add a limit to the number of sessions backed up

This commit is contained in:
Julian Descottes 2017-06-17 18:25:19 +02:00
parent f9570ea3c5
commit c6e106fe2d
2 changed files with 106 additions and 6 deletions

View File

@ -176,4 +176,80 @@
return deferred.promise;
};
ns.BackupDatabase.prototype.getSessions = function () {
// Create the backup promise.
var deferred = Q.defer();
// Open a transaction to the snapshots object store.
var objectStore = this.db.transaction(['snapshots']).objectStore('snapshots');
var sessions = {};
var _createSession = function (snapshot) {
sessions[snapshot.sessionId] = {
startDate: snapshot.date,
endDate: snapshot.date,
name: snapshot.name,
id: snapshot.sessionId
};
};
var _updateSessions = function (snapshot) {
var s = sessions[snapshot.sessionId];
s.startDate = Math.min(s.startDate, snapshot.startDate);
s.endDate = Math.max(s.endDate, snapshot.endDate);
if (s.endDate === snapshot.endDate) {
s.name = snapshot.name;
}
};
var index = objectStore.index('date');
var range = IDBKeyRange.upperBound(Infinity);
index.openCursor(range, 'prev').onsuccess = function(event) {
var cursor = event.target.result;
var snapshot = cursor && cursor.value;
if (!snapshot) {
deferred.resolve(sessions);
} else {
if (sessions[snapshot.sessionId]) {
_createSession(snapshot);
} else {
_updateSessions(snapshot);
}
cursor.continue();
}
};
return deferred.promise.then(function (sessions) {
// Convert the sessions map to an array.
return Object.keys(sessions).map(function (key) {
return sessions[key];
});
});
};
ns.BackupDatabase.prototype.deleteSnapshotsForSession = function (sessionId) {
// Create the backup promise.
var deferred = Q.defer();
// Open a transaction to the snapshots object store.
var objectStore = this.db.transaction(['snapshots']).objectStore('snapshots');
// Loop on all the saved snapshots for the provided piskel id
var index = objectStore.index('session_id');
var keyRange = IDBKeyRange.only(sessionId);
index.openCursor(keyRange).onsuccess = function(event) {
var cursor = event.target.result;
if (cursor) {
cursor.delete();
cursor.continue();
} else {
deferred.resolve();
}
};
return deferred.promise;
};
})();

View File

@ -10,13 +10,15 @@
var SNAPSHOT_INTERVAL = ONE_MINUTE * 5;
// Store up to 12 snapshots for a piskel session, min. 1 hour of work
var MAX_SNAPSHOTS_PER_SESSION = 12;
var MAX_SESSIONS = 10;
ns.BackupService = function (piskelController) {
ns.BackupService = function (piskelController, backupDatabase) {
this.piskelController = piskelController;
this.lastHash = null;
this.nextSnapshotDate = -1;
this.backupDatabase = new pskl.database.BackupDatabase();
// backupDatabase can be provided for testing purposes.
this.backupDatabase = backupDatabase || new pskl.database.BackupDatabase();
};
ns.BackupService.prototype.init = function () {
@ -25,13 +27,18 @@
}.bind(this));
};
// This is purely exposed for testing, so that backup dates can be set programmatically.
ns.BackupService.prototype.currentDate_ = function () {
return Date.now();
};
ns.BackupService.prototype.backup = function () {
var piskel = this.piskelController.getPiskel();
var hash = piskel.getHash();
// Do not save an unchanged piskel
if (hash === this.lastHash) {
return;
return Q.resolve();
}
// Update the hash
@ -40,7 +47,7 @@
// Prepare the backup snapshot.
var descriptor = piskel.getDescriptor();
var date = Date.now();
var date = this.currentDate_();
var snapshot = {
session_id: piskel.sessionId,
date: date,
@ -49,7 +56,7 @@
serialized: pskl.utils.serialization.Serializer.serialize(piskel)
};
this.backupDatabase.getSnapshotsBySessionId(piskel.sessionId).then(function (snapshots) {
return this.backupDatabase.getSnapshotsBySessionId(piskel.sessionId).then(function (snapshots) {
var latest = snapshots[0];
if (latest && date < this.nextSnapshotDate) {
@ -64,10 +71,27 @@
// remove oldest snapshot
return this.backupDatabase.deleteSnapshot(snapshots[snapshots.length - 1]);
}
}.bind(this)).then(function () {
var isNewSession = !latest;
if (!isNewSession) {
return;
}
return this.backupDatabase.getSessions().then(function (sessions) {
if (sessions.length <= MAX_SESSIONS) {
// If MAX_SESSIONS has not been reached, no need to delete
// previous sessions.
return;
}
var oldestSession = sessions.sort(function (s1, s2) {
return s1.startDate - s2.startDate;
})[0].id;
return this.backupDatabase.deleteSnapshotsForSession(oldestSession);
}.bind(this));
}.bind(this));
}
}.bind(this)).catch(function (e) {
console.log('Backup failed');
console.error(e);
});
};