cache module prototype item trees

Module prototypes can safely be reused.
For the qbs build this saves roughly 70% of memory.

Task-number: QBS-120
Change-Id: I2501e05088634d3403b1f8d1b424194f8e6a041a
Reviewed-by: Christian Kandeler <christian.kandeler@digia.com>

4 files changed, 27 insertions, 8 deletions

diff --git a/src/lib/corelib/language/itemreader.cpp b/src/lib/corelib/language/itemreader.cpp
index ba4859899..2a1d125aa 100644
--- a/src/lib/corelib/language/itemreader.cpp
+++ b/src/lib/corelib/language/itemreader.cpp
@@ -128,6 +128,11 @@ QStringList ItemReader::searchPaths() const
     return paths;
 }
 
+void ItemReader::clearItemCache()
+{
+    m_itemCache.clear();
+}
+
 void ItemReader::cacheDirectoryEntries(const QString &dirPath, const QStringList &entries)
 {
     m_directoryEntries.insert(dirPath, entries);
@@ -142,9 +147,9 @@ bool ItemReader::findDirectoryEntries(const QString &dirPath, QStringList *entri
     return true;
 }
 
-Item *ItemReader::readFile(const QString &filePath)
+Item *ItemReader::readFile(const QString &filePath, bool enableItemCache)
 {
-    Item * const item = internalReadFile(filePath).rootItem;
+    Item * const item = internalReadFile(filePath, enableItemCache).rootItem;
     return item;
 }
 
@@ -153,8 +158,15 @@ QSet<QString> ItemReader::filesRead() const
     return m_filesRead;
 }
 
-ItemReaderResult ItemReader::internalReadFile(const QString &filePath)
+ItemReaderResult ItemReader::internalReadFile(const QString &filePath, bool enableItemCache)
 {
+    ItemReaderResult result;
+    if (enableItemCache) {
+        result = m_itemCache.value(filePath);
+        if (result.rootItem)
+            return result;
+    }
+
     ASTCacheValue &cacheValue = (*m_astCache)[filePath];
     if (cacheValue.isValid()) {
         if (Q_UNLIKELY(cacheValue.isProcessing()))
@@ -185,13 +197,16 @@ ItemReaderResult ItemReader::internalReadFile(const QString &filePath)
         cacheValue.setAst(parser.ast());
     }
 
-    ItemReaderResult result;
     ItemReaderASTVisitor itemReader(this, &result);
     itemReader.setFilePath(QFileInfo(filePath).absoluteFilePath());
     itemReader.setSourceCode(cacheValue.code());
     cacheValue.setProcessingFlag(true);
     cacheValue.ast()->accept(&itemReader);
     cacheValue.setProcessingFlag(false);
+
+    if (enableItemCache)
+        m_itemCache.insert(filePath, result);
+
     return result;
 }
 
diff --git a/src/lib/corelib/language/itemreader.h b/src/lib/corelib/language/itemreader.h
index 266c30f93..75921577c 100644
--- a/src/lib/corelib/language/itemreader.h
+++ b/src/lib/corelib/language/itemreader.h
@@ -81,12 +81,13 @@ public:
     void popExtraSearchPaths();
     QStringList searchPaths() const;
 
-    Item *readFile(const QString &filePath);
+    void clearItemCache();
+    Item *readFile(const QString &filePath, bool enableItemCache = false);
 
     QSet<QString> filesRead() const;
 
 private:
-    ItemReaderResult internalReadFile(const QString &filePath);
+    ItemReaderResult internalReadFile(const QString &filePath, bool enableItemCache);
 
     void cacheDirectoryEntries(const QString &dirPath, const QStringList &entries);
     bool findDirectoryEntries(const QString &dirPath, QStringList *entries) const;
@@ -100,6 +101,7 @@ private:
 
     class ASTCache;
     ASTCache *m_astCache;
+    QHash<QString, ItemReaderResult> m_itemCache;
     QSet<QString> m_filesRead;
     QHash<QString, QStringList> m_directoryEntries;
 };
diff --git a/src/lib/corelib/language/itemreaderastvisitor.cpp b/src/lib/corelib/language/itemreaderastvisitor.cpp
index a48e259ac..9a333a989 100644
--- a/src/lib/corelib/language/itemreaderastvisitor.cpp
+++ b/src/lib/corelib/language/itemreaderastvisitor.cpp
@@ -312,7 +312,8 @@ bool ItemReaderASTVisitor::visit(AST::UiObjectDefinition *ast)
     const QStringList fullTypeName = toStringList(ast->qualifiedTypeNameId);
     const QString baseTypeFileName = m_typeNameToFile.value(fullTypeName);
     if (!baseTypeFileName.isEmpty()) {
-        const ItemReaderResult baseFile = m_reader->internalReadFile(baseTypeFileName);
+        const ItemReaderResult baseFile = m_reader->internalReadFile(baseTypeFileName, false);
+
         inheritItem(item, baseFile.rootItem, baseFile);
         if (baseFile.rootItem->m_file->m_idScope) {
             // Make ids from the derived file visible in the base file.
diff --git a/src/lib/corelib/language/moduleloader.cpp b/src/lib/corelib/language/moduleloader.cpp
index 2af998b28..caa427423 100644
--- a/src/lib/corelib/language/moduleloader.cpp
+++ b/src/lib/corelib/language/moduleloader.cpp
@@ -101,6 +101,7 @@ ModuleLoaderResult ModuleLoader::load(const QString &filePath,
 {
     if (m_logger.traceEnabled())
         m_logger.qbsTrace() << "[MODLDR] load" << filePath;
+    m_reader->clearItemCache();
     m_overriddenProperties = overriddenProperties;
     m_buildConfigProperties = buildConfigProperties;
     m_validItemPropertyNamesPerItem.clear();
@@ -759,7 +760,7 @@ Item *ModuleLoader::loadModuleFile(ProductContext *productContext, const QString
 
     m_logger.qbsTrace() << "[LDR] loadModuleFile " << filePath;
     *cacheHit = false;
-    module = m_reader->readFile(filePath);
+    module = m_reader->readFile(filePath, true);
     if (!isBaseModule) {
         DependsContext dependsContext;
         dependsContext.product = productContext;