OPFS VFS now lazily opens its sync access handle, as a step towards experimenting with relinquishing it during idle times to help avoid cross-tab and page-reload locking issues.

FossilOrigin-Name: a984e1ba435731413a541f86c50232bc7d6e33aff6ba4cca90f89188e7b82a2c

ext/wasm/api/sqlite3-api-glue.js

@@ -24,27 +24,32 @@ self.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
   self.WhWasmUtilInstaller(capi.wasm);
   delete self.WhWasmUtilInstaller;
 
+  /**
+     Install JS<->C struct bindings for the non-opaque struct types we
+     need... */
+  sqlite3.StructBinder = self.Jaccwabyt({
+    heap: 0 ? wasm.memory : wasm.heap8u,
+    alloc: wasm.alloc,
+    dealloc: wasm.dealloc,
+    functionTable: wasm.functionTable,
+    bigIntEnabled: wasm.bigIntEnabled,
+    memberPrefix: '$'
+  });
+  delete self.Jaccwabyt;
+
   if(0){
-    /*  "The problem" is that the following isn't type-safe.
-        OTOH, nothing about WASM pointers is. */
-    /**
-       Add the `.pointer` xWrap() signature entry to extend the
-       `pointer` arg handler to check for a `pointer` property. This
-       can be used to permit, e.g., passing an sqlite3.oo1.DB instance
-       to a C-style sqlite3_xxx function which takes an `sqlite3*`
-       argument.
-    */
-    const xPointer = wasm.xWrap.argAdapter('pointer');
-    const adapter = function(v){
-      if(v && v.constructor){
-        const x = v.pointer;
-        if(Number.isInteger(x)) return x;
-        else toss("Invalid (object) type for .pointer-type argument.");
+    /*  "The problem" is that the following isn't even remotely
+        type-safe. OTOH, nothing about WASM pointers is. */
+    const argPointer = wasm.xWrap.argAdapter('*');
+    wasm.xWrap.argAdapter('StructType', (v)=>{
+      if(v && v.constructor && v instanceof StructBinder.StructType){
+        v = v.pointer;
       }
-      return xPointer(v);
-    };
-    wasm.xWrap.argAdapter('.pointer', adapter);
-  } /* ".pointer" xWrap() argument adapter */
+      return (v === (v | 0) /* v is a 32-bit integer */)
+        ? argPointer(v)
+        : toss("Invalid (object) type for StructType-type argument.");
+    });
+  }
 
   if(1){/* Convert Arrays and certain TypedArrays to strings for
            'flexible-string'-type arguments */
@@ -605,19 +610,6 @@ self.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
     };
   }/*wasm.pstack filler*/
 
-  /**
-     Install JS<->C struct bindings for the non-opaque struct types we
-     need... */
-  sqlite3.StructBinder = self.Jaccwabyt({
-    heap: 0 ? wasm.memory : wasm.heap8u,
-    alloc: wasm.alloc,
-    dealloc: wasm.dealloc,
-    functionTable: wasm.functionTable,
-    bigIntEnabled: wasm.bigIntEnabled,
-    memberPrefix: '$'
-  });
-  delete self.Jaccwabyt;
-
   {/* Import C-level constants and structs... */
     const cJson = wasm.xCall('sqlite3_wasm_enum_json');
     if(!cJson){

ext/wasm/common/whwasmutil.js

@@ -371,16 +371,16 @@ self.WhWasmUtilInstaller = function(target){
   /**
      Creates a WASM function which wraps the given JS function and
      returns the JS binding of that WASM function. The signature
-     argument must be the Jaccwabyt-format or Emscripten
+     string must be the Jaccwabyt-format or Emscripten
      addFunction()-format function signature string. In short: in may
      have one of the following formats:
 
-     - Emscripten: `x...`, where the first x is a letter representing
+     - Emscripten: `"x..."`, where the first x is a letter representing
        the result type and subsequent letters represent the argument
        types. Functions with no arguments have only a single
        letter. See below.
 
-     - Jaccwabyt: `x(...)` where `x` is the letter representing the
+     - Jaccwabyt: `"x(...)"` where `x` is the letter representing the
        result type and letters in the parens (if any) represent the
        argument types. Functions with no arguments use `x()`. See
        below.
@@ -451,9 +451,9 @@ self.WhWasmUtilInstaller = function(target){
                   // is not yet documented on MDN. 
         sigToWasm: function(sig){
           const rc = {parameters:[], results: []};
-          if('v'!==sig[0]) rc.results.push(f._.letterType(sig[0]));
+          if('v'!==sig[0]) rc.results.push(f.sigTypes(sig[0]));
           for(const x of f._.sigParams(sig)){
-            rc.parameters.push(f._.letterType(x));
+            rc.parameters.push(f._.typeCodes(x));
           }
           return rc;
         },************/

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

@@ -25,6 +25,13 @@
   access to the sqlite3 JS/WASM bits, so any bits which it needs (most
   notably SQLITE_xxx integer codes) have to be imported into it via an
   initialization process.
+
+  Potential TODOs:
+
+  - When idle for "a long time", close the sync access handle in order
+  to release the lock, then re-open it on demand. Similarly, delay
+  fetching of the sync access handle until we need it. The intent
+  would be to help multi-tab access to a db avoid locking issues.
 */
 'use strict';
 const toss = function(...args){throw new Error(args.join(' '))};
@@ -132,6 +139,17 @@ const getDirForFilename = async function f(absFilename, createDirs = false){
   return [dh, filename];
 };
 
+/**
+   Returns the sync access handle associated with the given file
+   handle object (which must be a valid handle object), lazily opening
+   it if needed.
+*/
+const getSyncHandle = async (f)=>(
+  f.accessHandle || (
+    f.accessHandle =
+      await f.fileHandle.createSyncAccessHandle()
+  )
+);
 
 /**
    Stores the given value at state.sabOPView[state.opIds.rc] and then
@@ -294,7 +312,7 @@ const vfsAsyncImpls = {
     let sz;
     wTimeStart('xFileSize');
     try{
-      sz = await fh.accessHandle.getSize();
+      sz = await (await getSyncHandle(fh)).getSize();
       state.s11n.serialize(Number(sz));
       sz = 0;
     }catch(e){
@@ -322,23 +340,24 @@ const vfsAsyncImpls = {
         return;
       }
       const hFile = await hDir.getFileHandle(filenamePart, {create});
-      const fobj = Object.create(null);
       /**
          wa-sqlite, at this point, grabs a SyncAccessHandle and
          assigns it to the accessHandle prop of the file state
          object, but only for certain cases and it's unclear why it
          places that limitation on it.
       */
-      fobj.accessHandle = await hFile.createSyncAccessHandle();
       wTimeEnd();
+      const fobj = Object.assign(Object.create(null),{
+        filenameAbs: filename,
+        filenamePart: filenamePart,
+        dirHandle: hDir,
+        fileHandle: hFile,
+        sabView: state.sabFileBufView,
+        readOnly: create
+          ? false : (state.sq3Codes.SQLITE_OPEN_READONLY & flags),
+        deleteOnClose: deleteOnClose
+      });
       __openFiles[fid] = fobj;
-      fobj.filenameAbs = filename;
-      fobj.filenamePart = filenamePart;
-      fobj.dirHandle = hDir;
-      fobj.fileHandle = hFile;
-      fobj.sabView = state.sabFileBufView;
-      fobj.readOnly = create ? false : (state.sq3Codes.SQLITE_OPEN_READONLY & flags);
-      fobj.deleteOnClose = deleteOnClose;
       storeAndNotify(opName, 0);
     }catch(e){
       wTimeEnd();
@@ -354,7 +373,7 @@ const vfsAsyncImpls = {
     try{
       const fh = __openFiles[fid];
       wTimeStart('xRead');
-      const nRead = fh.accessHandle.read(
+      const nRead = (await getSyncHandle(fh)).read(
         fh.sabView.subarray(0, n),
         {at: Number(offset)}
       );
@@ -395,7 +414,7 @@ const vfsAsyncImpls = {
     wTimeStart('xTruncate');
     try{
       affirmNotRO('xTruncate', fh);
-      await fh.accessHandle.truncate(size);
+      await (await getSyncHandle(fh)).truncate(size);
     }catch(e){
       error("xTruncate():",e,fh);
       state.s11n.storeException(2,e);
@@ -413,8 +432,9 @@ const vfsAsyncImpls = {
       const fh = __openFiles[fid];
       affirmNotRO('xWrite', fh);
       rc = (
-        n === fh.accessHandle.write(fh.sabView.subarray(0, n),
-                                    {at: Number(offset)})
+        n === (await getSyncHandle(fh))
+          .write(fh.sabView.subarray(0, n),
+                 {at: Number(offset)})
       ) ? 0 : state.sq3Codes.SQLITE_IOERR_WRITE;
     }catch(e){
       error("xWrite():",e,fh);