ACE_Asynch_Read_File Class Reference

This class is a factory for starting off asynchronous reads on a file. This class forwards all methods to its implementation class. More...

#include <Asynch_IO.h>

Inheritance diagram for ACE_Asynch_Read_File:

[legend]Collaboration diagram for ACE_Asynch_Read_File:

[legend]List of all members.

Public Member Functions
	ACE_Asynch_Read_File (void)
	A do nothing constructor.
virtual	~ACE_Asynch_Read_File (void)
	Destructor.
int	open (ACE_Handler &handler, ACE_HANDLE handle=ACE_INVALID_HANDLE, const void *completion_key=0, ACE_Proactor *proactor=0)
int	read (ACE_Message_Block &message_block, size_t bytes_to_read, unsigned long offset=0, unsigned long offset_high=0, const void *act=0, int priority=0, int signal_number=ACE_SIGRTMIN)
int	readv (ACE_Message_Block &message_block, size_t bytes_to_read, unsigned long offset=0, unsigned long offset_high=0, const void *act=0, int priority=0, int signal_number=ACE_SIGRTMIN)
virtual ACE_Asynch_Operation_Impl *	implementation (void) const
	Return the underlying implementation class.
Protected Attributes
ACE_Asynch_Read_File_Impl *	implementation_

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Detailed Description

This class is a factory for starting off asynchronous reads on a file. This class forwards all methods to its implementation class.

Once {open} is called, multiple asynchronous {read}s can started using this class. An ACE_Asynch_Read_File::Result will be passed back to the {handler} when the asynchronous reads completes through the {ACE_Handler::handle_read_file} callback. This class differs slightly from ACE_Asynch_Read_Stream as it allows the user to specify an offset for the read.

Definition at line 550 of file Asynch_IO.h.

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Constructor & Destructor Documentation

ACE_Asynch_Read_File::ACE_Asynch_Read_File (  void   )

A do nothing constructor. Definition at line 360 of file Asynch_IO.cpp. : implementation_ (0) { }

ACE_Asynch_Read_File::~ACE_Asynch_Read_File (  void   )  [virtual]

Destructor. Definition at line 365 of file Asynch_IO.cpp. { // Delete the implementation. delete this->implementation_; this->implementation_ = 0; }

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Member Function Documentation

ACE_Asynch_Operation_Impl * ACE_Asynch_Read_File::implementation (  void   )  const [virtual]

Return the underlying implementation class. Reimplemented from ACE_Asynch_Read_Stream. Definition at line 431 of file Asynch_IO.cpp. { return this->implementation_; }

int ACE_Asynch_Read_File::open (  ACE_Handler &  handler, ACE_HANDLE  handle = ACE_INVALID_HANDLE, const void *  completion_key = 0, ACE_Proactor *  proactor = 0 )

Initializes the factory with information which will be used with each asynchronous call. If ({handle} == ACE_INVALID_HANDLE), {ACE_Handler::handle} will be called on the {handler} to get the correct handle. Reimplemented from ACE_Asynch_Read_Stream. Definition at line 373 of file Asynch_IO.cpp. References ACE_Proactor::create_asynch_read_file(), ACE_Asynch_Operation::get_proactor(), and ACE_Asynch_Operation::open(). { // Get a proactor for/from the user. proactor = this->get_proactor (proactor, handler); // Now let us get the implementation initialized. if ((this->implementation_ = proactor->create_asynch_read_file ()) == 0) return -1; // Call the <open> method of the base class. return ACE_Asynch_Operation::open (handler, handle, completion_key, proactor); }

int ACE_Asynch_Read_File::read (  ACE_Message_Block &  message_block, size_t  bytes_to_read, unsigned long  offset = 0, unsigned long  offset_high = 0, const void *  act = 0, int  priority = 0, int  signal_number = ACE_SIGRTMIN )

This starts off an asynchronous read. Upto {bytes_to_read} will be read and stored in the {message_block}. The read will start at {offset} from the beginning of the file. Priority of the operation is specified by {priority}. On POSIX4-Unix, this is supported. Works like {nice} in Unix. Negative values are not allowed. 0 means priority of the operation same as the process priority. 1 means priority of the operation is one less than process. And so forth. On Win32, this argument is a no-op. {signal_number} is the POSIX4 real-time signal number to be used for the operation. {signal_number} ranges from ACE_SIGRTMIN to ACE_SIGRTMAX. This argument is a no-op on non-POSIX4 systems. Definition at line 393 of file Asynch_IO.cpp. References ACE_Asynch_Read_File_Impl::read(). { return this->implementation_->read (message_block, bytes_to_read, offset, offset_high, act, priority, signal_number); }

int ACE_Asynch_Read_File::readv (  ACE_Message_Block &  message_block, size_t  bytes_to_read, unsigned long  offset = 0, unsigned long  offset_high = 0, const void *  act = 0, int  priority = 0, int  signal_number = ACE_SIGRTMIN )

Same as above but with scatter support, through chaining of composite message blocks using the continuation field. Note: In win32 Each data block payload must be at least the size of a system memory page and must be aligned on a system memory page size boundary Definition at line 412 of file Asynch_IO.cpp. References ACE_Asynch_Read_File_Impl::readv(). { return this->implementation_->readv (message_block, bytes_to_read, offset, offset_high, act, priority, signal_number); }

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Member Data Documentation

ACE_Asynch_Read_File_Impl* ACE_Asynch_Read_File::implementation_ [protected]

Delegation/implementation class that all methods will be forwarded to. Reimplemented from ACE_Asynch_Read_Stream. Definition at line 615 of file Asynch_IO.h.

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

• Asynch_IO.h
• Asynch_IO.cpp

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