Class: Raptor::Stats

Inherits:
Object
  • Object
show all
Defined in:
lib/raptor/stats.rb

Overview

Shared memory store for per-worker process statistics.

Stats uses an anonymous mmap (MAP_ANON | MAP_SHARED) created before forking so that worker processes can write their stats and the master process can read them without any pipes or signals. Each worker is assigned a fixed-size slot in the shared region.

Binary layout per slot (native byte order):

pid           uint32    4 bytes
requests      uint64    8 bytes
backlog       uint32    4 bytes
started_at    float64   8 bytes
last_checkin  float64   8 bytes
booted        uint8     1 byte
                       33 bytes total

Constant Summary collapse

SLOT_FORMAT = 
"LQLddC"
SLOT_SIZE = 
[0, 0, 0, 0.0, 0.0, 0].pack(SLOT_FORMAT).bytesize

Instance Method Summary collapse

Constructor Details

#initialize(num_workers) ⇒ void

Creates a new Stats instance backed by anonymous shared memory.

Allocates a MAP_ANON | MAP_SHARED mmap region large enough for num_workers slots. Must be called before forking so that all worker processes share the same backing memory.

Parameters:

  • num_workers (Integer) —

    number of worker slots to allocate



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# File 'lib/raptor/stats.rb', line 40

def initialize(num_workers)
  @num_workers = num_workers
  @mmap = Mmap.new(nil, length: num_workers * SLOT_SIZE, initialize: "\0")
end

Instance Method Details

#all ⇒ Array<Hash>

Returns stats for all worker slots.

Returns:

  • (Array<Hash>) —

    per-worker stat hashes with :pid, :requests, :backlog, :started_at, :last_checkin, and :booted



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# File 'lib/raptor/stats.rb', line 67

def all
  (0...@num_workers).map { |index| read(index) }
end

#unmap ⇒ void

This method returns an undefined value.

Releases the shared memory mapping.



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# File 'lib/raptor/stats.rb', line 76

def unmap
  @mmap.unmap
end

#write(index, pid:, requests:, backlog:, started_at:, last_checkin:, booted:) ⇒ void

This method returns an undefined value.

Writes stats for a worker slot into shared memory.

Parameters:

  • index (Integer) —

    slot index to write into

  • pid (Integer) —

    worker process ID

  • requests (Integer) —

    total requests handled by this worker

  • backlog (Integer) —

    current queue depth

  • started_at (Float) —

    process start time as a Unix timestamp

  • last_checkin (Float) —

    time of last stats write as a Unix timestamp

  • booted (Boolean) —

    whether the worker has finished starting



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# File 'lib/raptor/stats.rb', line 57

def write(index, pid:, requests:, backlog:, started_at:, last_checkin:, booted:)
  data = [pid, requests, backlog, started_at, last_checkin, booted ? 1 : 0].pack(SLOT_FORMAT)
  @mmap.semlock { @mmap[index * SLOT_SIZE, SLOT_SIZE] = data }
end