From 55c529f4323f3cd5e2dc629238c76b32ae0d79db Mon Sep 17 00:00:00 2001
From: n0099 <n@n0099.net>
Date: Wed, 12 Jun 2024 20:42:33 +0000
Subject: [PATCH] * move invocations to`IPostSaver.Save()` & `UserSaver.Save()`
 inside try block to ensure their `OnPostSave()` get invoked in finally block
 even if exception was thrown to fix 388ddc9026ef45491d7db448a4e50f6a27024d3d
 @ `CrawlFacade.SaveCrawled()`

* move the action returned by `Save()` into `IDisposable.Dispose()` to allow locks also get released by GC
* lift variable `(newly|already)LockedImages` from method `Save()` to nullable class field
@ ReplyContentImageSaver.cs
@ c#/crawler
---
 .../src/Tieba/Crawl/Facade/CrawlFacade.cs     | 17 +++----
 .../Crawl/Saver/ReplyContentImageSaver.cs     | 48 ++++++++++---------
 2 files changed, 35 insertions(+), 30 deletions(-)

diff --git a/c#/crawler/src/Tieba/Crawl/Facade/CrawlFacade.cs b/c#/crawler/src/Tieba/Crawl/Facade/CrawlFacade.cs
index 13644ce7..2f30ed11 100644
--- a/c#/crawler/src/Tieba/Crawl/Facade/CrawlFacade.cs
+++ b/c#/crawler/src/Tieba/Crawl/Facade/CrawlFacade.cs
@@ -47,20 +47,21 @@ public virtual void Dispose()
             using var transaction = db.Database.BeginTransaction(IsolationLevel.ReadCommitted);
 
             var postSaver = postSaverFactory(Posts);
-            var savedPosts = Posts.IsEmpty ? null : postSaver.Save(db);
-
             var userSaver = userSaverFactory(_users);
-            userSaver.Save(db,
-                postSaver.CurrentPostType,
-                postSaver.UserFieldUpdateIgnorance,
-                postSaver.UserFieldRevisionIgnorance);
-
-            OnBeforeCommitSave(db, userSaver);
             try
             {
+                var savedPosts = Posts.IsEmpty ? null : postSaver.Save(db);
+                userSaver.Save(db,
+                    postSaver.CurrentPostType,
+                    postSaver.UserFieldUpdateIgnorance,
+                    postSaver.UserFieldRevisionIgnorance);
+
+                OnBeforeCommitSave(db, userSaver);
+
                 db.TimestampingEntities();
                 _ = db.SaveChanges();
                 transaction.Commit();
+
                 if (savedPosts != null) OnPostCommitSave(savedPosts, stoppingToken);
                 return savedPosts;
             }
diff --git a/c#/crawler/src/Tieba/Crawl/Saver/ReplyContentImageSaver.cs b/c#/crawler/src/Tieba/Crawl/Saver/ReplyContentImageSaver.cs
index 5c66bd3d..9f06fb3c 100644
--- a/c#/crawler/src/Tieba/Crawl/Saver/ReplyContentImageSaver.cs
+++ b/c#/crawler/src/Tieba/Crawl/Saver/ReplyContentImageSaver.cs
@@ -1,9 +1,26 @@
 namespace tbm.Crawler.Tieba.Crawl.Saver;
 
-public class ReplyContentImageSaver(ILogger<ReplyContentImageSaver> logger)
+public sealed class ReplyContentImageSaver(ILogger<ReplyContentImageSaver> logger) : IDisposable
 {
     private static readonly ConcurrentDictionary<string, ImageInReply>
         GlobalLockedImagesInReplyKeyByUrlFilename = new();
+    private Dictionary<string, ImageInReply>? _newlyLockedImages;
+    private Dictionary<string, ImageInReply>? _alreadyLockedImages;
+
+    public void Dispose()
+    {
+        try
+        {
+            if (_newlyLockedImages != null && _newlyLockedImages.Any(pair =>
+                    !GlobalLockedImagesInReplyKeyByUrlFilename.TryRemove(pair)))
+                throw new InvalidOperationException();
+        }
+        finally
+        {
+            _newlyLockedImages?.Values().ForEach(Monitor.Exit);
+            _alreadyLockedImages?.Values().ForEach(Monitor.Exit);
+        }
+    }
 
     public Action Save(CrawlerDbContext db, IEnumerable<ReplyPost> replies)
     {
@@ -36,28 +53,28 @@ where images.Keys.Contains(e.UrlFilename)
         var newImages = images
             .ExceptByKey(existingImages.Keys).ToDictionary();
 
-        var newlyLockedImages = newImages
+        _newlyLockedImages = newImages
             .Where(pair => GlobalLockedImagesInReplyKeyByUrlFilename.TryAdd(pair.Key, pair.Value))
             .ToDictionary();
-        newlyLockedImages.Values()
+        _newlyLockedImages.Values()
             .Where(image => !Monitor.TryEnter(image, TimeSpan.FromSeconds(10)))
             .ForEach(image => logger.LogWarning(
                 "Wait for locking newly locked image {} timed out after 10s", image.UrlFilename));
 
-        var alreadyLockedImages = GlobalLockedImagesInReplyKeyByUrlFilename
+        _alreadyLockedImages = GlobalLockedImagesInReplyKeyByUrlFilename
             .IntersectByKey(newImages
-                .Keys().Except(newlyLockedImages.Keys()))
+                .Keys().Except(_newlyLockedImages.Keys()))
             .ToDictionary();
-        alreadyLockedImages.Values()
+        _alreadyLockedImages.Values()
             .Where(image => !Monitor.TryEnter(image, TimeSpan.FromSeconds(10)))
             .ForEach(image => logger.LogWarning(
                 "Wait for locking already locked image {} timed out after 10s", image.UrlFilename));
 
-        if (alreadyLockedImages.Count != 0)
+        if (_alreadyLockedImages.Count != 0)
             existingImages = existingImages
                 .Concat((
                     from e in db.ImageInReplies.AsTracking()
-                    where alreadyLockedImages.Keys().Contains(e.UrlFilename)
+                    where _alreadyLockedImages.Keys().Contains(e.UrlFilename)
                     select e).ToDictionary(e => e.UrlFilename))
                 .ToDictionary();
         (from existing in existingImages.Values
@@ -88,19 +105,6 @@ on existing.UrlFilename equals replyContentImage.ImageInReply.UrlFilename
             .ExceptBy(existingReplyContentImages.Select(e => (e.Pid, e.UrlFilename)),
                 e => (e.Pid, e.ImageInReply.UrlFilename)));
 
-        return () =>
-        {
-            try
-            {
-                if (newlyLockedImages.Any(pair =>
-                        !GlobalLockedImagesInReplyKeyByUrlFilename.TryRemove(pair)))
-                    throw new InvalidOperationException();
-            }
-            finally
-            {
-                newlyLockedImages.Values().ForEach(Monitor.Exit);
-                alreadyLockedImages.Values().ForEach(Monitor.Exit);
-            }
-        };
+        return Dispose;
     }
 }