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Merge pull request #39668 from Expensify/revert-38997-@chrispader/pre…
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…vent-simultaneous-calls-to-GetMissingOnyxMessages

[CP Staging] Revert "Defer local updates if there are missing updates and only call `GetMissingOnyxMessages` once"
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@jasperhuangg
jasperhuangg authored Apr 5, 2024
2 parents 42ee04c + ceec51e commit 3864cdb
Showing 1 changed file with 10 additions and 152 deletions.
162 changes: 10 additions & 152 deletions src/libs/actions/OnyxUpdateManager.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,6 @@ import Log from '@libs/Log';
import * as SequentialQueue from '@libs/Network/SequentialQueue';
import CONST from '@src/CONST';
import ONYXKEYS from '@src/ONYXKEYS';
import type {OnyxUpdatesFromServer, Response} from '@src/types/onyx';
import * as App from './App';
import * as OnyxUpdates from './OnyxUpdates';

Expand All @@ -28,134 +27,6 @@ Onyx.connect({
callback: (value) => (lastUpdateIDAppliedToClient = value),
});

let queryPromise: Promise<Response | Response[] | void> | undefined;

type DeferredUpdatesDictionary = Record<number, OnyxUpdatesFromServer>;
let deferredUpdates: DeferredUpdatesDictionary = {};

// This function will reset the query variables, unpause the SequentialQueue and log an info to the user.
function finalizeUpdatesAndResumeQueue() {
console.debug('[OnyxUpdateManager] Done applying all updates');
queryPromise = undefined;
deferredUpdates = {};
Onyx.set(ONYXKEYS.ONYX_UPDATES_FROM_SERVER, null);
SequentialQueue.unpause();
}

// This function applies a list of updates to Onyx in order and resolves when all updates have been applied
const applyUpdates = (updates: DeferredUpdatesDictionary) => Promise.all(Object.values(updates).map((update) => OnyxUpdates.apply(update)));

// In order for the deferred updates to be applied correctly in order,
// we need to check if there are any gaps between deferred updates.
type DetectGapAndSplitResult = {applicableUpdates: DeferredUpdatesDictionary; updatesAfterGaps: DeferredUpdatesDictionary; latestMissingUpdateID: number | undefined};
function detectGapsAndSplit(updates: DeferredUpdatesDictionary): DetectGapAndSplitResult {
const updateValues = Object.values(updates);
const applicableUpdates: DeferredUpdatesDictionary = {};

let gapExists = false;
let firstUpdateAfterGaps: number | undefined;
let latestMissingUpdateID: number | undefined;

for (const [index, update] of updateValues.entries()) {
const isFirst = index === 0;

// If any update's previousUpdateID doesn't match the lastUpdateID from the previous update, the deferred updates aren't chained and there's a gap.
// For the first update, we need to check that the previousUpdateID of the fetched update is the same as the lastUpdateIDAppliedToClient.
// For any other updates, we need to check if the previousUpdateID of the current update is found in the deferred updates.
// If an update is chained, we can add it to the applicable updates.
const isChained = isFirst ? update.previousUpdateID === lastUpdateIDAppliedToClient : !!updates[Number(update.previousUpdateID)];
if (isChained) {
// If a gap exists already, we will not add any more updates to the applicable updates.
// Instead, once there are two chained updates again, we can set "firstUpdateAfterGaps" to the first update after the current gap.
if (gapExists) {
// If "firstUpdateAfterGaps" hasn't been set yet and there was a gap, we need to set it to the first update after all gaps.
if (!firstUpdateAfterGaps) {
firstUpdateAfterGaps = Number(update.previousUpdateID);
}
} else {
// If no gap exists yet, we can add the update to the applicable updates
applicableUpdates[Number(update.lastUpdateID)] = update;
}
} else {
// When we find a (new) gap, we need to set "gapExists" to true and reset the "firstUpdateAfterGaps" variable,
// so that we can continue searching for the next update after all gaps
gapExists = true;
firstUpdateAfterGaps = undefined;

// If there is a gap, it means the previous update is the latest missing update.
latestMissingUpdateID = Number(update.previousUpdateID);
}
}

// When "firstUpdateAfterGaps" is not set yet, we need to set it to the last update in the list,
// because we will fetch all missing updates up to the previous one and can then always apply the last update in the deferred updates.
if (!firstUpdateAfterGaps) {
firstUpdateAfterGaps = Number(updateValues[updateValues.length - 1].lastUpdateID);
}

let updatesAfterGaps: DeferredUpdatesDictionary = {};
if (gapExists && firstUpdateAfterGaps) {
// eslint-disable-next-line @typescript-eslint/no-non-null-assertion
updatesAfterGaps = Object.fromEntries(Object.entries(updates).filter(([lastUpdateID]) => Number(lastUpdateID) >= firstUpdateAfterGaps!));
}

return {applicableUpdates, updatesAfterGaps, latestMissingUpdateID};
}

// This function will check for gaps in the deferred updates and
// apply the updates in order after the missing updates are fetched and applied
function validateAndApplyDeferredUpdates(): Promise<Response[] | void> {
// We only want to apply deferred updates that are newer than the last update that was applied to the client.
// At this point, the missing updates from "GetMissingOnyxUpdates" have been applied already, so we can safely filter out.
const pendingDeferredUpdates = Object.fromEntries(
Object.entries(deferredUpdates).filter(([lastUpdateID]) => {
// It should not be possible for lastUpdateIDAppliedToClient to be null,
// after the missing updates have been applied.
// If still so we want to keep the deferred update in the list.
if (!lastUpdateIDAppliedToClient) {
return true;
}
return (Number(lastUpdateID) ?? 0) > lastUpdateIDAppliedToClient;
}),
);

// If there are no remaining deferred updates after filtering out outdated ones,
// we can just unpause the queue and return
if (Object.values(pendingDeferredUpdates).length === 0) {
return Promise.resolve();
}

const {applicableUpdates, updatesAfterGaps, latestMissingUpdateID} = detectGapsAndSplit(pendingDeferredUpdates);

// If we detected a gap in the deferred updates, only apply the deferred updates before the gap,
// re-fetch the missing updates and then apply the remaining deferred updates after the gap
if (latestMissingUpdateID) {
return new Promise((resolve, reject) => {
deferredUpdates = {};
applyUpdates(applicableUpdates).then(() => {
// After we have applied the applicable updates, there might have been new deferred updates added.
// In the next (recursive) call of "validateAndApplyDeferredUpdates",
// the initial "updatesAfterGaps" and all new deferred updates will be applied in order,
// as long as there was no new gap detected. Otherwise repeat the process.
deferredUpdates = {...deferredUpdates, ...updatesAfterGaps};

// It should not be possible for lastUpdateIDAppliedToClient to be null, therefore we can ignore this case.
// If lastUpdateIDAppliedToClient got updated in the meantime, we will just retrigger the validation and application of the current deferred updates.
if (!lastUpdateIDAppliedToClient || latestMissingUpdateID <= lastUpdateIDAppliedToClient) {
validateAndApplyDeferredUpdates().then(resolve).catch(reject);
return;
}

// Then we can fetch the missing updates and apply them
App.getMissingOnyxUpdates(lastUpdateIDAppliedToClient, latestMissingUpdateID).then(validateAndApplyDeferredUpdates).then(resolve).catch(reject);
});
});
}

// If there are no gaps in the deferred updates, we can apply all deferred updates in order
return applyUpdates(applicableUpdates);
}

export default () => {
console.debug('[OnyxUpdateManager] Listening for updates from the server');
Onyx.connect({
Expand Down Expand Up @@ -195,45 +66,32 @@ export default () => {
// applied in their correct and specific order. If this queue was not paused, then there would be a lot of
// onyx data being applied while we are fetching the missing updates and that would put them all out of order.
SequentialQueue.pause();
let canUnpauseQueuePromise;

// The flow below is setting the promise to a reconnect app to address flow (1) explained above.
if (!lastUpdateIDAppliedToClient) {
// If there is a ReconnectApp query in progress, we should not start another one.
if (queryPromise) {
return;
}

Log.info('Client has not gotten reliable updates before so reconnecting the app to start the process');

// Since this is a full reconnectApp, we'll not apply the updates we received - those will come in the reconnect app request.
queryPromise = App.finalReconnectAppAfterActivatingReliableUpdates();
canUnpauseQueuePromise = App.finalReconnectAppAfterActivatingReliableUpdates();
} else {
// The flow below is setting the promise to a getMissingOnyxUpdates to address flow (2) explained above.

// Get the number of deferred updates before adding the new one
const existingDeferredUpdatesCount = Object.keys(deferredUpdates).length;

// Add the new update to the deferred updates
deferredUpdates[Number(updateParams.lastUpdateID)] = updateParams;

// If there are deferred updates already, we don't need to fetch the missing updates again.
if (existingDeferredUpdatesCount > 0) {
return;
}

console.debug(`[OnyxUpdateManager] Client is behind the server by ${Number(previousUpdateIDFromServer) - lastUpdateIDAppliedToClient} so fetching incremental updates`);
Log.info('Gap detected in update IDs from server so fetching incremental updates', true, {
lastUpdateIDFromServer,
previousUpdateIDFromServer,
lastUpdateIDAppliedToClient,
});

// Get the missing Onyx updates from the server and afterwards validate and apply the deferred updates.
// This will trigger recursive calls to "validateAndApplyDeferredUpdates" if there are gaps in the deferred updates.
queryPromise = App.getMissingOnyxUpdates(lastUpdateIDAppliedToClient, previousUpdateIDFromServer).then(validateAndApplyDeferredUpdates);
canUnpauseQueuePromise = App.getMissingOnyxUpdates(lastUpdateIDAppliedToClient, previousUpdateIDFromServer);
}

queryPromise.finally(finalizeUpdatesAndResumeQueue);
canUnpauseQueuePromise.finally(() => {
OnyxUpdates.apply(updateParams).finally(() => {
console.debug('[OnyxUpdateManager] Done applying all updates');
Onyx.set(ONYXKEYS.ONYX_UPDATES_FROM_SERVER, null);
SequentialQueue.unpause();
});
});
},
});
};

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