Cleanups in the opfs-sahpool VFS pause/unpause feature and its tests.

FossilOrigin-Name: 184ba37702f63196deca91d273e798ca895fbb301938e6264bc82815a4e33149

ext/wasm/api/sqlite3-vfs-opfs-sahpool.c-pp.js

@@ -501,22 +501,10 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
        currently-opened client-specified filenames. */
     getFileNames(){
       const rc = [];
-      const iter = this.#mapFilenameToSAH.keys();
+      for(const n of this.#mapFilenameToSAH.keys()) rc.push(n);
-      for(const n of iter) rc.push(n);
       return rc;
     }
 
-//    #createFileObject(sah,clientName,opaqueName){
-//      const f = Object.assign(Object.create(null),{
-//        clientName, opaqueName
-//      });
-//      this.#mapSAHToMeta.set(sah, f);
-//      return f;
-//    }
-//    #unmapFileObject(sah){
-//      this.#mapSAHToMeta.delete(sah);
-//    }
-
     /**
        Adds n files to the pool's capacity. This change is
        persistent across settings. Returns a Promise which resolves
@@ -557,8 +545,9 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
     }
 
     /**
-       Releases all currently-opened SAHs. The only legal
+       Releases all currently-opened SAHs. The only legal operation
-       operation after this is acquireAccessHandles().
+       after this is acquireAccessHandles() or (if this is called from
+       pauseVfs()) either of isPaused() or unpauseVfs().
     */
     releaseAccessHandles(){
       for(const ah of this.#mapSAHToName.keys()) ah.close();
@@ -568,17 +557,21 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
     }
 
     /**
-       Opens all files under this.vfsDir/this.#dhOpaque and acquires
+       Opens all files under this.vfsDir/this.#dhOpaque and acquires a
-       a SAH for each. returns a Promise which resolves to no value
+       SAH for each. Returns a Promise which resolves to no value but
-       but completes once all SAHs are acquired. If acquiring an SAH
+       completes once all SAHs are acquired. If acquiring an SAH
-       throws, SAHPool.$error will contain the corresponding
+       throws, this.$error will contain the corresponding Error
-       exception.
+       object.
+
+       If it throws, it releases any SAHs which it may have
+       acquired before the exception was thrown, leaving the VFS in a
+       well-defined but unusable state.
 
        If clearFiles is true, the client-stored state of each file is
        cleared when its handle is acquired, including its name, flags,
        and any data stored after the metadata block.
     */
-    async acquireAccessHandles(clearFiles){
+    async acquireAccessHandles(clearFiles=false){
       const files = [];
       for await (const [name,h] of this.#dhOpaque){
         if('file'===h.kind){
@@ -859,7 +852,7 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
         );
         this.#dhVfsRoot = this.#dhVfsParent = undefined;
       }catch(e){
-        sqlite3.config.error(this.vfsName,"removeVfs() failed:",e);
+        sqlite3.config.error(this.vfsName,"removeVfs() failed with no recovery strategy:",e);
         /*otherwise ignored - there is no recovery strategy*/
       }
       return true;
@@ -872,19 +865,26 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
        intact. If this object is already paused, this is a
        no-op. Returns this object.
 
-       This function throws if any database handles are active, as the
+       This function throws if SQLite has any opened file handles
-       alternative would be to invoke Undefined Behavior by closing
+       hosted by this VFS, as the alternative would be to invoke
-       that file handle out from under the database. Similarly,
+       Undefined Behavior by closing file handles out from under any
-       automatically closing any database handles opened by this VFS
+       the library. Similarly, automatically closing any database
-       would invoke Undefined Behavior in downstream code which is
+       handles opened by this VFS would invoke Undefined Behavior in
-       holding those pointers.
+       downstream code which is holding those pointers.
+
+       If this function throws due to open file handles then it has
+       no side effects. If the OPFS API throws while closing handles
+       then the VFS is left in an undefined state.
 
        @see isPaused()
        @see unpauseVfs()
     */
     pauseVfs(){
       if(this.#mapS3FileToOFile_.size>0){
-        toss("Cannot pause a VFS which has an opened database.")
+        sqlite3.SQLite3Error.toss(
+          capi.SQLITE_MISUSE, "Cannot pause VFS",
+          this.vfsName,"because it has opened files."
+        );
       }
       if(this.#mapSAHToName.size>0){
         capi.sqlite3_vfs_unregister(this.vfsName);
@@ -908,7 +908,9 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
        re-registering it with SQLite. This is a no-op if the VFS is
        not currently paused.
 
-       The returned Promise resolves to this object.
+       The returned Promise resolves to this object. See
+       acquireAccessHandles() for how it behaves if it throws due to
+       SAH acquisition failure.
 
        @see isPaused()
        @see pauseVfs()
@@ -1282,6 +1284,41 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
      Clears all client-defined state of all SAHs and makes all of them
      available for re-use by the pool. Results are undefined if any such
      handles are currently in use, e.g. by an sqlite3 db.
+
+     APIs specific to the "pause" capability (added in version 3.49):
+
+     Summary: "pausing" the VFS disassociates it from SQLite and
+     relinquishes its SAHs so that they may be opened by another
+     instance of this VFS (running in a separate tab/page or Worker).
+     "Unpausing" it takes back control, if able.
+
+     - pauseVfs()
+
+     "Pauses" this VFS by unregistering it from SQLite and
+     relinquishing all open SAHs, leaving the associated files intact.
+     This enables pages/tabs to coordinate semi-concurrent usage of
+     this VFS.  If this object is already paused, this is a
+     no-op. Returns this object. Throws if SQLite has any opened file
+     handles hosted by this VFS. If this function throws due to open
+     file handles then it has no side effects. If the OPFS API throws
+     while closing handles then the VFS is left in an undefined state.
+
+     - isPaused()
+
+     Returns true if this VFS is paused, else false.
+
+     - [async] unpauseVfs()
+
+     Restores the VFS to an active state after having called
+     pauseVfs() on it.  This is a no-op if the VFS is not paused. The
+     returned Promise resolves to this object on success. A rejected
+     Promise means there was a problem reacquiring the SAH handles
+     (possibly because they're in use by another instance or have
+     since been removed). Generically speaking, there is recovery
+     strategy for that type of error, but if the problem is simply
+     that the OPFS files are locked, then a later attempt to unpause
+     it, made after the concurrent instance releases the SAHs, may
+     recover from the situation.
   */
   sqlite3.installOpfsSAHPoolVfs = async function(options=Object.create(null)){
     options = Object.assign(Object.create(null), optionDefaults, (options||{}));

ext/wasm/tester1.c-pp.js

@@ -3155,12 +3155,23 @@ globalThis.sqlite3InitModule = sqlite3InitModule;
         T.assert(1 === u1.getFileCount());
         db = new u2.OpfsSAHPoolDb(dbName);
         T.assert(1 === u1.getFileCount())
-          .mustThrow(()=>u2.pauseVfs(), "Cannot pause VFS with opened db.");
+          .mustThrowMatching(
+            ()=>u1.pauseVfs(),
+            (err)=>{
+              return capi.SQLITE_MISUSE===err.resultCode
+                && /^SQLITE_MISUSE: Cannot pause VFS /.test(err.message);
+            },
+            "Cannot pause VFS with opened db."
+          );
         db.close();
         T.assert( u2===u2.pauseVfs() )
           .assert( u2.isPaused() )
           .assert( 0===capi.sqlite3_vfs_find(u2.vfsName) )
+          .mustThrowMatching(()=>new u2.OpfsSAHPoolDb(dbName),
+                             /.+no such vfs: .+/,
+                             "VFS is not available")
           .assert( u2===await u2.unpauseVfs() )
+          .assert( u2===await u1.unpauseVfs(), "unpause is a no-op if the VFS is not paused" )
           .assert( 0!==capi.sqlite3_vfs_find(u2.vfsName) );
         const fileNames = u1.getFileNames();
         T.assert(1 === fileNames.length)

manifest

@@ -1,5 +1,5 @@
-C Merge\strunk\sinto\sopfs-sahpool-pause\sbranch.
+C Cleanups\sin\sthe\sopfs-sahpool\sVFS\spause/unpause\sfeature\sand\sits\stests.
-D 2025-01-31T12:39:07.019
+D 2025-01-31T14:25:38.298
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md e108e1e69ae8e8a59e93c455654b8ac9356a11720d3345df2a4743e9590fb20d
@@ -645,7 +645,7 @@ F ext/wasm/api/sqlite3-api-worker1.c-pp.js 5cc22a3c0d52828cb32aad8691488719f47d2
 F ext/wasm/api/sqlite3-license-version-header.js 0c807a421f0187e778dc1078f10d2994b915123c1223fe752b60afdcd1263f89
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-F ext/wasm/api/sqlite3-vfs-opfs-sahpool.c-pp.js c8d6f02d834224290009d25876d2ec011cb9b8dc425e3a0761b7e55d9a67c24f
+F ext/wasm/api/sqlite3-vfs-opfs-sahpool.c-pp.js 4878cf2a19577093ea82b505f0b052147ca11d27575106c1bb30d2f58efc80a4
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 F ext/wasm/api/sqlite3-wasm.c 83f5e9f998e9fa4261eb84e9f092210e3ffe03895119f5ded0429eb34ab9d2be
@@ -696,7 +696,7 @@ F ext/wasm/test-opfs-vfs.html 1f2d672f3f3fce810dfd48a8d56914aba22e45c6834e262555
 F ext/wasm/test-opfs-vfs.js 1618670e466f424aa289859fe0ec8ded223e42e9e69b5c851f809baaaca1a00c
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 F ext/wasm/tester1.c-pp.html 1c1bc78b858af2019e663b1a31e76657b73dc24bede28ca92fbe917c3a972af2
-F ext/wasm/tester1.c-pp.js 7f239383c06078fe67919509f7e1691d3b970a5f6cd4dc4adab71bc8e6cf6fe8
+F ext/wasm/tester1.c-pp.js 0cda9a3180e743f4a42500cbcde1a14da920b34697eb4b05adedac0dab5381de
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 F ext/wasm/tests/opfs/concurrency/worker.js 0a8c1a3e6ebb38aabbee24f122693f1fb29d599948915c76906681bb7da1d3d2
@@ -2209,8 +2209,8 @@ F tool/version-info.c 3b36468a90faf1bbd59c65fd0eb66522d9f941eedd364fabccd7227350
 F tool/warnings-clang.sh bbf6a1e685e534c92ec2bfba5b1745f34fb6f0bc2a362850723a9ee87c1b31a7
 F tool/warnings.sh 49a486c5069de041aedcbde4de178293e0463ae9918ecad7539eedf0ec77a139
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
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+R af1dcaea4b1a4f1eb6d1dba2bd937843
 U stephan
-Z 411d369a110121e7891ed7e96e9dfba9
+Z 577676d1355d687b76945b6366664411
 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
-775a547eca2b0b3dbb6c03990236128a095cc34d28caec44b9a5072510c75b63
+184ba37702f63196deca91d273e798ca895fbb301938e6264bc82815a4e33149