MemoryArea.h revision affc150dc44fab1911775a49636d0ce85333b634 
1//===- MemoryArea.h -------------------------------------------------------===//
2//
3//                     The MCLinker Project
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9#ifndef MCLD_MEMORY_AREA_H
10#define MCLD_MEMORY_AREA_H
11#ifdef ENABLE_UNITTEST
12#include <gtest.h>
13#endif
14
15#include <mcld/ADT/Uncopyable.h>
16#include <mcld/Support/Path.h>
17#include <mcld/Support/FileSystem.h>
18#include <mcld/Support/FileHandle.h>
19#include <mcld/Support/Space.h>
20#include <fcntl.h>
21#include <string>
22#include <list>
23
24
25#if defined(ENABLE_UNITTEST)
26namespace mcldtest
27{
28  class MemoryAreaTest;
29} // namespace of mcldtest
30#endif
31
32namespace mcld
33{
34
35class MemoryRegion;
36class RegionFactory;
37
38/** \class MemoryArea
39 *  \brief MemoryArea is used to manage distinct MemoryRegions of address space.
40 *
41 *  Good linkers must well manipulate memory mapped I/O and dynamic memory.
42 *  In MCLinker, MemoryArea is the decision-maker to use memory mapped I/O or
43 *  dynamic memory. When a client requests MemoryArea for a piece of memory
44 *  to hold a part of a file, MemoryArea is going to see whether the requested
45 *  part of the file is already in any existing memory which is requested
46 *  before. If it is, MemoryArea creates a new MemoryRegion within the memory
47 *  requested before. Otherwise, MemoryArea uses memory mapped I/O or dynamic
48 *  memory to load the file.
49 *
50 *  If the part a file being loaded is larger than 3/4 pages, MemoryArea uses
51 *  memory mapped I/O to load the file. Otherwise, MemoryArea uses dynamic
52 *  memory to read the content of file into the memory space.
53 */
54class MemoryArea : private Uncopyable
55{
56public:
57  // constructor
58  MemoryArea(RegionFactory& pRegionFactory,
59             FileHandle& pFileHandle);
60
61  // destructor
62  ~MemoryArea();
63
64  // request - create a MemoryRegion within a sufficient space
65  // find an existing space to hold the MemoryRegion.
66  // if MemoryArea does not find such space, then it creates a new space and
67  // assign a MemoryRegion into the space.
68  MemoryRegion* request(size_t pOffset, size_t pLength);
69
70  // release - release a MemoryRegion.
71  // release a MemoryRegion does not cause
72  void release(MemoryRegion* pRegion);
73
74  // clear - release all memory regions.
75  void clear();
76
77  FileHandle* handler()
78  { return m_pFileHandle; }
79
80  const FileHandle* handler() const
81  { return m_pFileHandle; }
82
83private:
84  friend class MemoryAreaFactory;
85
86#if defined(ENABLE_UNITTEST)
87  friend class mcldtest::MemoryAreaTest;
88#endif
89
90  typedef llvm::iplist<Space> SpaceList;
91
92private:
93  // -----  special methods ----- //
94  // @param pRegionFactory  The factory of regions.
95  // @param pUniverse       A initial univeral space.
96  MemoryArea(RegionFactory& pRegionFactory, Space& pUniverse);
97
98  // -----  space list methods  ----- //
99  Space* find(size_t pOffset, size_t pLength);
100
101  const Space* find(size_t pOffset, size_t pLength) const;
102
103private:
104  RegionFactory& m_RegionFactory;
105  SpaceList m_SpaceList;
106  FileHandle* m_pFileHandle;
107};
108
109} // namespace of mcld
110
111#endif
112
113