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

This protocol class extends `bslma::Allocator` for allocators with the ability to `release` all memory currently allocated through the protocol back to the memory supplier of the derived concrete allocator object.

== Synopsis

Declared in `<bdlma_managedallocator.h>`

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

== Base Classes

[cols="1,4"]
|===
| Name| Description
| `xref:BloombergLP/bslma/Allocator.adoc[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`.
|===

== 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/bslma/Allocator/operator_assign.adoc[`operator=`] 
| 
| xref:BloombergLP/bslma/Allocator/allocate-03b.adoc[`allocate`] 
| Return a newly allocated block of memory of the specified `size` bytes.
| xref:BloombergLP/bslma/Allocator/deallocate-04.adoc[`deallocate`] 
| Return the memory block at the specified `address` to this 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`] 
| 
| xref:BloombergLP/bdlma/ManagedAllocator/release.adoc[`release`]  [.small]#[virtual]#
| Release all memory currently allocated through this allocator. The effect of using a pointer after this call that was obtained from this allocator before this call is undefined.
|===


== Static Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslma/Allocator/throwBadAlloc.adoc[`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.
|===


== 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 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.
| xref:BloombergLP/bslma/Allocator/do_deallocate.adoc[`do_deallocate`]  [.small]#[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.
| xref:BloombergLP/bslma/Allocator/do_is_equal.adoc[`do_is_equal`]  [.small]#[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`.
|===


== Derived Classes

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlma/BufferedSequentialAllocator.adoc[`BufferedSequentialAllocator`] 
| This class implements the `ManagedAllocator` protocol to provide a fast allocator that dispenses heterogeneous blocks of memory (of varying, user‐specified sizes) from an external buffer whose address and size (in bytes) are supplied at construction. If an allocation request exceeds the remaining free memory space in the external buffer, memory will be supplied by an (optional) allocator also supplied at construction; if no allocator is supplied, the currently installed default allocator is used. This class is _exception_ _neutral_: If memory cannot be allocated, the behavior is defined by the (optional) allocator supplied at construction. Note that in no case will the buffered sequential allocator attempt to deallocate the external buffer.
| xref:BloombergLP/bdlma/ConcurrentMultipoolAllocator.adoc[`ConcurrentMultipoolAllocator`] 
| This class implements the `bdlma::ManagedAllocator` protocol to provide a thread‐safe allocator that maintains a configurable number of `Pool` objects, each dispensing memory blocks of a unique size. The `Pool` objects are placed in an array, with each successive pool managing memory blocks of size twice that of the previous pool. Each multipool allocation (deallocation) request allocates memory from (returns memory to) the internal pool having the smallest block size not less than the requested size, or, if no pool manages memory blocks of sufficient sized, from a separately managed list of memory blocks. Both the `release` method and the destructor of a `ConcurrentMultipoolAllocator` release all memory currently allocated via the object.
| xref:BloombergLP/bdlma/MultipoolAllocator.adoc[`MultipoolAllocator`] 
| This class implements the `bdlma::ManagedAllocator` protocol to provide an allocator that maintains a configurable number of `bdlma::Pool` objects, each dispensing memory blocks of a unique size. The `bdlma::Pool` objects are placed in an array, with each successive pool managing memory blocks of size twice that of the previous pool. Each multipool allocation (deallocation) request allocates memory from (returns memory to) the internal pool having the smallest block size not less than the requested size, or, if no pool manages memory blocks of sufficient sized, from a separately managed list of memory blocks. Both the `release` method and the destructor of a `bdlma::MultipoolAllocator` release all memory currently allocated via the object.
| xref:BloombergLP/bdlma/SequentialAllocator.adoc[`SequentialAllocator`] 
| This class implements the `ManagedAllocator` protocol to provide a fast allocator that dispenses heterogeneous blocks of memory (of varying, user‐specified sizes) from a sequence of dynamically‐allocated buffers. Memory for the internal buffers is supplied by an (optional) allocator supplied at construction; if no allocator is supplied, the currently installed default allocator is used. If an allocation exceeds the remaining free memory space in the current buffer, the allocator replenishes its internal buffer with new memory to satisfy the request. This class is _exception_ _neutral_: If memory cannot be allocated, the behavior is defined by the (optional) allocator specified at construction.
| xref:BloombergLP/balst/StackTraceTestAllocator.adoc[`StackTraceTestAllocator`] 
| This class defines a concrete "test" allocator mechanism that implements the `bdlma::ManagedAllocator` protocol, and provides instrumentation to track the set of all blocks allocated by this allocator that have yet to be freed. At any time it can produce a report about such blocks, listing for each place that any unfreed blocks were allocated * the number of unfreed blocks allocated at that place * the stack trace at that place The allocator will also detect redundant frees of the same block, and frees by the wrong allocator. The client can choose whether such violations are handled by a core dump, or merely a report being written.
|===


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