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Merge pull request #230 from nolar/no-resumes-repeated
Prevent repeated resumes of a resource by remembering its resumed flag
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,83 @@ | ||
| """ | ||
| A in-memory storage of arbitrary information per resource/object. | ||
| The information is stored strictly in-memory and is not persistent. | ||
| On the operator restart, all the memories are lost. | ||
| It is used internally to track allocated system resources for each Kubernetes | ||
| object, even if that object does not show up in the event streams for long time. | ||
| """ | ||
| import dataclasses | ||
| from typing import MutableMapping | ||
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| from kopf.structs import bodies | ||
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| @dataclasses.dataclass(frozen=False) | ||
| class ResourceMemory: | ||
| """ A memo about a single resource/object. Usually stored in `Memories`. """ | ||
| noticed_by_listing: bool = False | ||
| fully_handled_once: bool = False | ||
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| class ResourceMemories: | ||
| """ | ||
| A container of all memos about every existing resource in a single operator. | ||
| Distinct operator tasks have their own memory containers, which | ||
| do not overlap. This solves the problem if storing the per-resource | ||
| entries in the global or context variables. | ||
| The memos can store anything the resource handlers need to persist within | ||
| a single process/operator lifetime, but not persisted on the resource. | ||
| For example, the runtime system resources: flags, threads, tasks, etc. | ||
| Or the scalar values, which have meaning only for this operator process. | ||
| The container is relatively async-safe: one individual resource is always | ||
| handled sequentially, never in parallel with itself (different resources | ||
| are handled in parallel through), so the same key will not be added/deleted | ||
| in the background during the operation, so the locking is not needed. | ||
| """ | ||
| _items: MutableMapping[str, ResourceMemory] | ||
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| def __init__(self) -> None: | ||
| super().__init__() | ||
| self._items = {} | ||
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| async def recall( | ||
| self, | ||
| body: bodies.Body, | ||
| *, | ||
| noticed_by_listing: bool = False, | ||
| ) -> ResourceMemory: | ||
| """ | ||
| Either find a resource's memory, or create and remember a new one. | ||
| """ | ||
| key = self._build_key(body) | ||
| if key not in self._items: | ||
| memory = ResourceMemory(noticed_by_listing=noticed_by_listing) | ||
| self._items[key] = memory | ||
| return self._items[key] | ||
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| async def forget(self, body: bodies.Body) -> None: | ||
| """ | ||
| Forget the resource's memory if it exists; or ignore if it does not. | ||
| """ | ||
| key = self._build_key(body) | ||
| if key in self._items: | ||
| del self._items[key] | ||
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| def _build_key( | ||
| self, | ||
| body: bodies.Body, | ||
| ) -> str: | ||
| """ | ||
| Construct an immutable persistent key of a resource. | ||
| Generally, a uid is sufficient, as it is unique within the cluster. | ||
| But it can be e.g. plural/namespace/name triplet, or anything else, | ||
| even of different types (as long as it satisfies the type checkers). | ||
| But it must be consistent within a single process lifetime. | ||
| """ | ||
| return body.get('metadata', {}).get('uid') or '' |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,40 @@ | ||
| from kopf.structs.bodies import Body | ||
| from kopf.structs.containers import ResourceMemory, ResourceMemories | ||
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| BODY: Body = { | ||
| 'metadata': { | ||
| 'uid': 'uid1', | ||
| } | ||
| } | ||
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| def test_creation_with_defaults(): | ||
| ResourceMemory() | ||
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| async def test_recalling_creates_when_absent(): | ||
| memories = ResourceMemories() | ||
| memory = await memories.recall(BODY) | ||
| assert isinstance(memory, ResourceMemory) | ||
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| async def test_recalling_reuses_when_present(): | ||
| memories = ResourceMemories() | ||
| memory1 = await memories.recall(BODY) | ||
| memory2 = await memories.recall(BODY) | ||
| assert memory1 is memory2 | ||
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| async def test_forgetting_deletes_when_present(): | ||
| memories = ResourceMemories() | ||
| memory1 = await memories.recall(BODY) | ||
| await memories.forget(BODY) | ||
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| # Check by recalling -- it should be a new one. | ||
| memory2 = await memories.recall(BODY) | ||
| assert memory1 is not memory2 | ||
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| async def test_forgetting_ignores_when_absent(): | ||
| memories = ResourceMemories() | ||
| await memories.forget(BODY) |
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