Added (but not activated) coding/mmap_reader.

@TODO Add Windows support

coding/coding.pro

@@ -25,6 +25,7 @@ SOURCES += \
     multilang_utf8_string.cpp \
     reader.cpp \
     zip_reader.cpp \
+    mmap_reader.cpp \
 
 HEADERS += \
     internal/xmlparser.h \
@@ -85,3 +86,4 @@ HEADERS += \
     zip_reader.hpp \
     trie.hpp \
     trie_builder.hpp \
+		mmap_reader.hpp \

coding/mmap_reader.cpp

@@ -0,0 +1,82 @@
+#include "mmap_reader.hpp"
+
+#include "../std/target_os.hpp"
+#include "../std/memcpy.hpp"
+
+// @TODO we don't support windows at the moment
+#ifndef OMIM_OS_WINDOWS
+  #include <sys/mman.h>
+  #include <sys/stat.h>
+  #include <sys/fcntl.h>
+  #include <unistd.h>
+#endif
+
+class MmapReader::MmapData
+{
+  int m_fd;
+
+public:
+  uint8_t * m_memory;
+  uint64_t m_size;
+
+  MmapData(string const & fileName)
+  {
+    // @TODO add windows support
+#ifndef OMIM_OS_WINDOWS
+    m_fd = open(fileName.c_str(), O_RDONLY | O_NONBLOCK | O_SYMLINK);
+    if (m_fd == -1)
+      MYTHROW(OpenException, ("open failed for file", fileName));
+
+    struct stat s;
+    if (-1 == fstat(m_fd, &s))
+      MYTHROW(OpenException, ("fstat failed for file", fileName));
+    m_size = s.st_size;
+
+    m_memory = (uint8_t *)mmap(0, m_size, PROT_READ, MAP_SHARED, m_fd, 0);
+    if (m_memory == MAP_FAILED)
+    {
+      close(m_fd);
+      MYTHROW(OpenException, ("mmap failed for file", fileName));
+    }
+#endif
+  }
+
+  ~MmapData()
+  {
+    // @TODO add windows support
+#ifndef OMIM_OS_WINDOWS
+    munmap(m_memory, m_size);
+    close(m_fd);
+#endif
+  }
+};
+
+MmapReader::MmapReader(string const & fileName)
+  : base_type(fileName), m_offset(0)
+{
+  m_data = shared_ptr<MmapData>(new MmapData(fileName));
+  m_size = m_data->m_size;
+}
+
+MmapReader::MmapReader(MmapReader const & reader, uint64_t offset, uint64_t size)
+  : base_type(reader.GetName()), m_data(reader.m_data),
+    m_offset(offset), m_size(size)
+{
+}
+
+uint64_t MmapReader::Size() const
+{
+  return m_size;
+}
+
+void MmapReader::Read(uint64_t pos, void * p, size_t size) const
+{
+  ASSERT_LESS_OR_EQUAL(pos + size, Size(), (pos, size));
+  memcpy(p, m_data->m_memory + m_offset + pos, size);
+}
+
+MmapReader * MmapReader::CreateSubReader(uint64_t pos, uint64_t size) const
+{
+  ASSERT_LESS_OR_EQUAL(pos + size, Size(), (pos, size));
+  return new MmapReader(*this, m_offset + pos, size);
+}

coding/mmap_reader.hpp

@@ -0,0 +1,25 @@
+#pragma once
+
+#include "reader.hpp"
+
+#include "../std/shared_ptr.hpp"
+
+/// @TODO Add Windows support
+class MmapReader : public ModelReader
+{
+  typedef ModelReader base_type;
+
+  class MmapData;
+  shared_ptr<MmapData> m_data;
+  uint64_t m_offset;
+  uint64_t m_size;
+
+  MmapReader(MmapReader const & reader, uint64_t offset, uint64_t size);
+
+public:
+  explicit MmapReader(string const & fileName);
+
+  virtual uint64_t Size() const;
+  virtual void Read(uint64_t pos, void * p, size_t size) const;
+  virtual MmapReader * CreateSubReader(uint64_t pos, uint64_t size) const;
+};