These functions programmtically process one or more migration operations. The arguments are as follows:

$options

Keyed array of optional options:

itemlimit

Maximum number of items to process

timelimit

Unix timestamp after which to stop processing

idlist

Comma-separated list of source IDs to process, instead of proceeding through all unmigrated rows

feedback

Keyed array controlling status feedback to the caller:

function

PHP function to call, passing a message to be displayed

frequency

How often to call the function

frequency_unit

How to interpret frequency (items or seconds)

$messages

Array of messages to (ultimately) be displayed by the caller.

These functions all return one of the following status code:

MIGRATE_RESULT_COMPLETED

The operation succeeded - all specified items were processed.

MIGRATE_RESULT_INCOMPLETE

The operation has proceeded to the point a resource limit (time or memory) was reached. The caller is expected to resume the operation in a fresh process.

MIGRATE_RESULT_STOPPED

The operation has cleanly terminated upon an external request (e.g., a drush migrate stop command).

MIGRATE_RESULT_FAILED

The operation failed - e.g. the source view for the content set no longer exists.

MIGRATE_RESULT_IN_PROGRESS

There was another process already in progress on this content set, so this one cannot proceed.

migrate_content_process_clear($mcsid, &$options = array())

Clear all previously-migrated items in the specified content set (subject to the provided options).

migrate_content_process_import($mcsid, &$options = array())

Import all unimported content for the specified content set (subject to the provided options).