Introduction

The AI Snake Lab codebase has a backend SQLite3 database. The database is used to house the following information:

Table	Description
Games	Holds a game ID and the number of moves.
Frames	State: state, action, reward, …
Highscore Events	Highscores widget and highscores plot widget data.
Average Loss	Loss plot widget data.
Game Score	Game score widget data.

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Games Table

This table represents a single game. The table is used by the ReplayMemory class.

A new row is added at the end of each epoch by the ReplayMemory class.

• Table name: games

Column	Data Type	Description
id	INTEGER	The primary key for the table.
score	INTEGER	The final game score
total_frames	INTEGER	The number of frames or moves in the game

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Frames Table

This table represents a single frame within a single game. This table is used by the ReplayMemory class.

At the end of each epoch, the ReplayMemory loads all of the game frame data for the completed game into this table.

• Table name: frames

Column	Data Type	Description
id	INTEGER	The primary key for the table.
game_id	INTEGER	A foreign key to the id field of the games table.
frame_index	INTEGER	The move number within a game.
state	BLOB	A blob containing the state map.
action	BLOB	A blob containing the action: Move left, right or straight ahead.
reward	INTEGER	The current reward value.
next_state	BLOB	The next state map.
done	INTEGER	0 or 1, indicating if the game is over or not.

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Highscore Events Table

This table holds a highscore event: The epoch, game number and a runtime string that represents when the highscore was achieved. This table is used in the TUI’s highscores widget and in the TUI’s highscores plot widget.

When a new highscore is achieved the SimServer inserts a row into this table.

When a SimClient connects connect to the SimRouter. It sends a GET_CUR_HIGHSCORE message, which is routed to the SimServer. The SimServer sends a OLD_HIGHSCORE_EVENTS message back to the SimRouter which routes it to the SimClient. The payload is the contents of the highscore_events table.

• Table name: highscore_events

Column	Data Type	Description
id	INTEGER	The primary key for the table.
epoch	INTEGER	The game number when the highscore was achieved.
score	INTEGER	The highscore value.
runtime	TEXT	A string (e.g. 1h 23m) indicating when the score was achieved.

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Average Loss Table

This table holds the average loss calulated by averaging the loss of each step within an epoch. This table is used in the TUI’s loss plot widget.

At the end of every step, the AITrainer captures the loss and adds it to a list. At the end of epoch, the SimServer asks the AITrainer for the average loss. The AITrainer averages all of the loss values it collected, zero’s out the list and returns the average. The SimServer inserts a row into the avg_loss table.

When a SimClient connects to the SimRouter. It sends a GET_AVG_LOSS_DATA message, which is routed to the SimServer. The SimServer sends a AVG_LOSS_DATA message back to the SimRouter which routes it back to the SimClient. The payload is the contents of the avg_loss table.

• Table name: avg_loss

Column	Data Type	Description
id	INTEGER	The primary key for the table.
epoch	INTEGER	The epoch or game number.
avg_loss	REAL	The average loss value.

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Game Score Table

The table holds the score for each game. It is used in the TUI’s game score plot widget.

At the end of each epoch, the SimServer inserts a row with the epoch number and the game score into the game_score table.

When a SimClient connects to the SimRouter. It sends a GET_GAME_SCORE_DATA message, which is routed to the SimServer. The SimServer sends a OLD_GAME_SCORE_DATA message back to the SimRouter which routes it back to the SimClient. The payload is the contents of the game_score table.

• Table name: game_score

Column	Data Type	Description
id	INTEGER	The primary key for the table.
epoch	INTEGER	The epoch or game number.
score	INTEGER	The score achieved for the epoch.