that cell be executed | |
| waiting : "w" # request to execute received, but still not running (because of another cell running) | |
| running : "r" # cell currently running | |
| interrupt : "c" # request execution of cell be interrupted | |
| this_session : "s" # if set, cell was executed during the current sage session. | |
| hide_input : "i" # hide input part of cell | |
| hide_output : "o" # hide output part of cell | |
| auto : "a" # if set, run the cell when the sage session first starts | |
| exports.ACTION_FLAGS = [FLAGS.execute, FLAGS.running, FLAGS.waiting, FLAGS.interrupt, FLAGS.this_session] | |
| # Return a list of the uuids of files that are displayed in the given document, | |
| # where doc is the string representation of a worksheet. | |
| # At present, this function finds all output messages of the form | |
| # {"file":{"uuid":"806f4f54-96c8-47f0-9af3-74b5d48d0a70",...}} | |
| # but it could do more at some point in the future. | |
| exports.uuids_of_linked_files = (doc) -> | |
| uuids = [] | |
| i = 0 | |
| while true | |
| i = doc.indexOf(exports.MARKERS.output, i) | |
| if i == -1 | |
| return uuids | |
| j = doc.indexOf('\n', i) | |
| if j == -1 | |
| j = doc.length | |
| line = doc.slice(i, j) | |
| for m in line.split(exports.MARKERS.output).slice(1) | |
| # Only bother to run the possibly slow JSON.parse on file messages; since | |
| # this function would block the global hub server, this is important. | |
| if m.slice(0,8) == '{"file":' | |
| mesg = JSON.parse(m) | |
| uuid = mesg.file?.uuid | |
| if uuid? | |
| uuids.push(uuid) | |
| i = j | |
| #--------------------------------------------------------------------------------------------------------- | |
| # Support for using a synchronized doc as a synchronized document database | |
| # storing one record per line in JSON. | |
| #--------------------------------------------------------------------------------------------------------- | |
| ### | |
| (c) William Stein, 2014 | |
| Synchronized document-oriented database, based on differential synchronization. | |
| NOTE: The API is sort of like <http://hood.ie/#docs>, though I found that *after* I wrote this. | |
| The main difference is my syncdb doesn't use a database, instead using a file, and also it | |
| doesn't use localStorage. HN discussion: <https://news.ycombinator.com/item?id=7767765> | |
| ### | |
| ### | |
| For now _doc -- in the constructor of SynchronizedDB | |
| has a different API than DiffSync objects above. | |
| The wrapper object below allows you to use a DiffSync | |
| object with this API. | |
| _doc._presync -- if set, is called before syncing | |
| _doc.on 'sync' -- event emitted on successful sync | |
| _doc.live() -- returns current live string | |
| _doc.live('new value') -- set current live string | |
| _doc.sync(cb) -- cause sync of _doc | |
| _doc.save(cb) -- cause save of _doc to persistent storage | |
| _doc.readonly -- true if and only if doc is readonly | |
| ### | |
| class exports.SynchronizedDB_DiffSyncWrapper extends EventEmitter | |
| constructor: (@doc) -> | |
| @doc.on 'sync', () => @emit('sync') | |
| sync: (cb) => | |
| @_presync?() | |
| @doc.sync(cb) | |
| live: (value) => | |
| if not value? | |
| return @doc.live | |
| else | |
| @doc.live = value | |
| save: (cb) => @doc.save(cb) | |
| class exports.SynchronizedDB extends EventEmitter | |
| constructor: (@_doc, @to_json, @from_json) -> | |
| if not @to_json? | |
| @to_json = misc.to_json | |
| if not @from_json? | |
| @from_json = misc.from_json | |
| @readonly = @_doc.readonly | |
| @_data = {} | |
| @_set_data_from_doc() | |
| @_doc._presync = () => | |
| @_live_before_sync = @_doc.live() | |
| @_doc.on('sync', @_on_sync) | |
| _on_sync: () => | |
| @emit('sync') | |
| #console.log("syncdb -- syncing") | |
| if not @_set_data_from_doc() and @_live_before_sync? | |
| #console.log("DEBUG: invalid/corrupt sync request; revert it") | |
| @_doc.live(@_live_before_sync) | |
| @_set_data_from_doc() | |
| @emit('presync') | |
| @_doc.sync() | |
| destroy: () => | |
| @_doc?.removeListener('sync', @_on_sync) | |
| @_doc?.disconnect_from_session() | |
| delete @_doc | |
| delete @_data | |
| # set the data object to equal what is defined in the syncdoc | |
| # | |
| _set_data_from_doc: () => | |
| # change/add anything that has changed or been added | |
| i = 0 | |
| hashes = {} | |
| changes = [] | |
| is_valid = true | |
| for x in @_doc.live().split('\n') | |
| if x.length > 0 | |
| h = hash_string(x) | |
| hashes[h] = true | |
| if not @_data[h]? | |
| try | |
| data = @from_json(x) | |
| catch | |
| # invalid/corrupted json -- still, we try out best | |
| # WE will revert this, unless it is on the initial load. | |
| data = {'corrupt':x} | |
| is_valid = false | |
| @_data[h] = {data:data, line:i} | |
| changes.push({insert:misc.deep_copy(data)}) | |
| i += 1 | |
| # delete anything that was deleted | |
| for h,v of @_data | |
| if not hashes[h]? | |
| changes.push({remove:v.data}) | |
| delete @_data[h] | |
| if changes.length > 0 | |
| @emit("change", changes) | |
| return is_valid | |
| _set_doc_from_data: (hash) => | |
| if hash? | |
| # only one line changed | |
| d = @_data[hash] | |
| v = @_doc.live().split('\n') | |
| v[d.line] = @to_json(d.data) | |
| else | |
| # major change to doc (e.g., deleting or adding records) | |
| m = [] | |
| for hash, x of @_data | |
| m[x.line] = {hash:hash, x:x} | |
| m = (x for x in m when x?) | |
| line = 0 | |
| v = [] | |
| for z in m | |
| if not z? | |
| continue | |
| z.x.line = line | |
| v.push(@to_json(z.x.data)) | |
| line += 1 | |
| @_doc.live(v.join('\n')) | |
| @emit('presync') | |
| @_doc.sync() | |
| save: (cb) => | |
| @sync (err) => | |
| if err | |
| setTimeout((()=>@save(cb)), 3000) | |
| else | |
| @_doc.save(cb) | |
| sync: (cb) => | |
| @_doc.sync(cb) | |
| # change (or create) exactly *one* database entry that matches the given where criterion. | |
| update: (opts) => | |
| opts = defaults opts, | |
| set : required | |
| where : required | |
| set = opts.set | |
| where = opts.where | |
| i = 0 | |
| for hash, val of @_data | |
| match = true | |
| x = val.data | |
| for k, v of where | |
| if x[k] != v | |
| match = false | |
| break | |
| if match | |
| for k, v of set | |
| x[k] = v | |
| @_set_doc_from_data(hash) | |
| return | |
| i += 1 | |
| new_obj = {} | |
| for k, v of set | |
| new_obj[k] = v | |
| for k, v of where | |
| new_obj[k] = v | |
| hash = hash_string(@to_json(new_obj)) | |
| @_data[hash] = {data:new_obj, line:len(@_data)} | |
| @_set_doc_from_data(hash) | |
| # return list of all database objects that match given condition. | |
| select: (opts={}) => | |
| {where} = defaults opts, | |
| where : {} | |
| result = [] | |
| for hash, val of @_data | |
| x = val.data | |
| match = true | |
| for k, v of where | |
| if x[k] != v | |
| match = false | |
| break | |
| if match | |
| result.push(x) | |
| return misc.deep_copy(result) | |
| # return first database objects that match given condition or undefined if there are no matches | |
| select_one: (opts={}) => | |
| {where} = defaults opts, | |
| where : {} | |
| for hash, val of @_data | |
| x = val.data | |
| match = true | |
| for k, v of where | |
| if x[k] != v | |
| match = false | |
| break | |
| if match | |
| return misc.deep_copy(x) | |
| # delete everything that matches the given criterion; returns number of deleted items | |
| delete: (opts) => | |
| {where, one} = defaults opts, | |
| where : required # give {} to delete everything ?! | |
| one : false | |
| result = [] | |
| i = 0 | |
| for hash, val of @_data | |
| x = val.data | |
| match = true | |
| for k, v of where | |
| if x[k] != v | |
| match = false | |
| break | |
| if match | |
| i += 1 | |
| delete @_data[hash] | |
| if one | |
| break | |
| @_set_doc_from_data() | |
| return i | |
| # delete first thing in db that matches the given criterion | |
| delete_one: (opts) => | |
| opts.one = true | |
| @delete(opts) | |
| # anything that couldn't be parsed from JSON as a map gets converted to {key:thing}. | |
| ensure_objects: (key) => | |
| changes = {} | |
| for h,v of @_data | |
| if typeof(v.data) != 'object' | |
| x = v.data | |
| v.data = {} | |
| v.data[key] = x | |
| h2 = hash_string(@to_json(v.data)) | |
| delete @_data[h] | |
| changes[h2] = v | |
| if misc.len(changes) > 0 | |
| for h, v of changes | |
| @_data[h] = v | |
| @_set_doc_from_data() | |
| # ensure that every db entry has a distinct uuid value for the given key | |
| ensure_uuid_primary_key: (key) => | |
| uuids = {} | |
| changes = {} | |
| for h,v of @_data | |
| if not v.data[key]? or uuids[v.data[key]] # not defined or seen before | |
| v.data[key] = misc.uuid() | |
| h2 = hash_string(@to_json(v.data)) | |
| delete @_data[h] | |
| changes[h2] = v | |
| uuids[v.data[key]] = true | |
| if misc.len(changes) > 0 | |
| for h, v of changes | |
| @_data[h] = v | |
| @_set_doc_from_data() | |
| # Here's what a patch looks like | |
| # | |
| # [{"diffs":[[1,"{\"x\":5,\"y\":3}"]],"start1":0,"start2":0,"length1":0,"length2":13},...] | |
| # | |
| exports.compress_patch = (patch) -> | |
| ([p.diffs, p.start1, p.start2, p.length1, p.length2] for p in patch) | |
| exports.decompress_patch = decompress_patch = (patch) -> | |
| ({diffs:p[0], start1:p[1], start2:p[2], length1:p[3], length2:p[4]} for p in patch) | |
| # this work on non-compressed patches as well. | |
| exports.decompress_patch_compat = (patch) -> | |
| if patch[0]?.diffs? | |
| patch | |
| else | |
| decompress_patch(patch) | |
| exports.invert_patch_in_place = (patch) -> | |
| # Beware of potential bugs in the following code -- I have only tried | |
| # it, not proved it correct. | |
| # I conjecture that this correctly computes the "inverse" of | |
| # a DMP patch, assuming the patch applies cleanly. -- Jonathan Lee | |
| if patch.length == 0 | |
| return patch | |
| for i in [0..patch.length-1] | |
| temp = patch[i].length1 | |
| patch[i].length1 = patch[i].length2 | |
| patch[i].length2 = temp | |
| for j in [0..patch[i].diffs.length-1] | |
| patch[i].diffs[j][0] = -patch[i].diffs[j][0] | |
| patch = patch.reverse() | |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment