Increase verbosity of error serialization #9105
Description
Currently, the __serialize error object method only prints the error message omitting all other potentially useful fields. We will change that so that __serialize will call the unpack error object method, which converts an error object to a table, so that the output includes all the payload fields, for example:
tarantool> box.error.new{type = 'MyError', message = 'Error!', foo = 42, bar = "abc"}
---
- trace:
- file: '[string "x = box.error.new{type = ''MyError'', message = ..."]'
line: 1
foo: 42
type: MyError
message: Error!
bar: abc
...The error cause will be unpacked when serialized as well, for example:
tarantool> prev = box.error.new{type = 'MyError', message = 'A', foo = 42}
---
...
tarantool> box.error.new{type = 'MyError', message = 'B', bar = 'abc', prev = prev}
---
- prev:
type: MyError
message: B
foo: 42
trace:
- file: '[string "e = box.error.new{type = ''MyError'', message = ..."]'
line: 1
type: MyError
message: B
bar: abc
trace:
- file: '[string "box.error.new{type = ''MyError'', message = ..."]'
line: 1
...The __tostring method will print the error message followed by a tab space (\t) and all the payload fields serialized as a JSON map, for example:
tarantool> tostring(box.error.new{type = 'MyError', message = 'Something wrong', foo = {1, 2, 3}}
---
- Something wrong {"type":"MyError","file":"...","line":1;"foo":[1,2,3]}
...If an error has a cause it’ll be printed on a separate line preceding the effect, for example:
tarantool> prev = box.error.new{'Error cause'}
---
...
tarantool> box.error.new{'Error effect', prev = prev}
---
- |-
Error cause {"file":"...","line":1}
Error effect {"file":"...","line":1}
...(The output was generated with the yaml_pretty_multiline compatibility option set to “new”.)
Here’s an example how errors will look when logged with the standard Tarantool logger:
local log = require('log')
box.cfg{log = 'tarantool.log'}
local e = box.error.new{
message = 'Error effect',
prev = box.error.new{message = 'Error cause'},
}
log.info(e)
log.info(e.prev)2023-05-16 17:13:40.753 [4065414] main/103/interactive/tarantool I> Error cause {"file":"example.lua","line":7}
Error effect {"file":"...","line":5}
2023-05-16 17:13:40.753 [4065414] main/103/interactive/tarantool I> Error cause {"file":"example.lua","line":7}
Since this change may potentially break existing users, we’ll introduce the new compat module option box_error_serialize_verbose to revert to the old behavior.
Note
The syslog server may mask the new line (\n) character although this behavior may usually be turned off. Still, we probably need to update the built-in Tarantool logger to split multi-line messages if the syslog logger is used.