Changeset 231708 in webkit

Timestamp:

May 11, 2018 11:11:21 AM (6 years ago)

Author:

Antti Koivisto

Message:

Network process should not stat() all cache files on startup to find their sizes
​https://bugs.webkit.org/show_bug.cgi?id=185542
<rdar://problem/40092953>

Reviewed by Chris Dumez.

This is done to compute how much disk space a cache is using. While the operation happens
in a background priority thread it is still quite a bit of work.

Large bodies are saved in separate blob files so record file sizes are capped. We can avoid work by
estimating their size instead of counting it exactly.

• NetworkProcess/cache/NetworkCacheStorage.cpp:

(WebKit::NetworkCache::estimateRecordsSize):
(WebKit::NetworkCache::Storage::synchronize):

Use size estimation if blob storage is in use.
Remove the code that would delete empty files. Normal cache shrinking handles this.

(WebKit::NetworkCache::Storage::shouldStoreBodyAsBlob):

Location:

trunk/Source/WebKit

Files:

• ChangeLog (modified) (1 diff)
• NetworkProcess/cache/NetworkCacheStorage.cpp (modified) (6 diffs)

trunk/Source/WebKit/ChangeLog

@@ +1 @@
+2018-05-11  Antti Koivisto  <antti@apple.com>
+
+        Network process should not stat() all cache files on startup to find their sizes
+        https://bugs.webkit.org/show_bug.cgi?id=185542
+        <rdar://problem/40092953>
+
+        Reviewed by Chris Dumez.
+
+        This is done to compute how much disk space a cache is using. While the operation happens
+        in a background priority thread it is still quite a bit of work.
+
+        Large bodies are saved in separate blob files so record file sizes are capped. We can avoid work by
+        estimating their size instead of counting it exactly.
+
+        * NetworkProcess/cache/NetworkCacheStorage.cpp:
+        (WebKit::NetworkCache::estimateRecordsSize):
+        (WebKit::NetworkCache::Storage::synchronize):
+
+            Use size estimation if blob storage is in use.
+            Remove the code that would delete empty files. Normal cache shrinking handles this.
+
+        (WebKit::NetworkCache::Storage::shouldStoreBodyAsBlob):
+
 2018-05-11  Brady Eidson  <beidson@apple.com>
 

trunk/Source/WebKit/NetworkProcess/cache/NetworkCacheStorage.cpp

@@ -46 +46 @@
 static const char blobsDirectoryName[] = "Blobs";
 static const char blobSuffix[] = "-blob";
+constexpr size_t maximumInlineBodySize { 16 * 1024 };
 
 static double computeRecordWorth(FileTimes);
@@ -262 +263 @@
 }
 
+static size_t estimateRecordsSize(unsigned recordCount, unsigned blobCount)
+{
+    auto inlineBodyCount = recordCount - std::min(blobCount, recordCount);
+    auto headerSizes = recordCount * 4096;
+    auto inlineBodySizes = (maximumInlineBodySize / 2) * inlineBodyCount;
+    return headerSizes + inlineBodySizes;
+}
+
 void Storage::synchronize()
 {
@@ -275 +284 @@
         auto recordFilter = std::make_unique<ContentsFilter>();
         auto blobFilter = std::make_unique<ContentsFilter>();
+
+        // Most of the disk space usage is in blobs if we are using them. Approximate records file sizes to avoid expensive stat() calls.
+        bool shouldComputeExactRecordsSize = !m_canUseBlobsForForBodyData;
         size_t recordsSize = 0;
-        unsigned count = 0;
+        unsigned recordCount = 0;
+        unsigned blobCount = 0;
+
         String anyType;
-        traverseRecordsFiles(recordsPath(), anyType, [&recordFilter, &blobFilter, &recordsSize, &count](const String& fileName, const String& hashString, const String& type, bool isBlob, const String& recordDirectoryPath) {
+        traverseRecordsFiles(recordsPath(), anyType, [&](const String& fileName, const String& hashString, const String& type, bool isBlob, const String& recordDirectoryPath) {
             auto filePath = WebCore::FileSystem::pathByAppendingComponent(recordDirectoryPath, fileName);
 
@@ -286 +300 @@
                 return;
             }
-            long long fileSize = 0;
-            WebCore::FileSystem::getFileSize(filePath, fileSize);
-            if (!fileSize) {
-                WebCore::FileSystem::deleteFile(filePath);
-                return;
-            }
 
             if (isBlob) {
+                ++blobCount;
                 blobFilter->add(hash);
                 return;
             }
 
+            ++recordCount;
+
+            if (shouldComputeExactRecordsSize) {
+                long long fileSize = 0;
+                WebCore::FileSystem::getFileSize(filePath, fileSize);
+                recordsSize += fileSize;
+            }
+
             recordFilter->add(hash);
-            recordsSize += fileSize;
-            ++count;
-        });
+        });
+
+        if (!shouldComputeExactRecordsSize)
+            recordsSize = estimateRecordsSize(recordCount, blobCount);
 
         RunLoop::main().dispatch([this, recordFilter = WTFMove(recordFilter), blobFilter = WTFMove(blobFilter), recordsSize]() mutable {
@@ -322 +340 @@
         deleteEmptyRecordsDirectories(recordsPath());
 
-        LOG(NetworkCacheStorage, "(NetworkProcess) cache synchronization completed size=%zu count=%u", recordsSize, count);
+        LOG(NetworkCacheStorage, "(NetworkProcess) cache synchronization completed size=%zu recordCount=%u", recordsSize, recordCount);
 
         RunLoop::main().dispatch([protectedThis = WTFMove(protectedThis)] { });
@@ -757 +775 @@
     if (!m_canUseBlobsForForBodyData)
         return false;
-    const size_t maximumInlineBodySize { 16 * 1024 };
     return bodyData.size() > maximumInlineBodySize;
 }