Implement cache size limit

https://bugs.webkit.org/show_bug.cgi?id=140844 Reviewed by Andreas Kling. Prevent the cache from growing without bounds. The simple scheme implemented here estimates the cache size from number of entries. When the estimated size exceeds the maximum size we randomly clear 1/4 of the entries. * NetworkProcess/cache/NetworkCacheStorage.h: * NetworkProcess/cache/NetworkCacheStorageCocoa.mm: (WebKit::NetworkCacheStorage::NetworkCacheStorage): (WebKit::NetworkCacheStorage::initialize): (WebKit::NetworkCacheStorage::removeEntry): (WebKit::NetworkCacheStorage::store): (WebKit::NetworkCacheStorage::setMaximumSize): (WebKit::NetworkCacheStorage::clear): (WebKit::NetworkCacheStorage::shrinkIfNeeded): (WebKit::NetworkCacheStorage::initializeKeyFilter): Deleted. Canonical link: https://commits.webkit.org/158835@main git-svn-id: https://svn.webkit.org/repository/webkit/trunk@179052 268f45cc-cd09-0410-ab3c-d52691b4dbfc
WebKit · Jan 24, 2015 · 5a15d2a · 5a15d2a
1 parent 4fc82fc
commit 5a15d2a
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Showing 3 changed files with 89 additions and 12 deletions.
diff --git a/Source/WebKit2/ChangeLog b/Source/WebKit2/ChangeLog
@@ -1,3 +1,25 @@
+2015-01-23  Antti Koivisto  <antti@apple.com>
+
+        Implement cache size limit
+        https://bugs.webkit.org/show_bug.cgi?id=140844
+
+        Reviewed by Andreas Kling.
+
+        Prevent the cache from growing without bounds. The simple scheme implemented here
+        estimates the cache size from number of entries. When the estimated size exceeds
+        the maximum size we randomly clear 1/4 of the entries.
+
+        * NetworkProcess/cache/NetworkCacheStorage.h:
+        * NetworkProcess/cache/NetworkCacheStorageCocoa.mm:
+        (WebKit::NetworkCacheStorage::NetworkCacheStorage):
+        (WebKit::NetworkCacheStorage::initialize):
+        (WebKit::NetworkCacheStorage::removeEntry):
+        (WebKit::NetworkCacheStorage::store):
+        (WebKit::NetworkCacheStorage::setMaximumSize):
+        (WebKit::NetworkCacheStorage::clear):
+        (WebKit::NetworkCacheStorage::shrinkIfNeeded):
+        (WebKit::NetworkCacheStorage::initializeKeyFilter): Deleted.
+
 2015-01-23  Timothy Horton  <timothy_horton@apple.com>
 
         Fix the pre-Yosemite build.

diff --git a/Source/WebKit2/NetworkProcess/cache/NetworkCacheStorage.h b/Source/WebKit2/NetworkProcess/cache/NetworkCacheStorage.h
@@ -96,7 +96,8 @@ class NetworkCacheStorage {
 private:
     NetworkCacheStorage(const String& directoryPath);
 
-    void initializeKeyFilter();
+    void initialize();
+    void shrinkIfNeeded();
 
     void removeEntry(const NetworkCacheKey&);
 
@@ -109,12 +110,14 @@ class NetworkCacheStorage {
 
     const String m_directoryPath;
 
-    size_t m_maximumSize;
+    size_t m_maximumSize { std::numeric_limits<size_t>::max() };
 
     BloomFilter<20> m_keyFilter;
+    std::atomic<size_t> m_approximateEntryCount { 0 };
+    std::atomic<bool> m_shrinkInProgress { false };
 
     Vector<Deque<RetrieveOperation>> m_pendingRetrieveOperationsByPriority;
-    unsigned m_activeRetrieveOperationCount;
+    unsigned m_activeRetrieveOperationCount { 0 };
 
 #if PLATFORM(COCOA)
     mutable OSObjectPtr<dispatch_queue_t> m_ioQueue;

diff --git a/Source/WebKit2/NetworkProcess/cache/NetworkCacheStorageCocoa.mm b/Source/WebKit2/NetworkProcess/cache/NetworkCacheStorageCocoa.mm
@@ -122,30 +122,30 @@ static void traverseCacheFiles(const String& cachePath, std::function<void (cons
 
 NetworkCacheStorage::NetworkCacheStorage(const String& directoryPath)
     : m_directoryPath(directoryPath)
-    , m_maximumSize(std::numeric_limits<size_t>::max())
-    , m_activeRetrieveOperationCount(0)
     , m_ioQueue(adoptOSObject(dispatch_queue_create("com.apple.WebKit.Cache.Storage", DISPATCH_QUEUE_CONCURRENT)))
     , m_backgroundIOQueue(adoptOSObject(dispatch_queue_create("com.apple.WebKit.Cache.Storage.Background", DISPATCH_QUEUE_CONCURRENT)))
 {
     dispatch_set_target_queue(m_backgroundIOQueue.get(), dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0));
 
-    initializeKeyFilter();
+    initialize();
 }
 
-void NetworkCacheStorage::initializeKeyFilter()
+void NetworkCacheStorage::initialize()
 {
     ASSERT(RunLoop::isMain());
 
     StringCapture cachePathCapture(m_directoryPath);
     auto& keyFilter = m_keyFilter;
+    auto& entryCount = m_approximateEntryCount;
 
-    dispatch_async(m_backgroundIOQueue.get(), [cachePathCapture, &keyFilter] {
+    dispatch_async(m_backgroundIOQueue.get(), [cachePathCapture, &keyFilter, &entryCount] {
         String cachePath = cachePathCapture.string();
-        traverseCacheFiles(cachePath, [&keyFilter](const String& fileName, const String&) {
+        traverseCacheFiles(cachePath, [&keyFilter, &entryCount](const String& fileName, const String&) {
             NetworkCacheKey::HashType hash;
             if (!NetworkCacheKey::stringToHash(fileName, hash))
                 return;
             keyFilter.add(hash);
+            ++entryCount;
         });
     });
 }
@@ -343,9 +343,11 @@ static bool decodeEntryMetaData(EntryMetaData& metaData, dispatch_data_t fileDat
         m_keyFilter.remove(key.hash());
 
     StringCapture filePathCapture(filePathForKey(key, m_directoryPath));
-    dispatch_async(m_ioQueue.get(), [filePathCapture] {
+    dispatch_async(m_ioQueue.get(), [this, filePathCapture] {
         CString path = WebCore::fileSystemRepresentation(filePathCapture.string());
         unlink(path.data());
+        if (m_approximateEntryCount)
+            --m_approximateEntryCount;
     });
 }
 
@@ -427,8 +429,11 @@ static bool decodeEntryMetaData(EntryMetaData& metaData, dispatch_data_t fileDat
         dispatch_io_write(channel.get(), 0, data.get(), dispatch_get_main_queue(), [this, key, completionHandler](bool done, dispatch_data_t, int error) {
             ASSERT_UNUSED(done, done);
             LOG(NetworkCacheStorage, "(NetworkProcess) write complete error=%d", error);
-            if (!error)
+            if (!error) {
                 m_keyFilter.add(key.hash());
+                ++m_approximateEntryCount;
+                shrinkIfNeeded();
+            }
             completionHandler(!error);
         });
     });
@@ -437,8 +442,9 @@ static bool decodeEntryMetaData(EntryMetaData& metaData, dispatch_data_t fileDat
 void NetworkCacheStorage::setMaximumSize(size_t size)
 {
     ASSERT(RunLoop::isMain());
-    // FIXME: Implement.
     m_maximumSize = size;
+
+    shrinkIfNeeded();
 }
 
 void NetworkCacheStorage::clear()
@@ -447,6 +453,7 @@ static bool decodeEntryMetaData(EntryMetaData& metaData, dispatch_data_t fileDat
     LOG(NetworkCacheStorage, "(NetworkProcess) clearing cache");
 
     m_keyFilter.clear();
+    m_approximateEntryCount = 0;
 
     StringCapture directoryPathCapture(m_directoryPath);
 
@@ -463,6 +470,51 @@ static bool decodeEntryMetaData(EntryMetaData& metaData, dispatch_data_t fileDat
     });
 }
 
+void NetworkCacheStorage::shrinkIfNeeded()
+{
+    const size_t assumedAverageResourceSize { 48 * 1024 };
+    const size_t everyNthResourceToDelete { 4 };
+
+    size_t estimatedCacheSize = assumedAverageResourceSize * m_approximateEntryCount;
+
+    if (estimatedCacheSize <= m_maximumSize)
+        return;
+    if (m_shrinkInProgress)
+        return;
+    m_shrinkInProgress = true;
+
+    LOG(NetworkCacheStorage, "(NetworkProcess) shrinking cache m_approximateEntryCount=%d estimatedCacheSize=%d, m_maximumSize=%d", static_cast<size_t>(m_approximateEntryCount), estimatedCacheSize, m_maximumSize);
+
+    StringCapture cachePathCapture(m_directoryPath);
+    dispatch_async(m_backgroundIOQueue.get(), [this, cachePathCapture] {
+        String cachePath = cachePathCapture.string();
+        size_t foundEntryCount = 0;
+        size_t deletedCount = 0;
+        traverseCacheFiles(cachePath, [this, &foundEntryCount, &deletedCount](const String& fileName, const String& directory) {
+            String partitionPath = WebCore::pathByAppendingComponent(directory, fileName);
+            CString path = WebCore::fileSystemRepresentation(partitionPath);
+            ++foundEntryCount;
+            if (foundEntryCount % everyNthResourceToDelete)
+                return;
+            ++deletedCount;
+
+            unlink(path.data());
+
+            NetworkCacheKey::HashType hash;
+            if (!NetworkCacheKey::stringToHash(fileName, hash))
+                return;
+            dispatch_async(dispatch_get_main_queue(), [this, hash] {
+                if (m_keyFilter.mayContain(hash))
+                    m_keyFilter.remove(hash);
+            });
+        });
+        m_approximateEntryCount = foundEntryCount - deletedCount;
+        m_shrinkInProgress = false;
+
+        LOG(NetworkCacheStorage, "(NetworkProcess) cache shrink completed m_approximateEntryCount=%d", static_cast<size_t>(m_approximateEntryCount));
+    });
+}
+
 }
 
 #endif