ACE
6.3.3
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Stores messages for use throughout ACE (particularly in an ACE_Message_Queue). More...
#include <Message_Block.h>
Public Types | |
enum | { MB_DATA = 0x01, MB_PROTO = 0x02, MB_BREAK = 0x03, MB_PASSFP = 0x04, MB_EVENT = 0x05, MB_SIG = 0x06, MB_IOCTL = 0x07, MB_SETOPTS = 0x08, MB_IOCACK = 0x81, MB_IOCNAK = 0x82, MB_PCPROTO = 0x83, MB_PCSIG = 0x84, MB_READ = 0x85, MB_FLUSH = 0x86, MB_STOP = 0x87, MB_START = 0x88, MB_HANGUP = 0x89, MB_ERROR = 0x8a, MB_PCEVENT = 0x8b, MB_NORMAL = 0x00, MB_PRIORITY = 0x80, MB_USER = 0x200 } |
enum | { DONT_DELETE = 01, USER_FLAGS = 0x1000 } |
typedef int | ACE_Message_Type |
typedef unsigned long | Message_Flags |
Public Member Functions | |
ACE_Message_Block (ACE_Allocator *message_block_allocator=0) | |
Create an empty message. More... | |
ACE_Message_Block (ACE_Data_Block *data_block, Message_Flags flags=0, ACE_Allocator *message_block_allocator=0) | |
ACE_Message_Block (const char *data, size_t size=0, unsigned long priority=ACE_DEFAULT_MESSAGE_BLOCK_PRIORITY) | |
ACE_Message_Block (size_t size, ACE_Message_Type type=MB_DATA, ACE_Message_Block *cont=0, const char *data=0, ACE_Allocator *allocator_strategy=0, ACE_Lock *locking_strategy=0, unsigned long priority=ACE_DEFAULT_MESSAGE_BLOCK_PRIORITY, const ACE_Time_Value &execution_time=ACE_Time_Value::zero, const ACE_Time_Value &deadline_time=ACE_Time_Value::max_time, ACE_Allocator *data_block_allocator=0, ACE_Allocator *message_block_allocator=0) | |
ACE_Message_Block (const ACE_Message_Block &mb, size_t align) | |
int | init (const char *data, size_t size=0) |
int | init (size_t size, ACE_Message_Type type=MB_DATA, ACE_Message_Block *cont=0, const char *data=0, ACE_Allocator *allocator_strategy=0, ACE_Lock *locking_strategy=0, unsigned long priority=ACE_DEFAULT_MESSAGE_BLOCK_PRIORITY, const ACE_Time_Value &execution_time=ACE_Time_Value::zero, const ACE_Time_Value &deadline_time=ACE_Time_Value::max_time, ACE_Allocator *data_block_allocator=0, ACE_Allocator *message_block_allocator=0) |
virtual | ~ACE_Message_Block (void) |
ACE_Message_Type | msg_type (void) const |
Get type of the message. More... | |
void | msg_type (ACE_Message_Type type) |
Set type of the message. More... | |
int | is_data_msg (void) const |
Find out what type of message this is. More... | |
ACE_Message_Type | msg_class (void) const |
Message_Flags | set_flags (Message_Flags more_flags) |
Message_Flags | clr_flags (Message_Flags less_flags) |
Message_Flags | flags (void) const |
Get the current message flags. More... | |
Message_Flags | set_self_flags (ACE_Message_Block::Message_Flags more_flags) |
Message_Flags | clr_self_flags (ACE_Message_Block::Message_Flags less_flags) |
Message_Flags | self_flags (void) const |
Get the current message flags. More... | |
unsigned long | msg_priority (void) const |
Get priority of the message. More... | |
void | msg_priority (unsigned long priority) |
Set priority of the message. More... | |
const ACE_Time_Value & | msg_execution_time (void) const |
Get execution time associated with the message. More... | |
void | msg_execution_time (const ACE_Time_Value &et) |
Set execution time associated with the message. More... | |
const ACE_Time_Value & | msg_deadline_time (void) const |
Get absolute time of deadline associated with the message. More... | |
void | msg_deadline_time (const ACE_Time_Value &dt) |
Set absolute time of deadline associated with the message. More... | |
virtual ACE_Message_Block * | clone (Message_Flags mask=0) const |
virtual ACE_Message_Block * | duplicate (void) const |
Return a "shallow" copy that increments our reference count by 1. More... | |
virtual ACE_Message_Block * | release (void) |
int | copy (const char *buf, size_t n) |
int | copy (const char *buf) |
int | crunch (void) |
void | reset (void) |
void | access_allocators (ACE_Allocator *&allocator_strategy, ACE_Allocator *&data_block_allocator, ACE_Allocator *&message_block_allocator) |
void | reset_allocators (ACE_Allocator *allocator_strategy=0, ACE_Allocator *data_block_allocator=0, ACE_Allocator *message_block_allocator=0) |
char * | base (void) const |
Get message data. More... | |
void | base (char *data, size_t size, Message_Flags=DONT_DELETE) |
Set message data (doesn't reallocate). More... | |
char * | end (void) const |
Return a pointer to 1 past the end of the allocated data in a message. More... | |
char * | mark (void) const |
char * | rd_ptr (void) const |
Get the read pointer. More... | |
void | rd_ptr (char *ptr) |
Set the read pointer to ptr. More... | |
void | rd_ptr (size_t n) |
Set the read pointer ahead n bytes. More... | |
char * | wr_ptr (void) const |
Get the write pointer. More... | |
void | wr_ptr (char *ptr) |
Set the write pointer to ptr. More... | |
void | wr_ptr (size_t n) |
ACE_Data_Block * | data_block (void) const |
void | data_block (ACE_Data_Block *) |
ACE_Data_Block * | replace_data_block (ACE_Data_Block *) |
ACE_Message_Block * | cont (void) const |
Get the continuation field. More... | |
void | cont (ACE_Message_Block *) |
Set the continuation field. More... | |
ACE_Message_Block * | next (void) const |
Get link to next message. More... | |
void | next (ACE_Message_Block *) |
Set link to next message. More... | |
ACE_Message_Block * | prev (void) const |
Get link to prev message. More... | |
void | prev (ACE_Message_Block *) |
Set link to prev message. More... | |
ACE_Lock * | locking_strategy (void) |
Get the locking strategy. More... | |
ACE_Lock * | locking_strategy (ACE_Lock *) |
Set a new locking strategy and return the hold one. More... | |
int | reference_count (void) const |
Get the current reference count. More... | |
void | dump (void) const |
Dump the state of an object. More... | |
Message length and size operations | |
Message length is (wr_ptr - rd_ptr). Message size is capacity of the message, including data outside the [rd_ptr,wr_ptr] range. | |
size_t | length (void) const |
Get the length of the message. More... | |
void | length (size_t n) |
Set the length of the message. More... | |
size_t | total_length (void) const |
size_t | total_size (void) const |
void | total_size_and_length (size_t &mb_size, size_t &mb_length) const |
size_t | size (void) const |
int | size (size_t length) |
size_t | total_capacity (void) const |
size_t | capacity (void) const |
Get the number of allocated bytes in the top-level Message_Block. More... | |
size_t | space (void) const |
Static Public Member Functions | |
static ACE_Message_Block * | duplicate (const ACE_Message_Block *mb) |
static ACE_Message_Block * | release (ACE_Message_Block *mb) |
Public Attributes | |
ACE_ALLOC_HOOK_DECLARE | |
Declare the dynamic allocation hooks. More... | |
Protected Member Functions | |
ACE_Message_Block (size_t size, ACE_Message_Type type, ACE_Message_Block *cont, const char *data, ACE_Allocator *allocator_strategy, ACE_Lock *locking_strategy, Message_Flags flags, unsigned long priority, const ACE_Time_Value &execution_time, const ACE_Time_Value &deadline_time, ACE_Data_Block *db, ACE_Allocator *data_block_allocator, ACE_Allocator *message_block_allocator) | |
Perform the actual initialization. More... | |
int | release_i (ACE_Lock *lock) |
int | init_i (size_t size, ACE_Message_Type type, ACE_Message_Block *cont, const char *data, ACE_Allocator *allocator_strategy, ACE_Lock *locking_strategy, Message_Flags flags, unsigned long priority, const ACE_Time_Value &execution_time, const ACE_Time_Value &deadline_time, ACE_Data_Block *db, ACE_Allocator *data_block_allocator, ACE_Allocator *message_block_allocator) |
Perform the actual initialization. More... | |
Protected Attributes | |
size_t | rd_ptr_ |
Pointer to beginning of next read. More... | |
size_t | wr_ptr_ |
Pointer to beginning of next write. More... | |
unsigned long | priority_ |
Priority of message. More... | |
ACE_Message_Block * | cont_ |
Pointer to next message block in the chain. More... | |
ACE_Message_Block * | next_ |
Pointer to next message in the list. More... | |
ACE_Message_Block * | prev_ |
Pointer to previous message in the list. More... | |
ACE_Message_Block::Message_Flags | flags_ |
Misc flags (e.g., DONT_DELETE and USER_FLAGS). More... | |
ACE_Data_Block * | data_block_ |
ACE_Allocator * | message_block_allocator_ |
Private Member Functions | |
ACE_Message_Block & | operator= (const ACE_Message_Block &) |
ACE_Message_Block (const ACE_Message_Block &) | |
Friends | |
class | ACE_Data_Block |
Stores messages for use throughout ACE (particularly in an ACE_Message_Queue).
An ACE_Message_Block is modeled after the message data structures used in System V STREAMS. Its purpose is to enable efficient manipulation of arbitrarily large messages without incurring much memory copying overhead. Here are the main characteristics of an ACE_Message_Block:
typedef int ACE_Message_Block::ACE_Message_Type |
typedef unsigned long ACE_Message_Block::Message_Flags |
anonymous enum |
anonymous enum |
ACE_Message_Block::ACE_Message_Block | ( | ACE_Allocator * | message_block_allocator = 0 | ) |
Create an empty message.
ACE_Message_Block::ACE_Message_Block | ( | ACE_Data_Block * | data_block, |
ACE_Message_Block::Message_Flags | flags = 0 , |
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ACE_Allocator * | message_block_allocator = 0 |
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Create an ACE_Message_Block that owns the specified ACE_Data_Block without copying it. If the flags is set to DONT_DELETE
we don't delete the ACE_Data_Block. It is left to the client's responsibility to take care of the memory allocated for the data_block
ACE_Message_Block::ACE_Message_Block | ( | const char * | data, |
size_t | size = 0 , |
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unsigned long | priority = ACE_DEFAULT_MESSAGE_BLOCK_PRIORITY |
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Create an ACE_Message_Block that refers to data without copying it. The data memory will not be freed when this block is destroyed; memory management of data is left to the caller. Note that the size
of the new ACE_Message_Block will be size, but the length
will be 0 until the write pointer is changed.
ACE_Message_Block::ACE_Message_Block | ( | size_t | size, |
ACE_Message_Type | type = MB_DATA , |
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ACE_Message_Block * | cont = 0 , |
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const char * | data = 0 , |
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ACE_Allocator * | allocator_strategy = 0 , |
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ACE_Lock * | locking_strategy = 0 , |
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unsigned long | priority = ACE_DEFAULT_MESSAGE_BLOCK_PRIORITY , |
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const ACE_Time_Value & | execution_time = ACE_Time_Value::zero , |
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const ACE_Time_Value & | deadline_time = ACE_Time_Value::max_time , |
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ACE_Allocator * | data_block_allocator = 0 , |
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ACE_Allocator * | message_block_allocator = 0 |
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Create an initialized message of type type containing size bytes. The cont argument initializes the continuation field in the ACE_Message_Block. If data == 0 then this block allocates and owns the block's memory, using allocator to get the data if it's non-0. If data != 0 then this block refers to that memory until this this block ceases to exist; this object will not free data on destruction. If locking_strategy is non-0 then this is used to protect regions of code that access shared state (e.g., reference counting) from race conditions. Note that the size
of the ACE_Message_Block will be size, but the length
will be 0 until the write pointer is set. The data_block_allocator is used to allocate the data blocks while the allocator_strategy is used to allocate the buffers contained by those. The message_block_allocator is used to allocate new ACE_Message_Block objects when the duplicate() method is called. If a message_block_allocator is given, this ACE_Message_Block and future ACE_Message_Block objects created by duplicate() will be freed using this allocator when they are released.
ACE_Message_Block::ACE_Message_Block | ( | const ACE_Message_Block & | mb, |
size_t | align | ||
) |
A copy constructor. This constructor is a bit different. If the incoming Message Block has a data block from the stack this constructor does a deep copy ie. allocates a new data block on the heap and does a copy of the data from the incoming message block. As a final note, the alignment information is used to align the data block if it is created afresh. If the incoming mb has a data block has a data block allocated from the heap, then this constructor just duplicates (ie. a shallow copy) the data block of the incoming mb.
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Perform the actual initialization.
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Access all the allocators in the message block.
This method returns the allocators only from the first message block in the chain.
allocator_strategy | Strategy used to allocate the underlying buffer |
data_block_allocator | Strategy used to allocate the underlying data block |
message_block_allocator | Strategy used to allocate the message block |
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Get message data.
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Set message data (doesn't reallocate).
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Get the number of allocated bytes in the top-level Message_Block.
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Return an exact "deep copy" of the message, i.e., create fresh new copies of all the Data_Blocks and continuations.
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Clear the message flag bits specified in less_flags and return the new value.
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Clear the message flag bits specified in less_flags and return the new value.
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Get the continuation field.
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Set the continuation field.
int ACE_Message_Block::copy | ( | const char * | buf, |
size_t | n | ||
) |
Copies data into this ACE_Message_Block. Data is copied into the block starting at the current write pointer.
buf | Pointer to the buffer to copy from. |
n | The number of bytes to copy. |
0 | on success; the write pointer is advanced by
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-1 | if the amount of free space following the write pointer in the block is less than
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int ACE_Message_Block::copy | ( | const char * | buf | ) |
Copies a 0-terminated character string into this ACE_Message_Block. The string is copied into the block starting at the current write pointer. The 0-terminator is included in the copied data.
buf | Pointer to the character string to copy from. |
0 | on success; the write pointer is advanced by the string's length, including the 0 terminator. |
-1 | if the amount of free space following the write pointer in the block is less than required to hold the entire string. Free space can be checked by calling space(). |
int ACE_Message_Block::crunch | ( | void | ) |
Normalizes data in the top-level Message_Block to align with the base, i.e., it "shifts" the data pointed to by <rd_ptr> down to the <base> and then readjusts <rd_ptr> to point to <base> and <wr_ptr> to point to <base> + the length of the moved data. Returns -1 and does nothing if the <rd_ptr> is > <wr_ptr>, else 0 on success.
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Get a pointer to the data block. Note that the ACE_Message_Block still references the block; this call does not change the reference count.
void ACE_Message_Block::data_block | ( | ACE_Data_Block * | db | ) |
Set a new data block pointer. The original ACE_Data_Block is released as a result of this call. If you need to keep the original block, call <replace_data_block> instead. Upon return, this ACE_Message_Block holds a pointer to the new ACE_Data_Block, taking over the reference you held on it prior to the call.
void ACE_Message_Block::dump | ( | void | ) | const |
Dump the state of an object.
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Return a "shallow" copy that increments our reference count by 1.
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Return a "shallow" copy that increments our reference count by 1. This is similar to CORBA's _duplicate() method, which is useful if you want to eliminate lots of checks for NULL mb pointers before calling _duplicate() on them.
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Return a pointer to 1 past the end of the allocated data in a message.
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Get the current message flags.
int ACE_Message_Block::init | ( | const char * | data, |
size_t | size = 0 |
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Create a Message Block that assumes it has ownership of data, but in reality it doesn't (i.e., cannot delete it since it didn't malloc it!). Note that the size
of the Message_Block will be size, but the length will be 0 until <wr_ptr> is set.
int ACE_Message_Block::init | ( | size_t | size, |
ACE_Message_Type | type = MB_DATA , |
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ACE_Message_Block * | cont = 0 , |
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const char * | data = 0 , |
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ACE_Allocator * | allocator_strategy = 0 , |
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ACE_Lock * | locking_strategy = 0 , |
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unsigned long | priority = ACE_DEFAULT_MESSAGE_BLOCK_PRIORITY , |
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const ACE_Time_Value & | execution_time = ACE_Time_Value::zero , |
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const ACE_Time_Value & | deadline_time = ACE_Time_Value::max_time , |
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ACE_Allocator * | data_block_allocator = 0 , |
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ACE_Allocator * | message_block_allocator = 0 |
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Create an initialized message of type type containing size bytes. The cont argument initializes the continuation field in the Message_Block. If data == 0 then we create and own the data, using allocator_strategy to get the data if it's non-0. If data != 0 we assume that we have ownership of the data till this object ceases to exist (and don't delete it during destruction). If locking_strategy is non-0 then this is used to protect regions of code that access shared state (e.g., reference counting) from race conditions. Note that the size of the Message_Block will be size, but the length will be 0 until <wr_ptr> is set. The data_block_allocator is use to allocate the data blocks while the allocator_strategy is used to allocate the buffers contained by those.
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Perform the actual initialization.
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Find out what type of message this is.
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Get the length of the message.
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Set the length of the message.
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Get the locking strategy.
Set a new locking strategy and return the hold one.
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Return a pointer to 1 past the end of the allotted data in a message. Allotted data may be less than allocated data if a value smaller than capacity() to is passed to size().
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Find out what class of message this is (there are two classes, normal
messages and high-priority
messages).
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Get absolute time of deadline associated with the message.
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Set absolute time of deadline associated with the message.
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Get execution time associated with the message.
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Set execution time associated with the message.
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Get priority of the message.
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Set priority of the message.
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Get type of the message.
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Set type of the message.
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Get link to next message.
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Set link to next message.
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Get link to prev message.
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Set link to prev message.
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Get the read pointer.
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Set the read pointer to ptr.
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Set the read pointer ahead n bytes.
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Get the current reference count.
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Decrease the shared ACE_Data_Block's reference count by 1. If the ACE_Data_Block's reference count goes to 0, it is deleted. In all cases, this ACE_Message_Block is deleted - it must have come from the heap, or there will be trouble.
release() is designed to release the continuation chain; the destructor is not. If we make the destructor release the continuation chain by calling release() or delete on the message blocks in the continuation chain, the following code will not work since the message block in the continuation chain is not off the heap:
ACE_Message_Block mb1 (1024); ACE_Message_Block mb2 (1024);
mb1.cont (&mb2);
And hence, call release() on a dynamically allocated message block. This will release all the message blocks in the continuation chain. If you call delete or let the message block fall off the stack, cleanup of the message blocks in the continuation chain becomes the responsibility of the user.
0,always,and | the object this method was invoked on is no longer valid. |
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Internal release implementation Returns 1 if the data block has to be destroyed.
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Set a new data block pointer. A pointer to the original ACE_Data_Block is returned, and not released (as it is with <data_block>).
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Resets the Message Block data to contain nothing, i.e., sets the read and write pointers to align with the base.
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Reset all the allocators in the message block.
This method resets the allocators in all the message blocks in the chain.
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Get the current message flags.
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Bitwise-or the more_flags into the existing message flags and return the new value.
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Bitwise-or the more_flags into the existing message flags and return the new value.
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Get the number of bytes in the top-level Message_Block (i.e., does not consider the bytes in chained Message_Blocks).
int ACE_Message_Block::size | ( | size_t | length | ) |
Set the number of bytes in the top-level Message_Block, reallocating space if necessary. However, the rd_ptr_
and wr_ptr_
remain at the original offsets into the buffer, even if it is reallocated. Returns 0 if successful, else -1.
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Get the number of bytes available after the <wr_ptr_> in the top-level Message_Block.
size_t ACE_Message_Block::total_capacity | ( | void | ) | const |
Get the number of allocated bytes in all Message_Block, including chained Message_Blocks.
size_t ACE_Message_Block::total_length | ( | void | ) | const |
Get the length of the Message_Blocks, including chained Message_Blocks.
size_t ACE_Message_Block::total_size | ( | void | ) | const |
Get the total number of bytes in all Message_Blocks, including chained Message_Blocks.
void ACE_Message_Block::total_size_and_length | ( | size_t & | mb_size, |
size_t & | mb_length | ||
) | const |
Get the total number of bytes and total length in all Message_Blocks, including chained Message_Blocks.
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Get the write pointer.
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Set the write pointer to ptr.
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Set the write pointer ahead n bytes. This is used to compute the <length> of a message.
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ACE_Message_Block::ACE_ALLOC_HOOK_DECLARE |
Declare the dynamic allocation hooks.
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Pointer to next message block in the chain.
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Pointer to the reference counted data structure that contains the actual memory buffer.
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Misc flags (e.g., DONT_DELETE and USER_FLAGS).
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The allocator used to destroy ourselves when release is called and create new message blocks on duplicate.
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Pointer to next message in the list.
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Pointer to previous message in the list.
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Priority of message.
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Pointer to beginning of next read.
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Pointer to beginning of next write.