# Svc::ActiveTextLogger Component

## 1. Introduction

The `Svc::ActiveTextLogger` component processes log texts from other components. The logs are written to standard output and optionally to a file.

## 2. Requirements

The requirements for `Svc::ActiveTextLogger` are as follows:

Requirement | Description | Verification Method
----------- | ----------- | -------------------
ISF-ATL-001 | The `Svc::ActiveTextLogger` component shall print received log texts to standard output. | Unit Test; Inspection
ISF-ATL-002 | The `Svc::ActiveTextLogger` component shall write received log texts to an optionally supplied file. | Unit Test
ISF-ATL-003 | The `Svc::ActiveTextLogger` component shall format the passed log text on the calling thread context, and perform all other processing on the component's thread. | Inspection
ISF-ATL-004 | The `Svc::ActiveTextLogger` component shall stop writing to the optional file if it would exceed its max size. | Unit Test
ISF-ATL-005 | The `Svc::ActiveTextLogger` component shall provide a public method to supply the filename to write to and max size. | Unit Test
ISF-ATL-006 | The `Svc::ActiveTextLogger` component shall attempt to create a new file to write to if the supplied one already exists.  It will try up to ten times, by adding an integer suffix to the filename, ie "file","file0","file1"..."file9". After the last possible attempt is failed, the initial file shall be overwritten; ie if "file9" already exists, the "file" shall be truncated and used as a log file. | Unit Test
ISF-ATL-007 | The `Svc::ActiveTextLogger` component shall support per-severity event filtering via a public `setSeverityFilter()` method. | Unit Test
ISF-ATL-008 | The `Svc::ActiveTextLogger` component shall never filter FATAL events regardless of filter configuration. | Unit Test


## 3. Design

### 3.1 Context

#### 3.1.1 Component Diagram

The `Svc::ActiveTextLogger` component has the following component diagram:

> TODO

#### 3.1.2 Ports

The `Svc::ActiveTextLogger` component uses the following port types:

Port Data Type | Name | Direction | Kind | Usage
-------------- | ---- | --------- | ---- | -----
[`Fw::LogText`](../../../Fw/Log/docs/sdd.md) | TextLogger | Input | Synchronous | Logging port

### 3.2 Functional Description

The `Svc::ActiveTextLogger` component provides a text logging function for the software that maintains consistent ordering by writing the logs from a thread.

#### 3.2.1 Severity Filtering

The `Svc::ActiveTextLogger` supports per-severity event filtering via the `setSeverityFilter(Fw::LogSeverity, bool)` method. Each of the six filterable severity levels (WARNING_HI, WARNING_LO, COMMAND, ACTIVITY_HI, ACTIVITY_LO, DIAGNOSTIC) can be independently enabled or disabled. When a severity is disabled, events at that severity level are silently dropped before processing. FATAL events are never filtered regardless of configuration.

Default filter states are configured via constants in `ActiveTextLoggerCfg.hpp`. By default, all severities pass through except DIAGNOSTIC, which is filtered out (`ACTIVE_TEXT_LOGGER_FILTER_DIAGNOSTIC_DEFAULT = false`). This preserves backward compatibility with the prior hardcoded DIAGNOSTIC suppression behavior.

The filtering logic is provided by the shared `Svc::EventSeverityFilter` utility class.

#### 3.2.2 File Writing

Once a valid file and max size is supplied via a public function call, the `Svc::ActiveTextLogger` component writes to that file as well as standard output.  The `Svc::ActiveTextLogger` component will stop writing to the file if it would exceed the maximum size.

If the file supplied already exists, the `Svc::ActiveTextLogger` component will attempt to create a new file up to ten times by appending an integer suffix to end of the file name. After the last possible attempt is failed, the initial file is overwritten.

### 3.3 Scenarios

TODO

### 3.4 State

`Svc::ActiveTextLogger` has no state machines.

### 3.5 Algorithms

`Svc::ActiveTextLogger` has no significant algorithms.

## 4. Dictionaries

## 5. Module Checklists

## 6. Unit Testing

To see unit test coverage run fprime-util check --coverage

## 7. Change Log

Date | Description
---- | -----------
5/11/2017 | Initial SDD