Logging Transaction

This module provides the transaction logging mechanism.

class AsyncTransaction(name, params={}, transaction_id='', transaction_id_key='transaction_id', logger=None)

class Transaction(name, params={}, transaction_id='', transaction_id_key='transaction_id', logger=None)

class TransactionBase(name, params={}, transaction_id='', transaction_id_key='transaction_id', logger=None)

Transaction context handler.

Provides:

- Transaction ID::

* Re-use existing transaction ID, if available

* If no transaction ID, or empty or None, then generate a new ID

* context handler returns the transaction ID used

- Log messages on entry, exit, and exception

def command(self, parameter_json):
    parameters = json.reads(parameter_json)
    with transaction('My Command', parameters) as transaction_id:
        # ...
        parameters['transaction_id'] = transaction_id
        device.further_command(json.dumps(pars))
        # ...

def command(self, parameter_json):
    parameters = json.reads(parameter_json)
    with transaction('My Command', parameters, transaction_id="123") as transaction_id:
        # ...
        parameters['transaction_id'] = transaction_id
        device.further_command(json.dumps(pars))
        # ...

def command(self, parameter_json):
    parameters = json.reads(parameter_json)
    parameters["txn_id_key"] = 123
    with transaction('My Command', parameters, transaction_id_key="txn_id_key")
        as transaction_id:
        # ...
        parameters['transaction_id'] = transaction_id
        device.further_command(json.dumps(pars))
        # ...

Log message formats:

On Entry:

Transaction[id]: Enter[name] with parameters [arguments] marker[marker]

On Exit:

Transaction[id]: Exit[name] marker[marker]

On exception:

Transaction[id]: Exception[name] marker[marker]

Stacktrace

__init__(name, params={}, transaction_id='', transaction_id_key='transaction_id', logger=None)

Create the transaction context handler.

A new transaction ID is generated if none is passed in via transaction_id or in params.

If there is a transaction ID in params and transaction_id is also passed in then the passed in transaction_id will take precedence.

However, if both transaction IDs provided in params and transaction_id are deemed invalid (not a string or an empty string), then a new transaction ID will be generated.

By default the key transaction_id will be used to get a transaction ID out of params. If a different key is required then transaction_id_key can be specified.

Parameters

• name (str) – A description for the context. This is usually the Tango device command.

• params (dict) – The parameters will be logged and will be used to retrieve the transaction ID if transaction_id is not passed in, defaults to {}

• transaction_id (str) – The transaction ID to be used for the context, defaults to “”

• transaction_id_key (str) – The key to use to get the transaction ID from params, defaults to “transaction_id”

• logger (Optional[logging.Logger], optional) – The logger to use for logging, by default None. If no logger is specified a new one named ska.transaction will be used.

Raises

TransactionParamsError – If the params passed is not valid.

log_entry()

Log the entry message

log_exit(exc_type)

Log the exit message and exception if it occurs

Parameters

exc_type (exception_type) – Exception type

class TransactionIdGenerator

TransactionIdGenerator retrieves a transaction id from skuid. Skuid may fetch the id from the service if the SKUID_URL is set or alternatively generate one.

__init__()

exception TransactionParamsError

Invalid data type for transaction parameters.