High-Level API

High-level API for SKA SDP configuration.

Connection to SKA SDP configuration.

property backend: Backend: Get the backend database object.

property client_lease: Lease

Return the lease associated with the client.

It will be kept alive until the client gets closed.

close() → None[source]: Close the client connection.

is_alive() → bool[source]

Is the connection alive in the sense that the keep-alive key exists?

Returns:: whether it is

lease(ttl=10) → Lease[source]

Generate a new lease.

Once entered can be associated with keys, which will be kept alive until the end of the lease. At that point a daemon thread will be started automatically to refresh the lease periodically (default seems to be TTL/4).

Parameters:: ttl – Time to live for lease
Returns:: lease object

property lease_is_lost: bool: Return whether this Config object’s lease has been lost.

revoke_lease() → None[source]: Revokes the lease internally held by this client, if any. Shouldn’t normally be called by users, but is useful for tests.

set_alive() → None[source]: Set the keep-alive key.

txn(max_retries: int = 64) → Iterable[Transaction | TxnWrapper][source]

Create a Transaction for atomic configuration query/change.

As we do not use locks, transactions might have to be repeated in order to guarantee atomicity. Suggested usage is as follows:

for watcher in config.watcher(timeout=0.1):
    for txn in watcher.txn():
        # Use txn to read+write configuration

As the for loop suggests, the code might get run multiple times. Any writes using the transaction will be discarded if the transaction fails, but the application must make sure that the loop body has no other observable side effects.

See also Usage Guide for best practices for using transactions.

Parameters:: max_retries – Number of transaction retries before a RuntimeError gets raised.

watcher(timeout: float | None = None) → Iterable[Watcher][source]

Create a new watcher.

Useful for waiting for changes in the configuration. Calling Etcd3Watcher.txn() on the returned watchers will create Transaction objects just like txn().

See also Usage Guide for best practices for using watchers.

Parameters:: timeout – Timeout for waiting. Watcher will loop after this time.

exception ska_sdp_config.config.LeaseLostError[source]: For when a Config object’s lease has been lost.

class ska_sdp_config.config.Transaction(owner: Owner, owned_entity: tuple[str, str] | None, lease_getter: Callable[[], Lease], txn: DbTransaction, global_prefix: str)[source]

High-level configuration queries and updates to execute atomically.

allocation: AllocationOperations: Operations over allocations

arbitrary: ArbitraryOperations: Operations over arbitrary paths

component: ComponentOperations: Operations over SDP components

deployment: DeploymentOperations: Operations over Deployments

execution_block: ExecutionBlockOperations: Operations over Execution Blocks

flow: FlowOperations: Operations over Flows

new_execution_block_id(generator: str) → str[source]

Generate a new execution block ID that is not yet in use.

Parameters:: generator – Name of the generator
Returns:: execution block ID

new_processing_block_id(generator: str) → str[source]

Generate a new processing block ID that is not yet in use.

Parameters:: generator – Name of the generator
Returns:: Processing block ID

processing_block: ProcessingBlockOperations: Operations over Processing Blocks

property raw: DbTransaction: Return transaction object for accessing database directly.

request: RequestOperations: Operations over requests

resource: ResourceOperations: Operations over resources

script: ScriptOperations: Operations over Scripts

property self: EntityOperations | None: Fast access to entity identified when creating the parent Config

system: SystemOperations: Operations over system config