javascript: rename and simplify DB.callInTransaction() as DB.transaction(). Add DB.savepoint(), which works the same as transaction() but uses savepoints. Correct concatenation of arguments to SQLite3Error to use spaces instead of commas. Test that demo-oo1.js works with persistent OPFS storage (output differs due to persistent rows, but the demo works).

FossilOrigin-Name: e8c323f12b6223bc9dcbbec40698969c7917128aa50cf599c247df23f607ae61

ext/wasm/api/sqlite3-api-oo1.js

@@ -59,12 +59,16 @@
      enabling clients to unambiguously identify such exceptions.
   */
   class SQLite3Error extends Error {
+    /**
+       Constructs this object with a message equal to all arguments
+       concatenated with a space between each one.
+    */
     constructor(...args){
-      super(...args);
+      super(args.join(' '));
       this.name = 'SQLite3Error';
     }
   };
-  const toss3 = (...args)=>{throw new SQLite3Error(args)};
+  const toss3 = (...args)=>{throw new SQLite3Error(...args)};
   sqlite3.SQLite3Error = SQLite3Error;
 
   /**
@@ -195,7 +199,7 @@
   };
 
   /**
-     Expects to be passed (arguments) from DB.exec() and
+     Expects to be passed the `arguments` object from DB.exec() and
      DB.execMulti(). Does the argument processing/validation, throws
      on error, and returns a new object on success:
 
@@ -842,26 +846,47 @@
 
     /**
        Starts a transaction, calls the given callback, and then either
-       rolls back or commits the transaction, depending on whether the
-       callback throw. The callback is pass this db object as its only
-       argument.  On success, returns the result of the callback.
-       Throws on error.
+       rolls back or commits the savepoint, depending on whether the
+       callback throws. The callback is passed this db object as its
+       only argument. On success, returns the result of the
+       callback. Throws on error.
+
+       Note that transactions may not be nested, so this will throw if
+       it is called recursively. For nested transactions, use the
+       savepoint() method or manually manage SAVEPOINTs using exec().
      */
-    callInTransaction: function(callback){
-      affirmDbOpen(this);
-      let err, rc;
-      this.exec("BEGIN");
-      try { rc = callback(this); }
-      catch(e){
-        err = e;
+    transaction: function(callback){
+      affirmDbOpen(this).exec("BEGIN");
+      try {
+        const rc = callback(this);
+        this.exec("COMMIT");
+        return rc;
+      }catch(e){
+        this.exec("ROLLBACK");
         throw e;
-      }finally{
-        if(err) this.exec("ROLLBACK");
-        else this.exec("COMMIT");
       }
-      return rc;
     },
 
+    /**
+       This works similarly to transaction() but uses sqlite3's SAVEPOINT
+       feature. This function starts a savepoint (with an unspecified name)
+       and calls the given callback function, passing it this db object.
+       If the callback returns, the savepoint is released (committed). If
+       the callback throws, the savepoint is rolled back. If it does not
+       throw, it returns the result of the callback.
+    */
+    savepoint: function(callback){
+      affirmDbOpen(this).exec("SAVEPOINT oo1");
+      try {
+        const rc = callback(this);
+        this.exec("RELEASE oo1");
+        return rc;
+      }catch(e){
+        this.execMulti("ROLLBACK to SAVEPOINT oo1; RELEASE SAVEPOINT oo1");
+        throw e;
+      }
+    },
+    
     /**
        This function currently does nothing and always throws.  It
        WILL BE REMOVED pending other refactoring, to eliminate a hard