Add preventAutoDelete method to ClassHandle (#70)

build/preamble_vips.d.ts

@@ -158,6 +158,12 @@ 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

@@ -64,8 +64,8 @@
     ],
     "ignore": [
       "src/closure-externs/wasm-vips.js",
-      "src/fixed-threadpool-web.js",
       "src/modules-pre.js",
+      "src/vips-library.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>
+        --js-library=${CMAKE_CURRENT_SOURCE_DIR}/vips-library.js
         -sAUTOLOAD_DYLIBS=0
         -sABORTING_MALLOC=0
         -sMALLOC=mimalloc
@@ -168,9 +169,6 @@ if ("web" IN_LIST ENVIRONMENT)
     set(WEB_CORS_WORKAROUND
             --pre-js=${CMAKE_CURRENT_SOURCE_DIR}/workaround-cors-pre.js
             )
-    set(WEB_FIXED_THREADPOOL
-            --js-library=${CMAKE_CURRENT_SOURCE_DIR}/fixed-threadpool-web.js
-            )
     set(WEB_MIN_TARGETS
             -sMIN_FIREFOX_VERSION=89
             -sMIN_CHROME_VERSION=91
@@ -182,7 +180,6 @@ if ("web" IN_LIST ENVIRONMENT)
     set(WEB_LINK_OPTIONS
             --use-preload-plugins
             -sPTHREAD_POOL_SIZE='navigator.hardwareConcurrency+2+1'
-            ${WEB_FIXED_THREADPOOL}
             ${WEB_MIN_TARGETS}
             )
 

src/vips-library.js

@@ -0,0 +1,35 @@
+var LibraryVips = {
+  $VIPS__deps: [
+#if ENVIRONMENT_MAY_BE_WEB
+    '$ENV',
+#endif
+    '$ClassHandle',
+    '$deletionQueue',
+  ],
+  $VIPS__postset: 'VIPS.init();',
+  $VIPS: {
+    init() {
+#if ENVIRONMENT_MAY_BE_WEB
+      addOnPreRun(() => {
+        // Enforce a fixed thread pool by default on web
+        ENV['VIPS_MAX_THREADS'] = {{{ PTHREAD_POOL_SIZE }}};
+      });
+#endif
+
+      // Add preventAutoDelete method to ClassHandle
+      Object.assign(ClassHandle.prototype, {
+        'preventAutoDelete'() {
+          const index = deletionQueue.indexOf(this);
+          if (index > -1) {
+            deletionQueue.splice(index, 1);
+          }
+          this.$$.deleteScheduled = false;
+          return this;
+        }
+      });
+    }
+  }
+}
+
+addToLibrary(LibraryVips);
+DEFAULT_LIBRARY_FUNCS_TO_INCLUDE.push('$VIPS');

test/unit/index.html

@@ -74,6 +74,7 @@
 </script>
 <script src="lib/vips.js"></script>
 <script type="module" src="test_arithmetic.js"></script>
+<script type="module" src="test_auto_delete.js"></script>
 <script type="module" src="test_block.js"></script>
 <script type="module" src="test_colour.js"></script>
 <script type="module" src="test_connection.js"></script>

test/unit/test_auto_delete.js

@@ -0,0 +1,63 @@
+/* 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);
+  });
+
+  describe('preventAutoDelete', () => {
+    it('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('cloned handle', function () {
+      const im = new vips.Image();
+      expect(vips.deletionQueue.length).to.equal(1);
+
+      im.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
+      expect(() => im.delete()).to.throw(/Image instance already deleted/);
+
+      // already deleted by cleanup, should fail
+      expect(() => cloned.delete()).to.throw(/Image instance already deleted/);
+    });
+  });
+});