src/ipc/mem/Segment.h

   1 /*
   2  */
   3
   4 #ifndef SQUID_IPC_MEM_SEGMENT_H
   5 #define SQUID_IPC_MEM_SEGMENT_H
   6
   7 #include "base/RunnersRegistry.h"
   8 #include "SquidString.h"
   9
  10 namespace Ipc
  11 {
  12
  13 namespace Mem
  14 {
  15
  16 /// POSIX shared memory segment
  17 class Segment
  18 {
  19 public:
  20     /// Create a shared memory segment.
  21     Segment(const char *const id);
  22     ~Segment();
  23
  24     /// Whether shared memory support is available
  25     static bool Enabled();
  26
  27     /// Create a new shared memory segment. Unlinks the segment on destruction.
  28     void create(const off_t aSize);
  29     void open(); ///< Open an existing shared memory segment.
  30
  31     const String &name() { return theName; } ///< shared memory segment name
  32     off_t size() { return theSize; } ///< shared memory segment size
  33     void *mem() { return reserve(0); } ///< pointer to the next chunk
  34     void *reserve(size_t chunkSize); ///< reserve and return the next chunk
  35
  36     /// common path of all segment names in path-based environments
  37     static const char *BasePath;
  38
  39 private:
  40
  41     // not implemented
  42     Segment(const Segment &);
  43     Segment &operator =(const Segment &);
  44
  45 #if HAVE_SHM
  46
  47     void attach();
  48     void detach();
  49     void unlink(); ///< unlink the segment
  50     off_t statSize(const char *context) const;
  51
  52     static String GenerateName(const char *id);
  53
  54     int theFD; ///< shared memory segment file descriptor
  55
  56 #else // HAVE_SHM
  57
  58     void checkSupport(const char *const context);
  59
  60 #endif // HAVE_SHM
  61
  62     const String theName; ///< shared memory segment file name
  63     void *theMem; ///< pointer to mmapped shared memory segment
  64     off_t theSize; ///< shared memory segment size
  65     off_t theReserved; ///< the total number of reserve()d bytes
  66     bool doUnlink; ///< whether the segment should be unlinked on destruction
  67 };
  68
  69 /// Base class for runners that create and open shared memory segments.
  70 /// First may run create() method and then open().
  71 class RegisteredRunner: public ::RegisteredRunner
  72 {
  73 public:
  74     /* RegisteredRunner API */
  75     virtual void useConfig();
  76
  77 protected:
  78     /// called when the runner should create a new memory segment
  79     virtual void create() = 0;
  80     /// called when the runner should open a previously created segment,
  81     /// not needed if segments are opened in constructor or init methods
  82     virtual void open() {}
  83 };
  84
  85 } // namespace Mem
  86
  87 } // namespace Ipc
  88
  89 #endif /* SQUID_IPC_MEM_SEGMENT_H */