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Use Promise chaining to enforce read/write queue #699

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Merged
delucis merged 2 commits into from
May 17, 2020
Merged

Use Promise chaining to enforce read/write queue #699

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ac8ae28
Use Promise chaining to enforce read/write queue
jabza May 16, 2020
04327f0
Wrap flatfile request chaining in function
jabza May 17, 2020
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79 changes: 65 additions & 14 deletions src/server/db/flatfile.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@ export class FlatFile extends StorageAPI.Async {
private dir: string;
private logging?: boolean;
private ttl?: boolean;
private requests: Promise<any>;

constructor({
dir,
Expand All @@ -39,6 +40,7 @@ export class FlatFile extends StorageAPI.Async {
this.dir = dir;
this.logging = logging || false;
this.ttl = ttl || false;
this.requests = Promise.resolve();
}

async connect() {
Expand All @@ -56,7 +58,11 @@ export class FlatFile extends StorageAPI.Async {
): Promise<void> {
// Store initial state separately for easy retrieval later.
const key = InitialStateKey(gameID);
await this.games.setItem(key, opts.initialState);

const setRequest = () => this.games.setItem(key, opts.initialState);
this.requests = this.requests.then(setRequest, setRequest);

await this.requests;

await this.setState(gameID, opts.initialState);
await this.setMetadata(gameID, opts.metadata);
Expand All @@ -69,22 +75,37 @@ export class FlatFile extends StorageAPI.Async {
let result = {} as StorageAPI.FetchFields;

if (opts.state) {
result.state = (await this.games.getItem(gameID)) as State;
const fetchRequest = () => this.games.getItem(gameID);
this.requests = this.requests.then(fetchRequest, fetchRequest);

result.state = (await this.requests) as State;
}

if (opts.metadata) {
const key = MetadataKey(gameID);
result.metadata = (await this.games.getItem(key)) as Server.GameMetadata;

const fetchRequest = () => this.games.getItem(key);
this.requests = this.requests.then(fetchRequest, fetchRequest);

result.metadata = (await this.requests) as Server.GameMetadata;
}

if (opts.log) {
const key = LogKey(gameID);
result.log = (await this.games.getItem(key)) as LogEntry[];

const fetchRequest = () => this.games.getItem(key);
this.requests = this.requests.then(fetchRequest, fetchRequest);

result.log = (await this.requests) as LogEntry[];
}

if (opts.initialState) {
const key = InitialStateKey(gameID);
result.initialState = (await this.games.getItem(key)) as State;

const fetchRequest = () => this.games.getItem(key);
this.requests = this.requests.then(fetchRequest, fetchRequest);

result.initialState = (await this.requests) as State;
}

return result as StorageAPI.FetchResult<O>;
Expand All @@ -97,28 +118,58 @@ export class FlatFile extends StorageAPI.Async {
async setState(id: string, state: State, deltalog?: LogEntry[]) {
if (deltalog && deltalog.length > 0) {
const key = LogKey(id);
const log: LogEntry[] =
((await this.games.getItem(key)) as LogEntry[]) || [];
await this.games.setItem(key, log.concat(deltalog));

const getRequest = () => this.games.getItem(key);
this.requests = this.requests.then(getRequest, getRequest);

const log: LogEntry[] = ((await this.requests) as LogEntry[]) || [];

const setRequest = () => this.games.setItem(key, log.concat(deltalog));
this.requests = this.requests.then(setRequest, setRequest);

await this.requests;
}
return await this.games.setItem(id, state);

const setRequest = () => this.games.setItem(id, state);
this.requests = this.requests.then(setRequest, setRequest);

return await this.requests;
}

async setMetadata(id: string, metadata: Server.GameMetadata): Promise<void> {
const key = MetadataKey(id);
return await this.games.setItem(key, metadata);

const setRequest = () => this.games.setItem(key, metadata);
this.requests = this.requests.then(setRequest, setRequest);

return await this.requests;
}

async wipe(id: string) {
var keys = await this.games.keys();
if (!(keys.indexOf(id) > -1)) return;
await this.games.removeItem(id);
await this.games.removeItem(LogKey(id));
await this.games.removeItem(MetadataKey(id));

const removeIdRequest = () => this.games.removeItem(id);
this.requests = this.requests.then(removeIdRequest, removeIdRequest);

await this.requests;

const removeLogRequest = () => this.games.removeItem(LogKey(id));
this.requests = this.requests.then(removeLogRequest, removeLogRequest);

await this.requests;

const removeMetaRequest = () => this.games.removeItem(MetadataKey(id));
this.requests = this.requests.then(removeMetaRequest, removeMetaRequest);

await this.requests;
}

async listGames(): Promise<string[]> {
const keys = await this.games.keys();
const getKeysRequest = () => this.games.keys();
this.requests = this.requests.then(getKeysRequest, getKeysRequest);

const keys = await this.requests;
const suffix = ':metadata';
return keys
.filter(k => k.endsWith(suffix))
Expand Down