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

Readers-writer lock

All the locking mechanisms that I have discussed so far were designed for symmetric scenarios. In all examples, they were synchronizing multiple threads that were all doing (more or less) the same work. This is, however, not the only type of shared data access we can encounter.

Another frequent situation that occurs in multithreaded applications is when multiple threads are just reading from the shared data without doing any modifications. That by itself would not require any locking at all, except that from time to time, the data has to be modified. To do that, we somehow have to stop the reading threads. We must also, as before, prevent two writers from working on the data at the same time.

In such a situation, we need a synchronization mechanism that allows multiple readers to share the resource while also allowing one writer to acquire exclusive access to the resource when necessary. We call such a synchronization mechanism a readers-writer or shared-exclusive lock...