ACE_Data_Block Class Reference

Stores the data payload that is accessed via one or more ACE_Message_Block's. More...

#include <Message_Block.h>

Inheritance diagram for ACE_Data_Block:

[legend]

Collaboration diagram for ACE_Data_Block:

[legend]

List of all members.

Public Member Functions
	ACE_Data_Block (void)
	Default "do-nothing" constructor.
	ACE_Data_Block (size_t size, ACE_Message_Block::ACE_Message_Type msg_type, const char *msg_data, ACE_Allocator *allocator_strategy, ACE_Lock *locking_strategy, ACE_Message_Block::Message_Flags flags, ACE_Allocator *data_block_allocator)
	Initialize.
virtual	~ACE_Data_Block (void)
	Delete all the resources held in the message.
ACE_Message_Block::ACE_Message_Type	msg_type (void) const
	Get type of the message.
void	msg_type (ACE_Message_Block::ACE_Message_Type type)
	Set type of the message.
char *	base (void) const
	Get message data pointer.
void	base (char *data, size_t size, ACE_Message_Block::Message_Flags mflags=ACE_Message_Block::DONT_DELETE)
	Set message data pointer (doesn't reallocate).
char *	end (void) const
	Return a pointer to 1 past the end of the allocated data in a message.
char *	mark (void) const
size_t	size (void) const
int	size (size_t length)
size_t	capacity (void) const
	Get the total amount of allocated space.
virtual ACE_Data_Block *	clone (ACE_Message_Block::Message_Flags mask=0) const
virtual ACE_Data_Block *	clone_nocopy (ACE_Message_Block::Message_Flags mask=0, size_t max_size=0) const
ACE_Data_Block *	duplicate (void)
	Return a "shallow" copy that increments our reference count by 1.
ACE_Data_Block *	release (ACE_Lock *lock=0)
ACE_Message_Block::Message_Flags	set_flags (ACE_Message_Block::Message_Flags more_flags)
ACE_Message_Block::Message_Flags	clr_flags (ACE_Message_Block::Message_Flags less_flags)
ACE_Message_Block::Message_Flags	flags (void) const
	Get the current message flags.
ACE_Allocator *	allocator_strategy (void) const
	Obtain the allocator strategy.
ACE_Lock *	locking_strategy (void)
	Get the locking strategy.
ACE_Lock *	locking_strategy (ACE_Lock *)
	Set a new locking strategy and return the hold one.
void	dump (void) const
	Dump the state of an object.
int	reference_count (void) const
	Get the current reference count.
ACE_Allocator *	data_block_allocator (void) const
	Get the allocator used to create this object.
Protected Member Functions
virtual ACE_Data_Block *	release_i (void)
	Internal release implementation.
int	reference_count_i (void) const
	Internal get the current reference count.
ACE_Data_Block *	release_no_delete (ACE_Lock *lock)
Protected Attributes
ACE_Message_Block::ACE_Message_Type	type_
	Type of message.
size_t	cur_size_
	Current size of message block.
size_t	max_size_
	Total size of buffer.
ACE_Message_Block::Message_Flags	flags_
	Misc flags (e.g., DONT_DELETE and USER_FLAGS).
char *	base_
	Pointer To beginning of message payload.
ACE_Allocator *	allocator_strategy_
ACE_Lock *	locking_strategy_
int	reference_count_
ACE_Allocator *	data_block_allocator_
	The allocator use to destroy ourselves.
Private Member Functions
ACE_Data_Block &	operator= (const ACE_Data_Block &)
	ACE_Data_Block (const ACE_Data_Block &)
Friends
class	ACE_Message_Block

---

Detailed Description

Stores the data payload that is accessed via one or more ACE_Message_Block's.

This data structure is reference counted to maximize sharing. It also contains the <locking_strategy_> (which protects the reference count from race conditions in concurrent programs) and the <allocation_strategy_> (which determines what memory pool is used to allocate the memory).

Definition at line 677 of file Message_Block.h.

---

Constructor & Destructor Documentation

ACE_Data_Block::ACE_Data_Block

(

void

)

Default "do-nothing" constructor.

Definition at line 315 of file Message_Block.cpp.

  : type_ (ACE_Message_Block::MB_DATA),
    cur_size_ (0),
    max_size_ (0),
    flags_ (ACE_Message_Block::DONT_DELETE),
    base_ (0),
    allocator_strategy_ (0),
    locking_strategy_ (0),
    reference_count_ (1),
    data_block_allocator_ (0)
{
  ACE_TRACE ("ACE_Data_Block::ACE_Data_Block");
  ACE_FUNCTION_TIMEPROBE (ACE_DATA_BLOCK_CTOR1_ENTER);

  ACE_ALLOCATOR (this->allocator_strategy_,
                 ACE_Allocator::instance ());

  ACE_ALLOCATOR (this->data_block_allocator_,
                 ACE_Allocator::instance ());
}

ACE_Data_Block::ACE_Data_Block	(	size_t	size,
		ACE_Message_Block::ACE_Message_Type	msg_type,
		const char *	msg_data,
		ACE_Allocator *	allocator_strategy,
		ACE_Lock *	locking_strategy,
		ACE_Message_Block::Message_Flags	flags,
		ACE_Allocator *	data_block_allocator
	)

Initialize.

Definition at line 336 of file Message_Block.cpp.

  : type_ (msg_type),
    cur_size_ (0),          // Reset later if memory alloc'd ok
    max_size_ (0),
    flags_ (flags),
    base_ (const_cast <char *> (msg_data)),
    allocator_strategy_ (allocator_strategy),
    locking_strategy_ (locking_strategy),
    reference_count_ (1),
    data_block_allocator_ (data_block_allocator)
{
  ACE_TRACE ("ACE_Data_Block::ACE_Data_Block");
  ACE_FUNCTION_TIMEPROBE (ACE_DATA_BLOCK_CTOR2_ENTER);

  // If the user didn't pass one in, let's use the
  // <ACE_Allocator::instance>.
  if (this->allocator_strategy_ == 0)
    ACE_ALLOCATOR (this->allocator_strategy_,
                   ACE_Allocator::instance ());

  if (this->data_block_allocator_ == 0)
    ACE_ALLOCATOR (this->data_block_allocator_,
                   ACE_Allocator::instance ());

  if (msg_data == 0)
    {
      ACE_ALLOCATOR (this->base_,
                     (char *) this->allocator_strategy_->malloc (size));
#if defined (ACE_INITIALIZE_MEMORY_BEFORE_USE)
      (void) ACE_OS::memset (this->base_,
                             '\0',
                             size);
#endif /* ACE_INITIALIZE_MEMORY_BEFORE_USE */
    }

  // ACE_ALLOCATOR returns on alloc failure but we cant throw, so setting
  // the size to 0 (i.e. "bad bit") ...
  if (this->base_ == 0)
    {
      size = 0;
    }

  // The memory is legit, whether passed in or allocated, so set
  // the size.
  this->cur_size_ = this->max_size_ = size;
}

ACE_Data_Block::~ACE_Data_Block

(

void

)

[virtual]

Delete all the resources held in the message.

Definition at line 758 of file Message_Block.cpp.

{
  // Sanity check...
  ACE_ASSERT (this->reference_count_ <= 1);

  // Just to be safe...
  this->reference_count_ = 0;

  if (ACE_BIT_DISABLED (this->flags_,
                        ACE_Message_Block::DONT_DELETE))
    {
      this->allocator_strategy_->free ((void *) this->base_);
      this->base_ = 0;
    }
}

ACE_Data_Block::ACE_Data_Block

(

const ACE_Data_Block &

)

[private]

---

Member Function Documentation

ACE_Allocator * ACE_Data_Block::allocator_strategy

(

void

)

const

Obtain the allocator strategy.

Definition at line 469 of file Message_Block.inl.

{
  ACE_TRACE ("ACE_Data_Block::allocator_strategy");
  return this->allocator_strategy_;
}

void ACE_Data_Block::base	(	char *	data,
		size_t	size,
		ACE_Message_Block::Message_Flags	mflags = ACE_Message_Block::DONT_DELETE
	)

Set message data pointer (doesn't reallocate).

Definition at line 1264 of file Message_Block.cpp.

{
  if (ACE_BIT_DISABLED (this->flags_,
                        ACE_Message_Block::DONT_DELETE))
    this->allocator_strategy_->free (this->base_);

  this->max_size_ = msg_length;
  this->cur_size_ = msg_length;
  this->base_ = msg_data;
  this->flags_ = msg_flags;
}

char * ACE_Data_Block::base

(

void

)

const

Get message data pointer.

Definition at line 52 of file Message_Block.inl.

{
  ACE_TRACE ("ACE_Data_Block::base");
  return this->base_;
}

size_t ACE_Data_Block::capacity

(

void

)

const

Get the total amount of allocated space.

Definition at line 66 of file Message_Block.inl.

{
  ACE_TRACE ("ACE_Data_Block::capacity");
  return this->max_size_;
}

ACE_Data_Block * ACE_Data_Block::clone

(

ACE_Message_Block::Message_Flags

mask = 0

)

const [virtual]

Return an exact "deep copy" of the message, i.e., create fresh new copies of all the Data_Blocks and continuations. Notice that Data_Blocks can act as "Prototypes", i.e. derived classes can override this method and create instances of themselves.

Definition at line 1107 of file Message_Block.cpp.

{
  ACE_TRACE ("ACE_Data_Block::clone");

  ACE_Data_Block *nb = this->clone_nocopy (mask);

  // Copy all of the payload memory into the new object. The new block
  // was allocated with max_size_ (and, thus, it's cur_size_ is the same
  // as max_size_). Maintain the same "has been written" boundary in the
  // new block by only copying cur_size_ bytes.
  if (nb != 0)
    {
      ACE_OS::memcpy (nb->base_,
                      this->base_,
                      this->cur_size_);
    }

  return nb;
}

ACE_Data_Block * ACE_Data_Block::clone_nocopy	(	ACE_Message_Block::Message_Flags	mask = 0,
		size_t	max_size = 0
	)			const [virtual]

As clone above, but it does not copy the contents of the buffer, i.e., create a new Data_Block of the same dynamic type, with the same allocator, locking_strategy, and with the same amount of storage available (if max_size is zero) but the buffer is unitialized. If max_size is specified other than zero, it will be used when creating the new data block.

Reimplemented in ACE_Locked_Data_Block< ACE_LOCK >.

Definition at line 1128 of file Message_Block.cpp.

{
  ACE_FUNCTION_TIMEPROBE(ACE_DATA_BLOCK_CLONE_ENTER);

  ACE_TRACE ("ACE_Data_Block::clone_nocopy");

  // You always want to clear this one to prevent memory leaks but you
  // might add some others later.
  const ACE_Message_Block::Message_Flags always_clear =
    ACE_Message_Block::DONT_DELETE;

  const size_t newsize =
    max_size == 0 ? this->max_size_ : max_size;

  ACE_Data_Block *nb = 0;

  ACE_NEW_MALLOC_RETURN (nb,
                         static_cast<ACE_Data_Block*> (
                           this->data_block_allocator_->malloc (sizeof (ACE_Data_Block))),
                         ACE_Data_Block (newsize, // size
                                         this->type_,     // type
                                         0,               // data
                                         this->allocator_strategy_, // allocator
                                         this->locking_strategy_, // locking strategy
                                         this->flags_,  // flags
                                         this->data_block_allocator_),
                         0);

  // Message block initialization may fail while the construction
  // succeds.  Since as a matter of policy, ACE may throw no
  // exceptions, we have to do a separate check like this.
  if (nb != 0 && nb->size () < newsize)
    {
      nb->ACE_Data_Block::~ACE_Data_Block();  // placement destructor ...
      this->data_block_allocator_->free (nb); // free ...
      errno = ENOMEM;
      return 0;
    }


  // Set new flags minus the mask...
  nb->clr_flags (mask | always_clear);
  return nb;
}

ACE_Message_Block::Message_Flags ACE_Data_Block::clr_flags

(

ACE_Message_Block::Message_Flags

less_flags

)

Clear the message flag bits specified in <less_flags> and return the new value.

Definition at line 82 of file Message_Block.inl.

{
  ACE_TRACE ("ACE_Data_Block::clr_flags");
  // Later we might mask more_flags so that user can't change internal
  // ones: less_flags &= ~(USER_FLAGS -1).
  return ACE_CLR_BITS (this->flags_, less_flags);
}

ACE_Allocator * ACE_Data_Block::data_block_allocator

(

void

)

const

Get the allocator used to create this object.

Definition at line 98 of file Message_Block.inl.

{
  ACE_TRACE ("ACE_Data_Block::data_block_allocator");
  return this->data_block_allocator_;
}

void ACE_Data_Block::dump

(

void

)

const

Dump the state of an object.

Definition at line 146 of file Message_Block.cpp.

{
#if defined (ACE_HAS_DUMP)
  ACE_TRACE ("ACE_Data_Block::dump");
  ACE_DEBUG ((LM_DEBUG, ACE_BEGIN_DUMP, this));
  ACE_DEBUG ((LM_DEBUG,
              ACE_TEXT ("-----( Data Block )-----\n")
              ACE_TEXT ("type_ = %d\n")
              ACE_TEXT ("cur_size_ = %u\n")
              ACE_TEXT ("max_size_ = %u\n")
              ACE_TEXT ("flags_ = %u\n")
              ACE_TEXT ("base_ = %@\n")
              ACE_TEXT ("locking_strategy_ = %u\n")
              ACE_TEXT ("reference_count_ = %u\n")
              ACE_TEXT ("---------------------------\n"),
              this->type_,
              this->cur_size_,
              this->max_size_,
              this->flags_,
              this->base_,
              this->locking_strategy_,
              this->reference_count_));
  this->allocator_strategy_->dump ();
  ACE_DEBUG ((LM_DEBUG, ACE_END_DUMP));
#endif /* ACE_HAS_DUMP */
}

ACE_Data_Block * ACE_Data_Block::duplicate

(

void

)

Return a "shallow" copy that increments our reference count by 1.

Definition at line 991 of file Message_Block.cpp.

{
  ACE_TRACE ("ACE_Data_Block::duplicate");

  // Create a new <ACE_Message_Block>, but share the <base_> pointer
  // data (i.e., don't copy that).
  if (this->locking_strategy_)
    {
      // We need to acquire the lock before incrementing the count.
      ACE_GUARD_RETURN (ACE_Lock, ace_mon, *this->locking_strategy_, 0);
      ++this->reference_count_;
    }
  else
    ++this->reference_count_;

  return this;
}

char * ACE_Data_Block::end

(

void

)

const

Return a pointer to 1 past the end of the allocated data in a message.

Definition at line 333 of file Message_Block.inl.

{
  ACE_TRACE ("ACE_Data_Block::end");
  return this->base_ + this->max_size_;
}

ACE_Message_Block::Message_Flags ACE_Data_Block::flags

(

void

)

const

Get the current message flags.

Definition at line 91 of file Message_Block.inl.

{
  ACE_TRACE ("ACE_Data_Block::flags");
   return this->flags_;
}

ACE_Lock * ACE_Data_Block::locking_strategy

(

ACE_Lock *

nls

)

Set a new locking strategy and return the hold one.

Definition at line 483 of file Message_Block.inl.

{
  ACE_TRACE ("ACE_Data_Block::locking_strategy");
  ACE_Lock *ols = this->locking_strategy_;

  this->locking_strategy_ = nls;
  return ols;
}

ACE_Lock * ACE_Data_Block::locking_strategy

(

void

)

Get the locking strategy.

Definition at line 476 of file Message_Block.inl.

{
  ACE_TRACE ("ACE_Data_Block::locking_strategy");
  return this->locking_strategy_;
}

char * ACE_Data_Block::mark

(

void

)

const

Return a pointer to 1 past the end of the allotted data in a message. The allotted data may be less than allocated data if <size()> is passed an argument less than <capacity()>.

Definition at line 319 of file Message_Block.inl.

{
  ACE_TRACE ("ACE_Data_Block::mark");
  return this->base_ + this->cur_size_;
}

void ACE_Data_Block::msg_type

(

ACE_Message_Block::ACE_Message_Type

type

)

Set type of the message.

Definition at line 168 of file Message_Block.inl.

{
  ACE_TRACE ("ACE_Data_Block::msg_type");
  this->type_ = t;
}

ACE_Message_Block::ACE_Message_Type ACE_Data_Block::msg_type

(

void

)

const

Get type of the message.

Definition at line 161 of file Message_Block.inl.

{
  ACE_TRACE ("ACE_Data_Block::msg_type");
  return this->type_;
}

ACE_Data_Block& ACE_Data_Block::operator=

(

const ACE_Data_Block &

)

[private]

int ACE_Data_Block::reference_count

(

void

)

const

Get the current reference count.

Definition at line 200 of file Message_Block.cpp.

{
  if (this->locking_strategy_)
    {
      // We need to acquire the lock before retrieving the count
      ACE_GUARD_RETURN (ACE_Lock, ace_mon, *this->locking_strategy_, 0);

      return this->reference_count_i ();
    }

  return this->reference_count_i ();
}

int ACE_Data_Block::reference_count_i

(

void

)

const [protected]

Internal get the current reference count.

Definition at line 40 of file Message_Block.inl.

{
  return reference_count_;
}

ACE_Data_Block * ACE_Data_Block::release

(

ACE_Lock *

lock = 0

)

Decrease the shared reference count by 1. If the reference count is > 0 then return this; else if reference count == 0 then delete this and mb and return 0. Behavior is undefined if reference count < 0.

Definition at line 840 of file Message_Block.cpp.

{
  ACE_TRACE ("ACE_Data_Block::release");

  ACE_Allocator *allocator = this->data_block_allocator_;

  ACE_Data_Block *result = this->release_no_delete (lock);

  // We must delete this outside the scope of the locking_strategy_
  // since otherwise we'd be trying to "release" through a deleted
  // pointer!
  if (result == 0)
    ACE_DES_FREE (this,
                  allocator->free,
                  ACE_Data_Block);
  return result;
}

ACE_Data_Block * ACE_Data_Block::release_i

(

void

)

[protected, virtual]

Internal release implementation.

Definition at line 775 of file Message_Block.cpp.

{
  ACE_TRACE ("ACE_Data_Block::release_i");

  ACE_ASSERT (this->reference_count_ > 0);

  ACE_Data_Block *result = 0;

  // decrement reference count
  --this->reference_count_;

  if (this->reference_count_ == 0)
    // this will cause deletion of this
    result = 0;
  else
    result = this;

  return result;
}

ACE_Data_Block * ACE_Data_Block::release_no_delete

(

ACE_Lock *

lock

)

[protected]

Definition at line 796 of file Message_Block.cpp.

{
  ACE_TRACE ("ACE_Data_Block::release_no_delete");

  ACE_Data_Block *result = 0;
  ACE_Lock *lock_to_be_used = 0;

  // Check if we were passed in a lock
  if (lock != 0)
    {
      // Make sure that the lock passed in and our lock are the same
      if (lock == this->locking_strategy_)
        // In this case no locking is required.
        lock_to_be_used = 0;

      // The lock passed in does not match our lock
      else
        // Lock to be used is our lock
        lock_to_be_used = this->locking_strategy_;
    }
  // This is the case when no lock was passed in
  else
    {
      // Lock to be used is our lock
      lock_to_be_used = this->locking_strategy_;
    }

  // If there's a locking strategy then we need to acquire the lock
  // before decrementing the count.
  if (lock_to_be_used != 0)
    {
      ACE_GUARD_RETURN (ACE_Lock, ace_mon, *lock_to_be_used, 0);

      result = this->release_i ();
    }
  else
    {
      result = this->release_i ();
    }

  return result;
}

ACE_Message_Block::Message_Flags ACE_Data_Block::set_flags

(

ACE_Message_Block::Message_Flags

more_flags

)

Bitwise-or the <more_flags> into the existing message flags and return the new value.

Definition at line 73 of file Message_Block.inl.

{
  ACE_TRACE ("ACE_Data_Block::set_flags");
  // Later we might mask more_glags so that user can't change internal
  // ones: more_flags &= ~(USER_FLAGS -1).
  return ACE_SET_BITS (this->flags_, more_flags);
}

int ACE_Data_Block::size

(

size_t

length

)

Set the total amount of space in the message. Returns 0 if successful, else -1.

Definition at line 214 of file Message_Block.cpp.

{
  ACE_TRACE ("ACE_Data_Block::size");

  if (length <= this->max_size_)
    this->cur_size_ = length;
  else
    {
      // We need to resize!
      char *buf = 0;
      ACE_ALLOCATOR_RETURN (buf,
                            (char *) this->allocator_strategy_->malloc (length),
                            -1);

      ACE_OS::memcpy (buf,
                      this->base_,
                      this->cur_size_);
      if (ACE_BIT_DISABLED (this->flags_,
                            ACE_Message_Block::DONT_DELETE))
        this->allocator_strategy_->free ((void *) this->base_);
      else
        // We now assume ownership.
        ACE_CLR_BITS (this->flags_,
                      ACE_Message_Block::DONT_DELETE);
      this->max_size_ = length;
      this->cur_size_ = length;
      this->base_ = buf;
    }
  return 0;
}

size_t ACE_Data_Block::size

(

void

)

const

Get the total amount of allotted space in the message. The amount of allotted space may be less than allocated space.

Definition at line 59 of file Message_Block.inl.

{
  ACE_TRACE ("ACE_Data_Block::size");
  return this->cur_size_;
}

---

Friends And Related Function Documentation

friend class ACE_Message_Block [friend]

Decrease the reference count, but don't delete the object. Returns 0 if the object should be removed. If lock is equal to the locking strategy then we assume that the lock is beign held by the current thread; this is used to release all the data blocks in a chain while holding a single lock.

Definition at line 810 of file Message_Block.h.

---

Member Data Documentation

ACE_Allocator* ACE_Data_Block::allocator_strategy_ [protected]

Pointer to the allocator defined for this ACE_Data_Block. Note that this pointer is shared by all owners of this ACE_Data_Block.

Definition at line 834 of file Message_Block.h.

char* ACE_Data_Block::base_ [protected]

Pointer To beginning of message payload.

Definition at line 826 of file Message_Block.h.

size_t ACE_Data_Block::cur_size_ [protected]

Current size of message block.

Definition at line 817 of file Message_Block.h.

ACE_Allocator* ACE_Data_Block::data_block_allocator_ [protected]

The allocator use to destroy ourselves.

Definition at line 853 of file Message_Block.h.

ACE_Message_Block::Message_Flags ACE_Data_Block::flags_ [protected]

Misc flags (e.g., DONT_DELETE and USER_FLAGS).

Definition at line 823 of file Message_Block.h.

ACE_Lock* ACE_Data_Block::locking_strategy_ [protected]

Pointer to the locking strategy defined for this ACE_Data_Block. This is used to protect regions of code that access shared ACE_Data_Block state. Note that this lock is shared by all owners of the ACE_Data_Block's data.

Definition at line 842 of file Message_Block.h.

size_t ACE_Data_Block::max_size_ [protected]

Total size of buffer.

Definition at line 820 of file Message_Block.h.

int ACE_Data_Block::reference_count_ [protected]

Reference count for this ACE_Data_Block, which is used to avoid deep copies (i.e., <clone>). Note that this pointer value is shared by all owners of the <Data_Block>'s data, i.e., all the ACE_Message_Blocks.

Definition at line 850 of file Message_Block.h.

ACE_Message_Block::ACE_Message_Type ACE_Data_Block::type_ [protected]

Type of message.

Definition at line 814 of file Message_Block.h.

---

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

• Message_Block.h
• Message_Block.cpp
• Message_Block.inl