example: add dataset generator

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>

examples/mk-dset.lua

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+--
+-- usage: mk-dset.lua pool prefix objsize, numobjs
+--
+rados = require "rados"
+randstr = require "randstr"
+
+pool_name = arg[1]
+prefix = arg[2]
+obj_size = arg[3]
+num_objs = arg[4]
+
+cluster = rados.create()
+cluster:conf_read_file()
+cluster:connect()
+
+ioctx = cluster:open_ioctx(pool_name)
+
+print("Summary")
+print(" pool:", pool_name)
+print(" prefix:", prefix)
+print(" dataset size:", obj_size * num_objs)
+print(" object size:", obj_size)
+print(" num objects:", num_objs)
+
+first_obj = nil
+obj_data = randstr(obj_size)
+for i=0, num_objs-1 do
+  obj_name = prefix .. ".obj." .. i
+  if i == 0 then first_obj = obj_name end
+  ioctx:write(obj_name, obj_data, #obj_data, 0)
+  if i % 10 == 0 then
+    print("finished writing object: " .. obj_name)
+  end
+end

examples/randstr.lua

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+--
+-- From the Lua wiki
+-- http://lua-users.org/wiki/RandomStrings
+--
+local Chars = {}
+for Loop = 0, 255 do
+  Chars[Loop+1] = string.char(Loop)
+end
+local String = table.concat(Chars)
+
+local Built = {['.'] = Chars}
+
+local AddLookup = function(CharSet)
+  local Substitute = string.gsub(String, '[^'..CharSet..']', '')
+  local Lookup = {}
+  for Loop = 1, string.len(Substitute) do
+    Lookup[Loop] = string.sub(Substitute, Loop, Loop)
+  end
+  Built[CharSet] = Lookup
+
+  return Lookup
+end
+
+function string.random(Length, CharSet)
+  -- Length (number)
+  -- CharSet (string, optional); e.g. %l%d for lower case letters and digits
+
+  local CharSet = CharSet or '.'
+
+  if CharSet == '' then
+    return ''
+  else
+    local Result = {}
+    local Lookup = Built[CharSet] or AddLookup(CharSet)
+    local Range = table.getn(Lookup)
+
+    for Loop = 1,Length do
+      Result[Loop] = Lookup[math.random(1, Range)]
+    end
+
+    return table.concat(Result)
+  end
+end
+
+return string.random