Learn more about FastDFS: an efficient and scalable distributed file system

FastDFS is an efficient and scalable distributed file system created by domestic developer Yu Lianghua to provide solutions for large-scale file storage. FastDFS adopts a distributed storage architecture, which can realize fast file upload, download and deletion, and also has the advantages of high availability and scalability.

In this article, we will gain an in-depth understanding of the working principle and implementation details of FastDFS, and provide corresponding Java code examples to help readers better understand and use FastDFS.

First, the working principle of FastDFS

FastDFS adopts a distributed storage architecture, which divides files into several small blocks for storage, and each small block has a unique identifier. When a user uploads a file, FastDFS will divide the file into several small blocks and store these small blocks on different storage nodes. At the same time, FastDFS will also record the storage node and identifier of each small block for subsequent file download and deletion operations.

When a user downloads a file, FastDFS will query the storage node according to the file identifier, and download all small blocks to the local for merging. When a user deletes a file, FastDFS queries the storage node based on the file identifier and deletes all small blocks from the storage node.

Second, the implementation details of FastDFS

1. File Upload

File upload is one of the core functions of FastDFS, and its implementation process is as follows:

(1) The client requests the Tracker Server to upload files, and the Tracker Server returns a list of available Storage Servers.

(2) The client selects one of the Storage Servers to upload, and sends an upload request to it.

(3) After the Storage Server receives the upload request, it generates a unique file identifier and divides the file into several small pieces for storage.

(4) Storage Server returns the identifier and storage node information of each small block to the client.

(5) The client sends the file identifier and small piece information to the Tracker Server, and requests to associate them.

(6) Tracker Server stores the file identifier and small block information in its own database, and returns a successful upload message to the client.

1. Download Document

File download is another core function of FastDFS, and its implementation process is as follows:

(1) The client requests the Tracker Server to download the file, and the Tracker Server returns the file identifier and storage node information.

(2) The client sends a download request to the specified Storage Server according to the storage node information.

(3) After the Storage Server receives the download request, it sends the content of all small pieces to the client.

(4) The client merges the content of all small pieces into a complete file and saves it locally.

1. file deletion

File deletion is the last core function of FastDFS, and its implementation process is as follows:

(1) The client requests the Tracker Server to delete the file, and the Tracker Server returns the file identifier and storage node information.

(2) The client sends a delete request to the specified Storage Server according to the storage node information.

(3) After the Storage Server receives the deletion request, it deletes all small blocks from the storage node.

(4) The Storage Server returns a successful deletion message to the client.

3. Java code example

The following is a Java code sample that demonstrates how to use FastDFS for file upload, download and delete operations.

1. File Upload

import org.csource.fastdfs.*;

public class FastDFSUploader {
    public static void main(String[] args) {
        try {
            ClientGlobal.init("fdfs_client.conf");
            TrackerClient tracker = new TrackerClient();
            TrackerServer trackerServer = tracker.getConnection();
            StorageServer storageServer = null;
            StorageClient1 client = new StorageClient1(trackerServer, storageServer);
            String fileId = client.upload_file1("test.jpg", "jpg", null);
            System.out.println("上传成功，文件ID为：" + fileId);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

1. Download Document

import org.csource.fastdfs.*;

public class FastDFSDownloader {
    public static void main(String[] args) {
        try {
            ClientGlobal.init("fdfs_client.conf");
            TrackerClient tracker = new TrackerClient();
            TrackerServer trackerServer = tracker.getConnection();
            StorageServer storageServer = null;
            StorageClient1 client = new StorageClient1(trackerServer, storageServer);
            byte[] content = client.download_file1("group1", "M00/00/00/wKgMqF5H5Z6Ae1J4AAJ4ZJzKJNk.jpg");
            System.out.println("下载成功，文件内容为：" + new String(content));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

1. file deletion

import org.csource.fastdfs.*;

public class FastDFSDeleter {
    public static void main(String[] args) {
        try {
            ClientGlobal.init("fdfs_client.conf");
            TrackerClient tracker = new TrackerClient();
            TrackerServer trackerServer = tracker.getConnection();
            StorageServer storageServer = null;
            StorageClient1 client = new StorageClient1(trackerServer, storageServer);
            int result = client.delete_file1("group1", "M00/00/00/wKgMqF5H5Z6Ae1J4AAJ4ZJzKJNk.jpg");
            System.out.println("删除成功，返回值为：" + result);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Four. Summary

FastDFS is an efficient and scalable distributed file system, which uses a distributed storage architecture to achieve fast file upload, download and deletion. This article provides an in-depth understanding of the working principle and implementation details of FastDFS, and provides corresponding Java code examples to help readers better understand and use FastDFS.