1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
|
# frozen_string_literal: true
require 'socket'
require 'timeout'
module Dalli
module Protocol
##
# Manages the buffer for responses from memcached.
# Uses an offset-based approach to avoid string allocations
# when advancing through parsed responses.
##
class ResponseBuffer
# Compact the buffer when the consumed portion exceeds this
# threshold and represents more than half the buffer
COMPACT_THRESHOLD = 4096
def initialize(io_source, response_processor)
@io_source = io_source
@response_processor = response_processor
@buffer = nil
@offset = 0
end
def read
@buffer << @io_source.read_nonblock
end
# Attempts to process a single response from the buffer,
# advancing the offset past the consumed bytes.
def process_single_getk_response
bytes, status, cas, key, value = @response_processor.getk_response_from_buffer(@buffer, @offset)
@offset += bytes
compact_if_needed
[status, cas, key, value]
end
# Resets the internal buffer to an empty state,
# so that we're ready to read pipelined responses
def reset
@buffer = ''.b
@offset = 0
end
# Ensures the buffer is initialized for reading without discarding
# existing data. Used by interleaved pipelined get which may have
# already buffered partial responses during the send phase.
def ensure_ready
return if in_progress?
@buffer = ''.b
@offset = 0
end
# Clear the internal response buffer
def clear
@buffer = nil
@offset = 0
end
def in_progress?
!@buffer.nil?
end
private
# Only compact when we've consumed a significant portion of the buffer.
# This avoids per-response string allocation while preventing unbounded
# memory growth for large pipelines.
def compact_if_needed
return unless @offset > COMPACT_THRESHOLD && @offset > @buffer.bytesize / 2
@buffer = @buffer.byteslice(@offset..)
@offset = 0
end
end
end
end
|
