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#!/usr/bin/env ruby
# Copyright (C) 2015 all contributors <dtas-all@nongnu.org>
# License: GPLv3 or later (https://www.gnu.org/licenses/gpl-3.0.txt)
#
# Really janky readahead script. Requires dtas-player to be
# running and unlikely to work outside of Linux as it depends on
# the contents of /proc
unless RUBY_PLATFORM =~ /linux/
warn "this relies on Linux /proc and probably does not work well for you"
end
require 'yaml'
require 'io/wait'
require 'dtas/unix_client'
require 'dtas/process'
include DTAS::Process
include DTAS::SpawnFix
trap(:CHLD) { DTAS::Process.reaper {} }
trap(:INT) { exit(0) }
trap(:TERM) { exit(0) }
w = DTAS::UNIXClient.new
w.req_ok('watch')
c = DTAS::UNIXClient.new
@max_ra = 30 * 1024 * 1024
null = DTAS.null
@redir = { err: null, out: null, in: null }.freeze
require 'pp'
if RUBY_VERSION.to_r >= '2.3'.to_r
# Old Rubies did FIONREAD, which breaks on SOCK_SEQPACKET
def wait_read(w, timeout)
w.to_io.wait_readable(timeout)
end
else
def wait_read(w, timeout)
r = IO.select([w], nil, nil, timeout)
r ? r[0] : nil
end
end
def seek_to_cur_pos(cur_pid, fp)
cur_fd = []
fpst = fp.stat
begin
Dir["/proc/#{cur_pid}/fd/*"].each do |l|
path = File.readlink(l)
begin
st = File.stat(path)
if st.dev == fpst.dev && st.ino == fpst.ino
cur_fd << l.split('/')[-1]
end
rescue Errno::ENOENT, Errno::EPERM
end
end
rescue Errno::ENOENT => e # race, process is dead
return false
rescue => e
warn "error reading FDs from for PID:#{cur_pid}: #{e.message}"
end
pos = 0
# get the position of the file of the sox process
cur_fd.each do |fd|
if File.read("/proc/#{cur_pid}/fdinfo/#{fd}") =~ /^pos:\s*(\d+)$/
n = $1.to_i
pos = n if n > pos
end
end
pos
rescue Errno::ENOENT => e # race, process is dead
return false
end
def children_of(ppid)
`ps h -o pid --ppid=#{ppid}`.split(/\s+/s).map(&:to_i)
end
def expand_pid(pid)
to_scan = Array(pid)
pids = []
while pid = to_scan.shift
pid > 0 or next
to_scan.concat(children_of(pid))
pids << pid
end
pids.uniq
end
def do_ra(fp, pos, w)
size = fp.size
len = size - pos
len = @todo_ra if len > @todo_ra
return if len <= 0
path = fp.path
pp({start_ra: File.basename(path),
len: '%.3f' % (len / (1024 * 1024.0)),
pos: pos })
Process.spawn('soxi', path, @redir)
Process.spawn('avprobe', path, @redir)
Process.spawn('ffprobe', path, @redir)
fp.advise(:sequential, pos, len)
Thread.new(fp.dup) { |d| d.advise(:willneed, pos, len); d.close }
at_once = 8192
adj = len
while len > 0
n = len > at_once ? at_once : len
n = IO.copy_stream(fp, DTAS.null, n, pos)
pos += n
len -= n
# stop reading immediately if there's an event
if wait_read(w, 0)
adj = @todo_ra
pos += size
break
end
end
@todo_ra -= adj
(pos + len) >= size ? fp.close : nil
end
def do_open(path)
if path =~ /\.ya?ml\z/
File.open(path) do |fp|
buf = fp.read(4)
case buf
when "---\n"
buf << fp.read(fp.size - 4)
Dir.chdir(File.dirname(path)) do
yml = YAML.load(buf)
x = yml['infile'] and return File.open(File.expand_path(x).freeze)
end
end
end
end
File.open(path)
end
begin
work = {}
cur_pid = nil
@todo_ra = @max_ra
t0 = DTAS.now
fp = nil
cur = YAML.load(c.req('current'))
while @todo_ra > 0 && fp.nil?
if current = cur['current']
track = current['infile'].freeze
work[track] ||= fp = do_open(track)
cur_pid = current['pid']
if fp
pos = expand_pid(cur_pid).map do |pid|
seek_to_cur_pos(pid, fp)
end.compact.max
pos and fp = do_ra(fp, pos, w)
end
else
break
end
# queue has priority, work on it, first
queue = YAML.load(c.req('queue cat'))
while @todo_ra > 0 && track = queue.shift
fp = nil
begin
work[track] ||= fp = do_open(track)
rescue SystemCallError
end
fp = do_ra(fp, 0, w) if fp
end
break if @todo_ra <= 0
# the normal tracklist
ids = c.req('tl tracks').split
ids.shift # ignore count
idx = ids.find_index(c.req('tl current-id'))
repeat = c.req('tl repeat').split[-1]
while @todo_ra > 0 && idx && (cid = ids[idx])
fp = nil
track = c.req("tl get #{cid}").sub!(/\A1 \d+=/, '').freeze
begin
work[track] ||= fp = do_open(track)
rescue SystemCallError
end
fp = do_ra(fp, 0, w) if fp
if @todo_ra > 0 && fp.nil? && ids[idx += 1].nil?
idx = repeat == 'true' ? 0 : nil
end
end
idx or break
cur = YAML.load(c.req('current'))
cur['current'] or break
end
elapsed = DTAS.now - t0
p [:elapsed, elapsed]
timeout = 5 - elapsed
timeout = 0 if timeout < 0
r = wait_read(w, timeout)
p w.res_wait if r
rescue EOFError
abort "dtas-player exited"
rescue => e
warn "#{e.message} #{e.class})"
e.backtrace.each {|l| warn l }
sleep 5
end while true
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