data: indexer processes

* TaskBuildIndex starts seperate indexer processes and communicates via shared memory
* indexer processes get restarted if they fail
* indexer processes are killed when the app closes or crashes
* added utility class SharedMemory to allocate and access shared memory, providing basic data structures
* added SharedMemoryGarbageCollector for keeping track of running instances and cleaning up shared memory in case of a crash
* show errors for source files that crashed during indexing
* added basic exception handling to task scheduling
* added option to turn off processes and use threads in preferences, but still use shared memory

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src/lib/data/indexer/interprocess/InterprocessIndexingStatusManager.h

@@ -0,0 +1,34 @@
+#ifndef INTERPROCESS_INDEXING_STATUS_MANAGER_H
+#define INTERPROCESS_INDEXING_STATUS_MANAGER_H
+
+#include <set>
+
+#include "utility/file/FilePath.h"
+#include "BaseInterprocessDataManager.h"
+
+class InterprocessIndexingStatusManager
+	: public BaseInterprocessDataManager
+{
+public:
+	InterprocessIndexingStatusManager(const std::string& instanceUuid, Id processId, bool isOwner);
+	virtual ~InterprocessIndexingStatusManager();
+
+	void setCurrentlyIndexedSourceFilePath(const FilePath& filePath);
+	void clearCurrentlyIndexedSourceFilePath();
+	FilePath getCurrentlyIndexedSourceFilePath();
+
+	std::vector<FilePath> getCrashedSourceFilePaths();
+
+	std::set<FilePath> getIndexedFiles();
+	void addIndexedFiles(std::set<FilePath> filePaths);
+
+private:
+	static const char* s_sharedMemoryNamePrefix;
+
+	static const char* s_lastFileKeyName;
+	static const char* s_currentFilesKeyName;
+	static const char* s_crashedFilesKeyName;
+	static const char* s_indexedFilesKeyName;
+};
+
+#endif // INTERPROCESS_INDEXING_STATUS_MANAGER_H