feat: slowlog injection accepts argument for time

inject_slow_query.rb

@@ -1,4 +1,6 @@
 #!/usr/bin/env ruby
+# WARNING: This will lock up CPU on the target Redis instance. Never run against production.
+#
 # Copyright 2020 Scribd, Inc.
 
 require 'logger'
@@ -12,20 +14,26 @@
   ssl: :true
   )
 
-SCRIPT =<<END
+if ARGV[0].nil?
+  raise "Specify milliseconds to inject as the first positional argument to `#{__FILE__}`"
+else
+  milliseconds = ARGV[0].to_i
+end
+
+SCRIPT =<<HEREDOC
 -- From https://medium.com/@stockholmux/simulating-a-slow-command-with-node-redis-and-lua-efadbf913cd9
 local aTempKey = "a-temp-key"
 local cycles
 redis.call("SET",aTempKey,"1")
-redis.call("PEXPIRE",aTempKey, 100)
-for i = 0, 1500000, 1 do
+redis.call("PEXPIRE",aTempKey, #{milliseconds})
+for i = 0, #{15000 * milliseconds}, 1 do
 	local apttl = redis.call("PTTL",aTempKey)
 	cycles = i;
 	if apttl == 0 then
 		break;
 	end
 end
 return cycles
-END
+HEREDOC
 
 LOGGER.info REDIS.eval(SCRIPT)