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# frozen_string_literal: true
module Aws
# @api private
# a LRU cache caching endpoints data
class EndpointCache
# default cache entries limit
MAX_ENTRIES = 1000
# default max threads pool size
MAX_THREADS = 10
def initialize(options = {})
@max_entries = options[:max_entries] || MAX_ENTRIES
@entries = {} # store endpoints
@max_threads = options[:max_threads] || MAX_THREADS
@pool = {} # store polling threads
@mutex = Mutex.new
@require_identifier = nil # whether endpoint operation support identifier
end
# @return [Integer] Max size limit of cache
attr_reader :max_entries
# @return [Integer] Max count of polling threads
attr_reader :max_threads
# return [Hash] Polling threads pool
attr_reader :pool
# @param [String] key
# @return [Endpoint]
def [](key)
@mutex.synchronize do
# fetching an existing endpoint delete it and then append it
endpoint = @entries[key]
if endpoint
@entries.delete(key)
@entries[key] = endpoint
end
endpoint
end
end
# @param [String] key
# @param [Hash] value
def []=(key, value)
@mutex.synchronize do
# delete the least recent used endpoint when cache is full
unless @entries.size < @max_entries
old_key, = @entries.shift
delete_polling_thread(old_key)
end
# delete old value if exists
@entries.delete(key)
@entries[key] = Endpoint.new(value.to_hash)
end
end
# checking whether an unexpired endpoint key exists in cache
# @param [String] key
# @return [Boolean]
def key?(key)
@mutex.synchronize do
if @entries.key?(key) && (@entries[key].nil? || @entries[key].expired?)
@entries.delete(key)
end
@entries.key?(key)
end
end
# checking whether an polling thread exist for the key
# @param [String] key
# @return [Boolean]
def threads_key?(key)
@pool.key?(key)
end
# remove entry only
# @param [String] key
def delete(key)
@mutex.synchronize do
@entries.delete(key)
end
end
# kill the old polling thread and remove it from pool
# @param [String] key
def delete_polling_thread(key)
Thread.kill(@pool[key]) if threads_key?(key)
@pool.delete(key)
end
# update cache with requests (using service endpoint operation)
# to fetch endpoint list (with identifiers when available)
# @param [String] key
# @param [RequestContext] ctx
def update(key, ctx)
resp = _request_endpoint(ctx)
if resp && resp.endpoints
resp.endpoints.each { |e| self[key] = e }
end
end
# extract the key to be used in the cache from request context
# @param [RequestContext] ctx
# @return [String]
def extract_key(ctx)
parts = []
# fetching from cred provider directly gives warnings
parts << ctx.config.credentials.credentials.access_key_id
if _endpoint_operation_identifier(ctx)
parts << ctx.operation_name
ctx.operation.input.shape.members.inject(parts) do |p, (name, ref)|
p << ctx.params[name] if ref['endpointdiscoveryid']
p
end
end
parts.join('_')
end
# update polling threads pool
# param [String] key
# param [Thread] thread
def update_polling_pool(key, thread)
unless @pool.size < @max_threads
_, thread = @pool.shift
Thread.kill(thread)
end
@pool[key] = thread
end
# kill all polling threads
def stop_polling!
@pool.each { |_, t| Thread.kill(t) }
@pool = {}
end
private
def _request_endpoint(ctx)
params = {}
if _endpoint_operation_identifier(ctx)
# build identifier params when available
params[:operation] = ctx.operation.name
ctx.operation.input.shape.members.inject(params) do |p, (name, ref)|
if ref['endpointdiscoveryid']
p[:identifiers] ||= {}
p[:identifiers][ref.location_name] = ctx.params[name]
end
p
end
end
begin
endpoint_operation_name = ctx.config.api.endpoint_operation
ctx.client.send(endpoint_operation_name, params)
rescue Aws::Errors::ServiceError
nil
end
end
def _endpoint_operation_identifier(ctx)
return @require_identifier unless @require_identifier.nil?
operation_name = ctx.config.api.endpoint_operation
operation = ctx.config.api.operation(operation_name)
@require_identifier = operation.input.shape.members.any?
end
class Endpoint
# default endpoint cache time, 1 minute
CACHE_PERIOD = 1
def initialize(options)
@address = options.fetch(:address)
@cache_period = options[:cache_period_in_minutes] || CACHE_PERIOD
@created_time = Time.now
end
# [String] valid URI address (with path)
attr_reader :address
def expired?
Time.now - @created_time > @cache_period * 60
end
end
end
end
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