Book Image

Hands-On Design Patterns with Delphi

By : Primož Gabrijelčič
Book Image

Hands-On Design Patterns with Delphi

By: Primož Gabrijelčič

Overview of this book

Design patterns have proven to be the go-to solution for many common programming scenarios. This book focuses on design patterns applied to the Delphi language. The book will provide you with insights into the language and its capabilities of a runtime library. You'll start by exploring a variety of design patterns and understanding them through real-world examples. This will entail a short explanation of the concept of design patterns and the original set of the 'Gang of Four' patterns, which will help you in structuring your designs efficiently. Next, you'll cover the most important 'anti-patterns' (essentially bad software development practices) to aid you in steering clear of problems during programming. You'll then learn about the eight most important patterns for each creational, structural, and behavioral type. After this, you'll be introduced to the concept of 'concurrency' patterns, which are design patterns specifically related to multithreading and parallel computation. These will enable you to develop and improve an interface between items and harmonize shared memories within threads. Toward the concluding chapters, you'll explore design patterns specific to program design and other categories of patterns that do not fall under the 'design' umbrella. By the end of this book, you'll be able to address common design problems encountered while developing applications and feel confident while building scalable projects.
Table of Contents (18 chapters)
Title Page
Copyright and Credits
About Packt

Lock striping

In the previous section, I recommended using one lock per shared resource. We also saw that sometimes we cannot do such fine-grained locking and that we have to implement locks that protect more than one resource at the same time.

The lock striping pattern covers the opposite case. Sometimes, one lock per resource is not enough. On some occasions, we may want to implement multiple locks for one shared resource. We could, for example, add a lock to each element in an array or list.


Imagine the fitting rooms in a clothing store. They are not protected with one master lock as that would prevent multiple customers from trying out clothes at the same time. Rather, each room has its own lock.

This pattern can only be applied when the size of the shared resource is not modified during the execution. It does not help us if we lock two elements in an array and then another thread ignores these locks and removes one element between them, shifting the data around.

It can also be expensive...