feat: add preventAutoDelete method to ClassHandle

build/preamble_vips.d.ts

@@ -157,6 +157,12 @@ declare module Vips {
          * @return `true` if this handle is deleted.
          */
         isDeleted(): boolean;
+
+        /**
+         * Prevents the C++ object from being auto deleted
+         * @return `this`
+         */
+        preventAutoDelete(): T;
     }
 
     /**

package.json

@@ -66,6 +66,7 @@
       "src/closure-externs/wasm-vips.js",
       "src/fixed-threadpool-web.js",
       "src/modules-pre.js",
+      "src/modules-post.js",
       "src/workaround-cors-pre.js"
     ],
     "env": [

src/CMakeLists.txt

@@ -121,6 +121,7 @@ set(MAIN_LINK_OPTIONS
         $<$<BOOL:${ENABLE_WASMFS}>:-sWASMFS>
         $<$<BOOL:${ENABLE_MODULES}>:-sMAIN_MODULE=2>
         $<$<BOOL:${ENABLE_MODULES}>:--pre-js=${CMAKE_CURRENT_SOURCE_DIR}/modules-pre.js>
+        --post-js=${CMAKE_CURRENT_SOURCE_DIR}/modules-post.js
         -sAUTOLOAD_DYLIBS=0
         -sABORTING_MALLOC=0
         -sMALLOC=mimalloc

src/modules-post.js

@@ -0,0 +1,10 @@
+Object.assign(ClassHandle.prototype, {
+  'preventAutoDelete' () {
+    const index = deletionQueue.indexOf(this);
+    if (index > -1) {
+      deletionQueue.splice(index, 1);
+    }
+    this.$$.deleteScheduled = false;
+    return this;
+  }
+});

test/unit/test_auto_delete.js

@@ -0,0 +1,72 @@
+/* global vips, expect, cleanup */
+'use strict';
+
+describe('auto delete', () => {
+  after(function () {
+    cleanup();
+    expect(vips.deletionQueue.length).to.equal(0);
+  });
+
+  it('auto delete', function () {
+    const im = vips.Image.black(100, 100);
+    expect(vips.deletionQueue.length).to.equal(1);
+    expect(() => im.clone()).to.throw(/Object already scheduled for deletion/);
+    im.gaussblur(0.3); // creates new handle
+    expect(vips.deletionQueue.length).to.equal(2);
+    cleanup();
+    expect(vips.deletionQueue.length).to.equal(0);
+  });
+
+  it('preventAutoDelete', function () {
+    const im = new vips.Image();
+    const source = new vips.SourceCustom();
+    expect(vips.deletionQueue.length).to.equal(2);
+    im.preventAutoDelete();
+    expect(vips.deletionQueue.length).to.equal(1);
+    source.preventAutoDelete();
+    expect(vips.deletionQueue.length).to.equal(0);
+
+    // cloned objects do not retain prevent auto delete status
+    const cloned = im.clone();
+    expect(vips.deletionQueue.length).to.equal(1);
+    cleanup();
+    expect(vips.deletionQueue.length).to.equal(0);
+
+    im.delete(); // should not fail
+    source.delete();
+    expect(() => im.delete()).to.throw(/Image instance already deleted/);
+    expect(() => source.delete()).to.throw(/SourceCustom instance already deleted/);
+    // already deleted by cleanup, should fail
+    expect(() => cloned.delete()).to.throw(/Image instance already deleted/);
+  });
+
+  it('preventAutoDelete on all handles', function () {
+    const handles = Object.entries(vips).filter(
+      ([key, Handle]) =>
+        key !== 'Object' && !!Handle?.prototype?.preventAutoDelete
+    );
+    expect(handles.length).to.equal(12);
+
+    for (const [name] of handles) {
+      const h = new vips[name]();
+      expect(vips.deletionQueue.length).to.equal(1);
+      h.preventAutoDelete();
+      expect(vips.deletionQueue.length).to.equal(0);
+      h.delete();
+      expect(() => h.delete()).to.throw(new RegExp(`${name} instance already deleted`));
+    }
+  });
+
+  it('preventAutoDelete on cloned handle', function () {
+    const im = new vips.Image();
+    expect(vips.deletionQueue.length).to.equal(1);
+    im.preventAutoDelete();
+    expect(vips.deletionQueue.length).to.equal(0);
+    const cloned = im.clone();
+    expect(vips.deletionQueue.length).to.equal(1);
+    cloned.preventAutoDelete();
+    expect(vips.deletionQueue.length).to.equal(0);
+    cloned.delete();
+    im.delete();
+  });
+});