`class Darwin`

Darwin (macOS) implementation of host memory metrics. Uses sysctl (hw.memsize), vm_stat (free + inactive pages), and vm.swapusage for swap.

Definitions

`def self.parse_swap_size(size_string)`

Parse a size string from vm.swapusage (e.g. "1024.00M", "512.00K") into bytes.

Signature

parameter　size_string　String | Nil: The size string from sysctl vm.swapusage.
returns　Integer | Nil: Size in bytes, or nil if size_string is nil/empty.

Implementation

def self.parse_swap_size(size_string)
	return nil unless size_string
	
	size_string = size_string.strip
	
	case size_string
	when /([\d.]+)M/i then ($1.to_f * 1024 * 1024).round
	when /([\d.]+)G/i then ($1.to_f * 1024 * 1024 * 1024).round
	when /([\d.]+)K/i then ($1.to_f * 1024).round
	else size_string.to_f.round
	end
end

`def self.capture`

Capture current host memory. Reads total (hw.memsize), free (vm_stat), and swap (vm.swapusage).

Signature

returns　Host::Memory | Nil: A Host::Memory instance, or nil if capture fails.

Implementation

def self.capture
	total = capture_total
	return nil unless total && total.positive?
	
	free = capture_free
	return nil unless free
	
	free = 0 if free.negative?
	used = [total - free, 0].max
	swap_total, swap_used = capture_swap
	
	return Host::Memory.new(total, used, swap_total, swap_used, nil)
end

`def self.capture_total`

Total physical RAM in bytes, from sysctl hw.memsize.

Signature

returns　Integer | Nil

Implementation

def self.capture_total
	IO.popen(["sysctl", "-n", "hw.memsize"], "r", &:read)&.strip&.to_i
end

`def self.capture_free`

Free + inactive (reclaimable) memory in bytes, from vm_stat. Matches Linux MemAvailable semantics.

Signature

returns　Integer | Nil

Implementation

def self.capture_free
	output = IO.popen(["vm_stat"], "r", &:read)
	page_size = output[/page size of (\d+) bytes/, 1]&.to_i
	return nil unless page_size && page_size.positive?
	
	pages_free = output[/Pages free:\s*(\d+)/, 1]&.to_i || 0
	pages_inactive = output[/Pages inactive:\s*(\d+)/, 1]&.to_i || 0
	return (pages_free + pages_inactive) * page_size
end

`def self.capture_swap`

Swap total and used in bytes, from sysctl vm.swapusage (e.g. "total = 64.00M used = 32.00M free = 32.00M").

Signature

returns　Array(Integer | Nil, Integer | Nil): [swap_total_bytes, swap_used_bytes], or [nil, nil] if unavailable.

Implementation

def self.capture_swap
	output = IO.popen(["sysctl", "-n", "vm.swapusage"], "r", &:read)
	return [nil, nil] unless output
	
	total_string = output[/total\s*=\s*([\d.]+\s*[KMG]?)/i, 1]
	used_string = output[/used\s*=\s*([\d.]+\s*[KMG]?)/i, 1]
	swap_total = total_string ? parse_swap_size(total_string) : nil
	swap_used = used_string ? parse_swap_size(used_string) : nil
	
	return swap_total, swap_used
end