0

我是 python 编程和 Azure 的新手。

我需要编写一个将由 2 个进程执行的脚本。

这两个进程将运行相同的 python 脚本。我知道 Azure 有 storageAccounts 可以在其中放置一些文件，我发现了这个： https ://docs.microsoft.com/en-us/python/api/azure-storage-file/azure.storage.file.fileservice .fileservice?view=azure-python

和： https ://github.com/Azure/azure-storage-python

这是一些伪代码来说明我需要实现的目标：

function useStorageFile
   if(fileFromStorage == null)
      createFileInStorage lockFileInStorage;
      executeDockerCommand;
      writeResultOFCommandInStorageFile;
   else
      if(fileFromStorage != null)
        X:if(fileFromStorage.status !== 'locked')
           readResultFromFile
        else
           wait 1s;
           continue X;

是否可以在 Azure 中锁定/解锁文件？例如，我如何在 python 中实现这一点？谢谢你。

编辑 我已经设法用 python 脚本在 Blob Storage 中编写了一个文件。现在的问题是：如何在第一个进程将命令结果写入文件时锁定文件，并在 Blob 存储锁（如果存在该选项......）被释放后立即由第二个进程读取它第一个过程？这是 iam 使用的 python 脚本：

import os, uuid, sys
from azure.storage.blob import BlockBlobService, PublicAccess

def run_sample():
    try:
        # Create the BlockBlockService that is used to call the Blob service for the storage account
        block_blob_service = BlockBlobService(account_name='xxxxxx', account_key='xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx')

        # Create a container called 'quickstartblobs'.
        container_name ='quickstartblobs'
        block_blob_service.create_container(container_name)

        # Set the permission so the blobs are public.
        block_blob_service.set_container_acl(container_name, public_access=PublicAccess.Container)

        # Create a file in Documents to test the upload and download.
        local_path=os.path.abspath(os.path.curdir)
        local_file_name ='youss.txt'
        full_path_to_file =os.path.join(local_path, local_file_name)

        # Write text to the file.
        file = open(full_path_to_file,  'w')
        file.write("Hello, World!")
        file.close()

        print("Temp file = " + full_path_to_file)
        print("\nUploading to Blob storage as blob" + local_file_name)

        # Upload the created file, use local_file_name for the blob name
        block_blob_service.create_blob_from_path(container_name, local_file_name, full_path_to_file)

        # List the blobs in the container
        print("\nList blobs in the container")
        generator = block_blob_service.list_blobs(container_name)
        for blob in generator:
            print("\t Blob name: " + blob.name)

        # Download the blob(s).
        # Add '_DOWNLOADED' as prefix to '.txt' so you can see both files in Documents.
        full_path_to_file2 = os.path.join(local_path, str.replace(local_file_name ,'.txt', '_DOWNLOADED.txt'))
        print("\nDownloading blob to " + full_path_to_file2)
        block_blob_service.get_blob_to_path(container_name, local_file_name, full_path_to_file2)

        sys.stdout.write("Sample finished running. When you hit <any key>, the sample will be deleted and the sample "
                         "application will exit.")
        sys.stdout.flush()
        input()

        # Clean up resources. This includes the container and the temp files
        block_blob_service.delete_container(container_name)
        os.remove(full_path_to_file)
        os.remove(full_path_to_file2)
    except Exception as e:
        print(e)


# Main method.
if __name__ == '__main__':
    run_sample()
4

1 回答 1

1

如何在第一个进程将命令结果写入文件时锁定文件，并在第一个进程释放 Blob 存储锁（如果存在该选项...）后立即由第二个进程读取它？

Azure Blob 存储有一项称为Lease您可以使用的功能。本质上Leasing，进程获取资源（在您的情况下为 blob）的排他锁，并且只有一个进程可以获取 blob 的租约。在 blob 上获取租约后，任何其他进程都无法修改或删除 blob。

因此，您需要做的是在写入之前尝试获取 blob 的租约。如果 blob 已被租用，您将收到错误消息（HTTP 状态代码 412，PreConditionFailed 错误）。假设您没有收到错误，您可以继续更新文件。文件更新后，您可以手动释放锁（中断租约或释放租约）或让租约自动到期。假设您收到错误，您应该等待并定期（例如每 5 秒）获取 blob 的租用状态。一旦您发现该 blob 不再被租用，您就可以读取该 blob 的内容。

于 2019-05-21T04:41:45.510 回答