Make emscripten with threads compile

Attempt at threads for webp encoder
2018-11-02 18:34:23 +00:00 · 2018-11-01 22:36:38 +00:00
7 changed files with 210 additions and 32 deletions
--- a/codecs/really_big.jpg
+++ b/codecs/really_big.jpg
--- a/codecs/webp_enc/build.sh
+++ b/codecs/webp_enc/build.sh
@ -14,9 +14,12 @@ echo "============================================="
  emcc \
    ${OPTIMIZE} \
    --bind \
-    -s ALLOW_MEMORY_GROWTH=1 \
-    -s MODULARIZE=1 \
-    -s 'EXPORT_NAME="webp_enc"' \
+    -D WEBP_USE_THREAD=1 \
+    -s USE_PTHREADS=1 \
+    -s ASSERTIONS=1 \
+    -s PTHREAD_POOL_SIZE=4 \
+    -s TOTAL_MEMORY=268435456 \
+    -s WASM_MEM_MAX=268435456 \
    --std=c++11 \
    -I node_modules/libwebp \
    -o ./webp_enc.js \
--- a/codecs/webp_enc/example.html
+++ b/codecs/webp_enc/example.html
@ -1,7 +1,7 @@
 <!doctype html>
 <script src='webp_enc.js'></script>
 <script>
-  const module = webp_enc();
+  // const Module = webp_enc();

  async function loadImage(src) {
    // Load image
@ -17,10 +17,11 @@
    return ctx.getImageData(0, 0, img.width, img.height);
  }

-  module.onRuntimeInitialized = async _ => {
-    console.log('Version:', module.version().toString(16));
-    const image = await loadImage('../example.png');
-    const result = module.encode(image.data, image.width, image.height, {
+  Module.onRuntimeInitialized = async _ => {
+    console.log('Version:', Module.version().toString(16));
+    const image = await loadImage('../really_big.jpg');
+    let start = performance.now();
+    const result = Module.encode(image.data, image.width, image.height, {
      quality: 75,
      target_size: 0,
      target_PSNR: 0,
@ -43,16 +44,18 @@
      exact: 0,
      image_hint: 0,
      emulate_jpeg_size: 0,
-      thread_level: 0,
+      thread_level: 1,
      low_memory: 0,
      near_lossless: 100,
      use_delta_palette: 0,
      use_sharp_yuv: 0,
    });
+    let stop = performance.now();
    console.log('size', result.length);
-    const blob = new Blob([result], {type: 'image/webp'});
+    console.log('time', stop - start);
+    const blob = new Blob([new Uint8Array(result)], {type: 'image/webp'});

-    module.free_result();
+    Module.free_result();

    const blobURL = URL.createObjectURL(blob);
    const img = document.createElement('img');
--- a/codecs/webp_enc/pthread-main.js
+++ b/codecs/webp_enc/pthread-main.js
@ -0,0 +1,192 @@
+// Copyright 2015 The Emscripten Authors.  All rights reserved.
+// Emscripten is available under two separate licenses, the MIT license and the
+// University of Illinois/NCSA Open Source License.  Both these licenses can be
+// found in the LICENSE file.
+
+// Pthread Web Worker startup routine:
+// This is the entry point file that is loaded first by each Web Worker
+// that executes pthreads on the Emscripten application.
+
+// Thread-local:
+var threadInfoStruct = 0; // Info area for this thread in Emscripten HEAP (shared). If zero, this worker is not currently hosting an executing pthread.
+var selfThreadId = 0; // The ID of this thread. 0 if not hosting a pthread.
+var parentThreadId = 0; // The ID of the parent pthread that launched this thread.
+var tempDoublePtr = 0; // A temporary memory area for global float and double marshalling operations.
+
+// Thread-local: Each thread has its own allocated stack space.
+var STACK_BASE = 0;
+var STACKTOP = 0;
+var STACK_MAX = 0;
+
+// These are system-wide memory area parameters that are set at main runtime startup in main thread, and stay constant throughout the application.
+var buffer; // All pthreads share the same Emscripten HEAP as SharedArrayBuffer with the main execution thread.
+var DYNAMICTOP_PTR = 0;
+var TOTAL_MEMORY = 0;
+var STATICTOP = 0;
+var staticSealed = true; // When threads are being initialized, the static memory area has been already sealed a long time ago.
+var DYNAMIC_BASE = 0;
+
+var ENVIRONMENT_IS_PTHREAD = true;
+
+// performance.now() is specced to return a wallclock time in msecs since that Web Worker/main thread launched. However for pthreads this can cause
+// subtle problems in emscripten_get_now() as this essentially would measure time from pthread_create(), meaning that the clocks between each threads
+// would be wildly out of sync. Therefore sync all pthreads to the clock on the main browser thread, so that different threads see a somewhat
+// coherent clock across each of them (+/- 0.1msecs in testing)
+var __performance_now_clock_drift = 0;
+
+// Cannot use console.log or console.error in a web worker, since that would risk a browser deadlock! https://bugzilla.mozilla.org/show_bug.cgi?id=1049091
+// Therefore implement custom logging facility for threads running in a worker, which queue the messages to main thread to print.
+var Module = {};
+
+// When error objects propagate from Web Worker to main thread, they lose helpful call stack and thread ID information, so print out errors early here,
+// before that happens.
+this.addEventListener('error', function(e) {
+  if (e.message.indexOf('SimulateInfiniteLoop') != -1) return e.preventDefault();
+
+  var errorSource = ' in ' + e.filename + ':' + e.lineno + ':' + e.colno;
+  console.error('Pthread ' + selfThreadId + ' uncaught exception' + (e.filename || e.lineno || e.colno ? errorSource : '') + ': ' + e.message + '. Error object:');
+  console.error(e.error);
+});
+
+function threadPrint() {
+  var text = Array.prototype.slice.call(arguments).join(' ');
+  console.log(text);
+}
+function threadPrintErr() {
+  var text = Array.prototype.slice.call(arguments).join(' ');
+  console.error(text);
+  console.error(new Error().stack);
+}
+function threadAlert() {
+  var text = Array.prototype.slice.call(arguments).join(' ');
+  postMessage({cmd: 'alert', text: text, threadId: selfThreadId});
+}
+out = threadPrint;
+err = threadPrintErr;
+this.alert = threadAlert;
+
+// #if WASM
+Module['instantiateWasm'] = function(info, receiveInstance) {
+  // Instantiate from the module posted from the main thread.
+  // We can just use sync instantiation in the worker.
+  instance = new WebAssembly.Instance(Module['wasmModule'], info);
+  // We don't need the module anymore; new threads will be spawned from the main thread.
+  delete Module['wasmModule'];
+  receiveInstance(instance);
+  return instance.exports;
+}
+//#endif
+
+this.onmessage = function(e) {
+  try {
+    if (e.data.cmd === 'load') { // Preload command that is called once per worker to parse and load the Emscripten code.
+      // Initialize the thread-local field(s):
+      tempDoublePtr = e.data.tempDoublePtr;
+
+      // Initialize the global "process"-wide fields:
+      Module['TOTAL_MEMORY'] = TOTAL_MEMORY = e.data.TOTAL_MEMORY;
+      STATICTOP = e.data.STATICTOP;
+      DYNAMIC_BASE = e.data.DYNAMIC_BASE;
+      DYNAMICTOP_PTR = e.data.DYNAMICTOP_PTR;
+
+
+//#if WASM
+      if (e.data.wasmModule) {
+        // Module and memory were sent from main thread
+        Module['wasmModule'] = e.data.wasmModule;
+        Module['wasmMemory'] = e.data.wasmMemory;
+        buffer = Module['wasmMemory'].buffer;
+      } else {
+//#else
+        buffer = e.data.buffer;
+      }
+//#endif
+
+      PthreadWorkerInit = e.data.PthreadWorkerInit;
+      if (typeof e.data.urlOrBlob === 'string') {
+        importScripts(e.data.urlOrBlob);
+      } else {
+        var objectUrl = URL.createObjectURL(e.data.urlOrBlob);
+        importScripts(objectUrl);
+        URL.revokeObjectURL(objectUrl);
+      }
+//#if !ASMFS
+      if (typeof FS !== 'undefined' && typeof FS.createStandardStreams === 'function') FS.createStandardStreams();
+//#endif
+      postMessage({ cmd: 'loaded' });
+    } else if (e.data.cmd === 'objectTransfer') {
+      PThread.receiveObjectTransfer(e.data);
+    } else if (e.data.cmd === 'run') { // This worker was idle, and now should start executing its pthread entry point.
+      __performance_now_clock_drift = performance.now() - e.data.time; // Sync up to the clock of the main thread.
+      threadInfoStruct = e.data.threadInfoStruct;
+      __register_pthread_ptr(threadInfoStruct, /*isMainBrowserThread=*/0, /*isMainRuntimeThread=*/0); // Pass the thread address inside the asm.js scope to store it for fast access that avoids the need for a FFI out.
+      assert(threadInfoStruct);
+      selfThreadId = e.data.selfThreadId;
+      parentThreadId = e.data.parentThreadId;
+      assert(selfThreadId);
+      assert(parentThreadId);
+      // TODO: Emscripten runtime has these variables twice(!), once outside the asm.js module, and a second time inside the asm.js module.
+      //       Review why that is? Can those get out of sync?
+      STACK_BASE = STACKTOP = e.data.stackBase;
+      STACK_MAX = STACK_BASE + e.data.stackSize;
+      assert(STACK_BASE != 0);
+      assert(STACK_MAX > STACK_BASE);
+      Module['establishStackSpace'](e.data.stackBase, e.data.stackBase + e.data.stackSize);
+      var result = 0;
+//#if STACK_OVERFLOW_CHECK
+      if (typeof writeStackCookie === 'function') writeStackCookie();
+//#endif
+
+      PThread.receiveObjectTransfer(e.data);
+      PThread.setThreadStatus(_pthread_self(), 1/*EM_THREAD_STATUS_RUNNING*/);
+
+      try {
+        // pthread entry points are always of signature 'void *ThreadMain(void *arg)'
+        // Native codebases sometimes spawn threads with other thread entry point signatures,
+        // such as void ThreadMain(void *arg), void *ThreadMain(), or void ThreadMain().
+        // That is not acceptable per C/C++ specification, but x86 compiler ABI extensions
+        // enable that to work. If you find the following line to crash, either change the signature
+        // to "proper" void *ThreadMain(void *arg) form, or try linking with the Emscripten linker
+        // flag -s EMULATE_FUNCTION_POINTER_CASTS=1 to add in emulation for this x86 ABI extension.
+        result = Module['dynCall_ii'](e.data.start_routine, e.data.arg);
+
+//#if STACK_OVERFLOW_CHECK
+        if (typeof checkStackCookie === 'function') checkStackCookie();
+//#endif
+
+      } catch(e) {
+        if (e === 'Canceled!') {
+          PThread.threadCancel();
+          return;
+        } else if (e === 'SimulateInfiniteLoop') {
+          return;
+        } else {
+          Atomics.store(HEAPU32, (threadInfoStruct + 4 /*{{{ C_STRUCTS.pthread.threadExitCode }}}*/ ) >> 2, (e instanceof ExitStatus) ? e.status : -2 /*A custom entry specific to Emscripten denoting that the thread crashed.*/);
+          Atomics.store(HEAPU32, (threadInfoStruct + 0 /*{{{ C_STRUCTS.pthread.threadStatus }}}*/ ) >> 2, 1); // Mark the thread as no longer running.
+          _emscripten_futex_wake(threadInfoStruct + 0 /*{{{ C_STRUCTS.pthread.threadStatus }}}*/, 0x7FFFFFFF/*INT_MAX*/); // Wake all threads waiting on this thread to finish.
+          if (!(e instanceof ExitStatus)) throw e;
+        }
+      }
+      // The thread might have finished without calling pthread_exit(). If so, then perform the exit operation ourselves.
+      // (This is a no-op if explicit pthread_exit() had been called prior.)
+      PThread.threadExit(result);
+    } else if (e.data.cmd === 'cancel') { // Main thread is asking for a pthread_cancel() on this thread.
+      if (threadInfoStruct && PThread.thisThreadCancelState == 0/*PTHREAD_CANCEL_ENABLE*/) {
+        PThread.threadCancel();
+      }
+    } else if (e.data.target === 'setimmediate') {
+      // no-op
+    } else if (e.data.cmd === 'processThreadQueue') {
+      if (threadInfoStruct) { // If this thread is actually running?
+        _emscripten_current_thread_process_queued_calls();
+      }
+    } else {
+      err('pthread-main.js received unknown command ' + e.data.cmd);
+      console.error(e.data);
+    }
+  } catch(e) {
+    console.error('pthread-main.js onmessage() captured an uncaught exception: ' + e);
+    console.error(e.stack);
+    throw e;
+  }
+}
--- a/codecs/webp_enc/webp_enc.js
+++ b/codecs/webp_enc/webp_enc.js
--- a/codecs/webp_enc/webp_enc.js.mem
+++ b/codecs/webp_enc/webp_enc.js.mem
--- a/codecs/webp_enc/webp_enc.wasm
+++ b/codecs/webp_enc/webp_enc.wasm
Author	SHA1	Message	Date
Surma	7a08815bcf	Make emscripten with threads compile	2018-11-02 18:34:23 +00:00
Surma	30e78e8ab7	Attempt at threads for webp encoder	2018-11-01 22:36:38 +00:00