50 lines
1.2 KiB
Ruby
50 lines
1.2 KiB
Ruby
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module Gitlab
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module Ci
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# This was inspired from: http://stackoverflow.com/a/10219411/1520132
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class TraceReader
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BUFFER_SIZE = 4096
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attr_accessor :path, :buffer_size
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def initialize(new_path, buffer_size: BUFFER_SIZE)
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self.path = new_path
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self.buffer_size = Integer(buffer_size)
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end
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def read(last_lines: nil)
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if last_lines
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read_last_lines(last_lines)
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else
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File.read(path)
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end
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end
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def read_last_lines(max_lines)
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File.open(path) do |file|
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chunks = []
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pos = lines = 0
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max = file.size
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# We want an extra line to make sure fist line has full contents
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while lines <= max_lines && pos < max
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pos += buffer_size
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buf = if pos <= max
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file.seek(-pos, IO::SEEK_END)
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file.read(buffer_size)
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else # Reached the head, read only left
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file.seek(0)
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file.read(buffer_size - (pos - max))
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end
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lines += buf.count("\n")
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chunks.unshift(buf)
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end
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chunks.join.lines.last(max_lines).join
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end
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end
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end
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end
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end
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