Class: OsCtld::Devices::V2::BpfProgramCache

Inherits:
Object
  • Object
show all
Extended by:
Forwardable
Includes:
OsCtl::Lib::Utils::Log, Singleton
Defined in:
lib/osctld/devices/v2/bpf_program_cache.rb

Overview

Manage a list of BPF programs and their links

Program name is a hash of the listed devices, so identical programs are loaded just once and reused. Program links (i.e. attach on a cgroup) are tracked and when a program has no links left, it is destroyed.

Instance Method Summary collapse

Constructor Details

#initialize ⇒ BpfProgramCache

Returns a new instance of BpfProgramCache.



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# File 'lib/osctld/devices/v2/bpf_program_cache.rb', line 22

def initialize
  @mutex = Mutex.new
  @programs = {}
  @links = {}
  @path_cache = {}

  load_programs
end

Instance Method Details

#assets(add) ⇒ Object

Parameters:



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# File 'lib/osctld/devices/v2/bpf_program_cache.rb', line 32

def assets(add)
  sync do
    @programs.each_value do |prog|
      add.file(
        prog.path,
        desc: "BPF program #{prog.name}",
        user: 0,
        group: 0,
        mode: 0o600
      )
    end

    @links.each_value do |cgroup_paths|
      cgroup_paths.each_value do |link|
        add.file(
          link.path,
          desc: "BPF program #{link.prog_name} attached on #{link.cgroup_path}",
          user: 0,
          group: 0,
          mode: 0o600
        )
      end
    end
  end
end

#get_prog_name(devices) ⇒ String

Parameters:

Returns:

  • (String) 


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# File 'lib/osctld/devices/v2/bpf_program_cache.rb', line 138

def get_prog_name(devices)
  data = devices.map(&:to_s).join(';')
  Digest::SHA2.hexdigest(data)[0..10]
end

#load_links(pool_name) ⇒ Object

Detect existing links in BPF FS

Parameters:

  • pool_name (String) 


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# File 'lib/osctld/devices/v2/bpf_program_cache.rb', line 60

def load_links(pool_name)
  sync do
    cnt = 0

    BpfFs.list_links(pool_name).each do |link_name|
      link = Devices::V2::BpfLink.from_name(pool_name, link_name)

      @links[link.prog_name] ||= {}
      @links[link.prog_name][link.cgroup_path] = link

      @path_cache[link.cgroup_path] = link

      cnt += 1
    end

    log(:info, "Loaded #{cnt} links")
  end
end

#load_programs ⇒ Object (protected) 



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# File 'lib/osctld/devices/v2/bpf_program_cache.rb', line 171

def load_programs
  sync do
    BpfFs.list_progs.each do |prog_name|
      @programs[prog_name] = Devices::V2::BpfProgram.new(prog_name, nil)
    end

    log(:info, "Loaded #{@programs.length} programs")
  end
end

#log_type ⇒ Object 



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# File 'lib/osctld/devices/v2/bpf_program_cache.rb', line 165

def log_type
  'bpf-program-cache'
end

#prune_cgroup_links(cgroup_path) ⇒ Object

Remove program links to the specified cgroup

Parameters:

  • cgroup_path (String) 


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# File 'lib/osctld/devices/v2/bpf_program_cache.rb', line 145

def prune_cgroup_links(cgroup_path)
  sync do
    link = @path_cache.delete(cgroup_path)
    return if link.nil?

    prog = @programs[link.prog_name]

    @links[link.prog_name].delete(cgroup_path)
    prog.detach(link)

    if @links[link.prog_name].empty?
      @links.delete(link.prog_name)
      @programs.delete(link.prog_name)
      prog.destroy
    end
  end

  nil
end

#set(pool_name, devices, cgroup_path, prog_name: nil) ⇒ String

Attach program allowing access to the specified devices to a cgroup

The program is attached only if it is not already attached. If ‘prog_name` is given and its link to the cgroup exists, program `prog_name` is replaced with the new program.

Parameters:

  • pool_name (String)
  • devices (Array<Devices::Device>)
  • cgroup_path (String)
  • prog_name (String, nil) (defaults to: nil) —

    previous program name

Returns:

  • (String) —

    program name



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# File 'lib/osctld/devices/v2/bpf_program_cache.rb', line 90

def set(pool_name, devices, cgroup_path, prog_name: nil)
  sync do
    new_prog_name = get_prog_name(devices)

    prog =
      if @programs.has_key?(new_prog_name)
        @programs[new_prog_name]
      else
        @programs[new_prog_name] = Devices::V2::BpfProgram.new(
          new_prog_name,
          devices
        )
      end

    prog.create unless prog.exist?

    link = Devices::V2::BpfLink.new(new_prog_name, pool_name, cgroup_path)

    if prog_name && prog_name != new_prog_name && @links[prog_name] && @links[prog_name][cgroup_path]
      old_link = @links[prog_name].delete(cgroup_path)
    end

    unless prog.attached?(link)
      if old_link
        prog.replace(old_link, link)
      else
        prog.attach(link)
      end

      @links[new_prog_name] ||= {}
      @links[new_prog_name][link.cgroup_path] = link

      @path_cache[link.cgroup_path] = link
    end

    if old_link && @links[prog_name].empty?
      old_prog = @programs.delete(prog_name)
      @links.delete(prog_name)

      old_prog.destroy
    end

    new_prog_name
  end
end

#sync(&block) ⇒ Object (protected) 



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# File 'lib/osctld/devices/v2/bpf_program_cache.rb', line 181

def sync(&block)
  if @mutex.owned?
    block.call
  else
    @mutex.synchronize(&block)
  end
end