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ACE_Dynamic_Message_Strategy Class Reference

An abstract base class which provides dynamic priority evaluation methods for use by the ACE_Dynamic_Message_Queue class or any other class which needs to manage the priorities of a collection of ACE_Message_Blocks dynamically. More...

#include <Message_Block.h>

Inheritance diagram for ACE_Dynamic_Message_Strategy:

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Collaboration diagram for ACE_Dynamic_Message_Strategy:

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List of all members.

Public Types

enum  Priority_Status { PENDING = 0x01, LATE = 0x02, BEYOND_LATE = 0x04, ANY_STATUS = 0x07 }

Public Member Functions

 ACE_Dynamic_Message_Strategy (unsigned long static_bit_field_mask, unsigned long static_bit_field_shift, unsigned long dynamic_priority_max, unsigned long dynamic_priority_offset)
 Constructor.

virtual ~ACE_Dynamic_Message_Strategy (void)
 Virtual destructor.

Priority_Status priority_status (ACE_Message_Block &mb, const ACE_Time_Value &tv)
 Updates the message's priority and returns its priority status.

unsigned long static_bit_field_mask (void) const
 Get static bit field mask.

void static_bit_field_mask (unsigned long)
 Set static bit field mask.

unsigned long static_bit_field_shift (void) const
 Get left shift value to make room for static bit field.

void static_bit_field_shift (unsigned long)
 Set left shift value to make room for static bit field.

unsigned long dynamic_priority_max (void) const
 Get maximum supported priority value.

void dynamic_priority_max (unsigned long)
 Set maximum supported priority value.

unsigned long dynamic_priority_offset (void) const
 Get offset to boundary between signed range and unsigned range.

void dynamic_priority_offset (unsigned long)
 Set offset to boundary between signed range and unsigned range.

virtual void dump (void) const
 Dump the state of the strategy.


Protected Member Functions

virtual void convert_priority (ACE_Time_Value &priority, const ACE_Message_Block &mb)=0
 Hook method for dynamic priority conversion.


Protected Attributes

unsigned long static_bit_field_mask_
 This is a bit mask with all ones in the static bit field.

unsigned long static_bit_field_shift_
unsigned long dynamic_priority_max_
 Maximum supported priority value.

unsigned long dynamic_priority_offset_
 Offset to boundary between signed range and unsigned range.

ACE_Time_Value max_late_
 Maximum late time value that can be represented.

ACE_Time_Value min_pending_
 Minimum pending time value that can be represented.

ACE_Time_Value pending_shift_
 Time value by which to shift pending priority.

Detailed Description

An abstract base class which provides dynamic priority evaluation methods for use by the ACE_Dynamic_Message_Queue class or any other class which needs to manage the priorities of a collection of ACE_Message_Blocks dynamically.

Methods for deadline and laxity based priority evaluation are provided. These methods assume a specific partitioning of the message priority number into a higher order dynamic bit field and a lower order static priority bit field. The default partitioning assumes an unsigned dynamic message priority field of 22 bits and an unsigned static message priority field of 10 bits. This corresponds to the initial values of the static class members. To provide a different partitioning, assign a different set of values to the static class memebers before using the static member functions.

Definition at line 880 of file Message_Block.h.

Member Enumeration Documentation

enum ACE_Dynamic_Message_Strategy::Priority_Status
 

Enumeration values:
PENDING  Message can still make its deadline.
LATE  Message cannot make its deadline.
BEYOND_LATE  Message is so late its priority is undefined.
ANY_STATUS  Mask to match any priority status.

Definition at line 889 of file Message_Block.h.

Referenced by priority_status(). 

00890   {
00891     /// Message can still make its deadline
00892     PENDING     = 0x01,
00893     /// Message cannot make its deadline
00894     LATE        = 0x02,
00895     /// Message is so late its priority is undefined
00896     BEYOND_LATE = 0x04,
00897     /// Mask to match any priority status
00898     ANY_STATUS  = 0x07
00899   };

Constructor & Destructor Documentation

ACE_Dynamic_Message_Strategy::ACE_Dynamic_Message_Strategy (  unsigned long  static_bit_field_mask,
unsigned long  static_bit_field_shift,
unsigned long  dynamic_priority_max,
unsigned long  dynamic_priority_offset
) 
 

Constructor.

Definition at line 1276 of file Message_Block.cpp. 

01280   : static_bit_field_mask_ (static_bit_field_mask),
01281     static_bit_field_shift_ (static_bit_field_shift),
01282     dynamic_priority_max_ (dynamic_priority_max),
01283     dynamic_priority_offset_ (dynamic_priority_offset),
01284     max_late_ (0, dynamic_priority_offset - 1),
01285     min_pending_ (0, dynamic_priority_offset),
01286     pending_shift_ (0, dynamic_priority_max)
01287 {
01288 }

ACE_Dynamic_Message_Strategy::~ACE_Dynamic_Message_Strategy (  void   )  [virtual]
 

Virtual destructor.

Definition at line 1292 of file Message_Block.cpp. 

01293 {
01294 }

Member Function Documentation

virtual void ACE_Dynamic_Message_Strategy::convert_priority (  ACE_Time_Value &  priority,
const ACE_Message_Block &  mb
)  [protected, pure virtual]
 

Hook method for dynamic priority conversion.

Implemented in ACE_Deadline_Message_Strategy, and ACE_Laxity_Message_Strategy.

Referenced by priority_status().

void ACE_Dynamic_Message_Strategy::dump (  void   )  const [virtual]
 

Dump the state of the strategy.

Reimplemented in ACE_Deadline_Message_Strategy, and ACE_Laxity_Message_Strategy.

Definition at line 1345 of file Message_Block.cpp.

References ACE_BEGIN_DUMP, ACE_DEBUG, ACE_END_DUMP, ACE_TEXT, ACE_TRACE, LM_DEBUG, max_late_, min_pending_, pending_shift_, ACE_Time_Value::sec(), and ACE_Time_Value::usec().

Referenced by ACE_Dynamic_Message_Queue<>::dump(), ACE_Laxity_Message_Strategy::dump(), and ACE_Deadline_Message_Strategy::dump(). 

01346 {
01347 #if defined (ACE_HAS_DUMP)
01348   ACE_TRACE ("ACE_Dynamic_Message_Strategy::dump");
01349 
01350   ACE_DEBUG ((LM_DEBUG, ACE_BEGIN_DUMP, this));
01351 
01352   ACE_DEBUG ((LM_DEBUG,
01353               ACE_TEXT ("static_bit_field_mask_ = %u\n")
01354               ACE_TEXT ("static_bit_field_shift_ = %u\n")
01355               ACE_TEXT ("dynamic_priority_max_ = %u\n")
01356               ACE_TEXT ("dynamic_priority_offset_ = %u\n")
01357               ACE_TEXT ("max_late_ = [%d sec, %d usec]\n")
01358               ACE_TEXT ("min_pending_ = [%d sec, %d usec]\n")
01359               ACE_TEXT ("pending_shift_ = [%d sec, %d usec]\n"),
01360               this->static_bit_field_mask_,
01361               this->static_bit_field_shift_,
01362               this->dynamic_priority_max_,
01363               this->dynamic_priority_offset_,
01364               this->max_late_.sec (),
01365               this->max_late_.usec (),
01366               this->min_pending_.sec (),
01367               this->min_pending_.usec (),
01368               this->pending_shift_.sec (),
01369               this->pending_shift_.usec ()));
01370 
01371   ACE_DEBUG ((LM_DEBUG, ACE_END_DUMP));
01372 #endif /* ACE_HAS_DUMP */
01373 }

ACE_INLINE void ACE_Dynamic_Message_Strategy::dynamic_priority_max (  unsigned  long  ) 
 

Set maximum supported priority value.

Definition at line 549 of file Message_Block.inl.

References ACE_Time_Value, dynamic_priority_max_, and pending_shift_. 

00550 {
00551   // pending_shift_ depends on dynamic_priority_max_: for performance
00552   // reasons, the value in pending_shift_ is (re)calculated only when
00553   // dynamic_priority_max_ is initialized or changes, and is stored
00554   // as a class member rather than being a derived value.
00555   dynamic_priority_max_ = ul;
00556   pending_shift_ = ACE_Time_Value (0, ul);
00557 }

ACE_INLINE unsigned long ACE_Dynamic_Message_Strategy::dynamic_priority_max (  void   )  const
 

Get maximum supported priority value.

Definition at line 542 of file Message_Block.inl.

References dynamic_priority_max_. 

00543 {
00544   return dynamic_priority_max_;
00545 }

ACE_INLINE void ACE_Dynamic_Message_Strategy::dynamic_priority_offset (  unsigned  long  ) 
 

Set offset to boundary between signed range and unsigned range.

Definition at line 568 of file Message_Block.inl.

References ACE_Time_Value, dynamic_priority_offset_, max_late_, and min_pending_. 

00569 {
00570   // max_late_ and min_pending_ depend on dynamic_priority_offset_:
00571   // for performance reasons, the values in max_late_ and min_pending_
00572   // are (re)calculated only when dynamic_priority_offset_ is
00573   // initialized or changes, and are stored as a class member rather
00574   // than being derived each time one of their values is needed.
00575   dynamic_priority_offset_ = ul;
00576   max_late_ = ACE_Time_Value (0, ul - 1);
00577   min_pending_ = ACE_Time_Value (0, ul);
00578 }

ACE_INLINE unsigned long ACE_Dynamic_Message_Strategy::dynamic_priority_offset (  void   )  const
 

Get offset to boundary between signed range and unsigned range.

Definition at line 561 of file Message_Block.inl.

References dynamic_priority_offset_. 

00562 {
00563   return dynamic_priority_offset_;
00564 }

ACE_Dynamic_Message_Strategy::Priority_Status ACE_Dynamic_Message_Strategy::priority_status (  ACE_Message_Block &  mb,
const ACE_Time_Value &  tv
) 
 

Updates the message's priority and returns its priority status.

Definition at line 1297 of file Message_Block.cpp.

References ACE_ONE_SECOND_IN_USECS, BEYOND_LATE, convert_priority(), LATE, max_late_, min_pending_, ACE_Message_Block::msg_priority(), PENDING, pending_shift_, Priority_Status, ACE_Time_Value::sec(), static_bit_field_mask_, static_bit_field_shift_, and ACE_Time_Value::usec().

Referenced by ACE_Dynamic_Message_Queue<>::enqueue_i(), ACE_Dynamic_Message_Queue<>::refresh_late_queue(), ACE_Dynamic_Message_Queue<>::refresh_pending_queue(), and ACE_Dynamic_Message_Queue<>::sublist_enqueue_i(). 

01299 {
01300   // default the message to have pending priority status
01301   Priority_Status status = ACE_Dynamic_Message_Strategy::PENDING;
01302 
01303   // start with the passed absolute time as the message's priority, then
01304   // call the polymorphic hook method to (at least partially) convert
01305   // the absolute time and message attributes into the message's priority
01306   ACE_Time_Value priority (tv);
01307   convert_priority (priority, mb);
01308 
01309   // if the priority is negative, the message is pending
01310   if (priority < ACE_Time_Value::zero)
01311     {
01312       // priority for pending messages must be shifted
01313       // upward above the late priority range
01314       priority += pending_shift_;
01315       if (priority < min_pending_)
01316         priority = min_pending_;
01317     }
01318   // otherwise, if the priority is greater than the maximum late
01319   // priority value that can be represented, it is beyond late
01320   else if (priority > max_late_)
01321     {
01322       // all messages that are beyond late are assigned lowest priority (zero)
01323       mb.msg_priority (0);
01324       return ACE_Dynamic_Message_Strategy::BEYOND_LATE;
01325     }
01326   // otherwise, the message is late, but its priority is correct
01327   else
01328     status = ACE_Dynamic_Message_Strategy::LATE;
01329 
01330   // use (fast) bitwise operators to isolate and replace
01331   // the dynamic portion of the message's priority
01332   mb.msg_priority((mb.msg_priority() & static_bit_field_mask_) |
01333                   ((priority.usec () +
01334                     ACE_ONE_SECOND_IN_USECS * (suseconds_t)(priority.sec())) <<
01335                    static_bit_field_shift_));
01336 
01337   // returns the priority status of the message
01338   return status;
01339 }

ACE_INLINE void ACE_Dynamic_Message_Strategy::static_bit_field_mask (  unsigned  long  ) 
 

Set static bit field mask.

Definition at line 521 of file Message_Block.inl.

References static_bit_field_mask_. 

00522 {
00523   static_bit_field_mask_ = ul;
00524 }

ACE_INLINE unsigned long ACE_Dynamic_Message_Strategy::static_bit_field_mask (  void   )  const
 

Get static bit field mask.

Definition at line 514 of file Message_Block.inl.

References static_bit_field_mask_. 

00515 {
00516   return static_bit_field_mask_;
00517 }

ACE_INLINE void ACE_Dynamic_Message_Strategy::static_bit_field_shift (  unsigned  long  ) 
 

Set left shift value to make room for static bit field.

Definition at line 535 of file Message_Block.inl.

References static_bit_field_shift_. 

00536 {
00537   static_bit_field_shift_ = ul;
00538 }

ACE_INLINE unsigned long ACE_Dynamic_Message_Strategy::static_bit_field_shift (  void   )  const
 

Get left shift value to make room for static bit field.

Definition at line 528 of file Message_Block.inl.

References static_bit_field_shift_. 

00529 {
00530   return static_bit_field_shift_;
00531 }

Member Data Documentation

unsigned long ACE_Dynamic_Message_Strategy::dynamic_priority_max_ [protected]
 

Maximum supported priority value.

Definition at line 957 of file Message_Block.h.

Referenced by dynamic_priority_max().

unsigned long ACE_Dynamic_Message_Strategy::dynamic_priority_offset_ [protected]
 

Offset to boundary between signed range and unsigned range.

Definition at line 960 of file Message_Block.h.

Referenced by dynamic_priority_offset().

ACE_Time_Value ACE_Dynamic_Message_Strategy::max_late_ [protected]
 

Maximum late time value that can be represented.

Definition at line 963 of file Message_Block.h.

Referenced by dump(), dynamic_priority_offset(), and priority_status().

ACE_Time_Value ACE_Dynamic_Message_Strategy::min_pending_ [protected]
 

Minimum pending time value that can be represented.

Definition at line 966 of file Message_Block.h.

Referenced by dump(), dynamic_priority_offset(), and priority_status().

ACE_Time_Value ACE_Dynamic_Message_Strategy::pending_shift_ [protected]
 

Time value by which to shift pending priority.

Definition at line 969 of file Message_Block.h.

Referenced by dump(), dynamic_priority_max(), and priority_status().

unsigned long ACE_Dynamic_Message_Strategy::static_bit_field_mask_ [protected]
 

This is a bit mask with all ones in the static bit field.

Definition at line 947 of file Message_Block.h.

Referenced by priority_status(), and static_bit_field_mask().

unsigned long ACE_Dynamic_Message_Strategy::static_bit_field_shift_ [protected]
 

This is a left shift value to make room for static bit field: this value should be the logarithm base 2 of (static_bit_field_mask_ + 1).

Definition at line 954 of file Message_Block.h.

Referenced by priority_status(), and static_bit_field_shift().

The documentation for this class was generated from the following files:
Generated on Sun Jan 27 12:54:34 2008 for ACE by doxygen 1.3.6