C++ coroutines provide a powerful and efficient way to build web crawlers that can be easily managed and scaled. In this blog post, we will explore how to leverage C++ coroutines to create a web crawler that can fetch and process web pages in a concurrent manner.

Getting Started

Before diving into the details, let’s ensure that you have the necessary tools set up to build a C++ coroutine-based web crawler.

Prerequisites

• C++ compiler that supports C++20 coroutines (e.g., GCC 10 or later)
• Networking library that provides support for coroutines (e.g., Boost.Beast or C++20 Networking TS)
• HTML parsing library (e.g., Gumbo-parser or libxml++) to extract information from web pages

Setting up the Project

Step 1: Create a new C++ project

Start by creating a new C++ project using your favorite IDE or build system. Make sure to configure it with the necessary dependencies as mentioned above.

Step 2: Define the WebCrawler class

class WebCrawler {
public:
  WebCrawler() = default;
  
  void crawl(const std::string& startUrl) {
    // TODO: Implement web crawling logic using coroutines
  }
};

Step 3: Implement the Coroutine

///////////////////////////////////////////
// Coroutine-based Web Crawler Implementation
///////////////////////////////////////////
#include <cppcoro/async_generator.hpp>
#include <cppcoro/single_consumer_async_auto_reset_event.hpp>

cppcoro::async_generator<std::string> fetchUrls(const std::string& url) {
    // TODO: Implement web page fetching logic
}

cppcoro::async_generator<std::string> webCrawler(const std::string& startUrl) {
    // TODO: Implement web crawling logic using fetchUrls coroutine
}

Step 4: Start the Crawler

int main() {
  WebCrawler crawler;
  
  try {
    crawler.crawl("https://example.com");
  } catch (const std::exception& ex) {
    // Handle any exceptions here
  }
  
  return 0;
}

Conclusion

By utilizing C++ coroutines, we can build efficient and scalable web crawlers that can handle fetching and processing of web pages in a concurrent manner. With the power of coroutines, we can easily manage the flow of asynchronous operations and achieve better performance compared to traditional approaches.

Start exploring the world of web crawling with C++ coroutines today and see how they can elevate your web scraping projects to new heights!

#webcrawling #cppcoroutine