Allow removing the updateHook callback

Also release the callback function when the callback is removed or the
database is closed.

Include the previously omitted database name in the callback args as the
sqlite callback does.

Author: Erik Soehnel

src/api.js

@@ -1124,6 +1124,12 @@ Module["onRuntimeInitialized"] = function onRuntimeInitialized() {
         });
         Object.values(this.functions).forEach(removeFunction);
         this.functions = {};
+
+        if (this.updateHookFunctionPtr) {
+            removeFunction(this.updateHookFunctionPtr);
+            this.updateHookFunctionPtr = undefined;
+        }
+
         this.handleError(sqlite3_close_v2(this.db));
         FS.unlink("/" + this.filename);
         this.db = null;
@@ -1394,27 +1400,39 @@ Module["onRuntimeInitialized"] = function onRuntimeInitialized() {
     };
 
     /** Registers the update hook with SQLite
-        @param {function(operation, tableName, rowId)} callback
+        @param {function(operation, database, table, rowId) | null} callback
              executed whenever a row in any rowid table is changed
 
         For each changed row, the callback is called once with the change
-        ('insert', 'update' or 'delete'), the table name where the change
-        happened and the rowid of the row that has been changed.
+        ('insert', 'update' or 'delete'), the database name and table name
+        where the change happened and the rowid of the row that has been
+        changed.
 
         rowid is cast to a plain number, if it exceeds Number.MAX_SAFE_INTEGER
         an error will be thrown.
 
         The callback MUST NOT modify the database in any way.
 
         Only a single callback can be registered. Unregister the callback by
-        passing an empty function.
+        passing null.
 
-        Not called for some updates like ON REPLACE CONFLICT and TRUNCATE.
+        Not called for some updates like ON REPLACE CONFLICT and TRUNCATE (a
+        DELETE FROM without a WHERE clause).
 
         See sqlite docs on sqlite3_update_hook for more details.
        */
     Database.prototype["updateHook"] = function updateHook(callback) {
-        this.updateHookCallback = callback;
+        if (this.updateHookFunctionPtr) {
+            // unregister and cleanup a previously registered update hook
+            sqlite3_update_hook(this.db, 0, 0);
+            removeFunction(this.updateHookFunctionPtr);
+            this.updateHookFunctionPtr = undefined;
+        }
+
+        if (!callback) {
+            // no new callback to register
+            return;
+        }
 
         // void(*)(void *,int ,char const *,char const *,sqlite3_int64)
         function wrappedCallback(
@@ -1441,6 +1459,7 @@ Module["onRuntimeInitialized"] = function onRuntimeInitialized() {
                         + operationCode;
             }
 
+            var databaseName = UTF8ToString(databaseNamePtr);
             var tableName = UTF8ToString(tableNamePtr);
 
             if (rowIdBigInt > Number.MAX_SAFE_INTEGER) {
@@ -1449,18 +1468,16 @@ Module["onRuntimeInitialized"] = function onRuntimeInitialized() {
 
             var rowId = Number(rowIdBigInt);
 
-            if (this.updateHookCallback) {
-                this.updateHookCallback(operation, tableName, rowId);
-            }
+            callback(operation, databaseName, tableName, rowId);
         }
 
-        var funcPtr = addFunction(wrappedCallback.bind(this), "viiiij");
+        this.updateHookFunctionPtr = addFunction(wrappedCallback, "viiiij");
 
-        this.handleError(sqlite3_update_hook(
+        sqlite3_update_hook(
             this.db,
-            funcPtr,
+            this.updateHookFunctionPtr,
             0 // passed as the first arg to wrappedCallback
-        ));
+        );
     };
 
     // export Database to Module

test/test_update_hook.js

@@ -7,37 +7,66 @@ exports.test = function(SQL, assert){
     "INSERT INTO consoles VALUES (2, 'Microsoft', 'Xbox');"
   );
 
-  // {operation: undefined, tableName: undefined, rowId: undefined};
+  // {operation: undefined, databaseName: undefined, tableName: undefined, rowId: undefined};
   var updateHookCalls = []
 
-  db.updateHook(function(operation, tableName, rowId) {
-    updateHookCalls.push({operation, tableName, rowId});
+  db.updateHook(function(operation, databaseName, tableName, rowId) {
+    updateHookCalls.push({operation, databaseName, tableName, rowId});
   });
 
   // INSERT
   db.exec("INSERT INTO consoles VALUES (3, 'Sega', 'Saturn');");
 
-  assert.deepEqual(updateHookCalls, [{operation: 'insert', tableName: 'consoles', rowId: 3}], 'insert a single row');
-  updateHookCalls = []
+  assert.deepEqual(updateHookCalls, [
+    {operation: "insert", databaseName: "main", tableName: "consoles", rowId: 3}
+  ], "insert a single row");
 
   // UPDATE
+  updateHookCalls = []
   db.exec("UPDATE consoles SET name = 'Playstation 5' WHERE id = 1");
 
-  assert.deepEqual(updateHookCalls, [{operation: 'update', tableName: 'consoles', rowId: 1}], 'update a single row');
-  updateHookCalls = []
+  assert.deepEqual(updateHookCalls, [
+    {operation: "update", databaseName: "main", tableName: "consoles", rowId: 1}
+  ], "update a single row");
 
   // UPDATE (multiple rows)
+  updateHookCalls = []
   db.exec("UPDATE consoles SET name = name + ' [legacy]' WHERE id IN (2,3)");
 
   assert.deepEqual(updateHookCalls, [
-    {operation: 'update', tableName: 'consoles', rowId: 2},
-    {operation: 'update', tableName: 'consoles', rowId: 3},
-  ], 'update two rows');
-  updateHookCalls = []
+    {operation: "update", databaseName: "main", tableName: "consoles", rowId: 2},
+    {operation: "update", databaseName: "main", tableName: "consoles", rowId: 3},
+  ], "update two rows");
 
   // DELETE
+  updateHookCalls = []
   db.exec("DELETE FROM consoles WHERE company = 'Sega'");
 
-  assert.deepEqual(updateHookCalls, [{operation: 'delete', tableName: 'consoles', rowId: 3}], 'delete a single row');
+  assert.deepEqual(updateHookCalls, [
+    {operation: "delete", databaseName: "main", tableName: "consoles", rowId: 3}
+  ], "delete a single row");
+
+  // UNREGISTER
   updateHookCalls = []
+
+  db.updateHook(null);
+
+  db.exec("DELETE FROM consoles WHERE company = 'Microsoft'");
+
+  assert.deepEqual(updateHookCalls, [], "unregister the update hook");
+
+  // REGISTER AGAIN
+  updateHookCalls = []
+
+  db.updateHook(function(operation, databaseName, tableName, rowId) {
+    updateHookCalls.push({operation, databaseName, tableName, rowId});
+  });
+
+  // need a where clause, just running "DELETE FROM consoles" would result in
+  // a TRUNCATE and not yield any update hook callbacks
+  db.exec("DELETE FROM consoles WHERE id > 0");
+
+  assert.deepEqual(updateHookCalls, [
+    {operation: 'delete', databaseName: 'main', tableName: 'consoles', rowId: 1}
+  ], "register the update hook again");
 }