Svc::PolyDb Component

1. Introduction

The Svc::PolyDb component is meant to act as a resident database of values that components can use for checking or for data in algorithms.

2. Requirements

The requirements for Svc::PolyDb are as follows:

Requirement	Description	Verification Method
PDB-001	The `Svc::PolyDb` component shall store `Fw::PolyType` values.	Inspection, Unit Test
PDB-002	The `Svc::PolyDb` component shall allow the `Fw::PolyType` values to be read and written.	Unit Test
PDB-003	The `Svc::PolyDb` component shall time tag the data	Unit Test
PDB-004	The `Svc::PolyDb` component shall report the measurement state of the data (good, stale, failure)	Unit Test

3. Design

3.1 Context

3.1.1 Component Diagram

The Svc::PolyDb component has the following component diagram:

3.1.2 Ports

The Svc::PolyDb component uses the following port types:

Port Data Type	Name	Direction	Kind	Usage
`Svc::Poly`	getValue	Input	Guarded	Write `Fw::PolyType` values
`Svc::Poly`	setValue	Input	Guarded	Write `Fw::PolyType` values

3.2 Functional Description

Fw::PolyType is different from binary telemetry in that it is not in a serialized form, but is stored as the native type. The component stores a table of `Fw::PolyType' objects which are read and written by a table index enumeration. The table is protected by a mutex to prevent simultaneous access.

Users can customize the index name by modifying the config/PolyDbCfg.fpp file in their own configuration directory.

Note that users should understand how the Fw::PolyType works to avoid asserts when reading a different type than was written. To avoid asserts, user code can verify the expected type matches by calling the correct isXX() function before trying to read the value out. The PolyDb will not assert on the read or write of a Fw::PolyType if there is a type mismatch. This only happens when trying to read out the value stored in the Fw::PolyType.

3.3 Scenarios

3.3.1 Read and Write Values

The following diagram shows how components can share a value by having one component write the value, and the other read it:

3.4 State

Svc::PolyDb has no state machines.

3.5 Algorithms

Svc::PolyDb has no significant algorithms.

4. Dictionaries

No dictionaries

4. Module Checklists

Checklist
Design
Code
Unit Test

5. Unit Testing

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

6. Change Log

Date	Description
6/19/2015	Design review edits
7/22/2015	Design review actions
9/15.2015	Unit Test actions