ceph/src/arrow/cpp/src/arrow/dbi/hiveserver2/operation.h

   1 // Licensed to the Apache Software Foundation (ASF) under one
   2 // or more contributor license agreements.  See the NOTICE file
   3 // distributed with this work for additional information
   4 // regarding copyright ownership.  The ASF licenses this file
   5 // to you under the Apache License, Version 2.0 (the
   6 // "License"); you may not use this file except in compliance
   7 // with the License.  You may obtain a copy of the License at
   8 //
   9 //   http://www.apache.org/licenses/LICENSE-2.0
  10 //
  11 // Unless required by applicable law or agreed to in writing,
  12 // software distributed under the License is distributed on an
  13 // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  14 // KIND, either express or implied.  See the License for the
  15 // specific language governing permissions and limitations
  16 // under the License.
  17
  18 #pragma once
  19
  20 #include <memory>
  21 #include <string>
  22 #include <vector>
  23
  24 #include "arrow/dbi/hiveserver2/columnar_row_set.h"
  25 #include "arrow/dbi/hiveserver2/types.h"
  26
  27 #include "arrow/util/macros.h"
  28 #include "arrow/util/visibility.h"
  29
  30 namespace arrow {
  31
  32 class Status;
  33
  34 namespace hiveserver2 {
  35
  36 struct ThriftRPC;
  37
  38 // Maps directly to TFetchOrientation in the HiveServer2 interface.
  39 enum class FetchOrientation {
  40   NEXT,      // supported
  41   PRIOR,     // not supported
  42   RELATIVE,  // not supported
  43   ABSOLUTE,  // not supported
  44   FIRST,     // supported if query result caching is enabled in Impala
  45   LAST       // not supported
  46 };
  47
  48 // Represents a single HiveServer2 operation. Used to monitor the status of an operation
  49 // and to retrieve its results. The only Operation function that will block is Fetch,
  50 // which blocks if there aren't any results ready yet.
  51 //
  52 // Operations are created using Session functions, eg. ExecuteStatement. They must
  53 // have Close called on them before they can be deleted.
  54 //
  55 // This class is not thread-safe.
  56 class ARROW_EXPORT Operation {
  57  public:
  58   // Maps directly to TOperationState in the HiveServer2 interface.
  59   enum class State {
  60     INITIALIZED,
  61     RUNNING,
  62     FINISHED,
  63     CANCELED,
  64     CLOSED,
  65     ERROR,
  66     UNKNOWN,
  67     PENDING,
  68   };
  69
  70   ~Operation();
  71
  72   // Fetches the current state of this operation. If successful, sets the operation state
  73   // in 'out' and returns an OK status, otherwise an error status is returned. May be
  74   // called after successfully creating the operation and before calling Close.
  75   Status GetState(Operation::State* out) const;
  76
  77   // May be called after successfully creating the operation and before calling Close.
  78   Status GetLog(std::string* out) const;
  79
  80   // May be called after successfully creating the operation and before calling Close.
  81   Status GetProfile(std::string* out) const;
  82
  83   // Fetches metadata for the columns in the output of this operation, such as the
  84   // names and types of the columns, and returns it as a list of column descriptions.
  85   // May be called after successfully creating the operation and before calling Close.
  86   Status GetResultSetMetadata(std::vector<ColumnDesc>* column_descs) const;
  87
  88   // Fetches a batch of results, stores them in 'results', and sets has_more_rows.
  89   // Fetch will block if there aren't any results that are ready.
  90   Status Fetch(std::unique_ptr<ColumnarRowSet>* results, bool* has_more_rows) const;
  91   Status Fetch(int max_rows, FetchOrientation orientation,
  92                std::unique_ptr<ColumnarRowSet>* results, bool* has_more_rows) const;
  93
  94   // May be called after successfully creating the operation and before calling Close.
  95   Status Cancel() const;
  96
  97   // Closes the operation. Must be called before the operation is deleted. May be safely
  98   // called on an invalid or already closed operation - will only return an error if the
  99   // operation is open but the close rpc fails.
 100   Status Close();
 101
 102   // May be called after successfully creating the operation and before calling Close.
 103   bool HasResultSet() const;
 104
 105   // Returns true iff this operation's results will be returned in a columnar format.
 106   // May be called at any time.
 107   bool IsColumnar() const;
 108
 109  protected:
 110   // Hides Thrift objects from the header.
 111   struct OperationImpl;
 112
 113   explicit Operation(const std::shared_ptr<ThriftRPC>& rpc);
 114
 115   std::unique_ptr<OperationImpl> impl_;
 116   std::shared_ptr<ThriftRPC> rpc_;
 117
 118   // True iff this operation has been successfully created and has not been closed yet,
 119   // corresponding to when the operation has a valid operation handle.
 120   bool open_;
 121
 122  private:
 123   ARROW_DISALLOW_COPY_AND_ASSIGN(Operation);
 124 };
 125
 126 }  // namespace hiveserver2
 127 }  // namespace arrow