Sha256: 12294c436681e16b459baf11c1347fc0617b012ba10dec60505e0a4cd0bd7275
Contents?: true
Size: 1.32 KB
Versions: 28
Compression:
Stored size: 1.32 KB
Contents
# frozen_string_literal: true
# Copyright The OpenTelemetry Authors
#
# SPDX-License-Identifier: Apache-2.0
module OpenTelemetry
module Instrumentation
module PG
# A simple LRU cache for the postgres instrumentation.
class LruCache
# Rather than take a dependency on another gem, we implement a very, very basic
# LRU cache here. We can take advantage of the fact that Ruby hashes are ordered
# to always keep the recently-accessed keys at the top.
def initialize(size)
raise ArgumentError, 'Invalid size' if size < 1
@limit = size
@store = {}
end
def [](key)
# We need to check for the key explicitly, because `nil` is a valid hash value.
return unless @store.key?(key)
# Since the cache contains the item, we delete and re-insert into the hash.
# This guarantees that hash keys are ordered by access recency.
value = @store.delete(key)
@store[key] = value
value
end
def []=(key, value)
# We remove the value if it's already present, so that the hash keys remain ordered
# by access recency.
@store.delete(key)
@store[key] = value
@store.shift if @store.length > @limit
end
end
end
end
end
Version data entries
28 entries across 28 versions & 1 rubygems