(improvement) log a warning when importing of lz4 or snappy packages …

[mykaul]

…fails.

If it is not available, the driver will silently not use compression. Not very very silently, as you will see in debug level only something like: "No available compression types supported on both ends. locally supported: odict_keys([]). remotely supported: ['lz4', 'snappy']"

Make it a warning. I think it wouldn't be too noisy and is clear enough for the developer.

Pre-review checklist

• I have split my patch into logically separate commits.
• All commit messages clearly explain what they change and why.
• I added relevant tests for new features and bug fixes.
• All commits compile, pass static checks and pass test.
• PR description sums up the changes and reasons why they should be introduced.
• I have provided docstrings for the public items that I want to introduce.
• I have adjusted the documentation in ./docs/source/.
• I added appropriate Fixes: annotations to PR description.

[Copilot]

Pull Request Overview

This PR improves user experience by adding warning logs when optional compression packages (lz4 and snappy) fail to import. Previously, missing compression packages would only show debug-level messages when compression negotiation failed, making it difficult for developers to understand why compression wasn't working.

• Added warning log messages when lz4 package import fails
• Added warning log messages when snappy package import fails

[Lorak-mmk]

One more thing we could (and should!) do is to specify those dependencies - right now they are totally absent from pyproject.toml, which makes them hard to discover.
Those should be listed in [project.optional-dependencies] section. We could either make it a single extra, like compression = ['lz4', 'snappy'], or extra-per-lib, like

compression-snappy = ['snappy']
compression-lz4 = ['lz4']

[mykaul]

One more thing we could (and should!) do is to specify those dependencies - right now they are totally absent from pyproject.toml, which makes them hard to discover. Those should be listed in [project.optional-dependencies] section. We could either make it a single extra, like compression = ['lz4', 'snappy'], or extra-per-lib, like

compression-snappy = ['snappy']
compression-lz4 = ['lz4']

Yes, that's a different issue - it also means we never test compression.

[mykaul]

MacOS failure:

=================================== FAILURES ===================================
  __________________ StrategiesTest.test_nts_token_performance ___________________
  
  self = <tests.unit.test_metadata.StrategiesTest testMethod=test_nts_token_performance>
  
      def test_nts_token_performance(self):
          """
          Tests to ensure that when rf exceeds the number of nodes available, that we dont'
          needlessly iterate trying to construct tokens for nodes that don't exist.
      
          @since 3.7
          @jira_ticket PYTHON-379
          @expected_result timing with 1500 rf should be same/similar to 3rf if we have 3 nodes
      
          @test_category metadata
          """
      
          token_to_host_owner = {}
          ring = []
          dc1hostnum = 3
          current_token = 0
          vnodes_per_host = 500
          for i in range(dc1hostnum):
      
              host = Host('dc1.{0}'.format(i), SimpleConvictionPolicy)
              host.set_location_info('dc1', "rack1")
              for vnode_num in range(vnodes_per_host):
                  md5_token = MD5Token(current_token+vnode_num)
                  token_to_host_owner[md5_token] = host
                  ring.append(md5_token)
              current_token += 1000
      
          nts = NetworkTopologyStrategy({'dc1': 3})
          start_time = timeit.default_timer()
          nts.make_token_replica_map(token_to_host_owner, ring)
          elapsed_base = timeit.default_timer() - start_time
      
          nts = NetworkTopologyStrategy({'dc1': 1500})
          start_time = timeit.default_timer()
          nts.make_token_replica_map(token_to_host_owner, ring)
          elapsed_bad = timeit.default_timer() - start_time
          difference = elapsed_bad - elapsed_base
  >       assert difference < 1 and difference > -1
  E       assert (-1.130967961999886 < 1 and -1.130967961999886 > -1)

[mykaul]

Looks like a flaky test to me. I have no idea what the test does - measure it's not more than 1 s difference? not sure who set it as such. Anyway... I can retry or whatnot.

[dkropachev]

@mykaul , can you please also bump log level to error for case when user picked compression, but there is no compression library available:

python-driver/cassandra/connection.py

Lines 1411 to 1414 in c7ca1c6

	log.debug("No available compression types supported on both ends."
	" locally supported: %r. remotely supported: %r",
	locally_supported_compressions.keys(),
	remote_supported_compressions)

It is probably makes sense to reduce log level for import errors to debug, warning is too high IMHO.

[mykaul]

@mykaul , can you please also bump log level to error for case when user picked compression, but there is no compression library available:

python-driver/cassandra/connection.py

Lines 1411 to 1414 in c7ca1c6

	log.debug("No available compression types supported on both ends."
	" locally supported: %r. remotely supported: %r",
	locally_supported_compressions.keys(),
	remote_supported_compressions)

It is probably makes sense to reduce log level for import errors to debug, warning is too high IMHO.

Done.