Ensure disableWebAssembly setting is loaded before use

Related issue:
- https://github.com/uBlockOrigin/uBlock-issues/issues/899

WASM modules are now loaded on demand rather than at
script evaluation time.

src/js/hntrie.js

@@ -139,9 +139,7 @@ const HNTrieContainer = class {
         this.buf32[TRIE1_SLOT] = this.buf32[TRIE0_SLOT];
         this.buf32[CHAR0_SLOT] = details.char0 || 65536;
         this.buf32[CHAR1_SLOT] = this.buf32[CHAR0_SLOT];
-        this.wasmInstancePromise = null;
         this.wasmMemory = null;
-        this.readyToUse();
     }
 
     //--------------------------------------------------------------------------
@@ -153,15 +151,6 @@ const HNTrieContainer = class {
         this.buf32[CHAR1_SLOT] = this.buf32[CHAR0_SLOT];
     }
 
-    readyToUse() {
-        if ( HNTrieContainer.wasmModulePromise instanceof Promise === false ) {
-            return Promise.resolve();
-        }
-        return HNTrieContainer.wasmModulePromise.then(
-            module => this.initWASM(module)
-        );
-    }
-
     setNeedle(needle) {
         if ( needle !== this.needle ) {
             const buf = this.buf;
@@ -407,6 +396,40 @@ const HNTrieContainer = class {
         return true;
     }
 
+    async enableWASM() {
+        if ( typeof WebAssembly !== 'object' ) { return false; }
+        if ( this.wasmMemory instanceof WebAssembly.Memory ) { return true; }
+        const module = await getWasmModule();
+        if ( module instanceof WebAssembly.Module === false ) {
+            return false;
+        }
+        const memory = new WebAssembly.Memory({ initial: 2 });
+        const instance = await WebAssembly.instantiate(
+            module,
+            {
+                imports: {
+                    memory,
+                    growBuf: this.growBuf.bind(this, 24, 256)
+                }
+            }
+        );
+        if ( instance instanceof WebAssembly.Instance === false ) {
+            return false;
+        }
+        this.wasmMemory = memory;
+        const curPageCount = memory.buffer.byteLength >>> 16;
+        const newPageCount = this.buf.byteLength + PAGE_SIZE-1 >>> 16;
+        if ( newPageCount > curPageCount ) {
+            memory.grow(newPageCount - curPageCount);
+        }
+        const buf = new Uint8Array(memory.buffer);
+        buf.set(this.buf);
+        this.buf = buf;
+        this.buf32 = new Uint32Array(this.buf.buffer);
+        this.matches = this.matchesWASM = instance.exports.matches;
+        this.add = this.addWASM = instance.exports.add;
+    }
+
     //--------------------------------------------------------------------------
     // Private methods
     //--------------------------------------------------------------------------
@@ -507,39 +530,6 @@ const HNTrieContainer = class {
             this.buf32[CHAR1_SLOT] = char0 + charDataLen;
         }
     }
-
-    initWASM(module) {
-        if ( module instanceof WebAssembly.Module === false ) {
-            return Promise.resolve(null);
-        }
-        if ( this.wasmInstancePromise === null ) {
-            const memory = new WebAssembly.Memory({ initial: 2 });
-            this.wasmInstancePromise = WebAssembly.instantiate(
-                module,
-                {
-                    imports: {
-                        memory,
-                        growBuf: this.growBuf.bind(this, 24, 256)
-                    }
-                }
-            );
-            this.wasmInstancePromise.then(instance => {
-                this.wasmMemory = memory;
-                const curPageCount = memory.buffer.byteLength >>> 16;
-                const newPageCount = this.buf.byteLength + PAGE_SIZE-1 >>> 16;
-                if ( newPageCount > curPageCount ) {
-                    memory.grow(newPageCount - curPageCount);
-                }
-                const buf = new Uint8Array(memory.buffer);
-                buf.set(this.buf);
-                this.buf = buf;
-                this.buf32 = new Uint32Array(this.buf.buffer);
-                this.matches = this.matchesWASM = instance.exports.matches;
-                this.add = this.addWASM = instance.exports.add;
-            });
-        }
-        return this.wasmInstancePromise;
-    }
 };
 
 HNTrieContainer.prototype.matches = HNTrieContainer.prototype.matchesJS;
@@ -698,35 +688,8 @@ HNTrieContainer.prototype.HNTrieRef.prototype.needle = '';
 // The WASM module is entirely optional, the JS implementations will be
 // used should the WASM module be unavailable for whatever reason.
 
-(( ) => {
+const getWasmModule = (( ) => {
-    HNTrieContainer.wasmModulePromise = null;
+    let wasmModulePromise;
-
-    if (
-        typeof WebAssembly !== 'object' ||
-        typeof WebAssembly.compileStreaming !== 'function'
-    ) {
-        return;
-    }
-
-    // Soft-dependency on vAPI so that the code here can be used outside of
-    // uBO (i.e. tests, benchmarks)
-    if ( typeof vAPI === 'object' && vAPI.canWASM !== true ) { return; }
-
-    // Soft-dependency on µBlock's advanced settings so that the code here can
-    // be used outside of uBO (i.e. tests, benchmarks)
-    if (
-        typeof µBlock === 'object' &&
-        µBlock.hiddenSettings.disableWebAssembly === true
-    ) {
-        return;
-    }
-
-    // The wasm module will work only if CPU is natively little-endian,
-    // as we use native uint32 array in our js code.
-    const uint32s = new Uint32Array(1);
-    const uint8s = new Uint8Array(uint32s.buffer);
-    uint32s[0] = 1;
-    if ( uint8s[0] !== 1 ) { return; }
 
     // The directory from which the current script was fetched should also
     // contain the related WASM file. The script is fetched from a trusted
@@ -741,15 +704,40 @@ HNTrieContainer.prototype.HNTrieRef.prototype.needle = '';
         workingDir = url.href;
     }
 
-    HNTrieContainer.wasmModulePromise = fetch(
+    return async function() {
-        workingDir + 'wasm/hntrie.wasm',
+        if ( wasmModulePromise instanceof Promise ) {
-        { mode: 'same-origin' }
+            return wasmModulePromise;
-    ).then(
+        }
-        WebAssembly.compileStreaming
+
-    ).catch(reason => {
+        if (
-        HNTrieContainer.wasmModulePromise = null;
+            typeof WebAssembly !== 'object' ||
-        log.info(reason);
+            typeof WebAssembly.compileStreaming !== 'function'
-    });
+        ) {
+            return;
+        }
+
+        // Soft-dependency on vAPI so that the code here can be used outside of
+        // uBO (i.e. tests, benchmarks)
+        if ( typeof vAPI === 'object' && vAPI.canWASM !== true ) { return; }
+
+        // The wasm module will work only if CPU is natively little-endian,
+        // as we use native uint32 array in our js code.
+        const uint32s = new Uint32Array(1);
+        const uint8s = new Uint8Array(uint32s.buffer);
+        uint32s[0] = 1;
+        if ( uint8s[0] !== 1 ) { return; }
+
+        wasmModulePromise = fetch(
+            workingDir + 'wasm/hntrie.wasm',
+            { mode: 'same-origin' }
+        ).then(
+            WebAssembly.compileStreaming
+        ).catch(reason => {
+            log.info(reason);
+        });
+
+        return wasmModulePromise;
+    };
 })();
 
 /******************************************************************************/

src/js/start.js

@@ -263,6 +263,12 @@ try {
     await µb.loadHiddenSettings();
     log.info(`Hidden settings ready ${Date.now()-vAPI.T0} ms after launch`);
 
+    if ( µb.hiddenSettings.disableWebAssembly !== true ) {
+        µb.staticNetFilteringEngine.enableWASM().then(( ) => {
+            log.info(`Static filtering engine WASM modules ready ${Date.now()-vAPI.T0} ms after launch`);
+        });
+    }
+
     const cacheBackend = await µb.cacheStorage.select(
         µb.hiddenSettings.cacheStorageAPI
     );

src/js/static-net-filtering.js

@@ -311,26 +311,15 @@ const bidiTrieMatchExtra = function(l, r, ix) {
     return 0;
 };
 
-const bidiTrie = (( ) => {
+const bidiTrie = new µb.BidiTrieContainer(
-    let trieDetails;
+    vAPI.localStorage.getItem('SNFE.bidiTrieDetails'),
-    try {
+    bidiTrieMatchExtra
-        trieDetails = JSON.parse(
+);
-            vAPI.localStorage.getItem('SNFE.bidiTrieDetails')
-        );
-    } catch(ex) {
-    }
-    const trie = new µb.BidiTrieContainer(trieDetails, bidiTrieMatchExtra);
-    if ( µb.hiddenSettings.disableWebAssembly !== true ) {
-        trie.enableWASM();
-    }
-    return trie;
-})();
 
 const bidiTrieOptimize = function(shrink = false) {
-    const trieDetails = bidiTrie.optimize(shrink);
     vAPI.localStorage.setItem(
         'SNFE.bidiTrieDetails',
-        JSON.stringify(trieDetails)
+        bidiTrie.optimize(shrink)
     );
 };
 
@@ -1157,14 +1146,9 @@ registerFilterClass(FilterRegex);
 
 const filterOrigin = new (class {
     constructor() {
-        let trieDetails;
+        this.trieContainer = new µb.HNTrieContainer(
-        try {
+            vAPI.localStorage.getItem('FilterOrigin.trieDetails')
-            trieDetails = JSON.parse(
+        );
-                vAPI.localStorage.getItem('FilterOrigin.trieDetails')
-            );
-        } catch(ex) {
-        }
-        this.trieContainer = new µb.HNTrieContainer(trieDetails);
         this.strToUnitMap = new Map();
         this.gcTimer = undefined;
     }
@@ -1244,10 +1228,9 @@ const filterOrigin = new (class {
     }
 
     optimize() {
-        const trieDetails = this.trieContainer.optimize();
         vAPI.localStorage.setItem(
             'FilterOrigin.trieDetails',
-            JSON.stringify(trieDetails)
+            this.trieContainer.optimize()
         );
     }
 
@@ -1689,10 +1672,9 @@ const FilterHostnameDict = class {
     }
 
     static optimize() {
-        const trieDetails = FilterHostnameDict.trieContainer.optimize();
         vAPI.localStorage.setItem(
             'FilterHostnameDict.trieDetails',
-            JSON.stringify(trieDetails)
+            FilterHostnameDict.trieContainer.optimize()
         );
     }
 
@@ -1701,16 +1683,9 @@ const FilterHostnameDict = class {
     }
 };
 
-FilterHostnameDict.trieContainer = (( ) => {
+FilterHostnameDict.trieContainer = new µb.HNTrieContainer(
-    let trieDetails;
+    vAPI.localStorage.getItem('FilterHostnameDict.trieDetails')
-    try {
+);
-        trieDetails = JSON.parse(
-            vAPI.localStorage.getItem('FilterHostnameDict.trieDetails')
-        );
-    } catch(ex) {
-    }
-    return new µb.HNTrieContainer(trieDetails);
-})();
 
 registerFilterClass(FilterHostnameDict);
 
@@ -3445,6 +3420,16 @@ FilterContainer.prototype.getFilterCount = function() {
 
 /******************************************************************************/
 
+FilterContainer.prototype.enableWASM = function() {
+    return Promise.all([
+        bidiTrie.enableWASM(),
+        filterOrigin.trieContainer.enableWASM(),
+        FilterHostnameDict.trieContainer.enableWASM(),
+    ]);
+};
+
+/******************************************************************************/
+
 // action: 1=test, 2=record
 
 FilterContainer.prototype.benchmark = async function(action, target) {

src/js/storage.js

@@ -198,7 +198,6 @@ self.addEventListener('hiddenSettingsChanged', ( ) => {
 µBlock.saveImmediateHiddenSettings = function() {
     const props = [
         'consoleLogLevel',
-        'disableWebAssembly',
         'suspendTabsUntilReady',
     ];
     const toSave = {};
@@ -1011,7 +1010,7 @@ self.addEventListener('hiddenSettingsChanged', ( ) => {
 /******************************************************************************/
 
 µBlock.loadPublicSuffixList = async function() {
-    if ( this.hiddenSettings.disableWebAssembly === false ) {
+    if ( this.hiddenSettings.disableWebAssembly !== true ) {
         publicSuffixList.enableWASM();
     }
 

src/js/strie.js

@@ -914,7 +914,20 @@ const roundToPageSize = v => (v + PAGE_SIZE-1) & ~(PAGE_SIZE-1);
 const getWasmModule = (( ) => {
     let wasmModulePromise;
 
-    return function() {
+    // The directory from which the current script was fetched should also
+    // contain the related WASM file. The script is fetched from a trusted
+    // location, and consequently so will be the related WASM file.
+    let workingDir;
+    {
+        const url = new URL(document.currentScript.src);
+        const match = /[^\/]+$/.exec(url.pathname);
+        if ( match !== null ) {
+            url.pathname = url.pathname.slice(0, match.index);
+        }
+        workingDir = url.href;
+    }
+
+    return async function() {
         if ( wasmModulePromise instanceof Promise ) {
             return wasmModulePromise;
         }
@@ -937,19 +950,6 @@ const getWasmModule = (( ) => {
         uint32s[0] = 1;
         if ( uint8s[0] !== 1 ) { return; }
 
-        // The directory from which the current script was fetched should also
-        // contain the related WASM file. The script is fetched from a trusted
-        // location, and consequently so will be the related WASM file.
-        let workingDir;
-        {
-            const url = new URL(document.currentScript.src);
-            const match = /[^\/]+$/.exec(url.pathname);
-            if ( match !== null ) {
-                url.pathname = url.pathname.slice(0, match.index);
-            }
-            workingDir = url.href;
-        }
-
         wasmModulePromise = fetch(
             workingDir + 'wasm/biditrie.wasm',
             { mode: 'same-origin' }