Configuration API
High-Level API
High-level API for SKA SDP configuration.
- class ska_sdp_config.config.Config(backend=None, global_prefix: str = '', owner: dict = None, component_name: str = None, wrapper: TxnWrapper | None = None, **cargs)[source]
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.
- 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
- 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 txn in config.txn(): # Use txn to read+write configuration # [Possibly call txn.loop()]
As the for loop suggests, the code might get run multiple times even if not forced by calling
Transaction.loop()
. 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 createTransaction
objects just liketxn()
.See also Usage Guide for best practices for using watchers.
- Parameters:
timeout – Timeout for waiting. Watcher will loop after this time.
- class ska_sdp_config.config.Transaction(config: Any, txn: DbTransaction, paths: dict[str, str])[source]
High-level configuration queries and updates to execute atomically.
- create_controller(state: dict) None [source]
Create controller state.
- Parameters:
state – controller state
- create_deployment(dpl: Deployment) None [source]
Request a change to cluster configuration.
- Parameters:
dpl – Deployment to add to database
- create_deployment_state(deploy_id: str, state: dict) None [source]
Create Deployment state.
- Parameters:
deploy_id – Deployment ID
state – Deployment state to create
- create_execution_block(eb_id: str, state: dict) None [source]
Create execution block.
- Parameters:
eb_id – execution block ID
state – execution block state
- create_is_alive(key: str, lease: Lease) str [source]
Create an “is_alive” entry.
- Parameters:
key – “is alive” key in database e.g. “lmc-controller/owner”
lease – to associate with the entry
- Returns:
the full path of the entry
- create_processing_block(pblock: ProcessingBlock) None [source]
Add a new
ProcessingBlock
to the configuration.- Parameters:
pblock – Processing block to create
- create_processing_block_state(pb_id: str, state: dict) None [source]
Create processing block state.
- Parameters:
pb_id – Processing block ID
state – Processing block state to create
- create_script(kind: str, name: str, version: str, script: dict) None [source]
Create processing script definition.
- Parameters:
kind – script kind
name – script name
version – script version
script – script definition
- create_subarray(subarray_id: str, state: dict) None [source]
Create subarray state.
- Parameters:
subarray_id – subarray ID
state – subarray state
- delete_deployment(dpl: Deployment) None [source]
Undo a change to cluster configuration.
- Parameters:
dpl – Deployment to remove
- delete_execution_block(eb_id: str, recurse: bool = True) None [source]
Delete an execution block (eb)
- Parameters:
eb_id – Execution block ID
recurse – if True, run recursive query and delete all objects
- delete_processing_block(pb_id: str, recurse: bool = True) None [source]
Delete a processing block (pb)
- Parameters:
pb_id – Processing block ID
recurse – if True, run recursive query and delete all includes deleting /state and /owner of pb if exists
- delete_script(kind: str, name: str, version: str) None [source]
Delete processing script definition.
- Parameters:
kind – script kind
name – script name
version – script version
- get_deployment(deploy_id: str) Deployment | None [source]
Retrieve details about a cluster configuration change.
- Parameters:
deploy_id – Name of the deployment
- Returns:
Deployment details
- get_deployment_state(deploy_id: str) dict | None [source]
Get the current Deployment state.
- Parameters:
deploy_id – Deployment ID
- Returns:
Deployment state, or None if not present
- get_execution_block(eb_id: str) dict [source]
Get execution block.
- Parameters:
eb_id – execution block ID
- Returns:
execution block state
- get_processing_block(pb_id: str) ProcessingBlock | None [source]
Look up processing block data.
- Parameters:
pb_id – Processing block ID to look up
- Returns:
Processing block entity, or None if it doesn’t exist
- get_processing_block_owner(pb_id: str) dict | None [source]
Look up the current processing block owner.
- Parameters:
pb_id – Processing block ID to look up
- Returns:
Processing block owner data, or None if not claimed
- get_processing_block_state(pb_id: str) dict | None [source]
Get the current processing block state.
- Parameters:
pb_id – Processing block ID
- Returns:
Processing block state, or None if not present
- get_script(kind: str, name: str, version: str) dict | None [source]
Get processing script definition.
- Parameters:
kind – script kind
name – script name
version – script version
- Returns:
script definition
- get_subarray(subarray_id: str) dict | None [source]
Get subarray state.
- Parameters:
subarray_id – subarray ID
- Returns:
subarray state
- is_alive(key: str) bool [source]
Check if the “is alive” key still exists.
- Parameters:
key – “is alive” key in database e.g. “lmc-controller/owner”
- Returns:
True if it does
- is_processing_block_owner(pb_id: str) bool [source]
Check whether this client is owner of the processing block.
- Parameters:
pb_id – Processing block ID to look up
- Returns:
Whether processing block exists and is claimed
- list_deployments(prefix: str = '') list[str] [source]
List all current deployments.
- Returns:
Deployment IDs
- list_execution_blocks(prefix: str = '') list[str] [source]
Query execution block IDs from the configuration.
- Parameters:
prefix – if given, only search for execution block IDs with the given prefix
- Returns:
execution block IDs, in lexicographical order
- list_processing_blocks(prefix: str = '') list[str] [source]
Query processing block IDs from the configuration.
- Parameters:
prefix – If given, only search for processing block IDs with the given prefix
- Returns:
Processing block ids, in lexicographical order
- list_scripts(kind: str = '', name: str = '') list[tuple[str]] [source]
List processing script definitions.
- Parameters:
kind – script kind. Default empty
name – script name. Default empty
- Returns:
list of script definitions
- list_subarrays(prefix: str = '') list[str] [source]
Query subarray IDs from the configuration.
- Parameters:
prefix – if given, only search for subarray IDs with the given prefix
- Returns:
subarray IDs, in lexicographical order
- loop(wait: bool = False, timeout: float | None = None) None [source]
Repeat transaction regardless of whether commit succeeds.
- Parameters:
wait – If transaction succeeded, wait for any read values to change before repeating it.
timeout – Maximum time to wait, in seconds
- 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
- property raw: DbTransaction
Return transaction object for accessing database directly.
- take_processing_block(pb_id: str, lease: Lease) None [source]
Take ownership of the processing block.
- Parameters:
pb_id – Processing block ID to take ownership of
lease – lease
- Raises:
backend.ConfigCollision
- update_controller(state: dict) None [source]
Update controller state.
- Parameters:
state – controller state
- update_deployment_state(deploy_id: str, state: dict) None [source]
Update Deployment state.
- Parameters:
deploy_id – Deployment ID
state – Deployment state to update
- update_execution_block(eb_id: str, state: dict) None [source]
Update execution block.
- Parameters:
eb_id – execution block ID
state – execution block state
- update_processing_block(pblock: ProcessingBlock) None [source]
Update a
ProcessingBlock
in the configuration.- Parameters:
pblock – Processing block to update
- update_processing_block_state(pb_id: str, state: dict) None [source]
Update processing block state.
- Parameters:
pb_id – Processing block ID
state – Processing block state to update
Entities
Processing Block
Processing block configuration entities.
- class ska_sdp_config.entity.pb.ProcessingBlock(pb_id, eb_id, script, parameters=None, dependencies=None, **kwargs)[source]
Processing block entity.
Collects configuration information relating to a processing job for the SDP. This might be either real-time (supporting a running observation) or batch (to process data after the fact).
Actual execution of processing steps will be performed by a (parameterised) processing script interpreting processing block information.
- property dependencies
Return dependencies on other processing blocks.
- property eb_id
Return execution block instance ID, if associated with one.
- property parameters
Return processing script-specific parameters.
- property pb_id
Return the processing block ID.
- property script
Return information identifying the processing script.
Deployment
Deployment configuration entities.
- class ska_sdp_config.entity.deployment.Deployment(dpl_id, kind, args)[source]
Deployment entity.
Collects configuration information relating to a cluster configuration change.
- property args
Return deployment arguments.
- property dpl_id
Return the deployment id.
- property kind
Return deployment kind.
Backends
Common
Common functionality for implementing backends.
- exception ska_sdp_config.backend.common.ConfigCollision(path: str, message: str)[source]
Exception generated if key to create already exists.
Etcd3 backend
Etcd3 backend for SKA SDP configuration DB.
- class ska_sdp_config.backend.etcd3.Etcd3Backend(host='localhost', port='2379', max_retries: int = 15, retry_time: float = 0.1, **kw_args)[source]
Highly consistent database backend store.
See https://github.com/kragniz/python-etcd3
- create(path: str, value: str, lease: etcd3.Lease | None = None) None [source]
Create a key and initialise it with the value.
- Parameters:
path – Path to create
value – Value to set
lease – Lease to associate
- Raises:
ConfigCollision if the key already exists
- delete(path: str, must_exist: bool = True, recursive: bool = False, prefix: bool = False, max_depth: int = 16)[source]
Delete the given key or key range.
- Parameters:
path – path (prefix) of keys to remove
must_exist – Fail if path does not exist?
recursive – Delete children keys at lower levels recursively
max_depth – Recursion limit
prefix – Delete all keys at given level with prefix
- get(path: str, revision: DbRevision | None = None) tuple[str, DbRevision] [source]
Get value of a key.
- Parameters:
path – Path of key to query
revision – to get
- Returns:
value and revision
- lease(ttl: float = 10) Lease [source]
Generate a new lease.
Once entered, it can be associated with keys which will be kept alive until the end of the lease.
Note that this involves starting a daemon thread that will refresh the lease periodically (default seems to be TTL/4).
- Parameters:
ttl – Time to live for lease
- Returns:
lease object
- list_keys(path: str, recurse: int | Iterable[int] = 0, revision: DbRevision | None = None, with_values: bool = False) tuple[list[str], DbRevision] [source]
List keys under given path.
- Parameters:
path – Prefix of keys to query. Append ‘/’ to list child paths.
recurse – Maximum recursion level to query. If iterable, cover exactly the recursion levels specified.
revision – Database revision for which to list
with_values – Also return key values and mod revisions (i.e. sorted list of key-value-rev tuples)
- Returns:
(sorted key list, DbRevision object)
- txn(max_retries: int = 64) Iterable[Etcd3Transaction] [source]
Create a new transaction.
Note that this uses an optimistic STM-style implementation, which cannot guarantee that a transaction runs through successfully. Therefore, this function returns an iterator, which loops until the transaction succeeds:
for txn in etcd3.txn(): # ... transaction steps ...
Note that this will in most cases only execute one iteration. If you actually want to loop - for instance because you intend to wait for something to happen in the configuration - use
watcher()
instead.- Parameters:
max_retries – Maximum number of transaction loops
- Returns:
Transaction iterator
- update(path: str, value: str) None [source]
Update an existing key. Fails if the key does not exist.
- Parameters:
path – Path to update
value – New value of key
- Raises:
ConfigVanished if the key does not exist
- watcher(timeout=None, txn_wrapper: Callable[['Etcd3Transaction'], object] = None, requery_progress: float = 0.2) Iterable[Etcd3Watcher] [source]
Create a new watcher.
Useful for waiting for changes in the configuration. See
Etcd3Watcher
.- Parameters:
timeout – Timeout for waiting. Watcher will loop after this time.
txn_wrapper – Function to wrap transactions returned by the wrapper.
requery_progress – How often we “refresh” the current database state for watcher transactions even without watcher notification (upper bound on how “stale” non-watched values retrieved in transactions can be)
- Returns:
Watcher iterator
- class ska_sdp_config.backend.etcd3.Etcd3Transaction(backend: Etcd3Backend, client: etcd3.client, max_retries: int = 64)[source]
A series of queries and updates to be executed atomically.
- commit() bool [source]
Commit the transaction to the database.
This can fail, in which case the transaction must get reset and built again.
- Returns:
Whether the commit succeeded
- create(path: str, value: str, lease: etcd3.Lease | None = None) None [source]
Create a key and initialise it with the value.
Fails if the key already exists. If a lease is given, the key will automatically get deleted once it expires.
- Parameters:
path – Path to create
value – Value to set
lease – Lease to associate
- Raises:
ConfigCollision if the key already exists
- delete(path: str, must_exist: bool = True, recursive: bool = False, max_depth: int = 16, prefix: bool = False) None [source]
Delete the given key.
- Parameters:
path – Path of key to remove
must_exist – Fail if path does not exist?
recursive – Delete children keys at lower levels recursively (not used yet)
- get(path: str) str | None [source]
Get value of a key.
- Parameters:
path – Path of key to query
- Returns:
Key value. None if it doesn’t exist.
- list_keys(path: str, recurse: int | Iterable[int] = 0) list[str] [source]
List keys under given path.
- Parameters:
path – Prefix of keys to query. Append ‘/’ to list child paths.
recurse – Children depths to include in search
- Returns:
sorted key list
- on_commit(callback: Callable[[], None]) None [source]
Register a callback to call when the transaction succeeds.
Exists mostly to enable test cases.
- Parameters:
callback – Callback to call
- reset(revision: DbRevision | None = None) None [source]
Reset the transaction, so it can be restarted after commit().
- Parameters:
revision – to reset
- Raises:
RuntimeError if the transaction is not committed.
Etcd3 backend revolution 1
Etcd3 backend for SKA SDP configuration DB, using client from https://github.com/Revolution1/etcd3-py
- class ska_sdp_config.backend.etcd3_revolution1.Etcd3BackendRevolution1(*args, max_retries: int = 15, retry_time: float = 0.1, **kw_args)[source]
Highly consistent database backend store.
See https://github.com/etcd-io/etcd
All parameters will be passed on to
etcd3.Client()
.- create(path: str, value: str, lease: etcd3_revolution1.Lease = None) None [source]
Create a key and initialise it with the value.
Fails if the key already exists. If a lease is given, the key will automatically get deleted once it expires.
- Parameters:
path – Path to create
value – Value to set
lease – Lease to associate
- Raises:
ConfigCollision
- delete(path: str, must_exist: bool = True, recursive: bool = False, prefix: bool = False, max_depth: int = 16) None [source]
Delete the given key or key range.
- Parameters:
path – Path (prefix) of keys to remove
must_exist – Fail if path does not exist?
recursive – Delete children keys at lower levels recursively
prefix – Delete all keys at given level with prefix
max_depth – Recursion limit
- Returns:
Whether transaction was successful
- get(path: str, revision: DbRevision | None = None) tuple[str, DbRevision] [source]
Get value of a key.
- Parameters:
path – Path of key to query
revision – Database revision for which to read key
- Returns:
(value, revision). value is None if it doesn’t exist
- lease(ttl: int = 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. Note that this involves starting a daemon thread that will refresh the lease periodically (default seems to be TTL/4).
- Parameters:
ttl – Time to live for lease
- Returns:
lease object
- list_keys(path: str, recurse: int = 0, revision: DbRevision | None = None) tuple[list[str], DbRevision] [source]
List keys under given path.
- Parameters:
path – Prefix of keys to query. Append ‘/’ to list child paths.
recurse – Maximum recursion level to query. If iterable, cover exactly the recursion levels specified.
revision – Database revision for which to list
- Returns:
(sorted key list, revision)
- txn(max_retries: int = 64) Iterable[Etcd3Transaction] [source]
Create a new transaction.
Note that this uses an optimistic STM-style implementation, which cannot guarantee that a transaction runs through successfully. Therefore, this function returns an iterator, which loops until the transaction succeeds:
for txn in etcd3.txn(): # ... transaction steps ...
Note that this will in most cases only execute one iteration. If you actually want to loop - for instance because you intend to wait for something to happen in the configuration - use
watcher()
instead.- Parameters:
max_retries – Maximum number of transaction loops
- Returns:
Transaction iterator
- update(path: str, value: str, must_be_rev: DbRevision | None = None) None [source]
Update an existing key. Fails if the key does not exist.
- Parameters:
path – Path to update
value – Value to set
must_be_rev – Fail if found value does not match given revision (atomic update)
- Raises:
ConfigVanished
- watch(path: str, prefix: bool = False, revision: DbRevision | None = None, depth: int | None = None)[source]
Watch key or key range.
Use a path ending with ‘/’ in combination with prefix to watch all child keys.
- Parameters:
path – Path of key to query, or prefix of keys.
prefix – Watch for keys with given prefix if set
revision – Database revision from which to watch
depth – tag depth
- Returns:
Etcd3Watch object for watch request
- watcher(timeout: float = None, txn_wrapper: TxnWrapper = None) Iterable[Etcd3Watcher] [source]
Create a new watcher.
Useful for waiting for changes in the configuration. See
Etcd3Watcher
.- Parameters:
timeout – Timeout for waiting. Watcher will loop after this time.
txn_wrapper – Function to wrap transactions returned by the wrapper.
- Returns:
Watcher iterator
- class ska_sdp_config.backend.etcd3_revolution1.Etcd3Transaction(backend: Etcd3BackendRevolution1, client: etcd3_revolution1.Client, max_retries: int = 64)[source]
A series of queries and updates to be executed atomically.
Use
Etcd3Backend.txn()
orEtcd3Watcher.txn()
to construct transactions.- clear_watch() None
Stop all currently active watchers.
Deprecated: Use
Etcd3Watcher
instead.
- commit() bool [source]
Commit the transaction to the database.
This can fail, in which case the transaction must get reset and built again.
- Returns:
Whether the commit succeeded
- create(path: str, value: str, lease: etcd3_revolution1.Lease = None) None [source]
Create a key and initialise it with the value.
Fails if the key already exists. If a lease is given, the key will automatically get deleted once it expires.
- Parameters:
path – Path to create
value – Value to set
lease – Lease to associate
- Raises:
ConfigCollision
- delete(path: str, must_exist: bool = True, recursive: bool = False) None [source]
Delete the given key.
- Parameters:
path – Path of key to remove
must_exist – Fail if path does not exist?
recursive – Delete children keys at lower levels recursively (not used)
- get(path: str) str [source]
Get value of a key.
- Parameters:
path – Path of key to query
- Returns:
Key value. None if it doesn’t exist.
- list_keys(path: str, recurse: int = 0) list[str] [source]
List keys under given path.
- Parameters:
path – Prefix of keys to query. Append ‘/’ to list child paths.
recurse – Children depths to include in search
- Returns:
sorted key list
- loop(watch: bool = False, watch_timeout: float | None = None)
Repeat transaction execution, even if it succeeds.
Deprecated: Use
Etcd3Watcher
instead, or loop manually.- Parameters:
watch – Once the transaction succeeds, block until one of the values read changes, then loop the transaction
watch_timeout – timeout value
- on_commit(callback: Callable[[], None]) None [source]
Register a callback to call when the transaction succeeds.
A bit of a hack, but occassionally useful to add additional side-effects to a transaction that are guaranteed to not get duplicated.
- Parameters:
callback – Callback to call
- reset(revision: DbRevision | None = None) None [source]
Reset the transaction, so it can be restarted after commit().
- property revision: int
The last-committed database revision.
Only valid to call after the transaction has been comitted.
- trigger_loop() None [source]
Manually triggers a loop
Effectively makes loop(True) behave like loop(False), looping immediately. This is useful for interrupting a blocking watch() from a different thread.
- update(path: str, value: str) None [source]
Update an existing key. Fails if the key does not exist.
- Parameters:
path – Path to update
value – Value to set
- Raises:
ConfigVanished
- watch() None [source]
Wait for a change on one of the values read.
Deprecated: Use
Etcd3Watcher
instead.- Returns:
The revision at which a change was detected.
- class ska_sdp_config.backend.etcd3_revolution1.Etcd3Watch(backend: Etcd3BackendRevolution1, tagged_path: str, start_revision: int, prefix: bool, max_retries: int = 20, retry_time: float = 0.1)[source]
Wrapper for etc3 watch requests.
Entering the watcher using a with block yields a queue of (key, val, rev) triples.
- class ska_sdp_config.backend.etcd3_revolution1.Etcd3Watcher(backend: Etcd3BackendRevolution1, client: etcd3_revolution1.Client, timeout: float = None, txn_wrapper: TxnWrapper = None)[source]
Watch for database changes by using nested transactions
Use as follows:
for watcher in config.watcher(): for txn in watcher.txn(): # ... do something for txn in watcher.txn(): # ... do something else
At the end of a for loop iteration, the watcher will start watching all values read by transactions started through
txn()
, and only repeat the execution of the loop body once one of these values has changed.- trigger() None [source]
Manually triggers a loop
Can be called from a different thread to force a loop, even if the watcher is currently waiting.
- txn(max_retries: int = 64) Iterable[Etcd3Transaction | TxnWrapper] [source]
Create nested transaction.
The watcher loop will iterate when any value read by transactions created by this method have changed in the database.
Note that these transactions otherwise behave exactly as normal transactions: As long as they are internally consistent, they will be commited. This means there is no consistency guarantees between transactions created from the same watcher, i.e. one transaction might read one value from the database while a later one reads another.
- Parameters:
max_retries – Maximum number of times the transaction will be tried before giving up.
Etcd3 watcher
Memory backend
Memory backend for SKA SDP configuration DB.
The main purpose of this is for use in testing. In principle, it should behave in the same way as the etcd backend. No attempt has been made to make it thread-safe, so it probably isn’t.
- class ska_sdp_config.backend.memory.MemoryBackend[source]
In-memory backend implementation, principally for testing.
- create(path: str, value: str, lease: Lease | None = None) None [source]
Create a key and initialise it with the value.
- Parameters:
path – Path to create
value – Value to set
lease – Lease to associate
- Raises:
ConfigCollision if the key already exists
- delete(path: str, must_exist: bool = True, recursive: bool = False, prefix: bool = False, max_depth: int = 16) None [source]
Delete the given key or key range.
- Parameters:
path – path (prefix) of keys to remove
must_exist – Fail if path does not exist?
recursive – Delete children keys at lower levels recursively
max_depth – Recursion limit
prefix – Delete all keys at given level with prefix
- get(path: str, revision: DbRevision | None = None) tuple[str, DbRevision] [source]
Get value of a key.
- Parameters:
path – Path of key to query
revision – to get
- Returns:
value and revision
- lease(ttl: float = 10) Lease [source]
Generate a dummy lease object.
- Parameters:
ttl – time to live
- Returns:
dummy lease object
- list_keys(path: str, recurse: int = 0) list[str] [source]
Get a list of the keys at the given path.
In common with the etcd backend, the structure is “flat” rather than a real hierarchy, even though it looks like one.
- Parameters:
path – prefix of keys to query
recurse – maximum recursion level to query
- Returns:
list of keys
- txn(max_retries: int = 64) Iterable[MemoryTransaction] [source]
Create an in-memory “transaction”.
- Parameters:
max_retries – Maximum number of transaction loops
- Returns:
transaction object
- class ska_sdp_config.backend.memory.MemoryTransaction(backend: Backend)[source]
Transaction wrapper around the backend implementation.
Transactions always succeed if they are valid, so there is no need to loop; however the iterator is supported for compatibility with the etcd backend.
- create(path: str, value: str, lease: Lease | None = None) None [source]
Create a key and initialise it with the value.
Fails if the key already exists. If a lease is given, the key will automatically get deleted once it expires.
- Parameters:
path – Path to create
value – Value to set
lease – Lease to associate
- Raises:
ConfigCollision if the key already exists
- delete(path: str, must_exist: bool = True, recursive: bool = False)[source]
Delete the given key.
- Parameters:
path – Path of key to remove
must_exist – Fail if path does not exist?
recursive – Delete children keys at lower levels recursively (not used yet)
- get(path: str) str [source]
Get value of a key.
- Parameters:
path – Path of key to query
- Returns:
Key value or None if it doesn’t exist.
- class ska_sdp_config.backend.memory.MemoryWatcher(backend: Backend, timeout: float | None = None, txn_wrapper: TxnWrapper = None)[source]
Watcher wrapper around the backend implementation (Etcd3Watcher).
- txn() Iterable[MemoryTransaction] [source]
Yield the wrapped MemoryTransaction object.
It does not implement the commit check that is part of Etcd3Watcher.txn(), hence it acts as MemoryBackend.txn()