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Add an experimental OPFS VFS-specific URI flag, opfs-unlock-asap, which tells the VFS to release implicit locks ASAP. This permits higher concurrency but hurts performance considerably. This may or may not be obsoleted by other concurrency-related experimentation.

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FossilOrigin-Name: d23c917013485ec2793125221f3936b05c39d6eca941629fb819b6b4aa714520
This commit is contained in:
stephan
2022-11-23 19:03:22 +00:00
parent ad1285c5c0
commit e79cb67c35
5 changed files with 41 additions and 31 deletions
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27
ext/wasm/api/sqlite3-api-opfs.js
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@ -355,6 +355,25 @@ const installOpfsVfs = function callee(options){
toss("Maintenance required: not found:",k);
}
});
state.opfsFlags = Object.assign(Object.create(null),{
/**
Flag for use with xOpen(). "opfs-unlock-asap=1" enables
this. See defaultUnlockAsap, below.
*/
OPFS_UNLOCK_ASAP: 0x01,
/**
If true, any async routine which implicitly acquires a sync
access handle (i.e. an OPFS lock) will release that locks at
the end of the call which acquires it. If false, such
"autolocks" are not released until the VFS is idle for some
brief amount of time.
The benefit of enabling this is much higher concurrency. The
down-side is much-reduced performance (as much as a 4x decrease
in speedtest1).
*/
defaultUnlockAsap: false
});
/**
Runs the given operation (by name) in the async worker
@ -845,9 +864,15 @@ const installOpfsVfs = function callee(options){
//xSleep is optionally defined below
xOpen: function f(pVfs, zName, pFile, flags, pOutFlags){
mTimeStart('xOpen');
let opfsFlags = 0;
if(0===zName){
zName = randomFilename();
}else if('number'===typeof zName){
if(capi.sqlite3_uri_boolean(zName, "opfs-unlock-asap", 0)){
/* -----------------------^^^^^ MUST pass the untranslated
C-string here. */
opfsFlags |= state.opfsFlags.OPFS_UNLOCK_ASAP;
}
zName = wasm.cstringToJs(zName);
}
const fh = Object.create(null);
@ -855,7 +880,7 @@ const installOpfsVfs = function callee(options){
fh.filename = zName;
fh.sab = new SharedArrayBuffer(state.fileBufferSize);
fh.flags = flags;
const rc = opRun('xOpen', pFile, zName, flags);
const rc = opRun('xOpen', pFile, zName, flags, opfsFlags);
if(!rc){
/* Recall that sqlite3_vfs::xClose() will be called, even on
error, unless pFile->pMethods is NULL. */