Merge branch 'dont-ask-the-disk-for-things-we-already-know' into 'master'

Avoid IO in resolveParentFileIndices

See merge request OpenMW/openmw!4627

Author: Capostrophic

apps/components_tests/esm3/readerscache.cpp

@@ -88,4 +88,31 @@ namespace
             EXPECT_EQ(reader->getFileOffset(), sInitialOffset);
         }
     }
+
+    TEST_F(ESM3ReadersCacheWithContentFile, CachedSizeAndName)
+    {
+        ESM::ReadersCache readers(2);
+        {
+            readers.get(0)->openRaw(std::make_unique<std::istringstream>("123"), "closed0.omwaddon");
+            readers.get(1)->openRaw(std::make_unique<std::istringstream>("12345"), "closed1.omwaddon");
+            readers.get(2)->openRaw(std::make_unique<std::istringstream>("1234567"), "free.omwaddon");
+        }
+        auto busy = readers.get(3);
+        busy->openRaw(std::make_unique<std::istringstream>("123456789"), "busy.omwaddon");
+
+        EXPECT_EQ(readers.getFileSize(0), 3);
+        EXPECT_EQ(readers.getName(0), "closed0.omwaddon");
+
+        EXPECT_EQ(readers.getFileSize(1), 5);
+        EXPECT_EQ(readers.getName(1), "closed1.omwaddon");
+
+        EXPECT_EQ(readers.getFileSize(2), 7);
+        EXPECT_EQ(readers.getName(2), "free.omwaddon");
+
+        EXPECT_EQ(readers.getFileSize(3), 9);
+        EXPECT_EQ(readers.getName(3), "busy.omwaddon");
+
+        // not-yet-seen indices give zero for their size
+        EXPECT_EQ(readers.getFileSize(4), 0);
+    }
 }

components/esm3/esmreader.cpp

@@ -73,10 +73,10 @@ namespace ESM
             int index = getIndex();
             for (int i = 0; i < getIndex(); i++)
             {
-                const ESM::ReadersCache::BusyItem reader = readers.get(static_cast<std::size_t>(i));
-                if (reader->getFileSize() == 0)
+                if (readers.getFileSize(static_cast<std::size_t>(i)) == 0)
                     continue; // Content file in non-ESM format
-                const auto fnamecandidate = Files::pathToUnicodeString(reader->getName().filename());
+                const auto fnamecandidate
+                    = Files::pathToUnicodeString(readers.getName(static_cast<std::size_t>(i)).filename());
                 if (Misc::StringUtils::ciEqual(fname, fnamecandidate))
                 {
                     index = i;

components/esm3/readerscache.cpp

@@ -47,6 +47,7 @@ namespace ESM
                     {
                         it->mReader.open(*it->mName);
                         it->mName.reset();
+                        it->mFileSize.reset();
                     }
                     mBusyItems.splice(mBusyItems.end(), mClosedItems, it);
                     break;
@@ -57,6 +58,46 @@ namespace ESM
         return BusyItem(*this, it);
     }
 
+    const std::filesystem::path& ReadersCache::getName(std::size_t index) const
+    {
+        const auto indexIt = mIndex.find(index);
+        if (indexIt == mIndex.end())
+            throw std::logic_error("ESMReader at index " + std::to_string(index) + " has not been created yet");
+        switch (indexIt->second->mState)
+        {
+            case State::Busy:
+            case State::Free:
+                return indexIt->second->mReader.getName();
+            case State::Closed:
+                if (indexIt->second->mName)
+                    return *indexIt->second->mName;
+                throw std::logic_error("ESMReader at index " + std::to_string(index) + " has forgotten its filename");
+            default:
+                throw std::logic_error("ESMReader at index " + std::to_string(index) + " in unknown state");
+        }
+    }
+
+    std::size_t ReadersCache::getFileSize(std::size_t index)
+    {
+        const auto indexIt = mIndex.find(index);
+        if (indexIt == mIndex.end())
+            return 0;
+        switch (indexIt->second->mState)
+        {
+            case State::Busy:
+            case State::Free:
+                if (!indexIt->second->mReader.getName().empty())
+                    return indexIt->second->mReader.getFileSize();
+                throw std::logic_error("ESMReader at index " + std::to_string(index) + " has not been opened yet");
+            case State::Closed:
+                if (indexIt->second->mFileSize)
+                    return *indexIt->second->mFileSize;
+                throw std::logic_error("ESMReader at index " + std::to_string(index) + " has forgotten its file size");
+            default:
+                throw std::logic_error("ESMReader at index " + std::to_string(index) + " in unknown state");
+        }
+    }
+
     void ReadersCache::closeExtraReaders()
     {
         while (!mFreeItems.empty() && mBusyItems.size() + mFreeItems.size() + 1 > mCapacity)
@@ -65,6 +106,7 @@ namespace ESM
             if (it->mReader.isOpen())
             {
                 it->mName = it->mReader.getName();
+                it->mFileSize = it->mReader.getFileSize();
                 it->mReader.close();
             }
             mClosedItems.splice(mClosedItems.end(), mFreeItems, it);

components/esm3/readerscache.hpp

@@ -26,6 +26,7 @@ namespace ESM
             State mState = State::Busy;
             ESMReader mReader;
             std::optional<std::filesystem::path> mName;
+            std::optional<std::size_t> mFileSize;
 
             Item() = default;
         };
@@ -55,6 +56,10 @@ namespace ESM
 
         BusyItem get(std::size_t index);
 
+        const std::filesystem::path& getName(std::size_t index) const;
+
+        std::size_t getFileSize(std::size_t index);
+
         void clear();
 
     private: