This class defines a concrete thread-safe "guarding" allocator mechanism that implements the bslma::Allocator protocol, and adjoins a read/write protected guard page to each block of memory returned by the allocate method. The guard page is placed immediately before or immediately following the block returned from allocate according to the GuardPageLocation enumerator value (optionally) supplied at construction. Note that, unlike many other allocators, an allocator cannot be (optionally) supplied at construction; instead, a system facility is used that allocates blocks of memory in multiples of the system page size. Also note that this allocator is intended for debugging purposes only.
| Name | Description |
|---|---|
bslma::Allocator | This protocol class provides a pure abstract interface and contract for clients and suppliers of raw memory. If the requested memory cannot be returned, the contract requires that an std::bad_alloc exception be thrown. Note that memory is guaranteed to be sufficiently aligned for any object of the requested size on the current platform, which may be less than the maximal alignment guarantee afforded by global operator new. |
| Name | Description |
|---|---|
size_type | Alias for an unsigned integral type capable of representing the number of bytes in this platform's virtual address space. |
| Name | Description |
|---|---|
GuardPageLocation | Enumerate the configuration options for GuardingAllocator that may be (optionally) supplied at construction. |
| Name | Description |
|---|---|
GuardingAllocator [constructor] | Create a guarding allocator. Optionally specify a guardLocation indicating where read/write protected guard pages should be placed with respect to the memory blocks returned by the allocate method. If guardLocation is not specified, guard pages are placed immediately following the memory blocks returned by allocate. |
~GuardingAllocator [destructor] [virtual] | Destroy this allocator object. Note that destroying this allocator has no effect on any outstanding allocated memory. |
operator= | |
allocate | allocate overloads |
deallocate | Return the memory block at the specified address back to this allocator. If address is 0, this method has no effect. Otherwise, the guard page associated with address is unprotected and also deallocated. The behavior is undefined unless address was returned by allocate and has not already been deallocated. |
deleteObject | deleteObject overloads |
deleteObjectRaw | deleteObjectRaw overloads |
is_equal |
| Name | Description |
|---|---|
throwBadAlloc | Throw std::bad_alloc if exceptions are enabled or abort the program otherwise. Derived classes and helper functions will typically call this function when they are unable to satisfy an allocation request. This function never returns. |
| Name | Description |
|---|---|
do_allocate [virtual] | Return a newly allocated block of memory of (at least) the specified positive bytes and having at least the specified alignment. Unless overriden in a derived class, the return value is this->allocate(bytes). If this allocator cannot return the requested number of bytes or cannot satisfy the alignment request, then it will throw a std::bad_alloc exception in an exception-enabled build, or else will abort the program in a non-exception build. Unless overriden in a derived class, this function will forward the allocation request to the allocate virtual function, padding bytes and adjusting the return value as necessary to ensure sufficient alignment. Note that if bytes is 0, the same non-null value will be returned every time. |
do_deallocate [virtual] | Return the memory block at the specified p address, having the specified bytes and specified alignment, back to this allocator. Unless overriden in a derived class, this function will forward the deallocation request to the deallocate virtual function, padding bytes and adjusting p as necessary to account for alignment values other than the natural alignment for an object of size bytes. The behavior is undefined unless address is a block allocated from this allocator object using the same bytes and alignment and not already deallocated. |
do_is_equal [virtual] | Return true if this allocator is equal to the specified other allocator, meaning (at least) that a memory block allocated by one can be deallocated by the other; otherwise return false. Unless overriden, this method returns this == &other. |