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store method to find events to connect with when filling gaps

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as fragments can be unaware of their chronological relationship,
we need to check whether the events received from /messages or /context
already exists, so we can later hook up the fragments.
This commit is contained in:
Bruno Windels 2019-05-11 13:10:31 +02:00
parent 35a5e3f21a
commit 53cdabb459
4 changed files with 248 additions and 24 deletions
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165
prototypes/idb-continue-key.html Normal file
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@ -0,0 +1,165 @@
<html>
<head><meta charset="utf-8"></head>
<body>
<script type="text/javascript">
function reqAsPromise(req) {
return new Promise((resolve, reject) => {
req.onsuccess = () => resolve(req);
req.onerror = (err) => reject(err);
});
}
function txnAsPromise(txn) {
return new Promise((resolve, reject) => {
txn.addEventListener("complete", resolve);
txn.addEventListener("abort", reject);
});
}
function iterateCursor(cursor, processValue) {
// TODO: does cursor already have a value here??
return new Promise((resolve, reject) => {
cursor.onerror = (event) => {
reject(new Error("Query failed: " + event.target.errorCode));
};
// collect results
cursor.onsuccess = (event) => {
const cursor = event.target.result;
if (!cursor) {
resolve(false);
return; // end of results
}
const {done, jumpTo} = processValue(cursor.value, cursor.key);
if (done) {
resolve(true);
} else {
cursor.continue(jumpTo);
}
};
});
}
/**
* Checks if a given set of keys exist.
* Calls `callback(key, found)` for each key in `keys`, in an unspecified order.
* If the callback returns true, the search is halted and callback won't be called again.
*/
async function findKeys(target, keys, backwards, callback) {
const direction = backwards ? "prev" : "next";
const compareKeys = (a, b) => backwards ? -indexedDB.cmp(a, b) : indexedDB.cmp(a, b);
const sortedKeys = keys.slice().sort(compareKeys);
console.log(sortedKeys);
const firstKey = backwards ? sortedKeys[sortedKeys.length - 1] : sortedKeys[0];
const lastKey = backwards ? sortedKeys[0] : sortedKeys[sortedKeys.length - 1];
const cursor = target.openKeyCursor(IDBKeyRange.bound(firstKey, lastKey), direction);
let i = 0;
let consumerDone = false;
await iterateCursor(cursor, (value, key) => {
// while key is larger than next key, advance and report false
while(i < sortedKeys.length && compareKeys(sortedKeys[i], key) < 0 && !consumerDone) {
console.log("before match", sortedKeys[i]);
consumerDone = callback(sortedKeys[i], false);
++i;
}
if (i < sortedKeys.length && compareKeys(sortedKeys[i], key) === 0 && !consumerDone) {
console.log("match", sortedKeys[i]);
consumerDone = callback(sortedKeys[i], true);
++i;
}
const done = consumerDone || i >= sortedKeys.length;
const jumpTo = !done && sortedKeys[i];
return {done, jumpTo};
});
// report null for keys we didn't to at the end
while (!consumerDone && i < sortedKeys.length) {
console.log("afterwards", sortedKeys[i]);
consumerDone = callback(sortedKeys[i], false);
++i;
}
}
async function findFirstOrLastOccurringEventId(target, roomId, eventIds, findLast = false) {
const keys = eventIds.map(eventId => [roomId, eventId]);
const results = new Array(keys.length);
let firstFoundEventId;
// find first result that is found and has no undefined results before it
function firstFoundAndPrecedingResolved() {
let inc = findLast ? -1 : 1;
let start = findLast ? results.length - 1 : 0;
for(let i = start; i >= 0 && i < results.length; i += inc) {
if (results[i] === undefined) {
return;
} else if(results[i] === true) {
return keys[i];
}
}
}
await findKeys(target, keys, findLast, (key, found) => {
const index = keys.indexOf(key);
results[index] = found;
firstFoundEventId = firstFoundAndPrecedingResolved();
return !!firstFoundEventId;
});
return firstFoundEventId;
}
(async () => {
let db;
let isNew = false;
// open db
{
const req = window.indexedDB.open("prototype-idb-continue-key");
req.onupgradeneeded = (ev) => {
const db = ev.target.result;
db.createObjectStore("timeline", {keyPath: ["roomId", "eventId"]});
isNew = true;
};
db = (await reqAsPromise(req)).result;
}
const roomId = "!abcdef:localhost";
if (isNew) {
const txn = db.transaction(["timeline"], "readwrite");
const store = txn.objectStore("timeline");
for (var i = 1; i <= 100; ++i) {
store.add({roomId, eventId: `$${i * 10}`});
}
await txnAsPromise(txn);
}
console.log("show all in order we get them");
{
const txn = db.transaction(["timeline"], "readonly");
const store = txn.objectStore("timeline");
const cursor = store.openKeyCursor();
await iterateCursor(cursor, (value, key) => {
console.log(key);
return {done: false};
});
}
console.log("run findKeys");
{
const txn = db.transaction(["timeline"], "readonly");
const store = txn.objectStore("timeline");
const eventIds = ["$992", "$1000", "$1010", "$991", "$500", "$990"];
// const eventIds = ["$992", "$1010"];
const keys = eventIds.map(eventId => [roomId, eventId]);
await findKeys(store, keys, false, (key, found) => {
console.log(key, found);
});
}
console.log("run findFirstOrLastOccurringEventId");
{
const txn = db.transaction(["timeline"], "readonly");
const store = txn.objectStore("timeline");
const eventIds = ["$992", "$1000", "$1010", "$991", "$500", "$990", "$123"];
const firstMatch = await findFirstOrLastOccurringEventId(store, roomId, eventIds, false);
console.log("firstMatch", firstMatch);
const lastMatch = await findFirstOrLastOccurringEventId(store, roomId, eventIds, true);
console.log("lastMatch", lastMatch);
}
})();
</script>
</body>
</html>

44
src/matrix/storage/idb/query-target.js
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@ -38,7 +38,7 @@ export default class QueryTarget {
const results = []; const results = [];
await iterateCursor(cursor, (value) => { await iterateCursor(cursor, (value) => {
results.push(value); results.push(value);
return false; return {done: false};
}); });
return results; return results;
} }
@ -59,12 +59,48 @@ export default class QueryTarget {
return this._find(range, predicate, "prev"); return this._find(range, predicate, "prev");
} }
/**
* Checks if a given set of keys exist.
* Calls `callback(key, found)` for each key in `keys`, in key sorting order (or reversed if backwards=true).
* If the callback returns true, the search is halted and callback won't be called again.
* `callback` is called with the same instances of the key as given in `keys`, so direct comparison can be used.
*/
async findExistingKeys(keys, backwards, callback) {
const direction = backwards ? "prev" : "next";
const compareKeys = (a, b) => backwards ? -indexedDB.cmp(a, b) : indexedDB.cmp(a, b);
const sortedKeys = keys.slice().sort(compareKeys);
const firstKey = backwards ? sortedKeys[sortedKeys.length - 1] : sortedKeys[0];
const lastKey = backwards ? sortedKeys[0] : sortedKeys[sortedKeys.length - 1];
const cursor = this._target.openKeyCursor(IDBKeyRange.bound(firstKey, lastKey), direction);
let i = 0;
let consumerDone = false;
await iterateCursor(cursor, (value, key) => {
// while key is larger than next key, advance and report false
while(i < sortedKeys.length && compareKeys(sortedKeys[i], key) < 0 && !consumerDone) {
consumerDone = callback(sortedKeys[i], false);
++i;
}
if (i < sortedKeys.length && compareKeys(sortedKeys[i], key) === 0 && !consumerDone) {
consumerDone = callback(sortedKeys[i], true);
++i;
}
const done = consumerDone || i >= sortedKeys.length;
const jumpTo = !done && sortedKeys[i];
return {done, jumpTo};
});
// report null for keys we didn't to at the end
while (!consumerDone && i < sortedKeys.length) {
consumerDone = callback(sortedKeys[i], false);
++i;
}
}
_reduce(range, reducer, initialValue, direction) { _reduce(range, reducer, initialValue, direction) {
let reducedValue = initialValue; let reducedValue = initialValue;
const cursor = this._target.openCursor(range, direction); const cursor = this._target.openCursor(range, direction);
return iterateCursor(cursor, (value) => { return iterateCursor(cursor, (value) => {
reducedValue = reducer(reducedValue, value); reducedValue = reducer(reducedValue, value);
return true; return {done: false};
}); });
} }
@ -79,7 +115,7 @@ export default class QueryTarget {
const results = []; const results = [];
await iterateCursor(cursor, (value) => { await iterateCursor(cursor, (value) => {
results.push(value); results.push(value);
return predicate(results); return {done: predicate(results)};
}); });
return results; return results;
} }
@ -92,7 +128,7 @@ export default class QueryTarget {
if (found) { if (found) {
result = value; result = value;
} }
return found; return {done: found};
}); });
if (found) { if (found) {
return result; return result;

51
src/matrix/storage/idb/stores/RoomTimelineStore.js
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@ -147,24 +147,47 @@ export default class RoomTimelineStore {
return events; return events;
} }
/** Looks up the first, if any, event entry (so excluding gap entries) after `sortKey`. /** Finds the first (or last if `findLast=true`) eventId that occurs in the store, if any.
* For optimal performance, `eventIds` should be in chronological order.
*
* The order in which results are returned might be different than `eventIds`.
* Call the return value to obtain the next {id, event} pair.
* @param {string} roomId * @param {string} roomId
* @param {SortKey} sortKey * @param {string[]} eventIds
* @return {Promise<(?Entry)>} a promise resolving to entry, if any. * @return {Function<Promise>}
*/ */
nextEvent(roomId, sortKey) { // performance comment from above refers to the fact that their *might*
const range = this.lowerBoundRange(sortKey, true).asIDBKeyRange(roomId); // be a correlation between event_id sorting order and chronology.
return this._timelineStore.find(range, entry => !!entry.event); // In that case we could avoid running over all eventIds, as the reported order by findExistingKeys
// would match the order of eventIds. That's why findLast is also passed as backwards to keysExist.
// also passing them in chronological order makes sense as that's how we'll receive them almost always.
async findFirstOrLastOccurringEventId(roomId, eventIds, findLast = false) {
const byEventId = this._timelineStore.index("byEventId");
const keys = eventIds.map(eventId => [roomId, eventId]);
const results = new Array(keys.length);
let firstFoundEventId;
// find first result that is found and has no undefined results before it
function firstFoundAndPrecedingResolved() {
let inc = findLast ? -1 : 1;
let start = findLast ? results.length - 1 : 0;
for(let i = start; i >= 0 && i < results.length; i += inc) {
if (results[i] === undefined) {
return;
} else if(results[i] === true) {
return keys[i];
}
}
} }
/** Looks up the first, if any, event entry (so excluding gap entries) before `sortKey`. await byEventId.findExistingKeys(keys, findLast, (key, found) => {
* @param {string} roomId const index = keys.indexOf(key);
* @param {SortKey} sortKey results[index] = found;
* @return {Promise<(?Entry)>} a promise resolving to entry, if any. firstFoundEventId = firstFoundAndPrecedingResolved();
*/ return !!firstFoundEventId;
previousEvent(roomId, sortKey) { });
const range = this.upperBoundRange(sortKey, true).asIDBKeyRange(roomId);
return this._timelineStore.findReverse(range, entry => !!entry.event); return firstFoundEventId;
} }
/** Inserts a new entry into the store. The combination of roomId and sortKey should not exist yet, or an error is thrown. /** Inserts a new entry into the store. The combination of roomId and sortKey should not exist yet, or an error is thrown.

8
src/matrix/storage/idb/utils.js
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@ -35,11 +35,11 @@ export function iterateCursor(cursor, processValue) {
resolve(false); resolve(false);
return; // end of results return; // end of results
} }
const isDone = processValue(cursor.value); const {done, jumpTo} = processValue(cursor.value, cursor.key);
if (isDone) { if (done) {
resolve(true); resolve(true);
} else { } else {
cursor.continue(); cursor.continue(jumpTo);
} }
}; };
}); });
@ -49,7 +49,7 @@ export async function fetchResults(cursor, isDone) {
const results = []; const results = [];
await iterateCursor(cursor, (value) => { await iterateCursor(cursor, (value) => {
results.push(value); results.push(value);
return isDone(results); return {done: isDone(results)};
}); });
return results; return results;
} }