Give processables the ability to defer their next processing. Make Threads/Boards use this to obey the newly named "MinSecondsBetweenScrapes" setting

Author: Issung

GChan/App.config

@@ -13,8 +13,8 @@
       <setting name="SavePath" serializeAs="String">
         <value>C:\GChan</value>
       </setting>
-      <setting name="ScanTimer" serializeAs="String">
-        <value>60000</value>
+      <setting name="MinSecondsBetweenScrapes" serializeAs="String">
+        <value>60</value>
       </setting>
       <setting name="SaveHtml" serializeAs="String">
         <value>False</value>

GChan/Forms/SettingsForm.cs

@@ -68,7 +68,7 @@ private void Settings_Shown(object sender, EventArgs e)
             directory = Settings.Default.SavePath;
             directoryTextBox.Text = directory;
 
-            timerNumeric.Value = (Settings.Default.ScanTimer / 1000);
+            minSecondsBetweenScrapesNumeric.Value = Settings.Default.MinSecondsBetweenScrapes;
             max1RequestPerSecondCheckBox.Checked = Settings.Default.Max1RequestPerSecond;
             concurrentDownloadsNumeric.Value = Settings.Default.MaximumConcurrentDownloads;
 
@@ -96,7 +96,7 @@ private void buttonSave_Click(object sender, EventArgs e)
                 return;
             }
 
-            if (timerNumeric.Value < 5)
+            if (minSecondsBetweenScrapesNumeric.Value < 5)
             {
                 MessageBox.Show("Timer must be greater than 5 seconds.");
                 return;
@@ -115,7 +115,7 @@ private void SaveSettings()
         {
             Settings.Default.UserAgent = userAgentTextBox.Text;
             Settings.Default.SavePath = directory;
-            Settings.Default.ScanTimer = (int)timerNumeric.Value * 1000;
+            Settings.Default.MinSecondsBetweenScrapes = (int)minSecondsBetweenScrapesNumeric.Value;
             Settings.Default.Max1RequestPerSecond = max1RequestPerSecondCheckBox.Checked;
             Settings.Default.MaximumConcurrentDownloads = (int)concurrentDownloadsNumeric.Value;
             Settings.Default.ImageFilenameFormat = (byte)imageFilenameFormatComboBox.SelectedIndex;

GChan/Forms/SettingsForm.designer.cs

@@ -21,6 +21,8 @@ public class Thumbnail : IAsset, IEquatable<Thumbnail>
 
         public bool ShouldProcess => Settings.Default.SaveThumbnails && thread.ShouldProcess;
 
+        public DateTimeOffset? ReadyToProcessAt => null;
+
         /// <summary>
         /// URL to download the thumbnail.
         /// </summary>

GChan/Models/Thumbnail.cs

@@ -1,4 +1,5 @@
 using GChan.Data.Models;
+using GChan.Properties;
 using GChan.Services;
 using System;
 using System.Linq;
@@ -48,6 +49,8 @@ public int ThreadCount
 
         public bool ShouldProcess => !cancellationTokenSource.IsCancellationRequested;
 
+        public DateTimeOffset? ReadyToProcessAt => LastScrape + TimeSpan.FromSeconds(Settings.Default.MinSecondsBetweenScrapes);
+
         protected Board(string url) : base(url)
         {
             Type = Type.Board;

GChan/Models/Trackers/Board.cs

@@ -33,6 +33,8 @@ public abstract class Thread : Tracker, IProcessable, INotifyPropertyChanged
 
         public bool ShouldProcess => !Gone && !cancellationTokenSource.IsCancellationRequested;
 
+        public DateTimeOffset? ReadyToProcessAt => LastScrape + TimeSpan.FromSeconds(Settings.Default.MinSecondsBetweenScrapes);
+
         public string Subject
         {
             get => subject ?? NO_SUBJECT;

GChan/Models/Trackers/Thread.cs

@@ -39,7 +39,7 @@ public abstract class Tracker
         /// When this tracker was last succesfully scraped, null if not yet scraped.<br/>
         /// <see cref="DateTimeOffset"/> because that's what HttpClient header property accepts.
         /// </summary>
-        public DateTimeOffset? LastScrape { get; internal set; }
+        public DateTimeOffset? LastScrape { get; protected set; }
 
         /// <summary>
         /// Whether or not to keep scraping this tracker.

GChan/Models/Trackers/Tracker.cs

@@ -59,6 +59,8 @@ public class Upload : IAsset, IEquatable<Upload>
 
         public bool ShouldProcess => Thread.ShouldProcess;
 
+        public DateTimeOffset? ReadyToProcessAt => null;
+
         public Upload(
             long tim,
             string url,

GChan/Models/Upload.cs

@@ -5,8 +5,8 @@
     <Setting Name="SavePath" Type="System.String" Scope="User">
       <Value Profile="(Default)">C:\GChan</Value>
     </Setting>
-    <Setting Name="ScanTimer" Type="System.Int32" Scope="User">
-      <Value Profile="(Default)">60000</Value>
+    <Setting Name="MinSecondsBetweenScrapes" Type="System.Int32" Scope="User">
+      <Value Profile="(Default)">60</Value>
     </Setting>
     <Setting Name="SaveHtml" Type="System.Boolean" Scope="User">
       <Value Profile="(Default)">False</Value>

GChan/Properties/Settings.Designer.cs

@@ -48,12 +48,18 @@ public interface IProcessable : IAsyncDisposable
         public CancellationToken CancellationToken { get; }
 
         /// <summary>
-        /// Should this item be downloaded.<br/>
-        /// Decision may have changed since being added to download manager.<br/>
-        /// If this ever goes false it should never go back to being true.
+        /// Should this item be processed<br/>
+        /// Decision may have changed since being added to queue.<br/>
+        /// If this ever goes false it should never go back to being true, thus it should be discarded from the queue.
         /// </summary>
         public bool ShouldProcess { get; }
 
+        /// <summary>
+        /// When will this processable by ready to process.<br/>
+        /// Set to null for any time, otherwise the item is deferred until it is next found in the queue with a ready time.
+        /// </summary>
+        public DateTimeOffset? ReadyToProcessAt { get; }
+
         /// <summary>
         /// Perform download for this item.<br/>
         /// Must never throw, must always return a <see cref="ProcessResult"/>.

GChan/Properties/Settings.settings

@@ -1,10 +1,13 @@
 using GChan.Models.Trackers;
 using GChan.Properties;
+using NetTopologySuite.Triangulate.QuadEdge;
 using NLog;
 using System;
 using System.Collections.Concurrent;
+using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
+using System.Windows.Documents;
 
 #nullable enable
 
@@ -78,22 +81,44 @@ public async Task WorkAsync()
         /// </summary>
         private IProcessable? MaybeDequeue()
         {
-            while (true)
+            var deferredProcessables = new List<IProcessable>();
+
+            try
             {
-                if (queue.TryDequeue(out var processable))
+                while (true)
                 {
-                    if (processable.ShouldProcess)
+                    if (queue.TryDequeue(out var processable))
                     {
-                        logger.Trace("Dequeued processable {0}.", processable);
-                        return processable;
+                        if (processable.ShouldProcess)
+                        {
+                            if (processable.ReadyToProcessAt == null || processable.ReadyToProcessAt <= DateTimeOffset.Now)
+                            {
+                                logger.Trace("Dequeued processable {0}.", processable);
+                                return processable;
+                            }
+                            else
+                            {
+                                deferredProcessables.Add(processable);
+                                logger.Trace("Deferring processable {0}. Ready to process at {1}.", processable, processable.ReadyToProcessAt);
+                            }
+                        }
+                        else
+                        {
+                            logger.Trace("Discarding dequeued processable {0}.", processable);
+                        }
+                    }
+                    else
+                    {
+                        logger.Trace("Processable queue empty.");
+                        return null;
                     }
-
-                    logger.Trace("Discarding dequeued processable {0}.", processable);
                 }
-                else
+            }
+            finally
+            {
+                foreach (var deferredProcessable in deferredProcessables)
                 {
-                    logger.Trace("Processable queue empty.");
-                    return null;
+                    queue.Enqueue(deferredProcessable);
                 }
             }
         }

GChan/Services/IProcessable.cs

@@ -35,7 +35,7 @@ public string NotificationTrayTooltip
         {
             get
             {
-                return $"Scraping {Threads.Count} thread{(Threads.Count != 1 ? "s" : "")} and {Boards.Count} board{(Boards.Count != 1 ? "s" : "")} every {Settings.Default.ScanTimer / 60 / 1000} minute{(Settings.Default.ScanTimer / 60 / 1000 != 1 ? "s" : "")}." +
+                return $"Scraping {Threads.Count} thread{(Threads.Count != 1 ? "s" : "")} and {Boards.Count} board{(Boards.Count != 1 ? "s" : "")} every {Settings.Default.MinSecondsBetweenScrapes / 60 / 1000} minute{(Settings.Default.MinSecondsBetweenScrapes / 60 / 1000 != 1 ? "s" : "")}." +
                     "\nClick to show/hide.";
             }
         }