1    :  // Copyright 2012 Google Inc. All Rights Reserved.
   2    :  //
   3    :  // Licensed under the Apache License, Version 2.0 (the "License");
   4    :  // you may not use this file except in compliance with the License.
   5    :  // You may obtain a copy of the License at
   6    :  //
   7    :  //     http://www.apache.org/licenses/LICENSE-2.0
   8    :  //
   9    :  // Unless required by applicable law or agreed to in writing, software
  10    :  // distributed under the License is distributed on an "AS IS" BASIS,
  11    :  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12    :  // See the License for the specific language governing permissions and
  13    :  // limitations under the License.
  14    :  //
  15    :  // Declares an ordering that randomizes blocks within their respective sections.
  16    :  
  17    :  #ifndef SYZYGY_BLOCK_GRAPH_ORDERERS_RANDOM_ORDERER_H_
  18    :  #define SYZYGY_BLOCK_GRAPH_ORDERERS_RANDOM_ORDERER_H_
  19    :  
  20    :  #include "syzygy/block_graph/orderers/named_orderer.h"
  21    :  #include "syzygy/core/random_number_generator.h"
  22    :  
  23  m :  namespace block_graph {
  24  m :  namespace orderers {
  25    :  
  26  m :  class RandomOrderer
  27  m :      : public block_graph::orderers::NamedOrdererImpl<RandomOrderer> {
  28  m :   public:
  29    :    // Constructs a random-orderer that works over the specified block-graph.
  30    :    // Initializes the random-number generator using the current time.
  31    :    // @param default_shuffle_section if true then the blocks in each section will
  32    :    //     be shuffled. If false the blocks in the section will remain in the same
  33    :    //     order as input. This sets the default value that is initially applied
  34    :    //     to all sections. Individual sections may have their value changed using
  35    :    //     SetShuffleSection.
  36  m :    explicit RandomOrderer(bool default_shuffle_section);
  37    :  
  38    :    // Constructs a random-orderer that works over the specified block-graph.
  39    :    // @param default_shuffle_section if true then the blocks in each section will
  40    :    //     be shuffled. If false the blocks in the section will remain in the same
  41    :    //     order as input. This sets the default value that is initially applied
  42    :    //     to all sections. Individual sections may have their value changed using
  43    :    //     SetShuffleSection.
  44    :    // @param seed the seed to be used by the random number generator.
  45  m :    RandomOrderer(bool default_shuffle_section, uint32 seed);
  46    :  
  47    :    // Configures whether or not the given section should have its blocks
  48    :    // shuffled. This overrides the default value specified in the constructor.
  49    :    // @param section the section to configure.
  50    :    // @param shuffle true if the section should be shuffled, false otherwise.
  51  m :    void SetShuffleSection(const BlockGraph::Section* section, bool shuffle);
  52    :  
  53    :    // Determines whether or not the blocks will be shuffled for the given
  54    :    // section.
  55  m :    bool ShouldShuffleSection(const BlockGraph::Section* section) const;
  56    :  
  57    :    // Applies this orderer to the provided block graph.
  58    :    //
  59    :    // @param ordered_block_graph the block graph to order.
  60    :    // @param header_block The header block of the block graph to transform.
  61    :    //     This transform does not use this value, so NULL may safely be passed
  62    :    //     in.
  63    :    // @returns true on success, false otherwise.
  64  m :    virtual bool OrderBlockGraph(OrderedBlockGraph* ordered_block_graph,
  65  m :                                 BlockGraph::Block* header_block) override;
  66    :  
  67  m :    static const char kOrdererName[];
  68    :  
  69  m :   private:
  70    :    // Shuffles the blocks in the given section.
  71  m :    void ShuffleBlocks(const OrderedBlockGraph::OrderedSection* section,
  72  m :                       OrderedBlockGraph* obg);
  73    :  
  74    :    // The default shuffle setting.
  75  m :    bool default_shuffle_section_;
  76    :    // The random number generator we use.
  77  m :    core::RandomNumberGenerator rng_;
  78    :  
  79    :    // A per-section shuffle setting.
  80  m :    typedef std::map<const BlockGraph::Section*, bool> ShuffleMap;
  81  m :    ShuffleMap shuffle_map_;
  82    :  
  83  m :    DISALLOW_COPY_AND_ASSIGN(RandomOrderer);
  84  m :  };
  85    :  
  86  m :  }  // namespace orderers
  87  m :  }  // namespace block_graph
  88    :  
  89    :  #endif  // SYZYGY_BLOCK_GRAPH_ORDERERS_RANDOM_ORDERER_H_