作者:京东科技 贾世闻
对象存储是云的基础组件之一,各大云厂商都有相关产品。这里跟大家介绍一下rust与对象存储交到的基本套路和其中的一些技巧。
基本连接
我们以 [S3 sdk](
https://github.com/awslabs/aws-sdk-rust)为例来说说基本的连接与操作,作者验证过aws、京东云、阿里云。主要的增删改查功能没有什么差别。
- let shared_config = SdkConfig::builder()
- .credentials_provider(SharedCredentialsProvider::new(Credentials::new(
- "LTAI5t7NPuPKsXm6UeSa1",
- "DGHuK03ESXQYqQ83buKMHs9NAwz",
- None,
- None,
- "Static",
- )))
- .endpoint_url("http://oss-cn-beijing.aliyuncs.com")
- .region(Region::new("oss-cn-beijing"))
- .build();
- let s3_config_builder = aws_sdk_s3::config::Builder::from(&shared_config);
- let client = aws_sdk_s3::Client::from_conf(s3_config_builder.build());
复制代码 建立Client所需要的参数主要有你需要访问的oss的AK、SK,endpoint url 以及服务所在的区域。以上信息都可以在服务商的帮助文档查询到。
- let mut obj_list = client
- .list_objects_v2()
- .bucket(bucket)
- .max_keys(max_keys)
- .prefix(prefix_str)
- .continuation_token(token_str);
- let list = obj_list.send().await.unwrap();
- println!("{:?}",list.contents());
- println!("{:?}",list.next_continuation_token());
复制代码 使用list_objects_v2函数返回对象列表,相比list_objects函数,list_objects_v2可以通过continuation_token和max_keys控制返回列表的长度。list.contents()返回对象列表数组,
list.next_continuation_token()返回继续查询的token。
- let content = ByteStream::from("content in file".as_bytes());
- let exp = aws_smithy_types::DateTime::from_secs(100);
- let upload = client
- .put_object()
- .bucket("bucket")
- .key("/test/key")
- .expires(exp)
- .body(content);
- upload.send().await.unwrap();
复制代码 指定bucket及对象路径,body接受ByteStream类型作为文件内容,最后设置过期时间expires,无过期时间时不指定该配置即可。
- let key = "/tmp/test/key".to_string();
- let resp = client
- .get_object()
- .bucket("bucket")
- .key(&key)
- .send()
- .await.unwrap();
- let data = resp.body.collect().await.unwrap();
- let bytes = data.into_bytes();
- let path = std::path::Path::new("/tmp/key")
- if let Some(p) = path.parent() {
- std::fs::create_dir_all(p).unwrap();
- }
- let mut file = OpenOptions::new()
- .write(true)
- .truncate(true)
- .create(true)
- .open(path).unwrap();
- let _ = file.write(&*bytes);
- file.flush().unwrap();
复制代码 通过get_object()函数获取GetObjectOutput。返回值的body 就是文件内容,将 body 转换为 bytes,最后打开文件写入即可。
- let mut keys = vec![];
- let key1 = ObjectIdentifier::builder()
- .set_key(Some("/tmp/key1".to_string()))
- .build();
- let key2 = ObjectIdentifier::builder()
- .set_key(Some("/tmp/key2".to_string()))
- .build()
- keys.push(key1);
- keys.push(key2)
- client
- .delete_objects()
- .bucket(bucket)
- .delete(Delete::builder().set_objects(Some(keys)).build())
- .send()
- .await
- .unwrap();
复制代码 delete_objects 批量删除对象。首先构建keys vector,定义要删除的对象,然后通过Delete::builder(),构建 Delete model。
大文件上传
- let mut file = fs::File::open("/tmp/file_name").unwrap();
- let chunk_size = 1024*1024;
- let mut part_number = 0;
- let mut upload_parts: Vec = Vec::new();
- //获取上传id
- let multipart_upload_res: CreateMultipartUploadOutput = self
- .client
- .create_multipart_upload()
- .bucket("bucket")
- .key("/tmp/key")
- .send()
- .await.unwrap();
- let upload_id = match multipart_upload_res.upload_id() {
- Some(id) => id,
- None => {
- return Err(anyhow!("upload id is None"));
- }
- };
- //分段上传文件并记录completer_part
- loop {
- let mut buf = vec![0; chuck_size];
- let read_count = file.read(&mut buf)?;
- part_number += 1;
- if read_count == 0 {
- break;
- }
- let body = &buf[..read_count];
- let stream = ByteStream::from(body.to_vec());
- let upload_part_res = self
- .client
- .upload_part()
- .key(key)
- .bucket(bucket)
- .upload_id(upload_id)
- .body(stream)
- .part_number(part_number)
- .send()
- .await.unwrap();
- let completer_part = CompletedPart::builder()
- .e_tag(upload_part_res.e_tag.unwrap_or_default())
- .part_number(part_number)
- .build();
- upload_parts.push(completer_part);
- if read_count != chuck_size {
- break;
- }
- }
- // 完成上传文件合并
- let completed_multipart_upload: CompletedMultipartUpload =
- CompletedMultipartUpload::builder()
- .set_parts(Some(upload_parts))
- .build();
- let _complete_multipart_upload_res = self
- .client
- .complete_multipart_upload()
- .bucket("bucket")
- .key(key)
- .multipart_upload(completed_multipart_upload)
- .upload_id(upload_id)
- .send()
- .await.unwrap();
复制代码 有时候面对大文件,比如几百兆甚至几个G的文件,为了节约带宽和内存,我才采取分段上传的方案,然后在对象存储的服务端做合并。基本流程是:指定bucket和key,获取一个上传id;按流读取文件,分段上传字节流,并记录CompletedPart;通知服务器按照CompletedPart 集合来合并文件。具体过程代码已加注释,这里不再累述。
大文件下载
- let mut file = match OpenOptions::new()
- .truncate(true)
- .create(true)
- .write(true)
- .open("/tmp/target_file");
- let key = "/tmp/test/key".to_string();
- let resp = client
- .get_object()
- .bucket("bucket")
- .key(&key)
- .send()
- .await.unwrap();
- let content_len = resp.content_length();
- let mut byte_stream_async_reader = resp.body.into_async_read();
- let mut content_len_usize: usize = content_len.try_into().unwrap();
- loop {
- if content_len_usize > chunk_size {
- let mut buffer = vec![0; chunk_size];
- let _ = byte_stream_async_reader.read_exact(&mut buffer).await.unwrap();
- file.write_all(&buffer).unwrap();
- content_len_usize -= chunk_size;
- continue;
- } else {
- let mut buffer = vec![0; content_len_usize];
- let _ = byte_stream_async_reader.read_exact(&mut buffer).await.unwrap();
- file.write_all(&buffer).unwrap();
- break;
- }
- }
- file.flush().unwrap();
复制代码 在从对象存储服务端下载文件的过程中也会遇到大文件问题。为了节约带宽和内存,我们采取读取字节流的方式分段写入文件。首先get_object()函数获取ByteStream,通过async_reader流式读取对象字节,分段写入文件。
对象存储的相关话题今天先聊到这儿,下期见。
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