Implement Python DownloadProgress void* mappings

[es-fabricemarie]

This is probably not the right way to do it, or it may not even be complete. But I just want to help to move along the issue I filled and contribute back. Hopefully it will help a maintainer to get started.

Fixes #1441

[es-fabricemarie]

Tested with the following test program:

#!/usr/bin/python3
import libdnf5

class DownloadProgress(libdnf5.repo.DownloadCallbacks):
    def add_new_download(self, user_data, description, total_to_download):
        print("Just added package %s to download list" % description)
        return description

    def progress(self, user_cb_data, total_to_download, downloaded):
        print(f"progress achieved on {user_cb_data}")
        return 0

    def end(self, user_cb_data, status, msg):
        print(f"download ended for {user_cb_data}, with status={status} and msg={msg}")
        return 0


base = libdnf5.base.Base()
base.load_config()
base.setup()
sack = base.get_repo_sack()
sack.create_repos_from_system_configuration()
sack.update_and_load_enabled_repos(True)
goal = libdnf5.base.Goal(base)
goal.add_rpm_upgrade()
transaction = goal.resolve()
downloader_callbacks = DownloadProgress()
base.set_download_callbacks(
    libdnf5.repo.DownloadCallbacksUniquePtr(downloader_callbacks)
)
transaction.download()
print("Done downloading")

I get:

Just added package enforce-0:1.7-18.ev40.x86_64 to download list
Just added package entutils-0:1.3-16.ev40.x86_64 to download list
Just added package util_assets_inventory-0:1.6-22.ev40.x86_64 to download list
progress achieved on entutils-0:1.3-16.ev40.x86_64
progress achieved on util_assets_inventory-0:1.6-22.ev40.x86_64
progress achieved on enforce-0:1.7-18.ev40.x86_64
progress achieved on entutils-0:1.3-16.ev40.x86_64
progress achieved on entutils-0:1.3-16.ev40.x86_64
progress achieved on enforce-0:1.7-18.ev40.x86_64
progress achieved on entutils-0:1.3-16.ev40.x86_64
progress achieved on util_assets_inventory-0:1.6-22.ev40.x86_64
progress achieved on util_assets_inventory-0:1.6-22.ev40.x86_64
progress achieved on enforce-0:1.7-18.ev40.x86_64
progress achieved on util_assets_inventory-0:1.6-22.ev40.x86_64
progress achieved on enforce-0:1.7-18.ev40.x86_64
progress achieved on entutils-0:1.3-16.ev40.x86_64
progress achieved on enforce-0:1.7-18.ev40.x86_64
progress achieved on util_assets_inventory-0:1.6-22.ev40.x86_64
progress achieved on entutils-0:1.3-16.ev40.x86_64
progress achieved on enforce-0:1.7-18.ev40.x86_64
progress achieved on util_assets_inventory-0:1.6-22.ev40.x86_64
progress achieved on entutils-0:1.3-16.ev40.x86_64
progress achieved on enforce-0:1.7-18.ev40.x86_64
progress achieved on util_assets_inventory-0:1.6-22.ev40.x86_64
progress achieved on entutils-0:1.3-16.ev40.x86_64
progress achieved on enforce-0:1.7-18.ev40.x86_64
progress achieved on util_assets_inventory-0:1.6-22.ev40.x86_64
progress achieved on entutils-0:1.3-16.ev40.x86_64
progress achieved on enforce-0:1.7-18.ev40.x86_64
progress achieved on util_assets_inventory-0:1.6-22.ev40.x86_64
progress achieved on entutils-0:1.3-16.ev40.x86_64
progress achieved on enforce-0:1.7-18.ev40.x86_64
progress achieved on util_assets_inventory-0:1.6-22.ev40.x86_64
progress achieved on entutils-0:1.3-16.ev40.x86_64
progress achieved on enforce-0:1.7-18.ev40.x86_64
progress achieved on util_assets_inventory-0:1.6-22.ev40.x86_64
progress achieved on entutils-0:1.3-16.ev40.x86_64
progress achieved on enforce-0:1.7-18.ev40.x86_64
progress achieved on util_assets_inventory-0:1.6-22.ev40.x86_64
progress achieved on entutils-0:1.3-16.ev40.x86_64
progress achieved on enforce-0:1.7-18.ev40.x86_64
progress achieved on util_assets_inventory-0:1.6-22.ev40.x86_64
progress achieved on entutils-0:1.3-16.ev40.x86_64
progress achieved on enforce-0:1.7-18.ev40.x86_64
progress achieved on util_assets_inventory-0:1.6-22.ev40.x86_64
progress achieved on entutils-0:1.3-16.ev40.x86_64
progress achieved on enforce-0:1.7-18.ev40.x86_64
progress achieved on util_assets_inventory-0:1.6-22.ev40.x86_64
progress achieved on entutils-0:1.3-16.ev40.x86_64
progress achieved on enforce-0:1.7-18.ev40.x86_64
progress achieved on util_assets_inventory-0:1.6-22.ev40.x86_64
progress achieved on entutils-0:1.3-16.ev40.x86_64
progress achieved on enforce-0:1.7-18.ev40.x86_64
progress achieved on util_assets_inventory-0:1.6-22.ev40.x86_64
progress achieved on entutils-0:1.3-16.ev40.x86_64
progress achieved on enforce-0:1.7-18.ev40.x86_64
progress achieved on util_assets_inventory-0:1.6-22.ev40.x86_64
progress achieved on entutils-0:1.3-16.ev40.x86_64
progress achieved on enforce-0:1.7-18.ev40.x86_64
progress achieved on util_assets_inventory-0:1.6-22.ev40.x86_64
progress achieved on entutils-0:1.3-16.ev40.x86_64
progress achieved on enforce-0:1.7-18.ev40.x86_64
progress achieved on util_assets_inventory-0:1.6-22.ev40.x86_64
progress achieved on entutils-0:1.3-16.ev40.x86_64
progress achieved on enforce-0:1.7-18.ev40.x86_64
progress achieved on entutils-0:1.3-16.ev40.x86_64
progress achieved on util_assets_inventory-0:1.6-22.ev40.x86_64
download ended for entutils-0:1.3-16.ev40.x86_64, with status=0 and msg=None
progress achieved on enforce-0:1.7-18.ev40.x86_64
progress achieved on util_assets_inventory-0:1.6-22.ev40.x86_64
progress achieved on enforce-0:1.7-18.ev40.x86_64
progress achieved on util_assets_inventory-0:1.6-22.ev40.x86_64
progress achieved on enforce-0:1.7-18.ev40.x86_64
download ended for enforce-0:1.7-18.ev40.x86_64, with status=0 and msg=None
progress achieved on util_assets_inventory-0:1.6-22.ev40.x86_64
progress achieved on util_assets_inventory-0:1.6-22.ev40.x86_64
download ended for util_assets_inventory-0:1.6-22.ev40.x86_64, with status=0 and msg=None
Done downloading

[jrohel]

Hi. Thank you for your work. I'm working on that too. I'm looking for a solution that would work correctly with memory and I need to solve all the languages ​​supported by the libdnf5 project - Python, Ruby, Perl.

I am considering whether there is a need to store objects in a helper container.

I looked at your code. I see you are dealing with Python and storing objects. You use std::map<void*, PyObject*> user_data_map for this. I have a question? Why are you saving the pointer twice?
key = reinterpret_cast<void *>(py_obj); -> py_obj = reinterpret_cast<PyObject *>(key);
The mapped value can be retrieved from the key using reinterpret_cast at any time. So std::set<void *> (or std::set<PyObject *>) could be enough.