Class xsi_shared_memory

boost::interprocess::xsi_shared_memory

Synopsis

// In header: <boost/interprocess/xsi_shared_memory.hpp>


class xsi_shared_memory {
public:
  // construct/copy/destruct
  xsi_shared_memory() noexcept;
  xsi_shared_memory(open_only_t, int);
  xsi_shared_memory(create_only_t, const xsi_key &, std::size_t, 
                    const permissions & = permissions());
  xsi_shared_memory(open_or_create_t, const xsi_key &, std::size_t, 
                    const permissions & = permissions());
  xsi_shared_memory(open_only_t, const xsi_key &);
  xsi_shared_memory(xsi_shared_memory &&) noexcept;
  xsi_shared_memory & operator=(xsi_shared_memory &&) noexcept;
  ~xsi_shared_memory();

  // public member functions
  void swap(xsi_shared_memory &) noexcept;
  int get_shmid() const noexcept;
  mapping_handle_t get_mapping_handle() const noexcept;

  // public static functions
  static bool remove(int);
};

Description

A class that wraps XSI (System V) shared memory. Unlike shared_memory_object, xsi_shared_memory needs a valid xsi_key to identify a shared memory object.

Warning: XSI shared memory and interprocess portable shared memory (boost::interprocess::shared_memory_object) can't communicate between them.

`xsi_shared_memory` public construct/copy/destruct

```
xsi_shared_memory() noexcept;
```
Default constructor. Represents an empty xsi_shared_memory.
```
xsi_shared_memory(open_only_t, int shmid);
```
Initializes *this with a shmid previously obtained (possibly from another process) This lower-level initializer allows shared memory mapping without having a key.

xsi_shared_memory(create_only_t, const xsi_key & key, std::size_t size, 
                  const permissions & perm = permissions());

Creates a new XSI shared memory from 'key', with size "size" and permissions "perm". If the shared memory previously exists, throws an error.

xsi_shared_memory(open_or_create_t, const xsi_key & key, std::size_t size, 
                  const permissions & perm = permissions());

Opens an existing shared memory with identifier 'key' or creates a new XSI shared memory from identifier 'key', with size "size" and permissions "perm".

```
xsi_shared_memory(open_only_t, const xsi_key & key);
```
Tries to open a XSI shared memory with identifier 'key' If the shared memory does not previously exist, it throws an error.
```
xsi_shared_memory(xsi_shared_memory && moved) noexcept;
```
Moves the ownership of "moved"'s shared memory object to *this. After the call, "moved" does not represent any shared memory object. Does not throw
```
xsi_shared_memory & operator=(xsi_shared_memory && moved) noexcept;
```
Moves the ownership of "moved"'s shared memory to *this. After the call, "moved" does not represent any shared memory. Does not throw
```
~xsi_shared_memory();
```
Destroys *this. The shared memory won't be destroyed, just this connection to it. Use remove() to destroy the shared memory.

`xsi_shared_memory` public member functions

void swap(xsi_shared_memory & other) noexcept;

Swaps two xsi_shared_memorys. Does not throw.

```
int get_shmid() const noexcept;
```
Returns the shared memory ID that identifies the shared memory

mapping_handle_t get_mapping_handle() const noexcept;

Returns the mapping handle. Never throws

`xsi_shared_memory` public static functions

```
static bool remove(int shmid);
```
Erases the XSI shared memory object identified by shmid from the system. Returns false on error. Never throws

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