109 lines
4.0 KiB
Python
109 lines
4.0 KiB
Python
import json
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from typing import List
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from redis import Redis
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class ResourceManager:
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def __init__(self, host: str, port: int,
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lease_ttl: int, heartbeat_ttl: int, pod_id: str) -> None:
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self.redis = Redis(host=host, port=port, decode_responses=True)
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self.lease_ttl = lease_ttl
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self.heartbeat_ttl = heartbeat_ttl
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self.pod_id = pod_id
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def get(self, key: str) -> dict:
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"""
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Retrieve a value from Redis by its key and return it as a dictionary.
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Args:
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key (str): The key to look up in Redis.
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Returns:
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dict: The value associated with the key, parsed as a dictionary,
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or None if the key does not exist or the value is empty.
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"""
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history = self.redis.get(key)
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return json.loads(history) if history else None
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def get_tag_slot(self, id: str) -> dict:
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"""
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Retrieve the tag slot information for a given ID.
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Args:
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id (str): The unique identifier of the tag slot to retrieve.
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Returns:
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dict: A dictionary containing the tag slot information associated with the given ID.
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"""
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return self.get(f"slot:opc_tags:{id}")
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def ingestor_heartbeat(self) -> None:
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"""
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Sends a heartbeat signal to Redis to indicate that the ingestor is active.
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This method sets a key in Redis with a specific format that includes the
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ingestor's pod ID. The key is set with a value of 1 and an expiration
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time defined by `self.heartbeat_ttl`. This allows monitoring systems to
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track the activity and health of the ingestor.
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Returns:
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None
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"""
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self.redis.set(
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f"heartbeat:ingestor:{self.pod_id}", 1, ex=self.heartbeat_ttl)
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def lease_tag(self, tag_id: str) -> bool:
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"""
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Attempts to lease a tag by setting a key in Redis with a specified TTL (time-to-live).
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This method uses the Redis `SET` command with the `NX` option to ensure that the key
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is only set if it does not already exist. The key is set with an expiration time
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defined by `lease_ttl`.
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Args:
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tag_id (str): The unique identifier of the tag to be leased.
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Returns:
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bool: True if the lease was successfully acquired, False otherwise.
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"""
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return self.redis.set(
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f"lease:opc_tags:{tag_id}", self.pod_id, nx=True, ex=self.lease_ttl)
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def renew_tag_lease(self, tag_id: str) -> bool:
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"""
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Renews the lease for a specific OPC tag if the current pod holds the lease.
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This method checks if the current pod (identified by `self.pod_id`) holds the lease
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for the given OPC tag. If so, it extends the lease by resetting its expiration time
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in Redis to the configured lease TTL (`self.lease_ttl`).
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Args:
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tag_id (str): The identifier of the OPC tag whose lease is to be renewed.
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Returns:
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bool: True if the lease was successfully renewed, False otherwise.
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"""
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current = self.redis.get(
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f"lease:opc_tags:{tag_id}")
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if current == self.pod_id:
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self.redis.expire(f"lease:opc_tags:{tag_id}", self.lease_ttl)
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return True
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return False
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def drop_tag_lease(self, tag_id: str) -> None:
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"""
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Drops the lease for a specific OPC tag.
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This method removes the lease for the given OPC tag by deleting the corresponding key in Redis.
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Args:
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tag_id (str): The identifier of the OPC tag whose lease is to be dropped.
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Returns:
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None
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"""
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self.redis.delete(f"lease:opc_tags:{tag_id}")
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def get_all_ingestors(self) -> List[str]:
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"""
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Retrieves all active ingestors from Redis.
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This method fetches all keys in Redis that match the pattern for ingestor leases
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and returns a list of active ingestors.
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Returns:
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list: A list of active ingestors.
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"""
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return self.redis.keys("heartbeat:ingestor:*")
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