Merge branch 'master' into sk-upgrade-metrics

services/track-changes/app/coffee/DiffGenerator.coffee

@@ -18,7 +18,7 @@ module.exports = DiffGenerator =
 				if e instanceof ConsistencyError and i = update.op.length - 1
 					# catch known case where the last op in an array has been
 					# merged into a later op
-					logger.error {update, op: JSON.stringify(op)}, "marking op as broken"
+					logger.error {err: e, update, op: JSON.stringify(op)}, "marking op as broken"
 					op.broken = true
 				else
 					throw e # rethrow the execption
@@ -47,6 +47,9 @@ module.exports = DiffGenerator =
 
 		else if op.d?
 			return content.slice(0, op.p) + op.d + content.slice(op.p)
+		
+		else
+			return content
 
 	rewindUpdates: (content, updates) ->
 		for update in updates.reverse()

services/track-changes/app/coffee/DiffManager.coffee

@@ -5,8 +5,8 @@ logger = require "logger-sharelatex"
 
 module.exports = DiffManager =
 	getLatestDocAndUpdates: (project_id, doc_id, fromVersion, toVersion, callback = (error, content, version, updates) ->) ->
-		# retrieve the document before retreiving the updates,
+		# Get updates last, since then they must be ahead and it
-		# because updates are written to mongo after the document
+		# might be possible to rewind to the same version as the doc.
 		DocumentUpdaterManager.getDocument project_id, doc_id, (error, content, version) ->
 			return callback(error) if error?
 			UpdatesManager.getDocUpdatesWithUserInfo project_id, doc_id, from: fromVersion, to: toVersion, (error, updates) ->
@@ -33,7 +33,28 @@ module.exports = DiffManager =
 			
 			callback(null, diff)
 
-	getDocumentBeforeVersion: (project_id, doc_id, version, callback = (error, document, rewoundUpdates) ->) ->
+	getDocumentBeforeVersion: (project_id, doc_id, version, _callback = (error, document, rewoundUpdates) ->) ->
+		# Whichever order we get the latest document and the latest updates,
+		# there is potential for updates to be applied between them so that
+		# they do not return the same 'latest' versions.
+		# If this happens, we just retry and hopefully get them at the compatible
+		# versions.
+		retries = 3
+		callback = (error, args...) ->
+			if error?
+				if error.retry and retries > 0
+					logger.warn {error, project_id, doc_id, version, retries}, "retrying getDocumentBeforeVersion"
+					retry()
+				else
+					_callback(error)
+			else
+				_callback(null, args...)
+
+		do retry = () ->
+			retries--
+			DiffManager._tryGetDocumentBeforeVersion(project_id, doc_id, version, callback)
+
+	_tryGetDocumentBeforeVersion: (project_id, doc_id, version, callback = (error, document, rewoundUpdates) ->) ->
 		logger.log project_id: project_id, doc_id: doc_id, version: version, "getting document before version"
 		DiffManager.getLatestDocAndUpdates project_id, doc_id, version, null, (error, content, version, updates) ->
 			return callback(error) if error?
@@ -48,7 +69,11 @@ module.exports = DiffManager =
 
 			lastUpdate = updates[0]
 			if lastUpdate? and lastUpdate.v != version - 1
-				return callback new Error("latest update version, #{lastUpdate.v}, does not match doc version, #{version}")
+				error = new Error("latest update version, #{lastUpdate.v}, does not match doc version, #{version}")
+				error.retry = true
+				return callback error
+			
+			logger.log {docVersion: version, lastUpdateVersion: lastUpdate?.v, updateCount: updates.length}, "rewinding updates"
 
 			tryUpdates = updates.slice().reverse()
 

services/track-changes/app/coffee/DocumentUpdaterManager.coffee

@@ -14,6 +14,7 @@ module.exports = DocumentUpdaterManager =
 					body = JSON.parse(body)
 				catch error
 					return callback(error)
+				logger.log {project_id, doc_id, version: body.version}, "got doc from document updater"
 				callback null, body.lines.join("\n"), body.version
 			else
 				error = new Error("doc updater returned a non-success status code: #{res.statusCode}")

services/track-changes/app/coffee/MongoManager.coffee

@@ -82,7 +82,7 @@ module.exports = MongoManager =
 		# For finding all updates that go into a diff for a doc
 		db.docHistory.ensureIndex { doc_id: 1, v: 1 }, { background: true }
 		# For finding all updates that affect a project
-		db.docHistory.ensureIndex { project_id: 1, "meta.end_ts": 1, "meta.start_ts": -1 }, { background: true }
+		db.docHistory.ensureIndex { project_id: 1, "meta.end_ts": 1 }, { background: true }
 		# For finding updates that don't yet have a project_id and need it inserting
 		db.docHistory.ensureIndex { doc_id: 1, project_id: 1 }, { background: true }
 		# For finding project meta-data

services/track-changes/app/coffee/PackManager.coffee

@@ -530,3 +530,9 @@ module.exports = PackManager =
 		}, (err) ->
 			logger.log {project_id, doc_id, pack_id}, "set expiry on pack"
 			callback()
+
+
+#	_getOneDayInFutureWithRandomDelay: ->
+#		thirtyMins = 1000 * 60 * 30
+#		randomThirtyMinMax = Math.ceil(Math.random() * thirtyMins)
+#		return new Date(Date.now() + randomThirtyMinMax + 1*DAYS)

services/track-changes/app/coffee/UpdateCompressor.coffee

@@ -1,6 +1,9 @@
 strInject = (s1, pos, s2) -> s1[...pos] + s2 + s1[pos..]
 strRemove = (s1, pos, length) -> s1[...pos] + s1[(pos + length)..]
 
+diff_match_patch = require("../lib/diff_match_patch").diff_match_patch
+dmp = new diff_match_patch()
+
 module.exports = UpdateCompressor =
 	NOOP: "noop"
 
@@ -21,7 +24,9 @@ module.exports = UpdateCompressor =
 	convertToSingleOpUpdates: (updates) ->
 		splitUpdates = []
 		for update in updates
-			if update.op.length == 0
+			# Reject any non-insert or delete ops, i.e. comments
+			ops = update.op.filter (o) -> o.i? or o.d?
+			if ops.length == 0
 				splitUpdates.push
 					op: UpdateCompressor.NOOP
 					meta:
@@ -30,7 +35,7 @@ module.exports = UpdateCompressor =
 						user_id:  update.meta.user_id
 					v: update.v
 			else
-				for op in update.op
+				for op in ops
 					splitUpdates.push
 						op: op
 						meta:
@@ -155,6 +160,59 @@ module.exports = UpdateCompressor =
 				# This will only happen if the delete extends outside the insert
 				return [firstUpdate, secondUpdate]
 
+		# A delete then an insert at the same place, likely a copy-paste of a chunk of content
+		else if firstOp.d? and secondOp.i? and firstOp.p == secondOp.p
+			offset = firstOp.p
+			diff_ops = @diffAsShareJsOps(firstOp.d, secondOp.i)
+			if diff_ops.length == 0
+				return [{ # Noop
+					meta:
+						start_ts: firstUpdate.meta.start_ts
+						end_ts:   secondUpdate.meta.end_ts
+						user_id:  firstUpdate.meta.user_id
+					op:
+						p: firstOp.p
+						i: ""
+					v: secondUpdate.v
+				}]
+			else
+				return diff_ops.map (op) ->
+					op.p += offset
+					return {
+						meta:
+							start_ts: firstUpdate.meta.start_ts
+							end_ts:   secondUpdate.meta.end_ts
+							user_id:  firstUpdate.meta.user_id
+						op: op
+						v: secondUpdate.v
+					}
+
 		else
 			return [firstUpdate, secondUpdate]
 
+	ADDED: 1
+	REMOVED: -1
+	UNCHANGED: 0
+	diffAsShareJsOps: (before, after, callback = (error, ops) ->) ->
+		diffs = dmp.diff_main(before, after)
+		dmp.diff_cleanupSemantic(diffs)
+
+		ops = []
+		position = 0
+		for diff in diffs
+			type = diff[0]
+			content = diff[1]
+			if type == @ADDED
+				ops.push
+					i: content
+					p: position
+				position += content.length
+			else if type == @REMOVED
+				ops.push
+					d: content
+					p: position
+			else if type == @UNCHANGED
+				position += content.length
+			else
+				throw "Unknown type"
+		return ops

services/track-changes/app/coffee/UpdatesManager.coffee

@@ -219,11 +219,35 @@ module.exports = UpdatesManager =
 			return !!user_id.match(/^[a-f0-9]{24}$/)
 
 	TIME_BETWEEN_DISTINCT_UPDATES: fiveMinutes = 5 * 60 * 1000
+	SPLIT_ON_DELETE_SIZE: 16 # characters
 	_summarizeUpdates: (updates, existingSummarizedUpdates = []) ->
 		summarizedUpdates = existingSummarizedUpdates.slice()
+		previousUpdateWasBigDelete = false
 		for update in updates
 			earliestUpdate = summarizedUpdates[summarizedUpdates.length - 1]
-			if earliestUpdate and earliestUpdate.meta.start_ts - update.meta.end_ts < @TIME_BETWEEN_DISTINCT_UPDATES
+			shouldConcat = false
+
+			# If a user inserts some text, then deletes a big chunk including that text,
+			# the update we show might concat the insert and delete, and there will be no sign
+			# of that insert having happened, or be able to restore to it (restoring after a big delete is common).
+			# So, we split the summary on 'big' deletes. However, we've stepping backwards in time with
+			# most recent changes considered first, so if this update is a big delete, we want to start
+			# a new summarized update next timge, hence we monitor the previous update.
+			if previousUpdateWasBigDelete
+				shouldConcat = false
+			else if earliestUpdate and earliestUpdate.meta.end_ts - update.meta.start_ts < @TIME_BETWEEN_DISTINCT_UPDATES
+				# We're going backwards in time through the updates, so only combine if this update starts less than 5 minutes before
+				# the end of current summarized block, so no block spans more than 5 minutes.
+				shouldConcat = true
+
+			isBigDelete = false
+			for op in update.op or []
+				if op.d? and op.d.length > @SPLIT_ON_DELETE_SIZE
+					isBigDelete = true
+
+			previousUpdateWasBigDelete = isBigDelete
+
+			if shouldConcat
 				# check if the user in this update is already present in the earliest update,
 				# if not, add them to the users list of the earliest update
 				earliestUpdate.meta.user_ids = _.union earliestUpdate.meta.user_ids, [update.meta.user_id]

services/track-changes/test/acceptance/coffee/AppendingUpdatesTests.coffee

@@ -233,6 +233,28 @@ describe "Appending doc ops to the history", ->
 			expect(@updates[0].pack[0].v).to.equal 3
 			expect(@updates[0].pack[1].v).to.equal 4
 
+	describe "when there is a comment update", ->
+		before (done) ->
+			@project_id = ObjectId().toString()
+			@doc_id = ObjectId().toString()
+			@user_id = ObjectId().toString()
+			MockWebApi.projects[@project_id] = features: versioning: false
+			TrackChangesClient.pushRawUpdates @project_id, @doc_id, [{
+				op: [{ c: "foo", p: 3 }, {d: "bar", p: 6}]
+				meta: { ts: Date.now(), user_id: @user_id }
+				v: 3
+			}], (error) =>
+				throw error if error?
+				TrackChangesClient.flushAndGetCompressedUpdates @project_id, @doc_id, (error, @updates) =>
+					throw error if error?
+					done()
+
+		it "should ignore the comment op", ->
+			expect(@updates[0].pack[0].op).to.deep.equal [{d: "bar", p: 6}]
+
+		it "should insert the correct version numbers into mongo", ->
+			expect(@updates[0].pack[0].v).to.equal 3
+
 	describe "when the project has versioning enabled", ->
 		before (done) ->
 			@project_id = ObjectId().toString()

services/track-changes/test/unit/coffee/DiffManager/DiffManagerTests.coffee

@@ -8,7 +8,7 @@ SandboxedModule = require('sandboxed-module')
 describe "DiffManager", ->
 	beforeEach ->
 		@DiffManager = SandboxedModule.require modulePath, requires:
-			"logger-sharelatex": @logger = { log: sinon.stub(), error: sinon.stub() }
+			"logger-sharelatex": @logger = { log: sinon.stub(), error: sinon.stub(), warn: sinon.stub() }
 			"./UpdatesManager": @UpdatesManager = {}
 			"./DocumentUpdaterManager": @DocumentUpdaterManager = {}
 			"./DiffGenerator": @DiffGenerator = {}
@@ -90,6 +90,76 @@ describe "DiffManager", ->
 					.should.equal true
 
 	describe "getDocumentBeforeVersion", ->
+		beforeEach ->
+			@DiffManager._tryGetDocumentBeforeVersion = sinon.stub()
+			@document = "mock-documents"
+			@rewound_updates = "mock-rewound-updates"
+
+		describe "succesfully", ->
+			beforeEach ->
+				@DiffManager._tryGetDocumentBeforeVersion.yields(null, @document, @rewound_updates)
+				@DiffManager.getDocumentBeforeVersion @project_id, @doc_id, @version, @callback
+			
+			it "should call _tryGetDocumentBeforeVersion", ->
+				@DiffManager._tryGetDocumentBeforeVersion
+					.calledWith(@project_id, @doc_id, @version)
+					.should.equal true
+			
+			it "should call the callback with the response", ->
+				@callback.calledWith(null, @document, @rewound_updates).should.equal true
+		
+		describe "with a retry needed", ->
+			beforeEach ->
+				retried = false
+				@DiffManager._tryGetDocumentBeforeVersion = (project_id, doc_id, version, callback) =>
+					if !retried
+						retried = true
+						error = new Error()
+						error.retry = true
+						callback error
+					else
+						callback(null, @document, @rewound_updates)
+				sinon.spy @DiffManager, "_tryGetDocumentBeforeVersion"
+				@DiffManager.getDocumentBeforeVersion @project_id, @doc_id, @version, @callback
+			
+			it "should call _tryGetDocumentBeforeVersion twice", ->
+				@DiffManager._tryGetDocumentBeforeVersion
+					.calledTwice
+					.should.equal true
+			
+			it "should call the callback with the response", ->
+				@callback.calledWith(null, @document, @rewound_updates).should.equal true
+		
+		describe "with a non-retriable error", ->
+			beforeEach ->
+				@error = new Error("oops")
+				@DiffManager._tryGetDocumentBeforeVersion.yields(@error)
+				@DiffManager.getDocumentBeforeVersion @project_id, @doc_id, @version, @callback
+			
+			it "should call _tryGetDocumentBeforeVersion once", ->
+				@DiffManager._tryGetDocumentBeforeVersion
+					.calledOnce
+					.should.equal true
+			
+			it "should call the callback with the error", ->
+				@callback.calledWith(@error).should.equal true
+		
+		describe "when retry limit is matched", ->
+			beforeEach ->
+				@error = new Error("oops")
+				@error.retry = true
+				@DiffManager._tryGetDocumentBeforeVersion.yields(@error)
+				@DiffManager.getDocumentBeforeVersion @project_id, @doc_id, @version, @callback
+			
+			it "should call _tryGetDocumentBeforeVersion three times (max retries)", ->
+				@DiffManager._tryGetDocumentBeforeVersion
+					.calledThrice
+					.should.equal true
+			
+			it "should call the callback with the error", ->
+				@callback.calledWith(@error).should.equal true
+
+	describe "_tryGetDocumentBeforeVersion", ->
 		beforeEach ->
 			@content = "hello world"
 			# Op versions are the version they were applied to, so doc is always one version
@@ -113,7 +183,7 @@ describe "DiffManager", ->
 					updates.reverse()
 					return @rewound_content
 				@rewindUpdatesWithArgs = @DiffGenerator.rewindUpdates.withArgs(@content, @updates.slice().reverse())
-				@DiffManager.getDocumentBeforeVersion @project_id, @doc_id, @fromVersion, @callback
+				@DiffManager._tryGetDocumentBeforeVersion @project_id, @doc_id, @fromVersion, @callback
 
 			it "should get the latest doc and version with all recent updates", ->
 				@DiffManager.getLatestDocAndUpdates
@@ -131,12 +201,12 @@ describe "DiffManager", ->
 				@version = 50
 				@updates = [ { op: "mock-1", v: 40 }, { op: "mock-1", v: 39 } ]
 				@DiffManager.getLatestDocAndUpdates = sinon.stub().callsArgWith(4, null, @content, @version, @updates)
-				@DiffManager.getDocumentBeforeVersion @project_id, @doc_id, @fromVersion, @callback
+				@DiffManager._tryGetDocumentBeforeVersion @project_id, @doc_id, @fromVersion, @callback
 
-			it "should call the callback with an error", ->
+			it "should call the callback with an error with retry = true set", ->
-				@callback
+				@callback.calledOnce.should.equal true
-					.calledWith(new Error("latest update version, 40, does not match doc version, 42"))
+				error = @callback.args[0][0]
-					.should.equal true
+				expect(error.retry).to.equal true
 
 		describe "when the updates are inconsistent", ->
 			beforeEach ->

services/track-changes/test/unit/coffee/PackManager/PackManagerTests.coffee

@@ -25,7 +25,6 @@ describe "PackManager", ->
 		@project_id = ObjectId().toString()
 		@PackManager.MAX_COUNT = 512
 
-
 	afterEach ->
 		tk.reset()
 
@@ -334,3 +333,33 @@ describe "PackManager", ->
 				@callback.called.should.equal true
 			it "should return with no error", ->
 				@callback.calledWith(undefined).should.equal true
+
+	# describe "setTTLOnArchivedPack", ->
+	# 	beforeEach ->
+	# 		@pack_id = "somepackid"
+	# 		@onedayinms = 86400000
+	# 		@db.docHistory =
+	# 			findAndModify : sinon.stub().callsArgWith(1)
+
+	# 	it "should set expires to 1 day", (done)->
+	# 		#@PackManager._getOneDayInFutureWithRandomDelay = sinon.stub().returns(@onedayinms)
+	# 		@PackManager.setTTLOnArchivedPack @project_id, @doc_id, @pack_id, =>
+	# 			args = @db.docHistory.findAndModify.args[0][0]
+	# 			args.query._id.should.equal @pack_id
+	# 			args.update['$set'].expiresAt.should.equal @onedayinms
+	# 			done()
+
+
+	# describe "_getOneDayInFutureWithRandomDelay", ->
+	# 	beforeEach ->
+	# 		@onedayinms = 86400000
+	# 		@thirtyMins = 1000 * 60 * 30
+
+	# 	it "should give 1 day + 30 mins random time", (done)->
+	# 		loops = 10000
+	# 		while --loops > 0
+	# 			randomDelay = @PackManager._getOneDayInFutureWithRandomDelay() - new Date(Date.now() + @onedayinms)
+	# 			randomDelay.should.be.above(0)
+	# 			randomDelay.should.be.below(@thirtyMins + 1)
+	# 		done()
+

services/track-changes/test/unit/coffee/UpdateCompressor/UpdateCompressorTests.coffee

@@ -5,13 +5,15 @@ expect = chai.expect
 modulePath = "../../../../app/js/UpdateCompressor.js"
 SandboxedModule = require('sandboxed-module')
 
+bigstring = ("a" for [0 .. 2*1024*1024]).join("")
+mediumstring = ("a" for [0 .. 1024*1024]).join("")
+
 describe "UpdateCompressor", ->
 	beforeEach ->
-		@UpdateCompressor = SandboxedModule.require modulePath
+		@UpdateCompressor = SandboxedModule.require modulePath, requires:
+			"../lib/diff_match_patch": require("../../../../app/lib/diff_match_patch")
 		@user_id = "user-id-1"
 		@other_user_id = "user-id-2"
-		@bigstring = ("a" for [0 .. 2*1024*1024]).join("")
-		@mediumstring = ("a" for [0 .. 1024*1024]).join("")
 		@ts1 = Date.now()
 		@ts2 = Date.now() + 1000
 
@@ -52,6 +54,22 @@ describe "UpdateCompressor", ->
 				v: 42
 			}]
 
+		it "should ignore comment ops", ->
+			expect(@UpdateCompressor.convertToSingleOpUpdates [{
+				op:   [ @op1 = { p: 0, i: "Foo" }, @op2 = { p: 9, c: "baz"}, @op3 = { p: 6, i: "bar"} ]
+				meta: { ts: @ts1, user_id: @user_id }
+				v: 42
+			}])
+			.to.deep.equal [{
+				op: @op1,
+				meta: { start_ts: @ts1, end_ts: @ts1, user_id: @user_id },
+				v: 42
+			}, {
+				op: @op3,
+				meta: { start_ts: @ts1, end_ts: @ts1, user_id: @user_id },
+				v: 42
+			}]
+
 	describe "concatUpdatesWithSameVersion", ->
 		it "should concat updates with the same version", ->
 			expect(@UpdateCompressor.concatUpdatesWithSameVersion [{
@@ -149,7 +167,7 @@ describe "UpdateCompressor", ->
 					meta: ts: @ts1, user_id: @user_id
 					v: 42
 				}, {
-					op: { p: 6, i: @bigstring }
+					op: { p: 6, i: bigstring }
 					meta: ts: @ts2, user_id: @user_id
 					v: 43
 				}])
@@ -158,47 +176,47 @@ describe "UpdateCompressor", ->
 					meta: start_ts: @ts1, end_ts: @ts1, user_id: @user_id
 					v: 42
 				}, {
-					op: { p: 6, i: @bigstring }
+					op: { p: 6, i: bigstring }
 					meta: start_ts: @ts2, end_ts: @ts2, user_id: @user_id
 					v: 43
 				}]
 
 			it "should not append inserts that are too big (first op)", ->
 				expect(@UpdateCompressor.compressUpdates [{
-					op: { p: 3, i: @bigstring }
+					op: { p: 3, i: bigstring }
 					meta: ts: @ts1, user_id: @user_id
 					v: 42
 				}, {
-					op: { p: 3 + @bigstring.length, i: "bar" }
+					op: { p: 3 + bigstring.length, i: "bar" }
 					meta: ts: @ts2, user_id: @user_id
 					v: 43
 				}])
 				.to.deep.equal [{
-					op: { p: 3, i: @bigstring }
+					op: { p: 3, i: bigstring }
 					meta: start_ts: @ts1, end_ts: @ts1, user_id: @user_id
 					v: 42
 				}, {
-					op: { p: 3 + @bigstring.length, i: "bar" }
+					op: { p: 3 + bigstring.length, i: "bar" }
 					meta: start_ts: @ts2, end_ts: @ts2, user_id: @user_id
 					v: 43
 				}]
 
 			it "should not append inserts that are too big (first and second op)", ->
 				expect(@UpdateCompressor.compressUpdates [{
-					op: { p: 3, i: @mediumstring }
+					op: { p: 3, i: mediumstring }
 					meta: ts: @ts1, user_id: @user_id
 					v: 42
 				}, {
-					op: { p: 3 + @mediumstring.length, i: @mediumstring }
+					op: { p: 3 + mediumstring.length, i: mediumstring }
 					meta: ts: @ts2, user_id: @user_id
 					v: 43
 				}])
 				.to.deep.equal [{
-					op: { p: 3, i: @mediumstring }
+					op: { p: 3, i: mediumstring }
 					meta: start_ts: @ts1, end_ts: @ts1, user_id: @user_id
 					v: 42
 				}, {
-					op: { p: 3 + @mediumstring.length, i: @mediumstring }
+					op: { p: 3 + mediumstring.length, i: mediumstring }
 					meta: start_ts: @ts2, end_ts: @ts2, user_id: @user_id
 					v: 43
 				}]
@@ -345,6 +363,43 @@ describe "UpdateCompressor", ->
 					meta: start_ts: @ts2, end_ts: @ts2, user_id: @user_id
 					v: 43
 				}]
+		
+		describe "delete - insert", ->
+			it "should do a diff of the content", ->
+				expect(@UpdateCompressor.compressUpdates [{
+					op: { p: 3, d: "one two three four five six seven eight" }
+					meta: ts: @ts1, user_id: @user_id
+					v: 42
+				}, {
+					op: { p: 3, i: "one 2 three four five six seven eight" }
+					meta: ts: @ts2, user_id: @user_id
+					v: 43
+				}])
+				.to.deep.equal [{
+					op: { p: 7, d: "two" }
+					meta: start_ts: @ts1, end_ts: @ts2, user_id: @user_id
+					v: 43
+				}, {
+					op: { p: 7, i: "2" }
+					meta: start_ts: @ts1, end_ts: @ts2, user_id: @user_id
+					v: 43
+				}]
+			
+			it "should return a no-op if the delete and insert are the same", ->
+				expect(@UpdateCompressor.compressUpdates [{
+					op: { p: 3, d: "one two three four five six seven eight" }
+					meta: ts: @ts1, user_id: @user_id
+					v: 42
+				}, {
+					op: { p: 3, i: "one two three four five six seven eight" }
+					meta: ts: @ts2, user_id: @user_id
+					v: 43
+				}])
+				.to.deep.equal [{
+					op: { p: 3, i: "" }
+					meta: start_ts: @ts1, end_ts: @ts2, user_id: @user_id
+					v: 43
+				}]
 
 		describe "noop - insert", ->
 			it "should leave them untouched", ->

services/track-changes/test/unit/coffee/UpdatesManager/UpdatesManagerTests.coffee

@@ -761,3 +761,41 @@ describe "UpdatesManager", ->
 					start_ts: @now
 					end_ts:   @now + 30
 			}]
+
+		it "should split updates before a big delete", ->
+			result = @UpdatesManager._summarizeUpdates [{
+				doc_id: "doc-id-1"
+				op: [{ d: "this is a long long long long long delete", p: 34 }]
+				meta:
+					user_id: @user_1.id
+					start_ts: @now + 20
+					end_ts:   @now + 30
+				v: 5
+			}, {
+				doc_id: "doc-id-1"
+				meta:
+					user_id: @user_2.id
+					start_ts: @now
+					end_ts:   @now + 10
+				v: 4
+			}]
+
+			expect(result).to.deep.equal [{
+				docs:
+					"doc-id-1":
+						fromV: 5
+						toV: 5
+				meta:
+					user_ids: [@user_1.id]
+					start_ts: @now + 20
+					end_ts:   @now + 30
+			}, {
+				docs:
+					"doc-id-1":
+						fromV: 4
+						toV: 4
+				meta:
+					user_ids: [@user_2.id]
+					start_ts: @now
+					end_ts:   @now + 10
+			}]