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Size: 1.65 KB
Versions: 25
Compression:
Stored size: 1.65 KB
Contents
# frozen_string_literal: true
#
# Copyright 2013 whiteleaf. All rights reserved.
#
module Command
class Log < CommandBase
# based on https://qiita.com/ymmtmdk/items/10cf80ec2fc7962ff9fc
class Tail
CHUNK_SIZE = 1024 * 16
attr_accessor :path, :num, :stream_io
def initialize(path, num)
self.path = path
self.num = num
raise unless num.to_i > 0
end
def stream
execute do |file|
loop do
stream_io.print file.read
sleep 0.1
end
end
end
def display
execute do |file|
stream_io.puts file.read
end
end
private
def execute
File.open(path, "r:UTF-8") do |file|
offset = offset_of_nth_chr_from_tail(file, num, "\n")
file.seek(file.size - offset)
yield file
end
end
def reverse_chunks(file, size)
n = file.size / size
n -= 1 if file.size == n * size
len = file.size - n * size
until n < 0
file.seek(n * size)
yield file.read(len)
n -= 1
len = size
end
end
def offset_of_nth_chr_from_tail(file, count, target)
offset = 0
reverse_chunks(file, CHUNK_SIZE) do |chunk|
chunk.size.times do |i|
chr = chunk[chunk.size - i - 1]
next unless chr == target || (offset == 0 && i == 0 && chr != target)
count -= 1
if count < 0
offset += i
return offset
end
end
offset += chunk.size
end
offset
end
end
end
end
Version data entries
25 entries across 25 versions & 1 rubygems