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LockedPool Class Reference

Pool for locked memory chunks. More...

#include <lockedpool.h>

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Classes

class  LockedPageArena
 Create an arena from locked pages. More...
 
struct  Stats
 Memory statistics. More...
 

Public Types

typedef bool(* LockingFailed_Callback) ()
 Callback when allocation succeeds but locking fails. More...
 

Public Member Functions

 LockedPool (std::unique_ptr< LockedPageAllocator > allocator, LockingFailed_Callback lf_cb_in=nullptr)
 Create a new LockedPool. More...
 
 ~LockedPool ()
 
 LockedPool (const LockedPool &other)=delete
 
LockedPooloperator= (const LockedPool &)=delete
 
void * alloc (size_t size)
 Allocate size bytes from this arena. More...
 
void free (void *ptr)
 Free a previously allocated chunk of memory. More...
 
Stats stats () const
 Get pool usage statistics. More...
 

Static Public Attributes

static const size_t ARENA_SIZE = 256*1024
 Size of one arena of locked memory. More...
 
static const size_t ARENA_ALIGN = 16
 Chunk alignment. More...
 

Private Member Functions

bool new_arena (size_t size, size_t align)
 

Private Attributes

std::unique_ptr< LockedPageAllocatorallocator
 
std::list< LockedPageArenaarenas
 
LockingFailed_Callback lf_cb
 
size_t cumulative_bytes_locked
 
std::mutex mutex
 Mutex protects access to this pool's data structures, including arenas. More...
 

Detailed Description

Pool for locked memory chunks.

To avoid sensitive key data from being swapped to disk, the memory in this pool is locked/pinned.

An arena manages a contiguous region of memory. The pool starts out with one arena but can grow to multiple arenas if the need arises.

Unlike a normal C heap, the administrative structures are separate from the managed memory. This has been done as the sizes and bases of objects are not in themselves sensitive information, as to conserve precious locked memory. In some operating systems the amount of memory that can be locked is small.

Definition at line 117 of file lockedpool.h.

Member Typedef Documentation

typedef bool(* LockedPool::LockingFailed_Callback) ()

Callback when allocation succeeds but locking fails.

Definition at line 133 of file lockedpool.h.

Constructor & Destructor Documentation

LockedPool::LockedPool ( std::unique_ptr< LockedPageAllocator allocator,
LockingFailed_Callback  lf_cb_in = nullptr 
)
explicit

Create a new LockedPool.

This takes ownership of the MemoryPageLocker, you can only instantiate this with LockedPool(std::move(...)).

The second argument is an optional callback when locking a newly allocated arena failed. If this callback is provided and returns false, the allocation fails (hard fail), if it returns true the allocation proceeds, but it could warn.

Definition at line 260 of file lockedpool.cpp.

LockedPool::~LockedPool ( )

Definition at line 265 of file lockedpool.cpp.

LockedPool::LockedPool ( const LockedPool other)
delete

Member Function Documentation

void * LockedPool::alloc ( size_t  size)

Allocate size bytes from this arena.

Returns pointer on success, or 0 if memory is full or the application tried to allocate 0 bytes.

Definition at line 268 of file lockedpool.cpp.

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void LockedPool::free ( void *  ptr)

Free a previously allocated chunk of memory.

Freeing the zero pointer has no effect. Raises std::runtime_error in case of error.

Definition at line 290 of file lockedpool.cpp.

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bool LockedPool::new_arena ( size_t  size,
size_t  align 
)
private

Definition at line 319 of file lockedpool.cpp.

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LockedPool& LockedPool::operator= ( const LockedPool )
delete
LockedPool::Stats LockedPool::stats ( ) const

Get pool usage statistics.

Definition at line 304 of file lockedpool.cpp.

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Member Data Documentation

std::unique_ptr<LockedPageAllocator> LockedPool::allocator
private

Definition at line 174 of file lockedpool.h.

const size_t LockedPool::ARENA_ALIGN = 16
static

Chunk alignment.

Another compromise. Setting this too high will waste memory, setting it too low will facilitate fragmentation.

Definition at line 129 of file lockedpool.h.

const size_t LockedPool::ARENA_SIZE = 256*1024
static

Size of one arena of locked memory.

This is a compromise. Do not set this too low, as managing many arenas will increase allocation and deallocation overhead. Setting it too high allocates more locked memory from the OS than strictly necessary.

Definition at line 125 of file lockedpool.h.

std::list<LockedPageArena> LockedPool::arenas
private

Definition at line 190 of file lockedpool.h.

size_t LockedPool::cumulative_bytes_locked
private

Definition at line 192 of file lockedpool.h.

LockingFailed_Callback LockedPool::lf_cb
private

Definition at line 191 of file lockedpool.h.

std::mutex LockedPool::mutex
mutableprivate

Mutex protects access to this pool's data structures, including arenas.

Definition at line 195 of file lockedpool.h.


The documentation for this class was generated from the following files: