[#BloombergLP-bdlma-HeapBypassAllocator]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bdlma.adoc[bdlma]::HeapBypassAllocator
:relfileprefix: ../../
:mrdocs:

Memory allocator that obtains storage directly from virtual memory.

== Synopsis

Declared in `<bdlma_heapbypassallocator.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
class HeapBypassAllocator
    : public xref:BloombergLP/bslma/Allocator.adoc[bslma::Allocator]
----

== Description

This class allows the caller to allocate memory directly from virtual memory, without going through the heap like `malloc` or `new` would. Note that the only way to free any memory allocated with this object is to destroy the object, at which point all memory it has allocated is freed. Thread‐safe.

== Base Classes

[cols="1,4"]
|===
| Name| Description
| `xref:BloombergLP/bslma/Allocator.adoc[bslma::Allocator]`
| Pure abstract protocol for clients and suppliers of raw memory.
|===

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslma/Allocator/size_type.adoc[`size_type`] 
| Alias for an unsigned integral type capable of representing the number of bytes in this platform's virtual address space.
|===


== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlma/HeapBypassAllocator/2constructor-08.adoc[`HeapBypassAllocator`]         [.small]#[constructor]#
| Constructors
| xref:BloombergLP/bdlma/HeapBypassAllocator/2destructor.adoc[`~HeapBypassAllocator`] [.small]#[destructor]# [.small]#[virtual]#
| Destroy this object, releasing all managed buffers of memory that it has allocated.
| xref:BloombergLP/bslma/Allocator/operator_assign.adoc[`operator=`] 
| 
| xref:BloombergLP/bdlma/HeapBypassAllocator/allocate-07.adoc[`allocate`] 
| `allocate` overloads
| xref:BloombergLP/bdlma/HeapBypassAllocator/deallocate-09.adoc[`deallocate`] 
| This method has no effect for this heap bypass allocator.
| xref:BloombergLP/bslma/Allocator/deleteObject-09.adoc[`deleteObject`] 
| `deleteObject` overloads
| xref:BloombergLP/bslma/Allocator/deleteObjectRaw-06f.adoc[`deleteObjectRaw`] 
| `deleteObjectRaw` overloads
| xref:BloombergLP/bslma/Allocator/is_equal.adoc[`is_equal`] 
| 
|===


== Static Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslma/Allocator/throwBadAlloc.adoc[`throwBadAlloc`] 
| Throw `std::bad_alloc` or abort the program.
|===


== Protected Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslma/Allocator/do_allocate.adoc[`do_allocate`]  [.small]#[virtual]#
| Return a newly allocated block of at least `bytes` with `alignment`.
| xref:BloombergLP/bslma/Allocator/do_deallocate.adoc[`do_deallocate`]  [.small]#[virtual]#
| Return the memory block at `p` having `bytes` and `alignment`.
| xref:BloombergLP/bslma/Allocator/do_is_equal.adoc[`do_is_equal`]  [.small]#[virtual]#
| Return whether this allocator can exchange memory with `other`.
|===



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