Class QueryState

be/src/runtime/query-state.h:122–574

Central class for all backend execution state (example: the FragmentInstanceStates of the individual fragment instances) created for a particular query. This class contains or makes accessible state that is shared across fragment instances; in contrast, fragment instance-specific state is collected in FragmentInstanceState. The lifetime of a QueryState is dictated by a reference count. Any thread

/// TODO:
/// - set up kudu clients in Init(), remove related locking
class QueryState {
 public:
  /// Stores information about which file is scheduled to which hosts.
  struct FileSchedulingInfo {
    std::string file_path;
    std::vector<NetworkAddressPB> hosts;
    bool is_relative_path;

    FileSchedulingInfo(const string& fn, bool is_rel)
        : file_path(fn), is_relative_path(is_rel) {}
  };

  /// Stores information about which file is scheduled to which hosts, grouped by scan
  /// node ID.
  typedef std::unordered_map<int, std::vector<FileSchedulingInfo>> NodeToFileSchedulings;

  /// Use this class to obtain a QueryState for the duration of a function/block,
  /// rather than manually via QueryExecMgr::Get-/ReleaseQueryState().
  /// Pattern:
  /// {
  ///   QueryState::ScopedRef qs(qid);
  ///   if (qs->query_state() == nullptr) <do something, such as return>
  ///   ...
  /// }
  class ScopedRef {
   public:
    /// Looks up the query state with GetQueryState(). The query state is non-NULL if
    /// the query was already registered.
    ScopedRef(const TUniqueId& query_id);
    ~ScopedRef();

    /// may return nullptr
    QueryState* get() const { return query_state_; }
    QueryState* operator->() const { return query_state_; }

   private:
    QueryState* query_state_;
    DISALLOW_COPY_AND_ASSIGN(ScopedRef);
  };

  /// a shared pool for all objects that have query lifetime
  ObjectPool* obj_pool() { return &obj_pool_; }

  const TQueryCtx& query_ctx() const { return query_ctx_; }
  const TUniqueId& query_id() const { return query_ctx().query_id; }
  const TQueryOptions& query_options() const {
    return query_ctx_.client_request.query_options;
  }
  bool codegen_cache_enabled() const;
  bool is_initialized();
  MemTracker* query_mem_tracker() const { return query_mem_tracker_; }
  RuntimeProfile* host_profile() const { return host_profile_; }
  const NodeToFileSchedulings* node_to_file_schedulings() const {
    return &node_to_file_schedulings_;
  }
  UniqueIdPB GetCoordinatorBackendId() const;

  /// The following getters are only valid after Init().