Incremental parsing issue fixes (#736)

Fix segmentation fault due to access of file ID on non-loaded file.
Eliminated use of size() on ODB query result in SourceManager. Added isSingletonResult instead to dbutil.

Author: dbukki

parser/src/sourcemanager.cpp

@@ -5,6 +5,7 @@
 
 #include <util/hash.h>
 #include <util/logutil.h>
+#include <util/dbutil.h>
 
 #include <parser/sourcemanager.h>
 
@@ -238,9 +239,9 @@ void SourceManager::removeFile(const model::File& file_)
   _transaction([&]() {
     if(file_.content)
     {
-      auto relFiles = _db->query<model::File>(
+      odb::result<model::File> relFiles = _db->query<model::File>(
         odb::query<model::File>::content == file_.content.object_id());
-      if (relFiles.size() == 1)
+      if (util::isSingleResult(relFiles))
       {
         removeContent = true;
         _db->erase<model::FileContent>(file_.content.object_id());

plugins/cpp_metrics/model/include/model/cppastnodemetrics.h

@@ -45,6 +45,19 @@ struct CppRecordMetricsView
   double value;
 };
 
+#pragma db view \
+  object(CppAstNodeMetrics) \
+  object(CppAstNode : CppAstNodeMetrics::astNodeId == CppAstNode::id) \
+  object(File : CppAstNode::location.file)
+struct CppAstNodeMetricsFileView
+{
+  #pragma db column(CppAstNode::id)
+  CppAstNodeId astNodeId;
+
+  #pragma db column(File::id)
+  FileId fileId;
+};
+  
 #pragma db view \
   object(CppAstNodeMetrics) \
   object(CppAstNode : CppAstNodeMetrics::astNodeId == CppAstNode::id) \

plugins/cpp_metrics/parser/src/cppmetricsparser.cpp

@@ -39,12 +39,10 @@ CppMetricsParser::CppMetricsParser(ParserContext& ctx_): AbstractParser(ctx_)
       _fileIdCache.insert(fm.file);
     }
 
-    for (const model::CppAstNodeMetrics& anm
-      : _ctx.db->query<model::CppAstNodeMetrics>())
+    for (const model::CppAstNodeMetricsFileView& anm
+      : _ctx.db->query<model::CppAstNodeMetricsFileView>())
     {
-      auto node = _ctx.db->query_one<model::CppAstNode>(
-        odb::query<model::CppAstNode>::id == anm.astNodeId);
-      _astNodeIdCache.insert({anm.astNodeId, node->location.file->id});
+      _astNodeIdCache.emplace(anm.astNodeId, anm.fileId);
     }
   });
 }

util/include/util/dbutil.h

@@ -97,6 +97,40 @@ inline std::string getDbDriver()
 #endif
 }
 
+/// @brief Determines if the specified ODB query result only contains
+/// a single entity. That single entity is then stored in 'single_'.
+/// @tparam TEntity The type of entities in the query result.
+/// @param result_ The ODB query result in question.
+/// @param single_ The variable that receives the first entity (if any).
+/// @return Returns true if 'result_' only contained 'single_';
+/// otherwise false.
+template<typename TEntity>
+bool isSingleResult(odb::result<TEntity>& result_, TEntity& single_)
+{
+  auto it_b = result_.begin();
+  const auto it_e = result_.end();
+  if (it_b != it_e)
+  {
+    single_ = *it_b;
+    return ++it_b == it_e;
+  }
+  else return false;
+}
+
+/// @brief Determines if the specified ODB query result only contains
+/// a single entity.
+/// @tparam TEntity The type of entities in the query result.
+/// @param result_ The ODB query result in question.
+/// @return Returns true if 'result_' only contained a single entity;
+/// otherwise false.
+template<typename TEntity>
+bool isSingleResult(odb::result<TEntity>& result_)
+{
+  auto it_b = result_.begin();
+  const auto it_e = result_.end();
+  return (it_b != it_e) && (++it_b == it_e);
+}
+
 } // util
 } // cc