84 lines
3.4 KiB
Markdown
84 lines
3.4 KiB
Markdown
# Log Level
|
|
|
|
Welcome to Log Level on Exercism's Elixir Track.
|
|
If you need help running the tests or submitting your code, check out `HELP.md`.
|
|
If you get stuck on the exercise, check out `HINTS.md`, but try and solve it without using those first :)
|
|
|
|
## Introduction
|
|
|
|
## Atoms
|
|
|
|
Elixir's `atom` type represents a fixed constant. An atom's value is simply its own name. This gives us a type-safe way to interact with data. Atoms can be defined as follows:
|
|
|
|
```elixir
|
|
# All atoms are preceded with a ':' then follow with alphanumeric snake-cased characters
|
|
variable = :an_atom
|
|
```
|
|
|
|
_Atoms_ are internally represented by an integer in a lookup table, which are set automatically. It is not possible to change this internal value.
|
|
|
|
## Cond
|
|
|
|
Often, we want to write code that can branch based on a condition. While there are many ways to do this in Elixir, one of the simplest ways is using `cond/1`.
|
|
|
|
At its simplest, `cond` follows the first path that evaluates to `true` with one or more branches:
|
|
|
|
```elixir
|
|
cond do
|
|
x > 10 -> :this_might_be_the_way
|
|
y < 7 -> :or_that_might_be_the_way
|
|
true -> :this_is_the_default_way
|
|
end
|
|
```
|
|
|
|
If no path evaluates to `true`, an error is raised by the runtime.
|
|
|
|
## Instructions
|
|
|
|
You are running a system that consists of a few applications producing many logs. You want to write a small program that will aggregate those logs and give them labels according to their severity level. All applications in your system use the same log codes, but some of the legacy applications don't support all the codes.
|
|
|
|
| Log code | Log label | Supported in legacy apps? |
|
|
|-----------------------| --------- | ------------------------- |
|
|
| 0 | trace | no |
|
|
| 1 | debug | yes |
|
|
| 2 | info | yes |
|
|
| 3 | warning | yes |
|
|
| 4 | error | yes |
|
|
| 5 | fatal | no |
|
|
| other / not supported | unknown | - |
|
|
|
|
## 1. Determine the log label
|
|
|
|
Implement the `LogLevel.to_label/2` function. It should take an integer code and a boolean flag telling you if the log comes from a legacy app, and return the label of a log line as an atom.
|
|
|
|
Log codes not specified in the table should return an _unknown_ label. Log codes specified in the table as not supported in legacy apps should also return an _unknown_ label if the log came from a legacy app.
|
|
|
|
```elixir
|
|
LogLevel.to_label(0, false)
|
|
# => :trace
|
|
|
|
LogLevel.to_label(0, true)
|
|
# => :unknown
|
|
```
|
|
|
|
## 2. Send an alert
|
|
|
|
Somebody has to be notified when unexpected things happen.
|
|
|
|
Implement the `LogLevel.alert_recipient/2` function to determine to whom the alert needs to be sent. The function should take an integer code and a boolean flag telling you if the log comes from a legacy app, and return the name of the recipient as an atom.
|
|
|
|
Use the `LogLevel.to_label/2` function from the previous task. If the log label is _error_ or _fatal_, send the alert to the _ops_ team. If you receive a log with an _unknown_ label from a legacy system, send the alert to the _dev1_ team, other unknown labels should be sent to the _dev2_ team. All other log labels can be safely ignored by returning _false_.
|
|
|
|
```elixir
|
|
LogLevel.alert_recipient(-1, true)
|
|
# => :dev1
|
|
|
|
LogLevel.alert_recipient(0, false)
|
|
# => false
|
|
```
|
|
|
|
## Source
|
|
|
|
### Created by
|
|
|
|
- @neenjaw |