Multipart Upload APIs (SDK for C)

If you have any questions during development, post them on the Issues page of GitHub.

You can upload a large file using multipart upload. Multipart upload is applicable to many scenarios. Below are some examples.

A file to be uploaded is larger than 100 MB.
The network connection to the OBS server breaks often.
The size of a file to be uploaded is unknown.

A multipart upload consists of the following steps:

Multipart upload is mainly used for large file upload or when the network connection is poor. This example uploads a large file in parts concurrently:

static void test_concurrent_upload_part(char *filename, char *key, uint64_t uploadSliceSize)
{
    obs_status ret_status = OBS_STATUS_BUTT;
    // Create and initialize option.
    obs_options option;
    init_obs_options(&option);
    option.bucket_options.host_name = "<your-endpoint>";
    option.bucket_options.bucket_name = "<Your bucketname>";

    //Read the AK/SK from environment variables.
    option.bucket_options.access_key = getenv("ACCESS_KEY_ID");
    option.bucket_options.secret_access_key = getenv("SECRET_ACCESS_KEY");
    char *concurrent_upload_id;
    uint64_t uploadSize = uploadSliceSize;                             
    uint64_t filesize =0;                                          
    // Initialize the put_properties structure.
    obs_put_properties put_properties;
    init_put_properties(&put_properties);
    // Large file information: file pointer, file size, number of parts determined by part size
    test_upload_file_callback_data data;
    memset(&data, 0, sizeof(test_upload_file_callback_data));
    filesize = get_file_info(filename,&data);
    data.noStatus = 1;
    data.part_size = uploadSize;
    data.part_num = (filesize % uploadSize == 0) ? (filesize / uploadSize) : (filesize / uploadSize +1);
    // Initialize the callback function of the uploading part.
    obs_response_handler Handler =
    { 
         &response_properties_callback, &response_complete_callback 
    };
    // Callback function for assembling parts
    obs_complete_multi_part_upload_handler complete_multi_handler =
    { 
        {&response_properties_callback,
         &response_complete_callback},
        &CompleteMultipartUploadCallback
    };
    //Initiating the multipart upload returns uploadId: uploadIdReturn.
    char uploadIdReturn[256] = {0};
    int upload_id_return_size = 255;
    initiate_multi_part_upload(&option,key,upload_id_return_size,uploadIdReturn, &putProperties,
            0,&Handler, &ret_status);
    if (OBS_STATUS_OK == ret_status) {
        printf("test init upload part return uploadIdReturn(%s). \n", uploadIdReturn);
        strcpy(concurrent_upload_id,uploadIdReturn);
    }
    else
    {
        printf("test init upload part failed(%s).\n", obs_get_status_name(ret_status));
    }
    // Concurrent upload
    test_concurrent_upload_file_callback_data *concurrent_upload_file;
    concurrent_upload_file =(test_concurrent_upload_file_callback_data *)malloc(
                    sizeof(test_concurrent_upload_file_callback_data)*(data.part_num+1));
    if(concurrent_upload_file == NULL)
    {
         printf("malloc test_concurrent_upload_file_callback_data failed!!!");
         return ;
    }
    test_concurrent_upload_file_callback_data *concurrent_upload_file_complete =   
                              concurrent_upload_file;
    start_upload_threads(data, concurrent_upload_id,filesize, key, option, concurrent_upload_file_complete);
    // Assemble parts.
    obs_complete_upload_Info *upload_Info = (obs_complete_upload_Info *)malloc(
                sizeof(obs_complete_upload_Info)*data.part_num);
    for(i=0; i<data.part_num; i++)
    {
        upload_Info[i].part_number = concurrent_upload_file_complete[i].part_num;
        upload_Info[i].etag = concurrent_upload_file_complete[i].etag;
    }
    complete_multi_part_upload(&option, key, uploadIdReturn, data.part_num,upload_Info,&putProperties,&complete_multi_handler,&ret_status);
    if (ret_status == OBS_STATUS_OK) {
        printf("test complete upload successfully. \n");
    }
    else
    {
        printf("test complete upload failed(%s).\n", obs_get_status_name(ret_status));
    }
    if(concurrent_upload_file)
    {
        free(concurrent_upload_file);
        concurrent_upload_file = NULL;
    }
    if(upload_Info)
    {
        free(upload_Info);
        upload_Info = NULL;
    }
}

When uploading a large file in parts, you need to use the Offset and PartSize parameters to specify the start and end positions of each part in the file.