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|
require 'prometheus/client'
require 'prometheus/client/mmaped_dict'
require 'json'
module Prometheus
module Client
# A float protected by a mutex backed by a per-process mmaped file.
class MmapedValue
VALUE_LOCK = Mutex.new
@@files = {}
@@pid = -1
def initialize(type, metric_name, name, labels, multiprocess_mode = '')
@file_prefix = type.to_s
@metric_name = metric_name
@name = name
@labels = labels
if type == :gauge
@file_prefix += '_' + multiprocess_mode.to_s
end
@pid = -1
@mutex = Mutex.new
initialize_file
end
def increment(amount = 1)
@mutex.synchronize do
initialize_file if pid_changed?
@value += amount
write_value(@key, @value)
@value
end
end
def decrement(amount = 1)
increment(-amount)
end
def set(value)
@mutex.synchronize do
initialize_file if pid_changed?
@value = value
write_value(@key, @value)
@value
end
end
def get
@mutex.synchronize do
initialize_file if pid_changed?
return @value
end
end
def pid_changed?
@pid != Process.pid
end
# method needs to be run in VALUE_LOCK mutex
def unsafe_reinitialize_file(check_pid = true)
unsafe_initialize_file if !check_pid || pid_changed?
end
def self.reset_and_reinitialize
VALUE_LOCK.synchronize do
@@pid = Process.pid
@@files = {}
ObjectSpace.each_object(MmapedValue).each do |v|
v.unsafe_reinitialize_file(false)
end
end
end
def self.reset_on_pid_change
if pid_changed?
@@pid = Process.pid
@@files = {}
end
end
def self.reinitialize_on_pid_change
VALUE_LOCK.synchronize do
reset_on_pid_change
ObjectSpace.each_object(MmapedValue, &:unsafe_reinitialize_file)
end
end
def self.pid_changed?
@@pid != Process.pid
end
def self.multiprocess
true
end
private
def initialize_file
VALUE_LOCK.synchronize do
unsafe_initialize_file
end
end
def unsafe_initialize_file
self.class.reset_on_pid_change
@pid = Process.pid
unless @@files.has_key?(@file_prefix)
unless @file.nil?
@file.close
end
mmaped_file = Helper::MmapedFile.open_exclusive_file(@file_prefix)
@@files[@file_prefix] = MmapedDict.new(mmaped_file)
end
@file = @@files[@file_prefix]
@key = rebuild_key
@value = read_value(@key)
end
def rebuild_key
keys = @labels.keys.sort
values = @labels.values_at(*keys)
[@metric_name, @name, keys, values].to_json
end
def write_value(key, val)
@file.write_value(key, val)
rescue StandardError => e
Prometheus::Client.logger.warn("writing value to #{@file.path} failed with #{e}")
Prometheus::Client.logger.debug(e.backtrace.join("\n"))
end
def read_value(key)
@file.read_value(key)
rescue StandardError => e
Prometheus::Client.logger.warn("reading value from #{@file.path} failed with #{e}")
Prometheus::Client.logger.debug(e.backtrace.join("\n"))
0
end
end
end
end
|
