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add prototype to test we can safely attempt to open two readwrite txns

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This commit is contained in:
Bruno Windels 2020-03-21 22:53:11 +01:00
parent 3ece193931
commit 7ce13b0fd0
1 changed files with 76 additions and 0 deletions
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prototypes/idb2rwtxn.html Normal file
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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
</head>
<body>
<button id="doit">Do It!</button>
<script type="module">
function reqAsPromise(req) {
return new Promise((resolve, reject) => {
req.addEventListener("success", event => resolve(event.target.result));
req.addEventListener("error", event => reject(event.target.error));
});
}
function txnAsPromise(txn) {
return new Promise((resolve, reject) => {
txn.addEventListener("complete", resolve);
txn.addEventListener("abort", reject);
});
}
async function main() {
let isNew = false;
const openReq = window.indexedDB.open("two-read-write-txn", 1);
openReq.onupgradeneeded = (ev) => {
const db = ev.target.result;
const store = db.createObjectStore("test", {keyPath: "id"});
store.add({id: 6});
};
const db = await reqAsPromise(openReq);
console.log("open txn1");
const txn1 = db.transaction("test", "readwrite");
const test1 = txn1.objectStore("test");
console.log("request value1");
const value1 = await reqAsPromise(test1.get(6));
console.log("value1", value1);
value1.previous = 5;
value1.next = null;
let txn2, test2, prom2, value2;
// prevent deadlock
(async function() {
console.log("open txn2");
txn2 = db.transaction("test", "readwrite");
test2 = txn2.objectStore("test");
console.log("request value2");
prom2 = reqAsPromise(test2.get(6));
value2 = await prom2;
console.log("read value2");
})();
console.log("write value1");
test1.put(value1);
await txnAsPromise(txn1);
await prom2;
console.log("value2", value2);
value2.next = 7;
console.log("write value2");
test2.put(value2);
await txnAsPromise(txn2);
const txn3 = db.transaction("test", "readonly");
const value3 = await reqAsPromise(txn3.objectStore("test").get(6));
alert("done " + JSON.stringify(value3));
}
document.getElementById("doit").addEventListener("click", main);
</script>
</body>
</html>