tests/test-eval-cache.sh

   1 #!/usr/bin/env bash
   2 # nbdkit
   3 # Copyright Red Hat
   4 #
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  17 # used to endorse or promote products derived from this software without
  18 # specific prior written permission.
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  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
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  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 # Check various .cache scenarios using eval
  34
  35 source ./functions.sh
  36 set -e
  37 set -x
  38
  39 requires_plugin eval
  40 requires_nbdsh_uri
  41 requires dd iflag=count_bytes </dev/null
  42
  43 files="eval-cache.witness eval-cache.cache"
  44 rm -f $files
  45 cleanup_fn rm -f $files
  46
  47 # This plugin requests nbdkit to emulate caching with pread. When the witness
  48 # file exists, cache reads; when absent, reads fail if not already cached.
  49 export witness="$PWD/eval-cache.witness"
  50 export cache="$PWD/eval-cache.cache"
  51 export script='
  52 import os
  53 import errno
  54
  55 witness = os.getenv("witness")
  56
  57 def touch(path):
  58     open(path, "a").close()
  59
  60 # Test that uncached read fails
  61 try:
  62     h.pread(1024 * 1024, 0)
  63 except nbd.Error as ex:
  64     assert ex.errnum == errno.EIO
  65
  66 # Cache the entire image; nbdkit should break it into 64M preads
  67 touch(witness)
  68 h.cache(h.get_size(), 0)
  69 os.unlink(witness)
  70
  71 # Now read should succeed
  72 buf = h.pread(64 * 1024 * 1024, 64 * 1024 * 1024)
  73 if hasattr(buf, "is_zero"):
  74     assert buf.is_zero()
  75 '
  76 nbdkit -U - -v eval \
  77     get_size='echo 128M' can_cache='echo emulate' open='touch "$cache"' \
  78     pread='
  79       if test -f "$witness"; then
  80         echo "$3 $4" >> "$cache"
  81       elif ! grep -q "^$3 $4$" "$cache"; then
  82         echo EIO >&2; exit 1
  83       fi
  84       dd if=/dev/zero count=$3 iflag=count_bytes
  85     ' --run 'nbdsh -u "$uri" -c "$script"'
  86
  87 # This plugin provides .cache but not .can_cache; eval should synthesize one.
  88 nbdkit -U - -v eval \
  89     get_size='echo 1M' cache='exit 0' pread='echo EIO >&2; exit 1' \
  90     --run 'nbdsh -u "$uri" -c "assert h.can_cache()" \
  91       -c "h.cache(1024*1024, 0)"'