Class: Unicorn::Worker

Inherits:
Object
  • Object
show all
Defined in:
lib/unicorn/worker.rb

Overview

This class and its members can be considered a stable interface and will not change in a backwards-incompatible fashion between releases of unicorn. Knowledge of this class is generally not not needed for most users of unicorn.

Some users may want to access it in the before_fork/after_fork hooks. See the Unicorn::Configurator RDoc for examples.

Constant Summary collapse

PER_DROP =
Raindrops::PAGE_SIZE / Raindrops::SIZE
DROPS =
[]

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(nr, pipe = nil) ⇒ Worker

Returns a new instance of Worker.


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# File 'lib/unicorn/worker.rb', line 20

def initialize(nr, pipe=nil)
  drop_index = nr / PER_DROP
  @raindrop = DROPS[drop_index] ||= Raindrops.new(PER_DROP)
  @offset = nr % PER_DROP
  @raindrop[@offset] = 0
  @nr = nr
  @switched = false
  @to_io, @master = pipe || Unicorn.pipe
end

Instance Attribute Details

#masterObject (readonly)

Returns the value of attribute master.


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# File 'lib/unicorn/worker.rb', line 15

def master
  @master
end

#nrObject

:stopdoc:


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# File 'lib/unicorn/worker.rb', line 13

def nr
  @nr
end

#switchedObject

:stopdoc:


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# File 'lib/unicorn/worker.rb', line 13

def switched
  @switched
end

#to_ioObject (readonly)

IO.select-compatible


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# File 'lib/unicorn/worker.rb', line 14

def to_io
  @to_io
end

Instance Method Details

#==(other_nr) ⇒ Object

worker objects may be compared to just plain Integers


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# File 'lib/unicorn/worker.rb', line 90

def ==(other_nr) # :nodoc:
  @nr == other_nr
end

#atfork_childObject

:nodoc:


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# File 'lib/unicorn/worker.rb', line 30

def atfork_child # :nodoc:
  # we _must_ close in child, parent just holds this open to signal
  @master = @master.close
end

#atfork_parentObject

parent does not read


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# File 'lib/unicorn/worker.rb', line 41

def atfork_parent # :nodoc:
  @to_io = @to_io.close
end

#closeObject

called in both the master (reaping worker) and worker (SIGQUIT handler)


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# File 'lib/unicorn/worker.rb', line 105

def close # :nodoc:
  @master.close if @master
  @to_io.close if @to_io
end

#fake_sig(sig) ⇒ Object

call a signal handler immediately without triggering EINTR We do not use the more obvious Process.kill(sig, $$) here since that signal delivery may be deferred. We want to avoid signal delivery while the Rack app.call is running because some database drivers (e.g. ruby-pg) may cancel pending requests.


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# File 'lib/unicorn/worker.rb', line 50

def fake_sig(sig) # :nodoc:
  old_cb = trap(sig, "IGNORE")
  old_cb.call
ensure
  trap(sig, old_cb)
end

#kgio_tryacceptObject

this only runs when the Rack app.call is not running act like a listener


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# File 'lib/unicorn/worker.rb', line 75

def kgio_tryaccept # :nodoc:
  case buf = @to_io.kgio_tryread(4)
  when String
    # unpack the buffer and trigger the signal handler
    signum = buf.unpack('l')
    fake_sig(signum[0])
    # keep looping, more signals may be queued
  when nil # EOF: master died, but we are at a safe place to exit
    fake_sig(:QUIT)
  when :wait_readable # keep waiting
    return false
  end while true # loop, as multiple signals may be sent
end

#quitObject

master fakes SIGQUIT using this


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# File 'lib/unicorn/worker.rb', line 36

def quit # :nodoc:
  @master = @master.close if @master
end

#soft_kill(sig) ⇒ Object

master sends fake signals to children


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# File 'lib/unicorn/worker.rb', line 58

def soft_kill(sig) # :nodoc:
  case sig
  when Integer
    signum = sig
  else
    signum = Signal.list[sig.to_s] or
        raise ArgumentError, "BUG: bad signal: #{sig.inspect}"
  end
  # writing and reading 4 bytes on a pipe is atomic on all POSIX platforms
  # Do not care in the odd case the buffer is full, here.
  @master.kgio_trywrite([signum].pack('l'))
rescue Errno::EPIPE
  # worker will be reaped soon
end

#tickObject

called in the master process


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# File 'lib/unicorn/worker.rb', line 100

def tick # :nodoc:
  @raindrop[@offset]
end

#tick=(value) ⇒ Object

called in the worker process


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# File 'lib/unicorn/worker.rb', line 95

def tick=(value) # :nodoc:
  @raindrop[@offset] = value
end

#user(user, group = nil, chroot = false) ⇒ Object

In most cases, you should be using the Unicorn::Configurator#user directive instead. This method should only be used if you need fine-grained control of exactly when you want to change permissions in your after_fork or after_worker_ready hooks, or if you want to use the chroot support.

Changes the worker process to the specified user and group, and chroots to the current working directory if chroot is set. This is only intended to be called from within the worker process from the after_fork hook. This should be called in the after_fork hook after any privileged functions need to be run (e.g. to set per-worker CPU affinity, niceness, etc)

group can be specified as a string, or as an array of two strings. If an array of two strings is given, the first string is used as the primary group of the process, and the second is used as the group of the log files.

Any and all errors raised within this method will be propagated directly back to the caller (usually the after_fork hook. These errors commonly include ArgumentError for specifying an invalid user/group and Errno::EPERM for insufficient privileges.

chroot support is only available in unicorn 5.3.0+ user and group switching appeared in unicorn 0.94.0 (2009-11-05)


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# File 'lib/unicorn/worker.rb', line 137

def user(user, group = nil, chroot = false)
  # we do not protect the caller, checking Process.euid == 0 is
  # insufficient because modern systems have fine-grained
  # capabilities.  Let the caller handle any and all errors.
  uid = Etc.getpwnam(user).uid

  if group
    if group.is_a?(Array)
      group, log_group = group
      log_gid = Etc.getgrnam(log_group).gid
    end
    gid = Etc.getgrnam(group).gid
    log_gid ||= gid
  end

  Unicorn::Util.chown_logs(uid, log_gid)
  if gid && Process.egid != gid
    Process.initgroups(user, gid)
    Process::GID.change_privilege(gid)
  end
  if chroot
    chroot = Dir.pwd if chroot == true
    Dir.chroot(chroot)
    Dir.chdir('/')
  end
  Process.euid != uid and Process::UID.change_privilege(uid)
  @switched = true
end