Moved batch download thread into BatchDownloader class.

BulkPrinting/BulkPrinting/BatchDownloader.cs

@@ -0,0 +1,269 @@
+using System;
+using System.Data.SQLite;
+using System.Threading;
+using Serilog;
+
+namespace BulkPrinting
+{
+    public class BatchDownloader : ThreadHelper
+    {
+        private const int _voucherPageSize = 5000;
+        private const int _retryInterval = 30000;
+
+        private DBHelper _db;
+        private Action _refreshAction;
+        private bool _checkForNewBatches;
+
+        public BatchDownloader(DBHelper db, Action refreshAction)
+        {
+            _db = db;
+            _refreshAction = refreshAction;
+        }
+
+        public void CheckForNewBatches()
+        {
+            lock (_lock)
+            {
+                _checkForNewBatches = true;
+                Monitor.Pulse(_lock);
+            }
+        }
+
+        protected override void Run()
+        {
+            var lastSyncedBatchId = Utility.GetSavedParameterAsInt(_db, "LastSyncedBatchId");
+
+            bool skipNewBatchCheck = false;
+            var isCancelled = false;
+            while (!isCancelled)
+            {
+                if (Globals.SessionMode == SessionModes.Online)
+                {
+                    Log.Debug("Checking for downloads");
+
+                    // Check for new batches if required.
+                    var doRefresh = false;
+                    try
+                    {
+                        while (!isCancelled && !skipNewBatchCheck)
+                        {
+                            Log.Debug("Querying batches");
+
+                            Page<Batch> BatchPage = new Page<Batch>();
+                            if (Utility.RESTRequest(ref BatchPage, String.Format("/api/batches/?minBatchId={0}", lastSyncedBatchId + 1)))
+                            {
+                                if (BatchPage.Items.Count == 0)
+                                {
+                                    // No more new batches, so stop checking until an order is placed.
+                                    skipNewBatchCheck = true;
+                                    Log.Debug("All batches downloaded");
+                                }
+                                else
+                                {
+                                    foreach (var batch in BatchPage.Items)
+                                    {
+                                        doRefresh = true;
+                                        Utility.SaveBatch(_db, batch);
+                                        lastSyncedBatchId = batch.Id;
+                                        if (!Utility.UpdateSavedParameter(_db, "LastSyncedBatchId", lastSyncedBatchId))
+                                        {
+                                            // Shouldn't happen.
+                                            throw new Exception("Failed to update LastSyncedBatchId");
+                                        }
+                                    }
+                                }
+                            }
+                            else
+                            {
+                                // Error, so leave skipNewBatchCheck unchanged.
+                                break;
+                            }
+
+                            lock (_lock)
+                            {
+                                isCancelled = _cancelled;
+                            }
+                        }
+                    }
+                    catch (Exception e)
+                    {
+                        Log.Error(e, "Error while downloading batch list");
+                    }
+
+                    if (!isCancelled && doRefresh)
+                    {
+                        doRefresh = false;
+                        _refreshAction();
+                    }
+
+                    // Continue downloading incomplete batches if any.
+                    try
+                    {
+                        using (var command = _db.CreateCommand(
+                            "SELECT Id FROM Batch WHERE Downloaded=0 ORDER BY Downloaded, Id"))
+                        {
+                            using (SQLiteDataReader row = command.ExecuteReader())
+                            {
+                                while (! isCancelled && row.Read())
+                                {
+                                    int batchId = (int)row["Id"];
+                                    try
+                                    {
+                                        Batch batch = new Batch();
+                                        if (Utility.RESTRequest(ref batch, String.Format("/api/batches/{0}", batchId)))
+                                        {
+                                            doRefresh = true;
+                                            Utility.SaveBatch(_db, batch);
+
+                                            if (batch.ReadyForDownload)
+                                            {
+                                                long result = (long)_db.ExecuteScalar(
+                                                    "SELECT COUNT(*) FROM Voucher WHERE BatchId=@BatchId",
+                                                    new SQLiteParameter("@BatchId", batchId));
+                                                int voucherCount = (int)result;
+
+                                                while (!isCancelled && (voucherCount < batch.DeliveredQuantity))
+                                                {
+                                                    Log.Debug("Downloading vouchers for batch {0} ({1} so far)", batchId, voucherCount);
+
+                                                    int page = voucherCount / _voucherPageSize + 1;
+                                                    int offset = voucherCount % _voucherPageSize;
+
+                                                    Page<Voucher> voucherPage = new Page<Voucher>();
+                                                    if (!Utility.RESTRequest(ref voucherPage, String.Format(
+                                                        "/api/batches/{0}/vouchers/?page={1}&pageSize={2}",
+                                                        batchId, page, _voucherPageSize)))
+                                                    {
+                                                        break;
+                                                    }
+                                                    if (voucherPage.Items.Count == 0)
+                                                    {
+                                                        throw new Exception(String.Format("Too few vouchers were returned for batch {0}", batchId));
+                                                    }
+
+                                                    Log.Debug("Downloaded vouchers for batch {0} ({1} so far)", batchId, voucherCount);
+
+                                                    lock (_db.WriteLock)
+                                                    {
+                                                        using (var trans = _db.BeginTransaction())
+                                                        {
+                                                            using (var insert = _db.CreateCommand(
+                                                                "INSERT INTO Voucher (Id, SequenceNumber, ExpiryDate, Serial, EncryptedPIN, BatchId)" +
+                                                                             "VALUES (@Id,@SequenceNumber,@ExpiryDate,@Serial,@EncryptedPin,@BatchId)",
+                                                                trans))
+                                                            {
+                                                                for (var i = offset; i < voucherPage.Items.Count; i++)
+                                                                {
+                                                                    var voucher = voucherPage.Items[i];
+                                                                    if (voucher.SequenceNumber != voucherCount + 1)
+                                                                    {
+                                                                        throw new Exception(String.Format("Vouchers for batch {0} are not sequential: expecting {1}, got {2}", batchId, voucherCount + 1, voucher.SequenceNumber));
+                                                                    }
+                                                                    insert.Parameters.Clear();
+                                                                    insert.Parameters.AddWithValue("@Id", voucher.Id);
+                                                                    insert.Parameters.AddWithValue("@SequenceNumber", voucher.SequenceNumber);
+                                                                    insert.Parameters.AddWithValue("@ExpiryDate", voucher.ExpiryDate.Date);
+                                                                    insert.Parameters.AddWithValue("@Serial", voucher.Serial);
+                                                                    insert.Parameters.AddWithValue("@EncryptedPIN", voucher.EncryptedPIN);
+                                                                    insert.Parameters.AddWithValue("@BatchId", batchId);
+                                                                    insert.ExecuteNonQuery();
+                                                                    voucherCount++;
+                                                                }
+                                                            }
+                                                            trans.Commit();
+                                                        }
+                                                    }
+
+                                                    Log.Debug("Inserted vouchers for batch {0}", batchId);
+
+                                                    lock (_lock)
+                                                    {
+                                                        isCancelled = _cancelled;
+                                                    }
+                                                }
+
+                                                if (voucherCount > batch.DeliveredQuantity)
+                                                {
+                                                    throw new Exception("Batch contains more than the specified number of vouchers");
+                                                }
+                                                else if (voucherCount == batch.DeliveredQuantity)
+                                                {
+                                                    Log.Debug("Batch {0} complete", batchId);
+
+                                                    _db.ExecuteNonQuery(
+                                                        "UPDATE Batch SET Downloaded=1 WHERE Id=@BatchId",
+                                                        new SQLiteParameter("@BatchId", batchId));
+                                                }
+                                            }
+                                        }
+                                        else if (batch == null)
+                                        {
+                                            // Batch will only be null if we got a 404.
+                                            Log.Debug("Removing deleted batch {0}", batchId);
+
+                                            _db.ExecuteNonQuery(
+                                                "DELETE FROM Voucher WHERE BatchId=@BatchId",
+                                                new SQLiteParameter("@BatchId", batchId));
+
+                                            _db.ExecuteNonQuery(
+                                                "DELETE FROM Batch WHERE Id=@BatchId",
+                                                new SQLiteParameter("@BatchId", batchId));
+
+                                            doRefresh = true;
+                                        }
+                                        // else retry later
+                                    }
+                                    catch (Exception e)
+                                    {
+                                        Log.Error(e, "Error while downloading vouchers for batch {0}", batchId);
+                                    }
+
+                                    if (!isCancelled && doRefresh)
+                                    {
+                                        doRefresh = false;
+                                        _refreshAction();
+                                    }
+
+                                    lock(_lock)
+                                    {
+                                        isCancelled = _cancelled;
+                                    }
+                                }
+                            }
+                        }
+                    }
+                    catch (Exception e)
+                    {
+                        Log.Error(e, "Error while downloading vouchers");
+                    }
+                }
+                else
+                {
+                    Log.Debug("Offline, skipping download check");
+                }
+
+                Log.Debug("Download thread sleeping");
+
+                lock (_lock)
+                {
+                    while (!_cancelled && !_checkForNewBatches)
+                    {
+                        if (! Monitor.Wait(_lock, _retryInterval))
+                        {
+                            // Timed out. Retry downloads.
+                            break;
+                        }
+                    }
+                    if (_checkForNewBatches)
+                    {
+                        _checkForNewBatches = false;
+                        skipNewBatchCheck = false;
+                    }
+                    isCancelled = _cancelled;
+                }
+
+                Log.Debug("Download thread woke up, cancelled={0}", isCancelled);
+            }
+        }
+    }
+}

BulkPrinting/BulkPrinting/BatchForm.Designer.cs

@@ -53,7 +53,6 @@
             this.dgvBatches = new System.Windows.Forms.DataGridView();
             this.LogoutTimer = new System.Windows.Forms.Timer(this.components);
             this.lblLoading = new System.Windows.Forms.Label();
-            this.ReSyncTimer = new System.Windows.Forms.Timer(this.components);
             this.pnlSplitGrids.SuspendLayout();
             this.grpFilter.SuspendLayout();
             ((System.ComponentModel.ISupportInitialize)(this.dgvBatches)).BeginInit();
@@ -365,11 +364,6 @@
             this.lblLoading.TabIndex = 6;
             this.lblLoading.Text = "Loading...";
             // 
-            // ReSyncTimer
-            // 
-            this.ReSyncTimer.Interval = 30000;
-            this.ReSyncTimer.Tick += new System.EventHandler(this.ReSyncTimer_Tick);
-            // 
             // BatchForm
             // 
             this.AutoScaleDimensions = new System.Drawing.SizeF(8F, 16F);
@@ -419,7 +413,6 @@
         private System.Windows.Forms.RadioButton rdoFilterReprinted;
         private System.Windows.Forms.RadioButton rdoFilterUnprinted;
         private System.Windows.Forms.RadioButton rdoFilterPrinted;
-        private System.Windows.Forms.Timer ReSyncTimer;
     }
 }
 

BulkPrinting/BulkPrinting/BatchForm.cs

@@ -2,21 +2,16 @@
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Data.SQLite;
-using System.Diagnostics;
 using System.Drawing;
 using System.Globalization;
-using System.Threading;
+using System.Security.Permissions;
 using System.Windows.Forms;
-using Serilog;
 
 namespace BulkPrinting
 {
     public partial class BatchForm : ObservedForm
     {
-        Thread LoadingThread;
-        readonly object LoadingThreadLock = new object();
-        bool CheckForNewBatches;
-        bool RetryDownloads;
+        private BatchDownloader BatchDownloader;
 
         public BatchForm()
         {
@@ -258,254 +253,36 @@ namespace BulkPrinting
             dtpFilterStartDate.Value = DateTime.Now.AddMonths(-3);
             Globals.OpenBatches = new List<int>();
 
-            RetryDownloads = true;
-            CheckForNewBatches = true;
+            var hwnd = new System.Runtime.InteropServices.HandleRef(this, Handle);
+            BatchDownloader = new BatchDownloader(Globals.DB, () =>
+            {
+                // DO NOT use Invoke as this can cause a deadlock if we are attempting to join the BatchDownloader after a cancel.
+                // Also, use PostMessage rather than SendMessage as PostMessage doesn't wait for the message to be processed and
+                // therefore won't block.
+                Utility.PostMessage(hwnd, Utility.WM_USER, IntPtr.Zero, IntPtr.Zero);
+            });
+            BatchDownloader.Start();
 
-            LoadingThread = new Thread(LoadingThreadWorker);
-            LoadingThread.Start();
             Utility.InitialiseUserLimits(Globals.DB);
-            ReSyncTimer.Enabled = true;
+
+            PopulateGrid();
         }
 
-        private void LoadingThreadWorker()
+        [SecurityPermissionAttribute(SecurityAction.InheritanceDemand, Flags = SecurityPermissionFlag.UnmanagedCode)]
+        [SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags = SecurityPermissionFlag.UnmanagedCode)]
+        protected override void WndProc(ref Message m)
         {
-            const int voucherPageSize = 5000;
-            var db = Globals.DB;
-            //using (var db = Utility.OpenDBConnection())
+            if (m.Msg == Utility.WM_USER)
             {
-                Invoke(new Action(() =>
-                {
-                    PopulateGrid();
-                }));
-
-                var lastSyncedBatchId = Utility.GetSavedParameterAsInt(db, "LastSyncedBatchId");
-
-                bool skipNewBatchCheck = false;
-                while (true)
-                {
-                    Log.Debug("Download thread sleeping");
-
-                    bool forceNewBatchCheck;
-                    lock (LoadingThreadLock)
-                    {
-                        while (!RetryDownloads)
-                        {
-                            Monitor.Wait(LoadingThreadLock);
-                        }
-                        forceNewBatchCheck = CheckForNewBatches;
-                        RetryDownloads = false;
-                        CheckForNewBatches = false;
-                    }
-
-                    Log.Debug("Download thread woke up");
-
-                    if (Globals.SessionMode == SessionModes.Online)
-                    {
-                        Log.Debug("Checking for downloads");
-
-                        if (forceNewBatchCheck)
-                        {
-                            skipNewBatchCheck = false;
-                        }
-
-                        // Check for new batches if required.
-                        var refreshGrid = false;
-                        try
-                        {
-                            while (!skipNewBatchCheck)
-                            {
-                                Log.Debug("Querying batches");
-
-                                Page<Batch> BatchPage = new Page<Batch>();
-                                if (Utility.RESTRequest(ref BatchPage, String.Format("/api/batches/?minBatchId={0}", lastSyncedBatchId + 1)))
-                                {
-                                    if (BatchPage.Items.Count == 0)
-                                    {
-                                        // No more new batches, so stop checking until an order is placed.
-                                        skipNewBatchCheck = true;
-                                    }
-                                    else
-                                    {
-                                        foreach (var batch in BatchPage.Items)
-                                        {
-                                            refreshGrid = true;
-                                            Utility.SaveBatch(db, batch);
-                                            lastSyncedBatchId = batch.Id;
-                                            if (!Utility.UpdateSavedParameter(db, "LastSyncedBatchId", lastSyncedBatchId))
-                                            {
-                                                // Shouldn't happen.
-                                                throw new Exception("Failed to update LastSyncedBatchId");
-                                            }
-                                        }
-                                    }
-                                }
-                                else
-                                {
-                                    // Error, so leave skipNewBatchCheck unchanged.
-                                    break;
-                                }
-                            }
-                        }
-                        catch (Exception e)
-                        {
-                            Log.Error(e, "Error while downloading batch list");
-                        }
-
-                        if (refreshGrid)
-                        {
-                            Invoke(new Action(() =>
-                            {
-                                PopulateGrid();
-                            }));
-                        }
-
-                        // Continue downloading incomplete batches if any.
-                        try
-                        {
-                            using (var command = db.CreateCommand("SELECT Id FROM Batch WHERE Downloaded=0 ORDER BY Downloaded, Id"))
-                            {
-                                using (SQLiteDataReader row = command.ExecuteReader())
-                                {
-                                    while (row.Read())
-                                    {
-                                        refreshGrid = false;
-
-                                        int batchId = (int)row["Id"];
-                                        try
-                                        {
-                                            Batch batch = new Batch();
-                                            if (Utility.RESTRequest(ref batch, String.Format("/api/batches/{0}", batchId)))
-                                            {
-                                                refreshGrid = true;
-                                                Utility.SaveBatch(db, batch);
-
-                                                if (batch.ReadyForDownload)
-                                                {
-                                                    long result = (long)db.ExecuteScalar(
-                                                        "SELECT COUNT(*) FROM Voucher WHERE BatchId=@BatchId",
-                                                        new SQLiteParameter("@BatchId", batchId));
-                                                    int voucherCount = (int)result;
-
-                                                    while (voucherCount < batch.DeliveredQuantity)
-                                                    {
-                                                        Log.Debug("Downloading vouchers for batch {0} ({1} so far)", batchId, voucherCount);
-
-                                                        int page = voucherCount / voucherPageSize + 1;
-                                                        int offset = voucherCount % voucherPageSize;
-
-                                                        Page<Voucher> voucherPage = new Page<Voucher>();
-                                                        if (!Utility.RESTRequest(ref voucherPage, String.Format("/api/batches/{0}/vouchers/?page={1}&pageSize={2}", batchId, page, voucherPageSize)))
-                                                        {
-                                                            break;
-                                                        }
-                                                        if (voucherPage.Items.Count == 0)
-                                                        {
-                                                            throw new Exception(String.Format("Too few vouchers were returned for batch {0}", batchId));
-                                                        }
-
-                                                        Log.Debug("Downloaded vouchers for batch {0} ({1} so far)", batchId, voucherCount);
-
-                                                        lock (db.WriteLock)
-                                                        {
-                                                            using (var trans = db.BeginTransaction())
-                                                            {
-                                                                using (var insert = db.CreateCommand(
-                                                                    "INSERT INTO Voucher (Id, SequenceNumber, ExpiryDate, Serial, EncryptedPIN, BatchId)" +
-                                                                                 "VALUES (@Id,@SequenceNumber,@ExpiryDate,@Serial,@EncryptedPin,@BatchId)",
-                                                                    trans))
-                                                                {
-                                                                    for (var i = offset; i < voucherPage.Items.Count; i++)
-                                                                    {
-                                                                        var voucher = voucherPage.Items[i];
-                                                                        if (voucher.SequenceNumber != voucherCount + 1)
-                                                                        {
-                                                                            throw new Exception(String.Format("Vouchers for batch {0} are not sequential: expecting {1}, got {2}", batchId, voucherCount + 1, voucher.SequenceNumber));
-                                                                        }
-                                                                        insert.Parameters.Clear();
-                                                                        insert.Parameters.AddWithValue("@Id", voucher.Id);
-                                                                        insert.Parameters.AddWithValue("@SequenceNumber", voucher.SequenceNumber);
-                                                                        insert.Parameters.AddWithValue("@ExpiryDate", voucher.ExpiryDate.Date);
-                                                                        insert.Parameters.AddWithValue("@Serial", voucher.Serial);
-                                                                        insert.Parameters.AddWithValue("@EncryptedPIN", voucher.EncryptedPIN);
-                                                                        insert.Parameters.AddWithValue("@BatchId", batchId);
-                                                                        insert.ExecuteNonQuery();
-                                                                        voucherCount++;
-                                                                    }
-                                                                }
-                                                                trans.Commit();
-                                                            }
-                                                        }
-
-                                                        Log.Debug("Inserted vouchers for batch {0}", batchId);
-                                                    }
-
-                                                    if (voucherCount > batch.DeliveredQuantity)
-                                                    {
-                                                        throw new Exception("Batch contains more than the specified number of vouchers");
-                                                    }
-                                                    else
-                                                    {
-                                                        Log.Debug("Batch {0} complete", batchId);
-
-                                                        db.ExecuteNonQuery(
-                                                            "UPDATE Batch SET Downloaded=1 WHERE Id=@BatchId",
-                                                            new SQLiteParameter("@BatchId", batchId));
-                                                    }
-                                                }
-                                            }
-                                            else if (batch == null)
-                                            {
-                                                // Batch will only be null if we got a 404.
-                                                Log.Debug("Removing deleted batch {0}", batchId);
-
-                                                db.ExecuteNonQuery(
-                                                    "DELETE FROM Voucher WHERE BatchId=@BatchId",
-                                                    new SQLiteParameter("@BatchId", batchId));
-
-                                                db.ExecuteNonQuery(
-                                                    "DELETE FROM Batch WHERE Id=@BatchId",
-                                                    new SQLiteParameter("@BatchId", batchId));
-
-                                                refreshGrid = true;
-                                            }
-                                        }
-                                        catch (Exception e)
-                                        {
-                                            Log.Error(e, "Error while downloading vouchers for batch {0}", batchId);
-                                        }
-
-                                        if (refreshGrid)
-                                        {
-                                            Invoke(new Action(() =>
-                                            {
-                                                PopulateGrid();
-                                            }));
-                                        }
-                                    }
-                                }
-                            }
-                        }
-                        catch (Exception e)
-                        {
-                            Log.Error(e, "Error while downloading vouchers");
-                        }
-                    }
-                    else
-                    {
-                        Log.Debug("Offline, skipping download check");
-                    }
-                }
+                PopulateGrid();
+                return;
             }
+            base.WndProc(ref m);
         }
 
         public void NewBatchAvailable()
         {
-            lock (LoadingThreadLock)
-            {
-                RetryDownloads = true;
-                CheckForNewBatches = true;
-                Monitor.Pulse(LoadingThreadLock);
-            }
+            BatchDownloader.CheckForNewBatches();
         }
 
         private void btnOrder_Click(object sender, EventArgs e)
@@ -588,11 +365,12 @@ namespace BulkPrinting
                 return;
             }
 
-            if ((LoadingThread != null) && (LoadingThread.IsAlive))
+            if (BatchDownloader != null)
             {
-                LoadingThread.Abort();
-                LoadingThread.Join();
+                BatchDownloader.Cancel();
+                BatchDownloader.Join();
             }
+
             Utility.Logout();
         }
 
@@ -774,14 +552,5 @@ namespace BulkPrinting
                 e.Graphics.DrawImage(b.BackgroundImage, b.ClientRectangle);
             }
         }
-
-        private void ReSyncTimer_Tick(object sender, EventArgs e)
-        {
-            lock (LoadingThreadLock)
-            {
-                RetryDownloads = true;
-                Monitor.Pulse(LoadingThreadLock);
-            }
-        }
     }
 }

BulkPrinting/BulkPrinting/BatchForm.resx

@@ -123,9 +123,6 @@
   <metadata name="LogoutTimer.TrayLocation" type="System.Drawing.Point, System.Drawing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a">
     <value>277, 17</value>
   </metadata>
-  <metadata name="ReSyncTimer.TrayLocation" type="System.Drawing.Point, System.Drawing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a">
-    <value>398, 3</value>
-  </metadata>
   <metadata name="$this.TrayHeight" type="System.Int32, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
     <value>59</value>
   </metadata>

BulkPrinting/BulkPrinting/BulkPrinting.csproj

@@ -154,6 +154,7 @@
     <Reference Include="System.Xml" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="BatchDownloader.cs" />
     <Compile Include="Configuration.cs" />
     <Compile Include="DBHelper.cs" />
     <Compile Include="ExportForm.cs">

BulkPrinting/BulkPrinting/Utility.cs

@@ -7,15 +7,20 @@ using System.IO;
 using System.Linq;
 using System.Management;
 using System.Net;
+using System.Runtime.InteropServices;
 using System.Security.Cryptography;
 using System.Text;
-using System.Threading;
 using System.Windows.Forms;
 
 namespace BulkPrinting
 {
     public class Utility
     {
+        public const int WM_USER = 0x400;
+
+        [DllImport("user32.dll", SetLastError = true)]
+        public static extern bool PostMessage(HandleRef hWnd, uint Msg, IntPtr wParam, IntPtr lParam);
+
         public static string GetHDDSerial()
         {
             ManagementObjectSearcher managementObjectSearcher = new ManagementObjectSearcher("SELECT * FROM Win32_PhysicalMedia");