CDRIVER-4629 Remove code requiring maxWireVersion less than WIRE_VERSION_OP_MSG

[eramongodb]

Description

Resolves CDRIVER-4629. Verified by this patch.

Removes code that is conditioned on the reported maxWireVersion being less than WIRE_VERSION_OP_MSG (6), which is also the current value of WIRE_VERSION_MIN (6), meaning we do not support conducting operations on such servers anymore since CDRIVER-4098 (#926, released in 1.21.0). In short, this PR removes obsolete code that is no longer being executed.

Obsolete WIRE_VERSION_* Macros

This PR's primary set of changes involve removal of code referencing WIRE_VERSION_* macros with values less than or equal to WIRE_VERSION_MIN.

For (almost) all such code, wire_version > WIRE_VERSION_OBSOLETE is assumed to be always true. Similarly, wire_version <= WIRE_VERSION_OBSOLETE is assumed to be always false. Using these assumptions, code transformations are applied to remove subsequently redundant or obsolete code. Changes include:

• removal of if/else branches.
• removal of wire_version parameters no longer needed by helper functions.
• removal of the mongoc-write-command-legacy component.

The only notable exception to the patterns above is in mongoc_cluster_run_command_private:

if (mongoc_cluster_uses_server_api (cluster) ||
      server_stream->sd->max_wire_version >= WIRE_VERSION_OP_MSG) {
   retval = mongoc_cluster_run_opmsg (cluster, cmd, reply, error);
} else {
   retval =
      mongoc_cluster_run_command_opquery (cluster, cmd, -1, reply, error);
}

server_stream->sd->max_wire_version >= WIRE_VERSION_OP_MSG cannot be assumed to be always true, as mongoc_cluster_run_command_private is sometimes used to run the initial connection handshake with a stream whose maxWireVersion has not yet been set (defaults to 0). The comparison was updated to use WIRE_VERSION_MIN instead to account for this behavior. All other comparisons with server_stream->sd->max_wire_version used a post-initial-connection-handshake stream that has an updated maxWireVersion (verified by this patch which temporarily inserts assertions in place of all the modified "always true/false" code paths).

Test Suite

Some tests had to be updated to account for the changes described above.

/max_staleness

CDRIVER-4152 and CDRIVER-4204 synced new and modified test files into src/libmongoc/tests/json/max_staleness, but did not remove deleted test files. Some of these files were triggering test failures after updates due to assumptions that no longer apply.

/retryable_writes/failover

The mock server "not primary" reply was missing the RetryableWriteError error label required by retryWrites since server 4.4.

/inheritance/aggregate

A workaround concerning readPreference with secondaries to account for CDRIVER-4224 is no longer applicable on server 5.0+ thanks to CDRIVER-3893. Bumped the mock server version to WIRE_VERSION_MAX for consistency and removed the workaround.

test_framework_skip_if_.*_6

References to WIRE_VERSION_CHECKS (6) functions were removed from the test suite as the corresponding conditions are now always true (3.6+) or always false. Use of test_framework_skip_if_not_rs_version_6 were replaced with test_framework_skip_if_not_replset to preserve the replica set condition.

[vector-of-bool]

So much code deleted ❤️.

Looks great to me!

[kevinAlbs]

Fantastic, LGTM

[kevinAlbs]

Suggested change

	test_retryable_writes_cb,
	test_retryable_writes_cb,
	TestSuite_CheckLive,

To skip test when environment variable MONGOC_TEST_SKIP_LIVE=ON is set.