tests/test-cow-on-read-caches.sh

   1 #!/usr/bin/env bash
   2 # nbdkit
   3 # Copyright Red Hat
   4 #
   5 # Redistribution and use in source and binary forms, with or without
   6 # modification, are permitted provided that the following conditions are
   7 # met:
   8 #
   9 # * Redistributions of source code must retain the above copyright
  10 # notice, this list of conditions and the following disclaimer.
  11 #
  12 # * Redistributions in binary form must reproduce the above copyright
  13 # notice, this list of conditions and the following disclaimer in the
  14 # documentation and/or other materials provided with the distribution.
  15 #
  16 # * Neither the name of Red Hat nor the names of its contributors may be
  17 # used to endorse or promote products derived from this software without
  18 # specific prior written permission.
  19 #
  20 # THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
  21 # ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  22 # THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
  23 # PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
  24 # CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  25 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  26 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  27 # USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  28 # ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  29 # OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  30 # OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31 # SUCH DAMAGE.
  32
  33 source ./functions.sh
  34 set -e
  35 set -x
  36
  37 requires_filter cow
  38 requires_filter delay
  39 requires_nbdsh_uri
  40
  41 # On Windows, calling ftruncate in the cow filter fails with:
  42 # nbdkit: memory[1]: error: ftruncate: File too large
  43 if is_windows; then
  44    echo "$0: the cow filter needs to be fixed to work on Windows"
  45    exit 77
  46 fi
  47
  48 sock=$(mktemp -u /tmp/nbdkit-test-sock.XXXXXX)
  49 files="$sock cow-on-read-caches.pid"
  50 rm -f $files
  51 cleanup_fn rm -f $files
  52
  53 # Run nbdkit with the cow filter, cow-on-read and a read delay.
  54 start_nbdkit -P cow-on-read-caches.pid -U $sock \
  55              --filter=cow --filter=delay \
  56              memory 64K cow-on-read=true rdelay=10
  57
  58 nbdsh --connect "nbd+unix://?socket=$sock" \
  59       -c '
  60 from time import time
  61
  62 # First read should suffer a penalty.  Because we are reading
  63 # a single 64K block (same size as the COW block), we should
  64 # only suffer one penalty of approx. 10 seconds.
  65 st = time()
  66 zb = h.pread(65536, 0)
  67 et = time()
  68 el = et-st
  69 print("elapsed time: %g" % el)
  70 assert et-st >= 10
  71 assert zb == bytearray(65536)
  72
  73 # Second read should not suffer a penalty.
  74 st = time()
  75 zb = h.pread(65536, 0)
  76 et = time()
  77 el = et-st
  78 print("elapsed time: %g" % el)
  79 assert el < 10
  80 assert zb == bytearray(65536)
  81
  82 # Write something.
  83 buf = b"abcd" * 16384
  84 h.pwrite(buf, 0)
  85
  86 # Reading back should be quick since it is stored in the overlay.
  87 st = time()
  88 buf2 = h.pread(65536, 0)
  89 et = time()
  90 el = et-st
  91 print("elapsed time: %g" % el)
  92 assert el < 10
  93 assert buf == buf2
  94 '