Inside Macintosh: Operating System Utilities /

Chapter 6 - Queue Utilities

This chapter describes how your application can directly add elements to and remove them from an operating-system queue. The Macintosh Operating System stores some of the information it uses in data structures called queues. The Queue Utilities allow you to manipulate those queues directly by adding and removing elements.

Ordinarily, you do not need to use the Queue Utilities. The Operating System itself is responsible for managing the various operating-system queues that it creates internally, and you should manipulate those queues only indirectly. For example, to add an element to the notification queue maintained by the Notification Manager, you should call the NMInstall function. To remove an element from that queue, you should call the NMRemove function. But if you discover some unusual need for adding or removing such elements directly, you can use the Queue Utilities routines. In addition, you can use the Queue Utilities routines for directly manipulating queues that you create.

This chapter describes the general structure of operating-system queues and then

• lists the routines your application should use to manipulate an operating-system queue indirectly
• shows how your application can use the Queue Utilities for directly manipulating queues that you create.

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Chapter Contents

About Queues

The Queue Header

The Queue Element

Using the Queue Utilities

Searching for an Element in an Operating-System Queue

Adding Elements to an Operating-System Queue

Removing Elements From an Operating-System Queue

Queue Utilities Reference

Data Structures

Queue Headers

Queue Elements

Routines

Summary of the Queue Utilities

Pascal Summary

Constants

Data Types

Routines

C Summary

Constants

Data Types

Routines

Assembly-Language Summary

QHdr Data Structure

QElem Data Structure

Result Codes