Implementing trimming background task.

src/Orchard.Web/Modules/Orchard.AuditTrail/Drivers/AuditTrailTrimmingSettingsPartDriver.cs

@@ -24,12 +24,12 @@ namespace Orchard.AuditTrail.Drivers {
 
             return ContentShape("Parts_AuditTrailTrimmingSettings_Edit", () => {
                 var viewModel = new AuditTrailTrimmingSettingsViewModel {
-                    AutoTrimThreshold = part.AutoTrimThreshold,
+                    Threshold = part.Threshold,
                 };
 
                 if (updater != null) {
                     if (updater.TryUpdateModel(viewModel, Prefix, null, null)) {
-                        part.AutoTrimThreshold = viewModel.AutoTrimThreshold;
+                        part.Threshold = viewModel.Threshold;
                     }
                 }
 

src/Orchard.Web/Modules/Orchard.AuditTrail/Models/AuditTrailTrimmingSettingsPart.cs

@@ -1,13 +1,22 @@
-using Orchard.ContentManagement;
+using System;
+using Orchard.ContentManagement;
 
 namespace Orchard.AuditTrail.Models {
     public class AuditTrailTrimmingSettingsPart : ContentPart {
         /// <summary>
         /// Threshold in days.
         /// </summary>
-        public int AutoTrimThreshold {
-            get { return this.Retrieve(x => x.AutoTrimThreshold, defaultValue: 10); }
-            set { this.Store(x => x.AutoTrimThreshold, value); }
+        public int Threshold {
+            get { return this.Retrieve(x => x.Threshold, defaultValue: 10); }
+            set { this.Store(x => x.Threshold, value); }
+        }
+
+        /// <summary>
+        /// The timestamp the audit trail was last trimmed.
+        /// </summary>
+        public DateTime? LastRunUtc {
+            get { return this.Retrieve(x => x.LastRunUtc); }
+            set { this.Store(x => x.LastRunUtc, value); }
         }
     }
 }

src/Orchard.Web/Modules/Orchard.AuditTrail/Orchard.AuditTrail.csproj

@@ -154,6 +154,7 @@
     <Compile Include="Providers\Content\DiffNode.cs" />
     <Compile Include="Providers\Content\DiffType.cs" />
     <Compile Include="Providers\Content\IDiffGramAnalyzer.cs" />
+    <Compile Include="Services\AuditTrailTrimmingBackgroundTask.cs" />
     <Compile Include="ViewModels\AuditTrailCategorySettingsViewModel.cs" />
     <Compile Include="ViewModels\AuditTrailEventSettingsViewModel.cs" />
     <Compile Include="ViewModels\AuditTrailTrimmingSettingsViewModel.cs" />

src/Orchard.Web/Modules/Orchard.AuditTrail/Services/AuditTrailManager.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Security.Cryptography;
 using Orchard.AuditTrail.Helpers;
 using Orchard.AuditTrail.Models;
 using Orchard.Caching;
@@ -152,5 +153,17 @@ namespace Orchard.AuditTrail.Services {
 
             return eventDescriptors.First();
         }
+
+        public IEnumerable<AuditTrailEventRecord> Trim(TimeSpan threshold) {
+            var dateThreshold = _clock.UtcNow.Date - threshold;
+            var query = _auditTrailRepository.Table.Where(x => x.CreatedUtc < dateThreshold);
+            var records = query.ToArray();
+
+            foreach (var record in records) {
+                _auditTrailRepository.Delete(record);
+            }
+
+            return records;
+        }
     }
 }

src/Orchard.Web/Modules/Orchard.AuditTrail/Services/AuditTrailTrimmingBackgroundTask.cs

@@ -0,0 +1,61 @@
+using System;
+using System.Linq;
+using System.Threading;
+using Orchard.AuditTrail.Models;
+using Orchard.ContentManagement;
+using Orchard.Environment.Extensions;
+using Orchard.Logging;
+using Orchard.Services;
+using Orchard.Settings;
+using Orchard.Tasks;
+
+namespace Orchard.AuditTrail.Services {
+    [OrchardFeature("Orchard.AuditTrail.Trimming")]
+    public class AuditTrailTrimmingBackgroundTask : Component, IBackgroundTask {
+        private static readonly object _sweepLock = new object();
+        private readonly ISiteService _siteService;
+        private readonly IClock _clock;
+        private readonly IAuditTrailManager _auditTrailManager;
+
+        public AuditTrailTrimmingBackgroundTask(ISiteService siteService, IClock clock, IAuditTrailManager auditTrailManager) {
+            _siteService = siteService;
+            _clock = clock;
+            _auditTrailManager = auditTrailManager;
+        }
+
+        public AuditTrailTrimmingSettingsPart Settings {
+            get { return _siteService.GetSiteSettings().As<AuditTrailTrimmingSettingsPart>(); }
+        }
+
+        public void Sweep() {
+            if (Monitor.TryEnter(_sweepLock)) {
+                try {
+                    Logger.Debug("Beginning sweep.");
+
+                    // We don't need to check the audit trail for events to remove every minute. Let's stick with twice a day.
+                    if (!TimeToTrim())
+                        return;
+
+                    Logger.Debug("Starting audit trail trimming operation.");
+                    var deletedRecords = _auditTrailManager.Trim(TimeSpan.FromDays(Settings.Threshold));
+                    Logger.Debug("Audit trail trimming operation completed. {0} Records were deleted.", deletedRecords.Count());
+                    Settings.LastRunUtc = _clock.UtcNow;
+                }
+                catch (Exception ex) {
+                    Logger.Error(ex, "Error during sweep.");
+                }
+                finally {
+                    Monitor.Exit(_sweepLock);
+                    Logger.Debug("Ending sweep.");
+                }
+            }
+        }
+
+        private bool TimeToTrim() {
+            var lastRun = Settings.LastRunUtc ?? DateTime.MinValue;
+            var now = _clock.UtcNow;
+            var interval = TimeSpan.FromHours(12);
+            return now - lastRun > interval;
+        }
+    }
+}

src/Orchard.Web/Modules/Orchard.AuditTrail/Services/IAuditTrailManager.cs

@@ -56,5 +56,11 @@ namespace Orchard.AuditTrail.Services {
         /// <param name="fullyQualifiedEventName">The fully qualified event name to describe.</param>
         /// <returns>Returns a single audit trail event descriptor.</returns>
         AuditTrailEventDescriptor Describe(string fullyQualifiedEventName);
+
+        /// <summary>
+        /// Trims the audit trail by deleting all records older than the specified threshold.
+        /// </summary>
+        /// <returns>Returns the deleted records.</returns>
+        IEnumerable<AuditTrailEventRecord> Trim(TimeSpan threshold);
     }
 }

src/Orchard.Web/Modules/Orchard.AuditTrail/ViewModels/AuditTrailTrimmingSettingsViewModel.cs

@@ -1,5 +1,5 @@
 namespace Orchard.AuditTrail.ViewModels {
     public class AuditTrailTrimmingSettingsViewModel {
-        public int AutoTrimThreshold { get; set; }
+        public int Threshold { get; set; }
     }
 }

src/Orchard.Web/Modules/Orchard.AuditTrail/Views/EditorTemplates/Parts.AuditTrailTrimmingSettings.cshtml

@@ -2,8 +2,8 @@
 <fieldset>
     <legend>@T("Auto Trim Settings")</legend>
     <div id="auditTrailAutoTrimthresholdSetting">
-        @Html.LabelFor(m => m.AutoTrimThreshold, T("Auto-trim threshold"))
-        @Html.TextBoxFor(m => m.AutoTrimThreshold, new { @class = "text small" })
+        @Html.LabelFor(m => m.Threshold, T("Auto-trim threshold"))
+        @Html.TextBoxFor(m => m.Threshold, new { @class = "text small" })
         <span class="hint">@T("Specify the number of days of audit log data to retain.")</span>
     </div>
 </fieldset>