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

Concrete thread&hyphen;safe guarding allocator that adjoins a protected guard page to each allocated block&period;

== Synopsis

Declared in `&lt;bdlma&lowbar;guardingallocator&period;h&gt;`

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

== Description

This class defines a concrete thread&hyphen;safe &quot;guarding&quot; allocator mechanism that implements the `bslma&colon;&colon;Allocator` protocol, and adjoins a read&sol;write protected guard page to each block of memory returned by the `allocate` method&period; 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&period; Note that, unlike many other allocators, an allocator cannot be (optionally) supplied at construction&semi; instead, a system facility is used that allocates blocks of memory in multiples of the system page size&period; Also note that this allocator is intended for debugging purposes _only_&period;

== Base Classes

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

== Type Aliases

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


== Enums

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlma/GuardingAllocator/GuardPageLocation.adoc[`GuardPageLocation`] 
| Enumerate the configuration options for `GuardingAllocator` that may be (optionally) supplied at construction&period;
|===


== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlma/GuardingAllocator/2constructor.adoc[`GuardingAllocator`]         [.small]#[constructor]#
| Create a guarding allocator&period;
| xref:BloombergLP/bdlma/GuardingAllocator/2destructor.adoc[`&#126;GuardingAllocator`] [.small]#[destructor]# [.small]#[virtual]#
| Destroy this allocator object&period; Note that destroying this allocator has no effect on any outstanding allocated memory&period;
| xref:BloombergLP/bslma/Allocator/operator_assign.adoc[`operator&equals;`] 
| 
| xref:BloombergLP/bdlma/GuardingAllocator/allocate-07.adoc[`allocate`] 
| `allocate` overloads
| xref:BloombergLP/bdlma/GuardingAllocator/deallocate-03.adoc[`deallocate`] 
| Return the memory block at the specified `address` back to this allocator&period;
| 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&lowbar;equal`] 
| 
|===


== Static Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslma/Allocator/throwBadAlloc.adoc[`throwBadAlloc`] 
| Throw `std&colon;&colon;bad&lowbar;alloc` or abort the program&period;
|===


== Protected Member Functions

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



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