/usr/lib/ruby/vendor_ruby/raindrops/watcher.rb is in ruby-raindrops 0.19.0-1build2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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require "thread"
require "time"
require "socket"
require "rack"
require "aggregate"
# Raindrops::Watcher is a stand-alone Rack application for watching
# any number of TCP and UNIX listeners (all of them by default).
#
# It depends on the {Aggregate RubyGem}[https://rubygems.org/gems/aggregate]
#
# In your Rack config.ru:
#
# run Raindrops::Watcher(options = {})
#
# It takes the following options hash:
#
# - :listeners - an array of listener names, (e.g. %w(0.0.0.0:80 /tmp/sock))
# - :delay - interval between stats updates in seconds (default: 1)
#
# Raindrops::Watcher is compatible any thread-safe/thread-aware Rack
# middleware. It does not work well with multi-process web servers
# but can be used to monitor them. It consumes minimal resources
# with the default :delay.
#
# == HTTP endpoints
#
# === GET /
#
# Returns an HTML summary listing of all listen interfaces watched on
#
# === GET /active/$LISTENER.txt
#
# Returns a plain text summary + histogram with X-* HTTP headers for
# active connections.
#
# e.g.: curl https://raindrops-demo.bogomips.org/active/0.0.0.0%3A80.txt
#
# === GET /active/$LISTENER.html
#
# Returns an HTML summary + histogram with X-* HTTP headers for
# active connections.
#
# e.g.: curl https://raindrops-demo.bogomips.org/active/0.0.0.0%3A80.html
#
# === GET /queued/$LISTENER.txt
#
# Returns a plain text summary + histogram with X-* HTTP headers for
# queued connections.
#
# e.g.: curl https://raindrops-demo.bogomips.org/queued/0.0.0.0%3A80.txt
#
# === GET /queued/$LISTENER.html
#
# Returns an HTML summary + histogram with X-* HTTP headers for
# queued connections.
#
# e.g.: curl https://raindrops-demo.bogomips.org/queued/0.0.0.0%3A80.html
#
# === POST /reset/$LISTENER
#
# Resets the active and queued statistics for the given listener.
#
# === GET /tail/$LISTENER.txt?active_min=1&queued_min=1
#
# Streams chunked a response to the client.
# Interval is the preconfigured +:delay+ of the application (default 1 second)
#
# The response is plain text in the following format:
#
# ISO8601_TIMESTAMP LISTENER_NAME ACTIVE_COUNT QUEUED_COUNT LINEFEED
#
# Query parameters:
#
# - active_min - do not stream a line until this active count is reached
# - queued_min - do not stream a line until this queued count is reached
#
# == Response headers (mostly the same names as Raindrops::LastDataRecv)
#
# - X-Count - number of samples polled
# - X-Last-Reset - date since the last reset
#
# The following headers are only present if X-Count is greater than one.
#
# - X-Min - lowest number of connections recorded
# - X-Max - highest number of connections recorded
# - X-Mean - mean number of connections recorded
# - X-Std-Dev - standard deviation of connection count
# - X-Outliers-Low - number of low outliers (hopefully many for queued)
# - X-Outliers-High - number of high outliers (hopefully zero for queued)
# - X-Current - current number of connections
# - X-First-Peak-At - date of when X-Max was first reached
# - X-Last-Peak-At - date of when X-Max was last reached
#
# = Demo Server
#
# There is a server running this app at https://raindrops-demo.bogomips.org/
# The Raindrops::Middleware demo is also accessible at
# https://raindrops-demo.bogomips.org/_raindrops
#
# The demo server is only limited to 30 users, so be sure not to abuse it
# by using the /tail/ endpoint too much.
class Raindrops::Watcher
# :stopdoc:
attr_reader :snapshot
include Rack::Utils
include Raindrops::Linux
DOC_URL = "https://bogomips.org/raindrops/Raindrops/Watcher.html"
Peak = Struct.new(:first, :last)
def initialize(opts = {})
@tcp_listeners = @unix_listeners = nil
if l = opts[:listeners]
tcp, unix = [], []
Array(l).each { |addr| (addr =~ %r{\A/} ? unix : tcp) << addr }
unless tcp.empty? && unix.empty?
@tcp_listeners = tcp
@unix_listeners = unix
end
end
@agg_class = opts[:agg_class] || Aggregate
@start_time = Time.now.utc
@active = Hash.new { |h,k| h[k] = @agg_class.new }
@queued = Hash.new { |h,k| h[k] = @agg_class.new }
@resets = Hash.new { |h,k| h[k] = @start_time }
@peak_active = Hash.new { |h,k| h[k] = Peak.new(@start_time, @start_time) }
@peak_queued = Hash.new { |h,k| h[k] = Peak.new(@start_time, @start_time) }
@snapshot = [ @start_time, {} ]
@delay = opts[:delay] || 1
@lock = Mutex.new
@start = Mutex.new
@cond = ConditionVariable.new
@thr = nil
end
def hostname
Socket.gethostname
end
# rack endpoint
def call(env)
@start.synchronize { @thr ||= aggregator_thread(env["rack.logger"]) }
case env["REQUEST_METHOD"]
when "GET"
get env
when "HEAD"
r = get(env)
r[2] = []
r
when "POST"
post env
else
Rack::Response.new(["Method Not Allowed"], 405).finish
end
end
def aggregate!(agg_hash, peak_hash, addr, number, now)
agg = agg_hash[addr]
if (max = agg.max) && number > 0 && number >= max
peak = peak_hash[addr]
peak.first = now if number > max
peak.last = now
end
agg << number
end
def aggregator_thread(logger) # :nodoc:
@socket = sock = Raindrops::InetDiagSocket.new
thr = Thread.new do
begin
combined = tcp_listener_stats(@tcp_listeners, sock)
combined.merge!(unix_listener_stats(@unix_listeners)) if @unix_listeners
@lock.synchronize do
now = Time.now.utc
combined.each do |addr,stats|
aggregate!(@active, @peak_active, addr, stats.active, now)
aggregate!(@queued, @peak_queued, addr, stats.queued, now)
end
@snapshot = [ now, combined ]
@cond.broadcast
end
rescue => e
logger.error "#{e.class} #{e.inspect}"
end while sleep(@delay) && @socket
sock.close
end
wait_snapshot
thr
end
def non_existent_stats(time)
[ time, @start_time, @agg_class.new, 0, Peak.new(@start_time, @start_time) ]
end
def active_stats(addr) # :nodoc:
@lock.synchronize do
time, combined = @snapshot
stats = combined[addr] or return non_existent_stats(time)
tmp, peak = @active[addr], @peak_active[addr]
[ time, @resets[addr], tmp.dup, stats.active, peak ]
end
end
def queued_stats(addr) # :nodoc:
@lock.synchronize do
time, combined = @snapshot
stats = combined[addr] or return non_existent_stats(time)
tmp, peak = @queued[addr], @peak_queued[addr]
[ time, @resets[addr], tmp.dup, stats.queued, peak ]
end
end
def wait_snapshot
@lock.synchronize do
@cond.wait @lock
@snapshot
end
end
def std_dev(agg)
agg.std_dev.to_s
rescue Errno::EDOM
"NaN"
end
def agg_to_hash(reset_at, agg, current, peak)
{
"X-Count" => agg.count.to_s,
"X-Min" => agg.min.to_s,
"X-Max" => agg.max.to_s,
"X-Mean" => agg.mean.to_s,
"X-Std-Dev" => std_dev(agg),
"X-Outliers-Low" => agg.outliers_low.to_s,
"X-Outliers-High" => agg.outliers_high.to_s,
"X-Last-Reset" => reset_at.httpdate,
"X-Current" => current.to_s,
"X-First-Peak-At" => peak.first.httpdate,
"X-Last-Peak-At" => peak.last.httpdate,
}
end
def histogram_txt(agg)
updated_at, reset_at, agg, current, peak = *agg
headers = agg_to_hash(reset_at, agg, current, peak)
body = agg.to_s # 7-bit ASCII-clean
headers["Content-Type"] = "text/plain"
headers["Expires"] = (updated_at + @delay).httpdate
headers["Content-Length"] = body.size.to_s
[ 200, headers, [ body ] ]
end
def histogram_html(agg, addr)
updated_at, reset_at, agg, current, peak = *agg
headers = agg_to_hash(reset_at, agg, current, peak)
body = "<html>" \
"<head><title>#{hostname} - #{escape_html addr}</title></head>" \
"<body><table>" <<
headers.map { |k,v|
"<tr><td>#{k.gsub(/^X-/, '')}</td><td>#{v}</td></tr>"
}.join << "</table><pre>#{escape_html agg}</pre>" \
"<form action='../reset/#{escape addr}' method='post'>" \
"<input type='submit' name='x' value='reset' /></form>" \
"</body>"
headers["Content-Type"] = "text/html"
headers["Expires"] = (updated_at + @delay).httpdate
headers["Content-Length"] = body.size.to_s
[ 200, headers, [ body ] ]
end
def get(env)
retried = false
begin
case env["PATH_INFO"]
when "/"
index
when %r{\A/active/(.+)\.txt\z}
histogram_txt(active_stats(unescape($1)))
when %r{\A/active/(.+)\.html\z}
addr = unescape $1
histogram_html(active_stats(addr), addr)
when %r{\A/queued/(.+)\.txt\z}
histogram_txt(queued_stats(unescape($1)))
when %r{\A/queued/(.+)\.html\z}
addr = unescape $1
histogram_html(queued_stats(addr), addr)
when %r{\A/tail/(.+)\.txt\z}
tail(unescape($1), env)
else
not_found
end
rescue Errno::EDOM
raise if retried
retried = true
wait_snapshot
retry
end
end
def not_found
Rack::Response.new(["Not Found"], 404).finish
end
def post(env)
case env["PATH_INFO"]
when %r{\A/reset/(.+)\z}
reset!(env, unescape($1))
else
not_found
end
end
def reset!(env, addr)
@lock.synchronize do
@active.include?(addr) or return not_found
@active.delete addr
@queued.delete addr
@resets[addr] = Time.now.utc
@cond.wait @lock
end
req = Rack::Request.new(env)
res = Rack::Response.new
url = req.referer || "#{req.host_with_port}/"
res.redirect(url)
res["Content-Type"] = "text/plain"
res.write "Redirecting to #{url}"
res.finish
end
def index
updated_at, all = snapshot
headers = {
"Content-Type" => "text/html",
"Last-Modified" => updated_at.httpdate,
"Expires" => (updated_at + @delay).httpdate,
}
body = "<html><head>" \
"<title>#{hostname} - all interfaces</title>" \
"</head><body><h3>Updated at #{updated_at.iso8601}</h3>" \
"<table><tr>" \
"<th>address</th><th>active</th><th>queued</th><th>reset</th>" \
"</tr>" <<
all.sort do |a,b|
a[0] <=> b[0] # sort by addr
end.map do |addr,stats|
e_addr = escape addr
"<tr>" \
"<td><a href='tail/#{e_addr}.txt' " \
"title='"tail" output in real time'" \
">#{escape_html addr}</a></td>" \
"<td><a href='active/#{e_addr}.html' " \
"title='show active connection stats'>#{stats.active}</a></td>" \
"<td><a href='queued/#{e_addr}.html' " \
"title='show queued connection stats'>#{stats.queued}</a></td>" \
"<td><form action='reset/#{e_addr}' method='post'>" \
"<input title='reset statistics' " \
"type='submit' name='x' value='x' /></form></td>" \
"</tr>" \
end.join << "</table>" \
"<p>" \
"This is running the #{self.class}</a> service, see " \
"<a href='#{DOC_URL}'>#{DOC_URL}</a> " \
"for more information and options." \
"</p>" \
"</body></html>"
headers["Content-Length"] = body.size.to_s
[ 200, headers, [ body ] ]
end
def tail(addr, env)
Tailer.new(self, addr, env).finish
end
# This is the response body returned for "/tail/$ADDRESS.txt". This
# must use a multi-threaded Rack server with streaming response support.
# It is an internal class and not expected to be used directly
class Tailer
def initialize(rdmon, addr, env) # :nodoc:
@rdmon = rdmon
@addr = addr
q = Rack::Utils.parse_query env["QUERY_STRING"]
@active_min = q["active_min"].to_i
@queued_min = q["queued_min"].to_i
len = addr.size
len = 35 if len > 35
@fmt = "%20s % #{len}s % 10u % 10u\n"
case env["HTTP_VERSION"]
when "HTTP/1.0", nil
@chunk = false
else
@chunk = true
end
end
def finish
headers = {
"Content-Type" => "text/plain",
"Cache-Control" => "no-transform",
"Expires" => Time.at(0).httpdate,
}
headers["Transfer-Encoding"] = "chunked" if @chunk
[ 200, headers, self ]
end
# called by the Rack server
def each # :nodoc:
begin
time, all = @rdmon.wait_snapshot
stats = all[@addr] or next
stats.queued >= @queued_min or next
stats.active >= @active_min or next
body = sprintf(@fmt, time.iso8601, @addr, stats.active, stats.queued)
body = "#{body.size.to_s(16)}\r\n#{body}\r\n" if @chunk
yield body
end while true
yield "0\r\n\r\n" if @chunk
end
end
# shuts down the background thread, only for tests
def shutdown
@socket = nil
@thr.join if @thr
@thr = nil
end
# :startdoc:
end
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