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

/*
 * decaffeinate suggestions:
 * DS101: Remove unnecessary use of Array.from
 * DS102: Remove unnecessary code created because of implicit returns
 * DS205: Consider reworking code to avoid use of IIFEs
 * DS207: Consider shorter variations of null checks
 * Full docs: https://github.com/decaffeinate/decaffeinate/blob/master/docs/suggestions.md
 */
let PackManager;
const async = require("async");
const _ = require("underscore");
const {db, ObjectId, BSON} = require("./mongojs");
const logger = require("logger-sharelatex");
const LockManager = require("./LockManager");
const MongoAWS = require("./MongoAWS");
const Metrics = require("metrics-sharelatex");
const ProjectIterator = require("./ProjectIterator");
const Settings = require("settings-sharelatex");
const keys = Settings.redis.lock.key_schema;

// Sharejs operations are stored in a 'pack' object
//
//  e.g.  a single sharejs update looks like
//
//   {
//     "doc_id" : 549dae9e0a2a615c0c7f0c98,
//     "project_id" : 549dae9c0a2a615c0c7f0c8c,
//     "op" : [ {"p" : 6981,	"d" : "?"	} ],
//     "meta" : {	"user_id" : 52933..., "start_ts" : 1422310693931,	"end_ts" : 1422310693931 },
//     "v" : 17082
//   }
//
//  and a pack looks like this
//
//   {
//     "doc_id" : 549dae9e0a2a615c0c7f0c98,
//     "project_id" : 549dae9c0a2a615c0c7f0c8c,
//     "pack" : [ U1, U2, U3, ...., UN],
//     "meta" : {	"user_id" : 52933..., "start_ts" : 1422310693931,	"end_ts" : 1422310693931 },
//     "v" : 17082
//     "v_end" : ...
//   }
//
//  where U1, U2, U3, .... are single updates stripped of their
//  doc_id and project_id fields (which are the same for all the
//  updates in the pack).
//
//  The pack itself has v and meta fields, this makes it possible to
//  treat packs and single updates in a similar way.
//
//  The v field of the pack itself is from the first entry U1, the
//  v_end field from UN.  The meta.end_ts field of the pack itself is
//  from the last entry UN, the meta.start_ts field from U1.

const DAYS = 24 * 3600 * 1000; // one day in milliseconds

module.exports = (PackManager = {

	MAX_SIZE:  1024*1024, // make these configurable parameters
	MAX_COUNT: 1024,

	insertCompressedUpdates(project_id, doc_id, lastUpdate, newUpdates, temporary, callback) {
		if (callback == null) { callback = function(error) {}; }
		if (newUpdates.length === 0) { return callback(); }

		// never append permanent ops to a pack that will expire
		if (((lastUpdate != null ? lastUpdate.expiresAt : undefined) != null) && !temporary) { lastUpdate = null; }

		const updatesToFlush = [];
		const updatesRemaining = newUpdates.slice();

		let n = (lastUpdate != null ? lastUpdate.n : undefined) || 0;
		let sz = (lastUpdate != null ? lastUpdate.sz : undefined) || 0;

		while (updatesRemaining.length && (n < PackManager.MAX_COUNT) && (sz < PackManager.MAX_SIZE)) {
			const nextUpdate = updatesRemaining[0];
			const nextUpdateSize = BSON.calculateObjectSize(nextUpdate);
			if (((nextUpdateSize + sz) > PackManager.MAX_SIZE) && (n > 0)) {
				break;
			}
			n++;
			sz += nextUpdateSize;
			updatesToFlush.push(updatesRemaining.shift());
		}

		return PackManager.flushCompressedUpdates(project_id, doc_id, lastUpdate, updatesToFlush, temporary, function(error) {
			if (error != null) { return callback(error); }
			return PackManager.insertCompressedUpdates(project_id, doc_id, null, updatesRemaining, temporary, callback);
		});
	},

	flushCompressedUpdates(project_id, doc_id, lastUpdate, newUpdates, temporary, callback) {
		if (callback == null) { callback = function(error) {}; }
		if (newUpdates.length === 0) { return callback(); }

		let canAppend = false;
		// check if it is safe to append to an existing pack
		if (lastUpdate != null) {
			if (!temporary && (lastUpdate.expiresAt == null)) {
				// permanent pack appends to permanent pack
				canAppend = true;
			}
			const age = Date.now() - (lastUpdate.meta != null ? lastUpdate.meta.start_ts : undefined);
			if (temporary && (lastUpdate.expiresAt != null) && (age < (1 * DAYS))) {
				// temporary pack appends to temporary pack if same day
				canAppend = true;
			}
		}

		if (canAppend) {
			return PackManager.appendUpdatesToExistingPack(project_id, doc_id, lastUpdate, newUpdates, temporary, callback);
		} else {
			return PackManager.insertUpdatesIntoNewPack(project_id, doc_id, newUpdates, temporary, callback);
		}
	},

	insertUpdatesIntoNewPack(project_id, doc_id, newUpdates, temporary, callback) {
		if (callback == null) { callback = function(error) {}; }
		const first = newUpdates[0];
		const last = newUpdates[newUpdates.length - 1];
		const n = newUpdates.length;
		const sz = BSON.calculateObjectSize(newUpdates);
		const newPack = {
			project_id: ObjectId(project_id.toString()),
			doc_id: ObjectId(doc_id.toString()),
			pack: newUpdates,
			n,
			sz,
			meta: {
				start_ts: first.meta.start_ts,
				end_ts: last.meta.end_ts
			},
			v: first.v,
			v_end: last.v,
			temporary
		};
		if (temporary) {
			newPack.expiresAt = new Date(Date.now() + (7 * DAYS));
			newPack.last_checked = new Date(Date.now() + (30 * DAYS)); // never check temporary packs
		}
		logger.log({project_id, doc_id, newUpdates}, "inserting updates into new pack");
		return db.docHistory.save(newPack, function(err, result) {
			if (err != null) { return callback(err); }
			Metrics.inc(`insert-pack-${temporary ? "temporary" : "permanent"}`);
			if (temporary) {
				return callback();
			} else {
				return PackManager.updateIndex(project_id, doc_id, callback);
			}
		});
	},

	appendUpdatesToExistingPack(project_id, doc_id, lastUpdate, newUpdates, temporary, callback) {
		if (callback == null) { callback = function(error) {}; }
		const first = newUpdates[0];
		const last = newUpdates[newUpdates.length - 1];
		const n = newUpdates.length;
		const sz = BSON.calculateObjectSize(newUpdates);
		const query = {
			_id: lastUpdate._id,
			project_id: ObjectId(project_id.toString()),
			doc_id: ObjectId(doc_id.toString()),
			pack: {$exists: true}
		};
		const update = {
			$push: {
				"pack": {$each: newUpdates}
			},
			$inc: {
				"n": n,
				"sz":  sz
			},
			$set: {
				"meta.end_ts": last.meta.end_ts,
				"v_end": last.v
			}
		};
		if (lastUpdate.expiresAt && temporary) {
			update.$set.expiresAt = new Date(Date.now() + (7 * DAYS));
		}
		logger.log({project_id, doc_id, lastUpdate, newUpdates}, "appending updates to existing pack");
		Metrics.inc(`append-pack-${temporary ? "temporary" : "permanent"}`);
		return db.docHistory.findAndModify({query, update,	new:true, fields:{meta:1,v_end:1}}, callback);
	},

	// Retrieve all changes for a document

	getOpsByVersionRange(project_id, doc_id, fromVersion, toVersion, callback) {
		if (callback == null) { callback = function(error, updates) {}; }
		return PackManager.loadPacksByVersionRange(project_id, doc_id, fromVersion, toVersion, function(error) {
			const query = {doc_id:ObjectId(doc_id.toString())};
			if (toVersion != null) { query.v = {$lte:toVersion}; }
			if (fromVersion != null) { query.v_end = {$gte:fromVersion}; }
			//console.log "query:", query
			return db.docHistory.find(query).sort({v:-1}, function(err, result) {
				if (err != null) { return callback(err); }
				//console.log "getOpsByVersionRange:", err, result
				const updates = [];
				const opInRange = function(op, from, to) {
					if ((fromVersion != null) && (op.v < fromVersion)) { return false; }
					if ((toVersion != null) && (op.v > toVersion)) { return false; }
					return true;
				};
				for (let docHistory of Array.from(result)) {
					//console.log 'adding', docHistory.pack
					for (let op of Array.from(docHistory.pack.reverse())) {
						if (opInRange(op, fromVersion, toVersion)) {
							op.project_id = docHistory.project_id;
							op.doc_id = docHistory.doc_id;
							//console.log "added op", op.v, fromVersion, toVersion
							updates.push(op);
						}
					}
				}
				return callback(null, updates);
			});
		});
	},

	loadPacksByVersionRange(project_id, doc_id, fromVersion, toVersion, callback) {
		return PackManager.getIndex(doc_id, function(err, indexResult) {
			let pack;
			if (err != null) { return callback(err); }
			const indexPacks = (indexResult != null ? indexResult.packs : undefined) || [];
			const packInRange = function(pack, from, to) {
				if ((fromVersion != null) && (pack.v_end < fromVersion)) { return false; }
				if ((toVersion != null) && (pack.v > toVersion)) { return false; }
				return true;
			};
			const neededIds = ((() => {
				const result = [];
				for (pack of Array.from(indexPacks)) { 					if (packInRange(pack, fromVersion, toVersion)) {
						result.push(pack._id);
					}
				}
				return result;
			})());
			if (neededIds.length) {
				return PackManager.fetchPacksIfNeeded(project_id, doc_id, neededIds, callback);
			} else {
				return callback();
			}
		});
	},

	fetchPacksIfNeeded(project_id, doc_id, pack_ids, callback) {
		let id;
		return db.docHistory.find({_id: {$in: ((() => {
			const result = [];
			for (id of Array.from(pack_ids)) { 				result.push(ObjectId(id));
			}
			return result;
		})())}}, {_id:1}, function(err, loadedPacks) {
			if (err != null) { return callback(err); }
			const allPackIds = ((() => {
				const result1 = [];
				for (id of Array.from(pack_ids)) { 					result1.push(id.toString());
				}
				return result1;
			})());
			const loadedPackIds = (Array.from(loadedPacks).map((pack) => pack._id.toString()));
			const packIdsToFetch = _.difference(allPackIds, loadedPackIds);
			logger.log({project_id, doc_id, loadedPackIds, allPackIds, packIdsToFetch}, "analysed packs");
			if (packIdsToFetch.length === 0) { return callback(); }
			return async.eachLimit(packIdsToFetch, 4, (pack_id, cb) => MongoAWS.unArchivePack(project_id, doc_id, pack_id, cb)
			, function(err) {
				if (err != null) { return callback(err); }
				logger.log({project_id, doc_id}, "done unarchiving");
				return callback();
			});
		});
	},

	// Retrieve all changes across a project

	makeProjectIterator(project_id, before, callback) {
		// get all the docHistory Entries
		return db.docHistory.find({project_id: ObjectId(project_id)},{pack:false}).sort({"meta.end_ts":-1}, function(err, packs) {
			let pack;
			if (err != null) { return callback(err); }
			const allPacks = [];
			const seenIds = {};
			for (pack of Array.from(packs)) {
				allPacks.push(pack);
				seenIds[pack._id] = true;
			}
			return db.docHistoryIndex.find({project_id: ObjectId(project_id)}, function(err, indexes) {
				if (err != null) { return callback(err); }
				for (let index of Array.from(indexes)) {
					for (pack of Array.from(index.packs)) {
						if (!seenIds[pack._id]) {
							pack.project_id = index.project_id;
							pack.doc_id = index._id;
							pack.fromIndex = true;
							allPacks.push(pack);
							seenIds[pack._id] = true;
						}
					}
				}
				return callback(null, new ProjectIterator(allPacks, before, PackManager.getPackById));
			});
		});
	},

	getPackById(project_id, doc_id, pack_id, callback) {
		return db.docHistory.findOne({_id: pack_id}, function(err, pack) {
			if (err != null) { return callback(err); }
			if ((pack == null)) {
				return MongoAWS.unArchivePack(project_id, doc_id, pack_id, callback);
			} else if ((pack.expiresAt != null) && (pack.temporary === false)) {
				// we only need to touch the TTL when listing the changes in the project
				// because diffs on individual documents are always done after that
				return PackManager.increaseTTL(pack, callback);
				// only do this for cached packs, not temporary ones to avoid older packs
				// being kept longer than newer ones (which messes up the last update version)
			} else {
				return callback(null, pack);
			}
		});
	},

	increaseTTL(pack, callback) {
		if (pack.expiresAt < new Date(Date.now() + (6 * DAYS))) {
			// update cache expiry since we are using this pack
			return db.docHistory.findAndModify({
				query: {_id: pack._id},
				update: {$set: {expiresAt: new Date(Date.now() + (7 * DAYS))}}
			}, err => callback(err, pack));
		} else {
			return callback(null, pack);
		}
	},

	// Manage docHistoryIndex collection

	getIndex(doc_id, callback) {
		return db.docHistoryIndex.findOne({_id:ObjectId(doc_id.toString())}, callback);
	},

	getPackFromIndex(doc_id, pack_id, callback) {
		return db.docHistoryIndex.findOne({_id:ObjectId(doc_id.toString()), "packs._id": pack_id}, {"packs.$":1}, callback);
	},

	getLastPackFromIndex(doc_id, callback) {
		return db.docHistoryIndex.findOne({_id: ObjectId(doc_id.toString())}, {packs:{$slice:-1}}, function(err, indexPack) {
			if (err != null) { return callback(err); }
			if ((indexPack == null)) { return callback(); }
			return callback(null,indexPack[0]);
		});
	},

	getIndexWithKeys(doc_id, callback) {
		return PackManager.getIndex(doc_id, function(err, index) {
			if (err != null) { return callback(err); }
			if ((index == null)) { return callback(); }
			for (let pack of Array.from((index != null ? index.packs : undefined) || [])) {
				index[pack._id] = pack;
			}
			return callback(null, index);
		});
	},

	initialiseIndex(project_id, doc_id, callback) {
		return PackManager.findCompletedPacks(project_id, doc_id, function(err, packs) {
			//console.log 'err', err, 'packs', packs, packs?.length
			if (err != null) { return callback(err); }
			if ((packs == null)) { return callback(); }
			return PackManager.insertPacksIntoIndexWithLock(project_id, doc_id, packs, callback);
		});
	},

	updateIndex(project_id, doc_id, callback) {
		// find all packs prior to current pack
		return PackManager.findUnindexedPacks(project_id, doc_id, function(err, newPacks) {
			if (err != null) { return callback(err); }
			if ((newPacks == null) || (newPacks.length === 0)) { return callback(); }
			return PackManager.insertPacksIntoIndexWithLock(project_id, doc_id, newPacks, function(err) {
				if (err != null) { return callback(err); }
				logger.log({project_id, doc_id, newPacks}, "added new packs to index");
				return callback();
			});
		});
	},

	findCompletedPacks(project_id, doc_id, callback) {
		const query = { doc_id: ObjectId(doc_id.toString()), expiresAt: {$exists:false} };
		return db.docHistory.find(query, {pack:false}).sort({v:1}, function(err, packs) {
			if (err != null) { return callback(err); }
			if ((packs == null)) { return callback(); }
			if (!(packs != null ? packs.length : undefined)) { return callback(); }
			const last = packs.pop(); // discard the last pack, if it's still in progress
			if (last.finalised) { packs.push(last); } // it's finalised so we push it back to archive it
			return callback(null, packs);
		});
	},

	findPacks(project_id, doc_id, callback) {
		const query = { doc_id: ObjectId(doc_id.toString()), expiresAt: {$exists:false} };
		return db.docHistory.find(query, {pack:false}).sort({v:1}, function(err, packs) {
			if (err != null) { return callback(err); }
			if ((packs == null)) { return callback(); }
			if (!(packs != null ? packs.length : undefined)) { return callback(); }
			return callback(null, packs);
		});
	},

	findUnindexedPacks(project_id, doc_id, callback) {
		return PackManager.getIndexWithKeys(doc_id, function(err, indexResult) {
			if (err != null) { return callback(err); }
			return PackManager.findCompletedPacks(project_id, doc_id, function(err, historyPacks) {
				let pack;
				if (err != null) { return callback(err); }
				if ((historyPacks == null)) { return callback(); }
				// select only the new packs not already in the index
				let newPacks = ((() => {
					const result = [];
					for (pack of Array.from(historyPacks)) { 						if (((indexResult != null ? indexResult[pack._id] : undefined) == null)) {
							result.push(pack);
						}
					}
					return result;
				})());
				newPacks = ((() => {
					const result1 = [];
					for (pack of Array.from(newPacks)) { 						result1.push(_.omit(pack, 'doc_id', 'project_id', 'n', 'sz', 'last_checked', 'finalised'));
					}
					return result1;
				})());
				if (newPacks.length) {
					logger.log({project_id, doc_id, n: newPacks.length}, "found new packs");
				}
				return callback(null, newPacks);
			});
		});
	},

	insertPacksIntoIndexWithLock(project_id, doc_id, newPacks, callback) {
		return LockManager.runWithLock(
			keys.historyIndexLock({doc_id}),
			releaseLock => PackManager._insertPacksIntoIndex(project_id, doc_id, newPacks, releaseLock),
			callback
		);
	},

	_insertPacksIntoIndex(project_id, doc_id, newPacks, callback) {
		return db.docHistoryIndex.findAndModify({
			query: {_id:ObjectId(doc_id.toString())},
			update: {
				$setOnInsert: { project_id: ObjectId(project_id.toString())
			},
				$push: {
					packs: {$each: newPacks, $sort: {v: 1}}
				}
			},
			upsert: true
		}, callback);
	},

	// Archiving packs to S3

	archivePack(project_id, doc_id, pack_id, callback) {
		const clearFlagOnError = function(err, cb) {
			if (err != null) { // clear the inS3 flag on error
				return PackManager.clearPackAsArchiveInProgress(project_id, doc_id, pack_id, function(err2) {
					if (err2 != null) { return cb(err2); }
					return cb(err);
				});
			} else {
				return cb();
			}
		};
		return async.series([
			cb => PackManager.checkArchiveNotInProgress(project_id, doc_id, pack_id, cb),
			cb => PackManager.markPackAsArchiveInProgress(project_id, doc_id, pack_id, cb),
			cb =>
				MongoAWS.archivePack(project_id, doc_id, pack_id, err => clearFlagOnError(err, cb))
			,
			cb =>
				PackManager.checkArchivedPack(project_id, doc_id, pack_id, err => clearFlagOnError(err, cb))
			,
			cb => PackManager.markPackAsArchived(project_id, doc_id, pack_id, cb),
			cb => PackManager.setTTLOnArchivedPack(project_id, doc_id, pack_id, callback)
		], callback);
	},


	checkArchivedPack(project_id, doc_id, pack_id, callback) {
		return db.docHistory.findOne({_id: pack_id}, function(err, pack) {
			if (err != null) { return callback(err); }
			if ((pack == null)) { return callback(new Error("pack not found")); }
			return MongoAWS.readArchivedPack(project_id, doc_id, pack_id, function(err, result) {
				delete result.last_checked;
				delete pack.last_checked;
				// need to compare ids as ObjectIds with .equals()
				for (let key of ['_id', 'project_id', 'doc_id']) {
					if (result[key].equals(pack[key])) { result[key] = pack[key]; }
				}
				for (let i = 0; i < result.pack.length; i++) {
					const op = result.pack[i];
					if ((op._id != null) && op._id.equals(pack.pack[i]._id)) { op._id = pack.pack[i]._id; }
				}
				if (_.isEqual(pack, result)) {
					return callback();
				} else {
					logger.err({pack, result, jsondiff: JSON.stringify(pack) === JSON.stringify(result)}, "difference when comparing packs");
					return callback(new Error("pack retrieved from s3 does not match pack in mongo"));
				}
			});
		});
	},
	// Extra methods to test archive/unarchive for a doc_id

	pushOldPacks(project_id, doc_id, callback) {
		return PackManager.findPacks(project_id, doc_id, function(err, packs) {
			if (err != null) { return callback(err); }
			if (!(packs != null ? packs.length : undefined)) { return callback(); }
			return PackManager.processOldPack(project_id, doc_id, packs[0]._id, callback);
		});
	},

	pullOldPacks(project_id, doc_id, callback) {
		return PackManager.loadPacksByVersionRange(project_id, doc_id, null, null, callback);
	},


	// Processing old packs via worker

	processOldPack(project_id, doc_id, pack_id, callback) {
		const markAsChecked = err =>
			PackManager.markPackAsChecked(project_id, doc_id, pack_id, function(err2) {
				if (err2 != null) { return callback(err2); }
				return callback(err);
			})
		;
		logger.log({project_id, doc_id}, "processing old packs");
		return db.docHistory.findOne({_id:pack_id}, function(err, pack) {
			if (err != null) { return markAsChecked(err); }
			if ((pack == null)) { return markAsChecked(); }
			if (pack.expiresAt != null) { return callback(); } // return directly
			return PackManager.finaliseIfNeeded(project_id, doc_id, pack._id, pack, function(err) {
				if (err != null) { return markAsChecked(err); }
				return PackManager.updateIndexIfNeeded(project_id, doc_id, function(err) {
					if (err != null) { return markAsChecked(err); }
					return PackManager.findUnarchivedPacks(project_id, doc_id, function(err, unarchivedPacks) {
						if (err != null) { return markAsChecked(err); }
						if (!(unarchivedPacks != null ? unarchivedPacks.length : undefined)) {
							logger.log({project_id, doc_id}, "no packs need archiving");
							return markAsChecked();
						}
						return async.eachSeries(unarchivedPacks, (pack, cb) => PackManager.archivePack(project_id, doc_id, pack._id, cb)
						, function(err) {
							if (err != null) { return markAsChecked(err); }
							logger.log({project_id, doc_id}, "done processing");
							return markAsChecked();
						});
					});
				});
			});
		});
	},

	finaliseIfNeeded(project_id, doc_id, pack_id, pack, callback) {
		const sz = pack.sz / (1024 * 1024); // in fractions of a megabyte
		const n = pack.n / 1024; // in fraction of 1024 ops
		const age = (Date.now() - pack.meta.end_ts) / DAYS;
		if (age < 30) { // always keep if less than 1 month old
			logger.log({project_id, doc_id, pack_id, age}, "less than 30 days old");
			return callback();
		}
		// compute an archiving threshold which decreases for each month of age
		const archive_threshold = 30 / age;
		if ((sz > archive_threshold) || (n > archive_threshold) || (age > 90)) {
			logger.log({project_id, doc_id, pack_id, age, archive_threshold, sz, n}, "meets archive threshold");
			return PackManager.markPackAsFinalisedWithLock(project_id, doc_id, pack_id, callback);
		} else {
			logger.log({project_id, doc_id, pack_id, age, archive_threshold, sz, n}, "does not meet archive threshold");
			return callback();
		}
	},

	markPackAsFinalisedWithLock(project_id, doc_id, pack_id, callback) {
		return LockManager.runWithLock(
			keys.historyLock({doc_id}),
			releaseLock => PackManager._markPackAsFinalised(project_id, doc_id, pack_id, releaseLock),
			callback
		);
	},

	_markPackAsFinalised(project_id, doc_id, pack_id, callback) {
		logger.log({project_id, doc_id, pack_id}, "marking pack as finalised");
		return db.docHistory.findAndModify({
			query: {_id: pack_id},
			update: {$set: {finalised: true}}
		}, callback);
	},


	updateIndexIfNeeded(project_id, doc_id, callback) {
		logger.log({project_id, doc_id}, "archiving old packs");
		return PackManager.getIndexWithKeys(doc_id, function(err, index) {
			if (err != null) { return callback(err); }
			if ((index == null)) {
				return PackManager.initialiseIndex(project_id, doc_id, callback);
			} else {
				return PackManager.updateIndex(project_id, doc_id, callback);
			}
		});
	},

	markPackAsChecked(project_id, doc_id, pack_id, callback) {
		logger.log({project_id, doc_id, pack_id}, "marking pack as checked");
		return db.docHistory.findAndModify({
			query: {_id: pack_id},
			update: {$currentDate: {"last_checked":true}}
		}, callback);
	},

	findUnarchivedPacks(project_id, doc_id, callback) {
		return PackManager.getIndex(doc_id, function(err, indexResult) {
			if (err != null) { return callback(err); }
			const indexPacks = (indexResult != null ? indexResult.packs : undefined) || [];
			const unArchivedPacks = ((() => {
				const result = [];
				for (let pack of Array.from(indexPacks)) { 					if ((pack.inS3 == null)) {
						result.push(pack);
					}
				}
				return result;
			})());
			if (unArchivedPacks.length) {
				logger.log({project_id, doc_id, n: unArchivedPacks.length}, "find unarchived packs");
			}
			return callback(null, unArchivedPacks);
		});
	},

	// Archive locking flags

	checkArchiveNotInProgress(project_id, doc_id, pack_id, callback) {
		logger.log({project_id, doc_id, pack_id}, "checking if archive in progress");
		return PackManager.getPackFromIndex(doc_id, pack_id, function(err, result) {
			if (err != null) { return callback(err); }
			if ((result == null)) { return callback(new Error("pack not found in index")); }
			if (result.inS3) {
				return callback(new Error("pack archiving already done"));
			} else if (result.inS3 != null) {
				return callback(new Error("pack archiving already in progress"));
			} else {
				return callback();
			}
		});
	},

	markPackAsArchiveInProgress(project_id, doc_id, pack_id, callback) {
		logger.log({project_id, doc_id}, "marking pack as archive in progress status");
		return db.docHistoryIndex.findAndModify({
			query: {_id:ObjectId(doc_id.toString()),  packs: {$elemMatch: {"_id": pack_id, inS3: {$exists:false}}}},
			fields:  { "packs.$": 1 },
			update: {$set: {"packs.$.inS3":false}}
		}, function(err, result) {
			if (err != null) { return callback(err); }
			if ((result == null)) { return callback(new Error("archive is already in progress")); }
			logger.log({project_id, doc_id, pack_id}, "marked as archive in progress");
			return callback();
		});
	},

	clearPackAsArchiveInProgress(project_id, doc_id, pack_id, callback) {
		logger.log({project_id, doc_id, pack_id}, "clearing as archive in progress");
		return db.docHistoryIndex.findAndModify({
			query: {_id:ObjectId(doc_id.toString()), "packs" : {$elemMatch: {"_id": pack_id, inS3: false}}},
			fields:  { "packs.$": 1 },
			update: {$unset: {"packs.$.inS3":true}}
		}, callback);
	},

	markPackAsArchived(project_id, doc_id, pack_id, callback) {
		logger.log({project_id, doc_id, pack_id}, "marking pack as archived");
		return db.docHistoryIndex.findAndModify({
			query: {_id:ObjectId(doc_id.toString()), "packs" : {$elemMatch: {"_id": pack_id, inS3: false}}},
			fields: { "packs.$": 1 },
			update: {$set: {"packs.$.inS3":true}}
		}, function(err, result) {
			if (err != null) { return callback(err); }
			if ((result == null)) { return callback(new Error("archive is not marked as progress")); }
			logger.log({project_id, doc_id, pack_id}, "marked as archived");
			return callback();
		});
	},

	setTTLOnArchivedPack(project_id, doc_id, pack_id, callback) {
		return db.docHistory.findAndModify({
			query: {_id: pack_id},
			update: {$set: {expiresAt: new Date(Date.now() + (1*DAYS))}}
		}, function(err) {
			logger.log({project_id, doc_id, pack_id}, "set expiry on pack");
			return callback();
		});
	}
});


//	_getOneDayInFutureWithRandomDelay: ->
//		thirtyMins = 1000 * 60 * 30
//		randomThirtyMinMax = Math.ceil(Math.random() * thirtyMins)
//		return new Date(Date.now() + randomThirtyMinMax + 1*DAYS)