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More work on the OPFS concurrency testing app.

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FossilOrigin-Name: c0458caca3508d5d252f9b5198bda4f51a5c1874540f014b17e409f2daab1706
This commit is contained in:
stephan
2022-11-24 17:53:09 +00:00
parent 056a71562f
commit df5d06d03e
7 changed files with 54 additions and 46 deletions
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28
ext/wasm/api/sqlite3-opfs-async-proxy.js
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@ -558,33 +558,17 @@ const vfsAsyncImpls = {
(opfsFlags & state.opfsFlags.OPFS_UNLOCK_ASAP)
|| state.opfsFlags.defaultUnlockAsap;
if(0 /* this block is modelled after something wa-sqlite
does but it leads to horrible contention on journal files. */
does but it leads to immediate contention on journal files. */
&& (0===(flags & state.sq3Codes.SQLITE_OPEN_MAIN_DB))){
/* sqlite does not lock these files, so go ahead and grab an OPFS
lock.
Regarding "immutable": that flag is not _really_ applicable
here. It's intended for use on read-only media. If,
however, a file is opened with that flag but changes later
(which can happen if we _don't_ grab a sync handle here)
then sqlite may misbehave.
Regarding "nolock": ironically, the nolock flag forces us
to lock the file up front. "nolock" tells sqlite to _not_
use its locking API, but OPFS requires a lock to perform
most of the operations performed in this file. If we don't
grab that lock up front, another handle could end up grabbing
it and mutating the database out from under our nolocked'd
handle. In the interest of preventing corruption, at the cost
of decreased concurrency, we have to lock it for the duration
of this file handle.
https://www.sqlite.org/uri.html
*/
fh.xLock = "atOpen"/* Truthy value to keep entry from getting
flagged as auto-locked. String value so
that we can easily distinguish is later
if needed. */;
fh.xLock = "xOpen"/* Truthy value to keep entry from getting
flagged as auto-locked. String value so
that we can easily distinguish is later
if needed. */;
await getSyncHandle(fh,'xOpen');
}
__openFiles[fid] = fh;
@ -824,7 +808,7 @@ const waitLoop = async function f(){
to do other things. If this is too high (e.g. 500ms) then
even two workers/tabs can easily run into locking errors.
*/
const waitTime = 150;
const waitTime = 100;
while(!flagAsyncShutdown){
try {
if('timed-out'===Atomics.wait(