geopm::SharedMemory(3) – abstractions for shared memory
Namespaces
The SharedMemory is a member of the namespace geopm,
but the full name geopm::SharedMemory has been abbreviated in this manual.
Similarly, the std:: namespace specifier has been omitted from the
interface definitions for the following standard types: std::vector,
std::string, std::unique_ptr, std::vector, and std::function, to enable
better rendering of this manual.
Synopsis
#include <geopm/SharedMemory.hpp>
Link with -lgeopmd
static unique_ptr<SharedMemory> SharedMemory::make_unique_owner(const string &shm_key,
size_t size);
static unique_ptr<SharedMemory> SharedMemory::make_unique_owner_secure(const string &shm_key,
size_t size);
static unique_ptr<SharedMemory> SharedMemory::make_unique_user(const string &shm_key,
unsigned int timeout);
void* SharedMemory::pointer(void) const;
string SharedMemory::key(void) const;
size_t SharedMemory::size(void) const;
void SharedMemory::unlink(void);
unique_ptr<SharedMemoryScopedLock> SharedMemory::get_scoped_lock(void);
void SharedMemory::chown(const unsigned int uid,
const unsigned int gid);
Description
The SharedMemory class encapsulates the creation and use of
inter-process shared memory. In the GEOPM runtime, shared memory is
used to communicate between the user application’s MPI calls and calls
to geopm_prof(3) methods, and the Controller
running on the same node.
SharedMemory is a pure virtual abstract base class.
Class Methods
make_unique_owner()Creates a shared memory region with key shm_key and size and returns a pointer to a
SharedMemoryobject managing it.make_unique_owner_secure()Creates a shared memory region with key shm_key and size without group or world permissions and returns a pointer to a
SharedMemoryobject managing it.make_unique_user()Attempts to attach to a inter-process shared memory region with key shm_key within timeout and returns a pointer to a
SharedMemoryobject managing it. If it cannot attach within the timeout, throws an exception.pointer()Returns a pointer to the shared memory region.
key()Returns the key to the shared memory region.
size()Returns the size of the shared memory region.
unlink()Unlink the shared memory region.
get_scoped_lock()Attempt to lock the mutex for the shared memory region and returns a temporary object that holds the mutex lock for the shared memory region while in scope, and releases it when it goes out of scope. This method should be called before accessing the memory with
pointer().chown()Modifies the shared memory to be owned by the specified gid and uid if current permissions allow for the change.