refactor PluginsManifest to use conditional requests

Author: JohnTheGr8

Flow.Launcher.Core/ExternalPlugins/PluginsManifest.cs

@@ -1,7 +1,8 @@
-using Flow.Launcher.Infrastructure.Http;
 using Flow.Launcher.Infrastructure.Logger;
 using System;
 using System.Collections.Generic;
+using System.Net;
+using System.Net.Http;
 using System.Text.Json;
 using System.Threading;
 using System.Threading.Tasks;
@@ -10,43 +11,45 @@ namespace Flow.Launcher.Core.ExternalPlugins
 {
     public static class PluginsManifest
     {
-        static PluginsManifest()
-        {
-            UpdateTask = UpdateManifestAsync();
-        }
-
-        public static List<UserPlugin> UserPlugins { get; private set; } = new List<UserPlugin>();
+        private const string manifestFileUrl = "https://raw.githubusercontent.com/Flow-Launcher/Flow.Launcher.PluginsManifest/plugin_api_v2/plugins.json";
 
-        public static Task UpdateTask { get; private set; }
+        private static HttpClient httpClient = new HttpClient();
 
         private static readonly SemaphoreSlim manifestUpdateLock = new(1);
 
-        public static Task UpdateManifestAsync()
-        {
-            if (manifestUpdateLock.CurrentCount == 0)
-            {
-                return UpdateTask;
-            }
+        private static string latestEtag = "";
 
-            return UpdateTask = DownloadManifestAsync();
-        }
+        public static List<UserPlugin> UserPlugins { get; private set; } = new List<UserPlugin>();
 
-        private static async Task DownloadManifestAsync()
+        public static async Task UpdateManifestAsync()
         {
             try
             {
                 await manifestUpdateLock.WaitAsync().ConfigureAwait(false);
 
-                await using var jsonStream = await Http.GetStreamAsync("https://raw.githubusercontent.com/Flow-Launcher/Flow.Launcher.PluginsManifest/plugin_api_v2/plugins.json")
-                                 .ConfigureAwait(false);
+                var request = new HttpRequestMessage(HttpMethod.Get, manifestFileUrl);
+                request.Headers.Add("If-None-Match", latestEtag);
+
+                var response = await httpClient.SendAsync(request).ConfigureAwait(false);
+
+                if (response.StatusCode == HttpStatusCode.OK)
+                {
+                    Log.Info($"|PluginsManifest.{nameof(UpdateManifestAsync)}|Fetched plugins from manifest repo");
 
-                UserPlugins = await JsonSerializer.DeserializeAsync<List<UserPlugin>>(jsonStream).ConfigureAwait(false);
+                    var json = await response.Content.ReadAsStreamAsync().ConfigureAwait(false);
+
+                    UserPlugins = await JsonSerializer.DeserializeAsync<List<UserPlugin>>(json).ConfigureAwait(false);
+
+                    latestEtag = response.Headers.ETag.Tag;
+                }
+                else if (response.StatusCode != HttpStatusCode.NotModified)
+                {
+                    Log.Warn($"|PluginsManifest.{nameof(UpdateManifestAsync)}|Http response for manifest file was {response.StatusCode}");
+                }
             }
             catch (Exception e)
             {
-                Log.Exception("|PluginManagement.GetManifest|Encountered error trying to download plugins manifest", e);
-
-                UserPlugins = new List<UserPlugin>();
+                Log.Exception($"|PluginsManifest.{nameof(UpdateManifestAsync)}|Http request failed", e);
             }
             finally
             {

Plugins/Flow.Launcher.Plugin.PluginsManager/Main.cs

@@ -24,8 +24,6 @@ public class Main : ISettingProvider, IAsyncPlugin, IContextMenu, IPluginI18n, I
 
         internal PluginsManager pluginManager;
 
-        private DateTime lastUpdateTime = DateTime.MinValue;
-
         public Control CreateSettingPanel()
         {
             return new PluginsManagerSettings(viewModel);
@@ -38,12 +36,6 @@ public Task InitAsync(PluginInitContext context)
             viewModel = new SettingsViewModel(context, Settings);
             contextMenu = new ContextMenu(Context);
             pluginManager = new PluginsManager(Context, Settings);
-            _manifestUpdateTask = pluginManager
-                .UpdateManifestAsync(true)
-                .ContinueWith(_ =>
-                {
-                    lastUpdateTime = DateTime.Now;
-                }, TaskContinuationOptions.OnlyOnRanToCompletion);
 
             return Task.CompletedTask;
         }
@@ -53,23 +45,13 @@ public List<Result> LoadContextMenus(Result selectedResult)
             return contextMenu.LoadContextMenus(selectedResult);
         }
 
-        private Task _manifestUpdateTask = Task.CompletedTask;
-
         public async Task<List<Result>> QueryAsync(Query query, CancellationToken token)
         {
             var search = query.Search;
 
             if (string.IsNullOrWhiteSpace(search))
                 return pluginManager.GetDefaultHotKeys();
 
-            if ((DateTime.Now - lastUpdateTime).TotalHours > 12 && _manifestUpdateTask.IsCompleted) // 12 hours
-            {
-                _manifestUpdateTask = pluginManager.UpdateManifestAsync().ContinueWith(t =>
-                {
-                    lastUpdateTime = DateTime.Now;
-                }, TaskContinuationOptions.OnlyOnRanToCompletion);
-            }
-
             return search switch
             {
                 //search could be url, no need ToLower() when passed in
@@ -100,7 +82,6 @@ public string GetTranslatedPluginDescription()
         public async Task ReloadDataAsync()
         {
             await pluginManager.UpdateManifestAsync();
-            lastUpdateTime = DateTime.Now;
         }
     }
 }

Plugins/Flow.Launcher.Plugin.PluginsManager/PluginsManager.cs

@@ -59,7 +59,7 @@ internal Task UpdateManifestAsync(bool silent = false)
             }
             else
             {
-                _downloadManifestTask = PluginsManifest.UpdateTask;
+                _downloadManifestTask = PluginsManifest.UpdateManifestAsync();
                 if (!silent)
                     _downloadManifestTask.ContinueWith(_ =>
                             Context.API.ShowMsg(Context.API.GetTranslation("plugin_pluginsmanager_update_failed_title"),
@@ -181,10 +181,7 @@ internal async Task InstallOrUpdate(UserPlugin plugin)
 
         internal async ValueTask<List<Result>> RequestUpdate(string search, CancellationToken token)
         {
-            if (!PluginsManifest.UserPlugins.Any())
-            {
-                await UpdateManifestAsync();
-            }
+            await UpdateManifestAsync();
 
             token.ThrowIfCancellationRequested();
 
@@ -371,10 +368,7 @@ private bool InstallSourceKnown(string url)
 
         internal async ValueTask<List<Result>> RequestInstallOrUpdate(string searchName, CancellationToken token)
         {
-            if (!PluginsManifest.UserPlugins.Any())
-            {
-                await UpdateManifestAsync();
-            }
+            await UpdateManifestAsync();
 
             token.ThrowIfCancellationRequested();