os::rtos::memory::memory_resource Class Reference

Memory resource manager (abstract class). More...

#include <cmsis-plus/rtos/os.h>

Inheritance diagram for os::rtos::memory::memory_resource:

Public Member Functions
Constructors & Destructor
	memory_resource ()=default
	Default constructor. Construct a memory resource object instance.
	memory_resource (const char *name)
	Construct a named memory resource object instance.
virtual	~memory_resource ()
	Destruct the memory resource object instance.
Public Member Functions
void *	allocate (std::size_t bytes, std::size_t alignment=max_align)
	Allocate a memory block.
void	deallocate (void *addr, std::size_t bytes, std::size_t alignment=max_align) noexcept
	Deallocate the previously allocated memory block.
bool	is_equal (memory_resource const &other) const noexcept
	Compare for equality with another memory_resource.
void	reset (void) noexcept
	Reset the memory manager to the initial state.
bool	coalesce (void) noexcept
	Coalesce free blocks.
std::size_t	max_size (void) const noexcept
	Get the largest value that can be passed to allocate().
out_of_memory_handler_t	out_of_memory_handler (out_of_memory_handler_t handler)
	Set the out of memory handler.
out_of_memory_handler_t	out_of_memory_handler (void)
	Get the out of memory handler.
std::size_t	total_bytes (void)
	Get the total size of managed memory.
std::size_t	allocated_bytes (void)
	Get the current size of all allocated chunks.
std::size_t	max_allocated_bytes (void)
	Get the maximum allocated size.
std::size_t	free_bytes (void)
	Get the current size of all free chunks.
std::size_t	allocated_chunks (void)
	Get the current number of allocated chunks.
std::size_t	free_chunks (void)
	Get the current number of free chunks.
std::size_t	allocations (void)
	Get the number of allocations.
std::size_t	deallocations (void)
	Get the number of deallocations.
void	trace_print_statistics (void)
	Print a long message with usage statistics.
Public Member Functions
const char *	name (void) const
	Get object name.

Static Public Attributes
static constexpr std::size_t	max_align = alignof (std::max_align_t)
	The largest alignment for the platform. Also default when supplied alignment is not supported.

Protected Member Functions
Private Member Functions
virtual void *	do_allocate (std::size_t bytes, std::size_t alignment)=0
	Implementation of the memory allocator.
virtual void	do_deallocate (void *addr, std::size_t bytes, std::size_t alignment) noexcept=0
	Implementation of the memory deallocator.
virtual bool	do_is_equal (memory_resource const &other) const noexcept
	Implementation of the equality comparator.
virtual std::size_t	do_max_size (void) const noexcept
	Implementation of the function to get max size.
virtual void	do_reset (void) noexcept
	Implementation of the function to reset the memory manager.
virtual bool	do_coalesce (void) noexcept
	Implementation of the function to coalesce free blocks.
void	internal_increase_allocated_statistics (std::size_t bytes) noexcept
	Update statistics after allocation.
void	internal_decrease_allocated_statistics (std::size_t bytes) noexcept
	Update statistics after deallocation.

Detailed Description

This class is based on the standard C++17 memory manager, with several extensions, to control the throw behaviour and to add statistics.

Definition at line 158 of file os-memory.h.

Constructor & Destructor Documentation

memory_resource() [1/2]

os::rtos::memory::memory_resource::memory_resource ( )

default

memory_resource() [2/2]

os::rtos::memory::memory_resource::memory_resource ( const char *  name )

inline

Parameters

name	Pointer to name.

Definition at line 1264 of file os-memory.h.

          : object_named{ name }
      {
      }

~memory_resource()

os::rtos::memory::memory_resource::~memory_resource ( )

virtual

Definition at line 365 of file os-memory.cpp.

      {
      }

Member Function Documentation

allocate()

void * os::rtos::memory::memory_resource::allocate ( std::size_t  bytes, std::size_t  alignment = max_align  )

inline

Parameters

bytes	Number of bytes to allocate.
alignment	Alignment constraint (power of 2).

Returns

Pointer to newly allocated block, or nullptr.

Allocate storage with a size of at least bytes bytes. The returned storage is aligned to the specified alignment if such alignment is supported, and to alignof(std::max_align_t) otherwise.

If the storage of the requested size and alignment cannot be obtained:

• if the out of memory handler is not set, return nullptr;
• if the out of memory handler is set, call it and retry.

Equivalent to return do_allocate(bytes, alignment);.

Exceptions

The code itself throws nothing, but if the out of memory handler is set, it may throw a bad_alloc() exception.

See also

do_allocate();

Definition at line 1290 of file os-memory.h.

      {
        ++allocations_;
        return do_allocate (bytes, alignment);
      }

References do_allocate().

Referenced by os::estd::pmr::polymorphic_allocator< T >::allocate(), calloc(), malloc(), operator new(), and realloc().

allocated_bytes()

std::size_t os::rtos::memory::memory_resource::allocated_bytes ( void  )

inline

Parameters

None.

Returns

Number of bytes.

Definition at line 1402 of file os-memory.h.

      {
        return allocated_bytes_;
      }

Referenced by trace_print_statistics().

allocated_chunks()

std::size_t os::rtos::memory::memory_resource::allocated_chunks ( void  )

inline

Parameters

None.

Returns

Number of chunks.

Definition at line 1420 of file os-memory.h.

      {
        return allocated_chunks_;
      }

Referenced by trace_print_statistics().

allocations()

std::size_t os::rtos::memory::memory_resource::allocations ( void  )

inline

Parameters

None.

Returns

Number of allocations.

Definition at line 1432 of file os-memory.h.

      {
        return allocations_;
      }

Referenced by trace_print_statistics().

coalesce()

bool os::rtos::memory::memory_resource::coalesce ( void  )

inlinenoexcept

Parameters

None.

Return values

true	if the operation freed more memory.
false	if the operation was ineffective.

In case the memory manager does not coalesce during deallocation, traverse the list of free blocks and coalesce.

Return true if the operation was successful and at least one larger block resulted.

See also

do_coalesce();

Definition at line 1365 of file os-memory.h.

      {
        return do_coalesce ();
      }

deallocate()

void os::rtos::memory::memory_resource::deallocate ( void *  addr, std::size_t  bytes, std::size_t  alignment = max_align  )

inlinenoexcept

Parameters

addr	Address of the block to free.
bytes	Number of bytes to deallocate (may be 0 if unknown).
alignment	Alignment constraint (power of 2).

Returns

Nothing.

Deallocate the storage pointed to by addr. The address shall have been returned by a prior call to allocate() on a memory_resource that compares equal to *this, and the storage it points to shall not yet have been deallocated.

Equivalent to return do_deallocate(p, bytes, alignment);.

Exceptions

Throws nothing.

See also

do_deallocate();

Definition at line 1312 of file os-memory.h.

      {
        ++deallocations_;
        do_deallocate (addr, bytes, alignment);
      }

Referenced by os::estd::pmr::polymorphic_allocator< T >::deallocate(), free(), and realloc().

deallocations()

std::size_t os::rtos::memory::memory_resource::deallocations ( void  )

inline

Parameters

None.

Returns

Number of deallocations

Definition at line 1438 of file os-memory.h.

      {
        return deallocations_;
      }

Referenced by trace_print_statistics().

do_allocate()

os::rtos::memory::memory_resource::do_allocate ( std::size_t  bytes, std::size_t  alignment  )

protectedpure virtual

Parameters

bytes	Number of bytes to allocate.
alignment	Alignment constraint (power of 2).

Returns

Pointer to newly allocated block, or nullptr.

Allocates storage with a size of at least bytes bytes. The returned storage is aligned to the specified alignment if such alignment is supported, and to alignof(std::max_align_t) otherwise.

The function should return a nullptr when no more memory is available.

Exceptions

The code itself should throw nothing, but if the out of memory handler is set, it may throw a bad_alloc() exception.

Implemented in os::memory::block_pool, os::memory::first_fit_top, os::memory::lifo, os::memory::malloc_memory_resource, and os::memory::null_memory_resource.

Referenced by allocate().

do_coalesce()

bool os::rtos::memory::memory_resource::do_coalesce ( void  )

protectedvirtualnoexcept

Parameters

None.

Return values

true	if the operation resulted in larger blocks.
false	if the operation was ineffective.

The default implementation of this virtual function returns false, meaning the operation was ineffective.

Override this function to perform the action.

Standard compliance

Extension to standard.

Definition at line 468 of file os-memory.cpp.

      {
        return false;
      }

do_deallocate()

os::rtos::memory::memory_resource::do_deallocate ( void *  addr, std::size_t  bytes, std::size_t  alignment  )

protectedpure virtualnoexcept

Parameters

addr	Address of a previously allocated block to free.
bytes	Number of bytes to deallocate (may be 0 if unknown).
alignment	Alignment constraint (power of 2).

Returns

Nothing.

Deallocates the storage pointed to by addr. The address must have been returned by a prior call to allocate(bytes, alignment) on a memory_resource that compares equal to *this, and the storage it points to must not yet have been deallocated, otherwise the behaviour is undefined.

Exceptions

Should throw nothing itself.

Implemented in os::memory::block_pool, os::memory::first_fit_top, os::memory::malloc_memory_resource, and os::memory::null_memory_resource.

do_is_equal()

bool os::rtos::memory::memory_resource::do_is_equal ( memory_resource const &  other ) const

protectedvirtualnoexcept

Parameters

other

Reference to another memory_resource.

Return values

true	The memory_resource objects are equal.
false	The memory_resource objects are not equal.

Compares *this for equality with other. Two memory_resources compare equal if and only if memory allocated from one memory_resource can be deallocated from the other and vice versa.

The most-derived type of other may not match the most derived type of *this. A derived class implementation therefore must typically check whether the most derived types of *this and other match using dynamic_cast, and immediately return false if the cast fails.

Exceptions

Throws nothing.

Definition at line 419 of file os-memory.cpp.

      {
        return &other == this;
      }

do_max_size()

std::size_t os::rtos::memory::memory_resource::do_max_size ( void  ) const

protectedvirtualnoexcept

Parameters

None.

Returns

Integer with size in bytes, or 0 if unknown.

The default implementation of this virtual function returns zero, meaning the size is not known.

Override this function to return the actual size.

Standard compliance

Extension to standard.

Reimplemented in os::memory::block_pool, and os::memory::first_fit_top.

Definition at line 436 of file os-memory.cpp.

      {
        return 0;
      }

do_reset()

void os::rtos::memory::memory_resource::do_reset ( void  )

protectedvirtualnoexcept

Parameters

None.

Returns

Nothing.

The default implementation of this virtual function does nothing.

Override this function to perform the action.

Standard compliance

Extension to standard.

Reimplemented in os::memory::block_pool, and os::memory::first_fit_top.

Definition at line 452 of file os-memory.cpp.

      {
        return;
      }

free_bytes()

std::size_t os::rtos::memory::memory_resource::free_bytes ( void  )

inline

Parameters

None.

Returns

Number of bytes.

Definition at line 1414 of file os-memory.h.

      {
        return free_bytes_;
      }

Referenced by trace_print_statistics().

free_chunks()

std::size_t os::rtos::memory::memory_resource::free_chunks ( void  )

inline

Parameters

None.

Returns

Number of chunks.

Definition at line 1426 of file os-memory.h.

      {
        return free_chunks_;
      }

Referenced by trace_print_statistics().

internal_decrease_allocated_statistics()

void os::rtos::memory::memory_resource::internal_decrease_allocated_statistics ( std::size_t  bytes )

protectednoexcept

Parameters

[in]

bytes

Number of deallocated bytes.

Returns

Nothing.

Definition at line 490 of file os-memory.cpp.

      {
        // Update statistics.
        // What is subtracted from allocated is added to free.
        allocated_bytes_ -= bytes;
        free_bytes_ += bytes;
        --allocated_chunks_;
        ++free_chunks_;
      }

internal_increase_allocated_statistics()

void os::rtos::memory::memory_resource::internal_increase_allocated_statistics ( std::size_t  bytes )

protectednoexcept

Parameters

[in]

bytes

Number of allocated bytes.

Returns

Nothing.

Definition at line 474 of file os-memory.cpp.

      {
        // Update statistics.
        // What is subtracted from free is added to allocated.
        allocated_bytes_ += bytes;
        if (allocated_bytes_ > max_allocated_bytes_)
          {
            max_allocated_bytes_ = allocated_bytes_;
          }
        free_bytes_ -= bytes;
        ++allocated_chunks_;
        --free_chunks_;
      }

Referenced by os::memory::block_pool::do_allocate(), and os::memory::first_fit_top::internal_align_().

is_equal()

bool os::rtos::memory::memory_resource::is_equal ( memory_resource const &  other ) const

inlinenoexcept

Parameters

other

Reference to another memory_resource.

Return values

true	The memory_resource objects are equal.
false	The memory_resource objects are not equal.

Compare *this for equality with other. Two memory_resources compare equal if and only if memory allocated from one memory_resource can be deallocated from the other and vice versa.

Exceptions

Throws nothing.

See also

do_is_equal();

Definition at line 1331 of file os-memory.h.

      {
        return do_is_equal (other);
      }

max_allocated_bytes()

std::size_t os::rtos::memory::memory_resource::max_allocated_bytes ( void  )

inline

Parameters

None.

Returns

Number of bytes.

Definition at line 1408 of file os-memory.h.

      {
        return max_allocated_bytes_;
      }

Referenced by trace_print_statistics().

max_size()

std::size_t os::rtos::memory::memory_resource::max_size ( void  ) const

inlinenoexcept

Parameters

None.

Returns

Number of bytes or 0 if unknown.

See also

do_max_size();

Definition at line 1340 of file os-memory.h.

      {
        return do_max_size ();
      }

name()

const char * os::rtos::internal::object_named::name ( void  ) const

inlineinherited

Parameters

None.

Returns

A null terminated string.

All objects return a non-null string; anonymous objects return "-".

Note

Can be invoked from Interrupt Service Routines.

Definition at line 753 of file os-decls.h.

      {
        return name_;
      }

Referenced by os::memory::lifo::lifo(), os::memory::malloc_memory_resource::malloc_memory_resource(), os::rtos::message_queue_typed< T, Allocator >::message_queue_typed(), os::memory::block_pool::~block_pool(), os::rtos::event_flags::~event_flags(), os::memory::first_fit_top::~first_fit_top(), os::memory::lifo::~lifo(), os::memory::malloc_memory_resource::~malloc_memory_resource(), os::rtos::memory_pool::~memory_pool(), os::rtos::message_queue::~message_queue(), os::rtos::mutex::~mutex(), os::rtos::semaphore::~semaphore(), os::rtos::thread::~thread(), os::rtos::timer::~timer(), os::rtos::memory_pool::alloc(), os::rtos::thread::cancel(), os::rtos::event_flags::clear(), os::rtos::mutex::consistent(), os::rtos::thread::detach(), os::memory::new_delete_memory_resource::do_allocate(), os::memory::block_pool::do_allocate(), os::memory::first_fit_top::do_allocate(), os::memory::lifo::do_allocate(), os::memory::malloc_memory_resource::do_allocate(), os::rtos::thread::flags_raise(), os::rtos::memory_pool::free(), os::rtos::event_flags::get(), os::rtos::thread::interrupt(), os::rtos::thread::join(), os::rtos::thread::kill(), os::rtos::internal::terminated_threads_list::link(), os::rtos::mutex::lock(), out_of_memory_handler(), os::rtos::semaphore::post(), os::rtos::mutex::prio_ceiling(), os::rtos::mutex::prio_ceiling(), os::rtos::thread::priority(), os::rtos::thread::priority_inherited(), os::rtos::event_flags::raise(), os::rtos::message_queue::receive(), os::rtos::memory_pool::reset(), os::rtos::message_queue::reset(), os::rtos::mutex::reset(), os::rtos::semaphore::reset(), os::rtos::thread::resume(), os::rtos::message_queue::send(), os::rtos::clock::sleep_for(), os::rtos::timer::start(), os::rtos::timer::stop(), os::rtos::memory_pool::timed_alloc(), os::rtos::mutex::timed_lock(), os::rtos::message_queue::timed_receive(), os::rtos::message_queue::timed_send(), os::rtos::semaphore::timed_wait(), os::rtos::event_flags::timed_wait(), trace_print_statistics(), os::rtos::memory_pool::try_alloc(), os::rtos::mutex::try_lock(), os::rtos::message_queue::try_receive(), os::rtos::message_queue::try_send(), os::rtos::event_flags::try_wait(), os::rtos::semaphore::try_wait(), os::rtos::internal::ready_threads_list::unlink_head(), os::rtos::mutex::unlock(), os::rtos::event_flags::wait(), os::rtos::semaphore::wait(), and os::rtos::event_flags::waiting().

out_of_memory_handler() [1/2]

out_of_memory_handler_t os::rtos::memory::memory_resource::out_of_memory_handler ( out_of_memory_handler_t  handler )

inline

Parameters

handler

Pointer to new handler.

Returns

Pointer to old handler.

Standard compliance

Extension to standard.

Definition at line 1375 of file os-memory.h.

      {
        trace::printf ("%s(%p) @%p %s\n", __func__, handler, this, name ());
 
        out_of_memory_handler_t tmp = out_of_memory_handler_;
        out_of_memory_handler_ = handler;
 
        return tmp;
      }

References os::rtos::internal::object_named::name(), and os::trace::printf().

Referenced by os_startup_initialize_free_store().

out_of_memory_handler() [2/2]

out_of_memory_handler_t os::rtos::memory::memory_resource::out_of_memory_handler ( void  )

inline

Parameters

None.

Returns

Pointer to existing handler.

Standard compliance

Extension to standard.

Definition at line 1390 of file os-memory.h.

      {
        return out_of_memory_handler_;
      }

reset()

void os::rtos::memory::memory_resource::reset ( void  )

inlinenoexcept

Parameters

None.

Returns

Nothing.

See also

do_reset();

Definition at line 1349 of file os-memory.h.

      {
        do_reset ();
      }

total_bytes()

std::size_t os::rtos::memory::memory_resource::total_bytes ( void  )

inline

Returns

Number of bytes.

Definition at line 1396 of file os-memory.h.

      {
        return total_bytes_;
      }

Referenced by trace_print_statistics().

trace_print_statistics()

void os::rtos::memory::memory_resource::trace_print_statistics ( void  )

inline

Parameters

None.

Returns

Nothing.

Definition at line 1444 of file os-memory.h.

      {
#if defined(TRACE)
        trace::printf ("Memory '%s' @%p: \n"
                       "\ttotal: %u bytes, \n"
                       "\tallocated: %u bytes in %u chunk(s), \n"
                       "\tfree: %u bytes in %u chunk(s), \n"
                       "\tmax: %u bytes, \n"
                       "\tcalls: %u allocs, %u deallocs\n",
                       name (), this, total_bytes (), allocated_bytes (),
                       allocated_chunks (), free_bytes (), free_chunks (),
                       max_allocated_bytes (), allocations (),
                       deallocations ());
#endif /* defined(TRACE) */
      }

References allocated_bytes(), allocated_chunks(), allocations(), deallocations(), free_bytes(), free_chunks(), max_allocated_bytes(), os::rtos::internal::object_named::name(), os::trace::printf(), and total_bytes().

Referenced by os_terminate_goodbye().

Member Data Documentation

max_align

constexpr std::size_t os::rtos::memory::memory_resource::max_align = alignof (std::max_align_t)

staticconstexpr

Definition at line 166 of file os-memory.h.

---

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

• os-memory.h
• os-memory.cpp