Clang: Minimize reindexing

We optimal indexer is only reindexing if the index would be changed. This
patch is a step in that direction. We only reindex now if the file or
project has changed. It fixes some typos too.

Task-number: QTCREATORBUG-21150
Change-Id: I6ea1c13282fbcd70253b9b2939aed37580dbd160
Reviewed-by: Ivan Donchevskii <ivan.donchevskii@qt.io>

src/tools/clangrefactoringbackend/source/symbolstorage.h

@@ -41,7 +41,7 @@
 
 namespace ClangBackEnd {
 
-template <typename DatabaseType>
+template<typename DatabaseType = Sqlite::Database>
 class SymbolStorage final : public SymbolStorageInterface
 {
     using Database = DatabaseType;
@@ -70,6 +70,93 @@ public:
         deleteNewLocationsTable();
     }
 
+    void insertOrUpdateIndexingTimeStamps(const FilePathIds &filePathIds, TimeStamp indexingTimeStamp)
+    {
+        try {
+            Sqlite::ImmediateTransaction transaction{database};
+
+            for (FilePathId filePathId : filePathIds) {
+                inserOrUpdateIndexingTimesStampStatement.write(filePathId.filePathId,
+                                                               indexingTimeStamp.value);
+            }
+
+            transaction.commit();
+        } catch (const Sqlite::StatementIsBusy &) {
+            insertOrUpdateIndexingTimeStamps(filePathIds, indexingTimeStamp);
+        }
+    }
+
+    void insertOrUpdateIndexingTimeStamps(const FileStatuses &fileStatuses) override
+    {
+        for (FileStatus fileStatus : fileStatuses) {
+            inserOrUpdateIndexingTimesStampStatement.write(fileStatus.filePathId.filePathId,
+                                                           fileStatus.lastModified);
+        }
+    }
+
+    SourceTimeStamps fetchIndexingTimeStamps() const
+    {
+        try {
+            Sqlite::DeferredTransaction transaction{database};
+
+            auto timeStamps = fetchIndexingTimeStampsStatement.template values<SourceTimeStamp, 2>(
+                1024);
+
+            transaction.commit();
+
+            return timeStamps;
+        } catch (const Sqlite::StatementIsBusy &) {
+            return fetchIndexingTimeStamps();
+        }
+    }
+
+    SourceTimeStamps fetchIncludedIndexingTimeStamps(FilePathId sourcePathId) const
+    {
+        try {
+            Sqlite::DeferredTransaction transaction{database};
+
+            auto timeStamps = fetchIncludedIndexingTimeStampsStatement
+                                  .template values<SourceTimeStamp, 2>(1024, sourcePathId.filePathId);
+
+            transaction.commit();
+
+            return timeStamps;
+        } catch (const Sqlite::StatementIsBusy &) {
+            return fetchIncludedIndexingTimeStamps(sourcePathId);
+        }
+    }
+
+    FilePathIds fetchDependentSourceIds(const FilePathIds &sourcePathIds) const override
+    {
+        try {
+            FilePathIds dependentSourceIds;
+
+            Sqlite::DeferredTransaction transaction{database};
+
+            for (FilePathId sourcePathId : sourcePathIds) {
+                FilePathIds newDependentSourceIds;
+                newDependentSourceIds.reserve(dependentSourceIds.size() + 1024);
+
+                auto newIds = fetchDependentSourceIdsStatement
+                                  .template values<FilePathId>(1024, sourcePathId.filePathId);
+
+                std::set_union(dependentSourceIds.begin(),
+                               dependentSourceIds.end(),
+                               newIds.begin(),
+                               newIds.end(),
+                               std::back_inserter(newDependentSourceIds));
+
+                dependentSourceIds = std::move(newDependentSourceIds);
+            }
+
+            transaction.commit();
+
+            return dependentSourceIds;
+        } catch (const Sqlite::StatementIsBusy &) {
+            return fetchDependentSourceIds(sourcePathIds);
+        }
+    }
+
     void fillTemporarySymbolsTable(const SymbolEntries &symbolEntries)
     {
         WriteStatement &statement = insertSymbolsToNewSymbolsStatement;
@@ -191,6 +278,25 @@ public:
         database};
     WriteStatement deleteNewSymbolsTableStatement{"DELETE FROM newSymbols", database};
     WriteStatement deleteNewLocationsTableStatement{"DELETE FROM newLocations", database};
+    WriteStatement inserOrUpdateIndexingTimesStampStatement{
+        "INSERT INTO fileStatuses(sourceId, indexingTimeStamp) VALUES (?001, ?002) ON "
+        "CONFLICT(sourceId) DO UPDATE SET indexingTimeStamp = ?002",
+        database};
+    mutable ReadStatement fetchIncludedIndexingTimeStampsStatement{
+        "WITH RECURSIVE collectedDependencies(sourceId) AS (VALUES(?) UNION SELECT "
+        "dependencySourceId FROM sourceDependencies, collectedDependencies WHERE "
+        "sourceDependencies.sourceId == collectedDependencies.sourceId) SELECT DISTINCT sourceId, "
+        "indexingTimeStamp FROM collectedDependencies NATURAL JOIN fileStatuses ORDER BY sourceId",
+        database};
+    mutable ReadStatement fetchIndexingTimeStampsStatement{
+        "SELECT sourceId, indexingTimeStamp FROM fileStatuses", database};
+    mutable ReadStatement fetchDependentSourceIdsStatement{
+        "WITH RECURSIVE collectedDependencies(sourceId) AS (VALUES(?) UNION SELECT "
+        "sourceDependencies.sourceId FROM sourceDependencies, collectedDependencies WHERE "
+        "sourceDependencies.dependencySourceId == collectedDependencies.sourceId) SELECT sourceId "
+        "FROM collectedDependencies WHERE sourceId NOT IN (SELECT dependencySourceId FROM "
+        "sourceDependencies) ORDER BY sourceId",
+        database};
 };
 
 } // namespace ClangBackEnd