Graham McIntire
efaf5558ff
Phase 1: Foundation Types (100% complete)
- query_helpers: SQL LIKE sanitization with pipe operators
- numeric: Integer parsing with pattern matching guards
- result: Pure Elixir Result monad (map, and_then, unwrap_or)
Phase 2: Ecto Domain Types (100% complete)
- ip_address: IPv4/IPv6 validation using :inet directly
- mac_address: Multi-format MAC parsing (colon/hyphen/dot/compact)
- snmp_oid: OID parsing/manipulation with recursive pattern matching
All 198 tests passing across converted modules.
API changed from Gleam-style {:some/:none to idiomatic {:ok/:error.
Refactored parse_numeric_oid to use with statement, reducing nesting depth.
Reviewed-on: graham/towerops-web#196
30 lines
997 B
Elixir
30 lines
997 B
Elixir
defmodule Towerops.Workers.PollingOffset do
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@moduledoc """
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Calculates deterministic polling offsets to distribute load across time.
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Uses erlang's phash2 to generate stable offsets from device IDs,
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ensuring each device polls at a different time within the interval.
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This prevents the "thundering herd" problem.
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"""
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@doc """
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Calculates a deterministic offset for polling based on device ID.
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Returns an integer in the range [0, interval_seconds).
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## Examples
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iex> offset = PollingOffset.calculate_offset("device-123", 300)
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iex> offset >= 0 and offset < 300
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true
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iex> offset1 = PollingOffset.calculate_offset("same-id", 60)
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iex> offset2 = PollingOffset.calculate_offset("same-id", 60)
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iex> offset1 == offset2
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true
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"""
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@spec calculate_offset(term(), pos_integer()) :: non_neg_integer()
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def calculate_offset(device_id, interval_seconds) when interval_seconds > 0 do
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rem(:erlang.phash2(device_id), interval_seconds)
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end
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end
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