OPFS: if an op which needs a lock is called when no lock has been obtained, automatically lock it at the start of the op and unlock it at the end of that op. This is an attempt to alleviate the cross-tab contention described in [forum post 58a377083cd24a|forum:58a377083cd24a] but it increases speedtest1 run time by approximately 4x. Perhaps auto-lock can be combined with the older idle-time-based auto-unlock to unlock such locks (but not those from xLock()) to improve this?

FossilOrigin-Name: 46304ba057707c3b072b6e7bb8c4af774f653aa5814099f0866cd87b2b73abeb

ext/wasm/api/sqlite3-opfs-async-proxy.js

@@ -214,6 +214,24 @@ const closeSyncHandle = async (fh)=>{
   }
 };
 
+/**
+   A proxy for closeSyncHandle() which is guaranteed to not throw.
+
+   This function is part of a lock/unlock step in functions which
+   require a sync access handle but may be called without xLock()
+   having been called first. Such calls need to release that
+   handle to avoid locking the file for all of time. This is an
+   _attempt_ at reducing cross-tab contention but it may prove
+   to be more of a problem than a solution and may need to be
+   removed.
+*/
+const closeSyncHandleNoThrow = async (fh)=>{
+  try{await closeSyncHandle(fh)}
+  catch(e){
+    warn("closeSyncHandleNoThrow() ignoring:",e,fh);
+  }
+};
+
 /**
    Stores the given value at state.sabOPView[state.opIds.rc] and then
    Atomics.notify()'s it.
@@ -403,6 +421,7 @@ const vfsAsyncImpls = {
     mTimeStart('xFileSize');
     const fh = __openFiles[fid];
     let rc;
+    const hadLock = !!fh.syncHandle;
     wTimeStart('xFileSize');
     try{
       affirmLocked('xFileSize',fh);
@@ -413,6 +432,7 @@ const vfsAsyncImpls = {
       state.s11n.storeException(2,e);
       rc = state.sq3Codes.SQLITE_IOERR;
     }
+    if(!hadLock) closeSyncHandleNoThrow(fh);
     wTimeEnd();
     storeAndNotify('xFileSize', rc);
     mTimeEnd();
@@ -483,6 +503,7 @@ const vfsAsyncImpls = {
     mTimeStart('xRead');
     let rc = 0, nRead;
     const fh = __openFiles[fid];
+    const hadLock = !!fh.syncHandle;
     try{
       affirmLocked('xRead',fh);
       wTimeStart('xRead');
@@ -501,6 +522,7 @@ const vfsAsyncImpls = {
       state.s11n.storeException(1,e);
       rc = state.sq3Codes.SQLITE_IOERR_READ;
     }
+    if(!hadLock) closeSyncHandleNoThrow(fh);
     storeAndNotify('xRead',rc);
     mTimeEnd();
   },
@@ -525,6 +547,7 @@ const vfsAsyncImpls = {
     mTimeStart('xTruncate');
     let rc = 0;
     const fh = __openFiles[fid];
+    const hadLock = !!fh.syncHandle;
     wTimeStart('xTruncate');
     try{
       affirmLocked('xTruncate',fh);
@@ -535,6 +558,7 @@ const vfsAsyncImpls = {
       state.s11n.storeException(2,e);
       rc = state.sq3Codes.SQLITE_IOERR_TRUNCATE;
     }
+    if(!hadLock) closeSyncHandleNoThrow(fh);
     wTimeEnd();
     storeAndNotify('xTruncate',rc);
     mTimeEnd();
@@ -561,6 +585,7 @@ const vfsAsyncImpls = {
     mTimeStart('xWrite');
     let rc;
     const fh = __openFiles[fid];
+    const hadLock = !!fh.syncHandle;
     wTimeStart('xWrite');
     try{
       affirmLocked('xWrite',fh);
@@ -575,6 +600,7 @@ const vfsAsyncImpls = {
       state.s11n.storeException(1,e);
       rc = state.sq3Codes.SQLITE_IOERR_WRITE;
     }
+    if(!hadLock) closeSyncHandleNoThrow(fh);
     wTimeEnd();
     storeAndNotify('xWrite',rc);
     mTimeEnd();

ext/wasm/module-symbols.html

@@ -189,7 +189,7 @@
     <div id='list-compile-options' class='pseudolist wide2'></div>
 
   </div><!-- .initially-hidden -->
-  <script src="jswasm/sqlite3.js">/* This tag MUST be in side the
+  <script src="jswasm/sqlite3.js">/* This tag MUST be inside the
   fossil-doc block so that this part can work without modification in
   the wasm docs repo.  */</script>
   <script>(async function(){

manifest

@@ -1,5 +1,5 @@
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-D 2022-11-09T11:17:57.759
+C OPFS:\sif\san\sop\swhich\sneeds\sa\slock\sis\scalled\swhen\sno\slock\shas\sbeen\sobtained,\sautomatically\slock\sit\sat\sthe\sstart\sof\sthe\sop\sand\sunlock\sit\sat\sthe\send\sof\sthat\sop.\sThis\sis\san\sattempt\sto\salleviate\sthe\scross-tab\scontention\sdescribed\sin\s[forum\spost\s58a377083cd24a|forum:58a377083cd24a]\sbut\sit\sincreases\sspeedtest1\srun\stime\sby\sapproximately\s4x.\sPerhaps\sauto-lock\scan\sbe\scombined\swith\sthe\solder\sidle-time-based\sauto-unlock\sto\sunlock\ssuch\slocks\s(but\snot\sthose\sfrom\sxLock())\sto\simprove\sthis?
+D 2022-11-10T11:35:10.700
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -506,7 +506,7 @@ F ext/wasm/api/sqlite3-api-opfs.js cdcbb57acc66f4569ac9e18f9d13d5a3657d8aae19572
 F ext/wasm/api/sqlite3-api-prologue.js fd526fa017fa2578673ca18158354515c719e719a5d93f2f6d0e43f39170430e
 F ext/wasm/api/sqlite3-api-worker1.js e94ba98e44afccfa482874cd9acb325883ade50ed1f9f9526beb9de1711f182f
 F ext/wasm/api/sqlite3-license-version-header.js a661182fc93fc2cf212dfd0b987f8e138a3ac98f850b1112e29b5fbdaecc87c3
-F ext/wasm/api/sqlite3-opfs-async-proxy.js ab7d2888ad9b3dd24bb782bd882fcada2a20cb88eb78c8f36e7bfe708857dbd1
+F ext/wasm/api/sqlite3-opfs-async-proxy.js 721ea9f716749a47b71be618fb33881afa828a46756f32836fc75c3e4bf11b4e
 F ext/wasm/api/sqlite3-wasi.h 25356084cfe0d40458a902afb465df8c21fc4152c1d0a59b563a3fba59a068f9
 F ext/wasm/api/sqlite3-wasm.c 778409e00fb25a4d6989be17fc856c84460198fd3b05ba2ef8289e60c50157ca
 F ext/wasm/api/sqlite3-worker1-promiser.js 0c7a9826dbf82a5ed4e4f7bf7816e825a52aff253afbf3350431f5773faf0e4b
@@ -536,7 +536,7 @@ F ext/wasm/index-dist.html cb0da16cba0f21cda2c25724c5869102d48eb0af04446acd3cd0c
 F ext/wasm/index.html ce6a68a75532b47e3c0adb83381a06d15de8c0ac0331fb7bf31d33f8e7c77dc4
 F ext/wasm/jaccwabyt/jaccwabyt.js 95f573de1826474c9605dda620ee622fcb1673ae74f191eb324c0853aa4dcb66
 F ext/wasm/jaccwabyt/jaccwabyt.md 9aa6951b529a8b29f578ec8f0355713c39584c92cf1708f63ba0cf917cb5b68e
-F ext/wasm/module-symbols.html eca884ef4380612145ee550213be57478ee2b9cd9a9c2b27530cc23359c99682
+F ext/wasm/module-symbols.html b8eebafef8e536624bbe5f7a3da40c07a9062b843dfd3161a0bb72cbb6763dc5
 F ext/wasm/scratchpad-wasmfs-main.html 20cf6f1a8f368e70d01e8c17200e3eaa90f1c8e1029186d836d14b83845fbe06
 F ext/wasm/scratchpad-wasmfs-main.js 4c140457f4d6da9d646a49addd91edb6e9ad1643c6c48e3258b5bce24725dc18
 F ext/wasm/speedtest1-wasmfs.html bc28eb29b69a73864b8d7aae428448f8b7e1de81d8bfb9bba99541322054dbd0
@@ -2055,8 +2055,11 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 2e70d1e5c9b2c9e068be3ccf8a6062edf7bdde2e46d60ba8ce54eda851af6008
-R 5b3228ef5a47231a8a5df1bba248e63f
-U dan
-Z 85fe5476882fbe08da2a9ca03d046c66
+P ae43e97087a3207a5ca3ffae75fbe7a33c01f4a38ce0d1d7eed8591ae3083617
+R 2fca99324f13ba1d5a012e300d10f561
+T *branch * opfs-lock-without-xlock
+T *sym-opfs-lock-without-xlock *
+T -sym-trunk * Cancelled\sby\sbranch.
+U stephan
+Z f1d3a3f55481503869b687bc0b9f2eae
 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
-ae43e97087a3207a5ca3ffae75fbe7a33c01f4a38ce0d1d7eed8591ae3083617
+46304ba057707c3b072b6e7bb8c4af774f653aa5814099f0866cd87b2b73abeb