WIP

[mykaul]

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.

[mykaul]

TODO: make_header_prefix() needs to be adjusted, as it used the old protocol (with stream_id being a single byte, now it's 2) . That probably explains most failures.

[Copilot]

Pull Request Overview

This PR removes legacy support for protocol versions 1 and 2, standardizes on protocol v3+ handling throughout code, tests, and documentation, and simplifies collection serialization to always use 32-bit length prefixes.

• Drop all v1/v2-specific branches in protocol framing, query parameters, and metadata parsing.
• Update tests to assume protocol version 3 (or higher) as the baseline.
• Refactor collection types to always use int32_pack/int32_unpack for lengths.

Reviewed Changes

Copilot reviewed 18 out of 18 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
tests/unit/test_parameter_binding.py	Consolidated legacy BoundStatementTestV* into v3+ class
tests/unit/test_orderedmap.py	Updated default protocol for OrderedMapSerializedKey
tests/unit/test_marshalling.py	Switched marshalling/unmarshalling calls to proto v3+
tests/unit/test_host_connection_pool.py	Removed unused get_max_requests_per_connection override
tests/unit/test_connection.py	Removed legacy header logic for protocol <3
tests/unit/io/utils.py	Adjusted header prefix to include MSB byte for v3+
tests/integration/.../test_cluster.py	Deleted outdated tests for v1/v2 settings and decorators
tests/integration/init.py	Removed obsolete protocol decorators
docs/api/cassandra/cluster.rst	Removed automethod listings for min/max request APIs
cassandra/protocol.py	Eliminated protocol <2 error checks and branches
cassandra/connection.py	Always use v3 header struct; drop v1/v2 variants
cassandra/pool.py	Removed per-connection request thresholds for v1/v2
cassandra/metadata.py	Dropped keyspace update for legacy protocol versions
cassandra/cqltypes.py	Always use 32-bit length prefixes; removed 16-bit paths
cassandra/cluster.py	Deleted min/max requests methods and fields
cassandra/init.py	Updated SUPPORTED_VERSIONS to drop v1 and v2
benchmarks/callback_full_pipeline.py	Removed conditional concurrency for protocols <3

Comments suppressed due to low confidence (1)

cassandra/pool.py:1016

• [nitpick] By removing the in_flight threshold check before spawning new connections, the pool may create connections too aggressively under load. Consider reintroducing a minimal in-flight requests threshold to prevent unnecessary connections.

            if len(self._connections) < max_conns:

[Copilot]

The SUPPORTED_VERSIONS tuple no longer includes V2 and V1, but get_supported_protocol_versions can still return versions 1 and 2. This mismatch may cause negotiation of unsupported protocols; please align both lists or enforce protocol >=3.

[mykaul]

OK, makes sense.