Commit 200a492a authored 5 years ago by Kirill Shcherbatov Committed by Konstantin Osipov 5 years ago

box: introduce Lua persistent functions

Closes #4182
Closes #4219
Needed for #1260

@TarantoolBot document
Title: Persistent Lua functions

Now Tarantool supports 'persistent' Lua functions.
Such functions are stored in snapshot and are available after
restart.
To create a persistent Lua function, specify a function body
in box.schema.func.create call:
e.g. body = "function(a, b) return a + b end"

A Lua persistent function may be 'sandboxed'. The 'sandboxed'
function is executed in isolated environment:
  a. only limited set of Lua functions and modules are available:
    -assert -error -pairs -ipairs -next -pcall -xpcall -type
    -print -select -string -tonumber -tostring -unpack -math -utf8;
  b. global variables are forbidden

Finally, the new 'is_deterministic' flag allows to mark a
registered function as deterministic, i.e. the function that
can produce only one result for a given list of parameters.

The new box.schema.func.create interface is:
box.schema.func.create('funcname', <setuid = true|FALSE>,
	<if_not_exists = true|FALSE>, <language = LUA|c>,
	<body = string ('')>, <is_deterministic = true|FALSE>,
	<is_sandboxed = true|FALSE>, <comment = string ('')>)

This schema change is also reserves names for sql builtin
functions:
    TRIM, TYPEOF, PRINTF, UNICODE, CHAR, HEX, VERSION,
    QUOTE, REPLACE, SUBSTR, GROUP_CONCAT, JULIANDAY, DATE,
    TIME, DATETIME, STRFTIME, CURRENT_TIME, CURRENT_TIMESTAMP,
    CURRENT_DATE, LENGTH, POSITION, ROUND, UPPER, LOWER,
    IFNULL, RANDOM, CEIL, CEILING, CHARACTER_LENGTH,
    CHAR_LENGTH, FLOOR, MOD, OCTET_LENGTH, ROW_COUNT, COUNT,
    LIKE, ABS, EXP, LN, POWER, SQRT, SUM, TOTAL, AVG,
    RANDOMBLOB, NULLIF, ZEROBLOB, MIN, MAX, COALESCE, EVERY,
    EXISTS, EXTRACT, SOME, GREATER, LESSER, SOUNDEX,
    LIKELIHOOD, LIKELY, UNLIKELY,
    _sql_stat_get, _sql_stat_push, _sql_stat_init, LUA

A new Lua persistent function LUA is introduced to evaluate
LUA strings from SQL in future.

This names could not be used for user-defined functions.

Example:
lua_code = [[function(a, b) return a + b end]]
box.schema.func.create('summarize', {body = lua_code,
		is_deterministic = true, is_sandboxed = true})
box.func.summarize
---
- aggregate: none
  returns: any
  exports:
    lua: true
    sql: false
  id: 60
  is_sandboxed: true
  setuid: false
  is_deterministic: true
  body: function(a, b) return a + b end
  name: summarize
  language: LUA
...
box.func.summarize:call({1, 3})
---
- 4
...

@kostja: fix style, remove unnecessary module dependencies,
add comments

parent 77051a11

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