From 33f2c2b1d29731f890d3835032d911610e4fc69d Mon Sep 17 00:00:00 2001
From: dec05eba <dec05eba@protonmail.com>
Date: Wed, 16 May 2018 12:02:40 +0200
Subject: Unload content if it's not visible on the screen for a while

---
 src/Cache.cpp | 51 +++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 49 insertions(+), 2 deletions(-)

(limited to 'src/Cache.cpp')

diff --git a/src/Cache.cpp b/src/Cache.cpp
index 1295475..15af6e7 100644
--- a/src/Cache.cpp
+++ b/src/Cache.cpp
@@ -24,9 +24,10 @@ using namespace TinyProcessLib;
 
 namespace dchat
 {
-    unordered_map<string, ContentByUrlResult> contentUrlCache;
+    static unordered_map<string, ContentByUrlResult> contentUrlCache;
+    const i64 CONTENT_NOT_VISIBLE_AGE_MS = 20000; // Delete content from cache after a specified amount of time if the content is not visible on the screen
     
-    boost::filesystem::path getHomeDir()
+    static boost::filesystem::path getHomeDir()
     {
     #if OS_FAMILY == OS_FAMILY_POSIX
         const char *homeDir = getenv("HOME");
@@ -209,6 +210,7 @@ namespace dchat
                         else
                         {
                             contentByUrlResult = loadImageFromFile(filepath);
+                            contentByUrlResult.lastAccessed = chrono::duration_cast<chrono::milliseconds>(chrono::steady_clock::now().time_since_epoch()).count();
                             if(contentByUrlResult.type == ContentByUrlResult::Type::CACHED)
                             {
                                 printf("Download content from url: %s\n", it->url.c_str());
@@ -246,12 +248,53 @@ namespace dchat
                 this_thread::sleep_for(chrono::milliseconds(20));
             }
         });
+        
+        checkContentAccessTimeThread = thread([this]
+        {
+            while(alive)
+            {
+                this_thread::sleep_for(chrono::milliseconds(500));
+                lock_guard<mutex> lock(imageDownloadMutex);
+                
+                i64 now = chrono::duration_cast<chrono::milliseconds>(chrono::steady_clock::now().time_since_epoch()).count();
+                for(unordered_map<string, ContentByUrlResult>::iterator it = contentUrlCache.begin(); it != contentUrlCache.end();)
+                {
+                    if(it->second.type == ContentByUrlResult::Type::CACHED && now - it->second.lastAccessed > CONTENT_NOT_VISIBLE_AGE_MS)
+                    {
+                        switch(it->second.cachedType)
+                        {
+                            case ContentByUrlResult::CachedType::TEXTURE:
+                            {
+                                delete it->second.texture;
+                                break;
+                            }
+                            case ContentByUrlResult::CachedType::GIF:
+                            {
+                                delete it->second.gif;
+                                break;
+                            }
+                            case ContentByUrlResult::CachedType::WEB_PAGE_PREVIEW:
+                            {
+                                delete it->second.webPagePreview;
+                                break;
+                            }
+                            default:
+                                break;
+                        }
+                        it = contentUrlCache.erase(it);
+                    }
+                    else
+                        ++it;
+                }
+            }
+        });
     }
     
     Cache::~Cache()
     {
         alive = false;
         downloadWaitThread.join();
+        checkContentAccessTimeThread.join();
     }
     
     void replaceFileIgnoreError(const boost::filesystem::path &path)
@@ -271,7 +314,10 @@ namespace dchat
         lock_guard<mutex> lock(imageDownloadMutex);
         auto it = contentUrlCache.find(url);
         if(it != contentUrlCache.end())
+        {
+            it->second.lastAccessed = chrono::duration_cast<chrono::milliseconds>(chrono::steady_clock::now().time_since_epoch()).count();
             return it->second;
+        }
         
         // TODO: Verify hashed url is not too long for filepath on windows
         boost::filesystem::path filepath = getImagesDir();
@@ -292,6 +338,7 @@ namespace dchat
         ContentByUrlResult contentByUrlResult = loadImageFromFile(filepath);
         if(contentByUrlResult.type == ContentByUrlResult::Type::CACHED)
         {
+            contentByUrlResult.lastAccessed = chrono::duration_cast<chrono::milliseconds>(chrono::steady_clock::now().time_since_epoch()).count();
             contentUrlCache[url] = contentByUrlResult;
             printf("Loaded content from file cache: %s\n", url.c_str());
             return contentByUrlResult;
-- 
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