sieve.worker.js

/**
 * @license
 * Copyright 2015 The Emscripten Authors
 * SPDX-License-Identifier: MIT
 */

// 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.

'use strict';

var Module = {};

// Node.js support
if (typeof process === 'object' && typeof process.versions === 'object' && typeof process.versions.node === 'string') {
  // Create as web-worker-like an environment as we can.

  var nodeWorkerThreads = require('worker_threads');

  var parentPort = nodeWorkerThreads.parentPort;

  parentPort.on('message', function(data) {
    onmessage({ data: data });
  });

  var nodeFS = require('fs');

  Object.assign(global, {
    self: global,
    require: require,
    Module: Module,
    location: {
      href: __filename
    },
    Worker: nodeWorkerThreads.Worker,
    importScripts: function(f) {
      (0, eval)(nodeFS.readFileSync(f, 'utf8'));
    },
    postMessage: function(msg) {
      parentPort.postMessage(msg);
    },
    performance: global.performance || {
      now: function() {
        return Date.now();
      }
    },
  });
}

// Thread-local:

function assert(condition, text) {
  if (!condition) abort('Assertion failed: ' + text);
}

function threadPrintErr() {
  var text = Array.prototype.slice.call(arguments).join(' ');
  console.error(text);
}
function threadAlert() {
  var text = Array.prototype.slice.call(arguments).join(' ');
  postMessage({cmd: 'alert', text: text, threadId: Module['_pthread_self']()});
}
// We don't need out() for now, but may need to add it if we want to use it
// here. Or, if this code all moves into the main JS, that problem will go
// away. (For now, adding it here increases code size for no benefit.)
var out = function() {
  throw 'out() is not defined in worker.js.';
}
var err = threadPrintErr;
self.alert = threadAlert;

Module['instantiateWasm'] = function(info, receiveInstance) {
  // Instantiate from the module posted from the main thread.
  // We can just use sync instantiation in the worker.
  var instance = new WebAssembly.Instance(Module['wasmModule'], info);
  // TODO: Due to Closure regression https://github.com/google/closure-compiler/issues/3193,
  // the above line no longer optimizes out down to the following line.
  // When the regression is fixed, we can remove this if/else.
  receiveInstance(instance);
  // We don't need the module anymore; new threads will be spawned from the main thread.
  Module['wasmModule'] = null;
  return instance.exports;
};

function moduleLoaded() {
}

self.onmessage = function(e) {
  try {
    if (e.data.cmd === 'load') { // Preload command that is called once per worker to parse and load the Emscripten code.

      // Module and memory were sent from main thread
      Module['wasmModule'] = e.data.wasmModule;

      Module['wasmMemory'] = e.data.wasmMemory;

      Module['buffer'] = Module['wasmMemory'].buffer;

      Module['ENVIRONMENT_IS_PTHREAD'] = true;

      if (typeof e.data.urlOrBlob === 'string') {
        importScripts(e.data.urlOrBlob);
      } else {
        var objectUrl = URL.createObjectURL(e.data.urlOrBlob);
        importScripts(objectUrl);
        URL.revokeObjectURL(objectUrl);
      }

      // MINIMAL_RUNTIME always compiled Wasm (&Wasm2JS) asynchronously, even in pthreads. But
      // regular runtime and asm.js are loaded synchronously, so in those cases
      // we are now loaded, and can post back to main thread.
      moduleLoaded();

    } else if (e.data.cmd === 'objectTransfer') {
      Module['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() 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).
      Module['__performance_now_clock_drift'] = performance.now() - e.data.time;

      // Pass the thread address inside the asm.js scope to store it for fast access that avoids the need for a FFI out.
      Module['__emscripten_thread_init'](e.data.threadInfoStruct, /*isMainBrowserThread=*/0, /*isMainRuntimeThread=*/0);

      // Establish the stack frame for this thread in global scope
      // The stack grows downwards
      var max = e.data.stackBase;
      var top = e.data.stackBase + e.data.stackSize;
      assert(e.data.threadInfoStruct);
      assert(top != 0);
      assert(max != 0);
      assert(top > max);
      // Also call inside JS module to set up the stack frame for this pthread in JS module scope
      Module['establishStackSpace'](top, max);
      Module['PThread'].receiveObjectTransfer(e.data);
      Module['PThread'].threadInit();

      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.
        var result = Module['invokeEntryPoint'](e.data.start_routine, e.data.arg);

        Module['checkStackCookie']();
        if (Module['keepRuntimeAlive']()) {
          Module['PThread'].setExitStatus(result);
        } else {
          Module['PThread'].threadExit(result);
        }
      } catch(ex) {
        if (ex === 'Canceled!') {
          Module['PThread'].threadCancel();
        } else if (ex != 'unwind') {
          // FIXME(sbc): Figure out if this is still needed or useful.  Its not
          // clear to me how this check could ever fail.  In order to get into
          // this try/catch block at all we have already called bunch of
          // functions on `Module`.. why is this one special?
          if (typeof(Module['_emscripten_futex_wake']) !== "function") {
            err("Thread Initialisation failed.");
            throw ex;
          }
          // ExitStatus not present in MINIMAL_RUNTIME
          if (ex instanceof Module['ExitStatus']) {
            if (Module['keepRuntimeAlive']()) {
              err('Pthread 0x' + Module['_pthread_self']().toString(16) + ' called exit(), staying alive due to noExitRuntime.');
            } else {
              err('Pthread 0x' + Module['_pthread_self']().toString(16) + ' called exit(), calling threadExit.');
              Module['PThread'].threadExit(ex.status);
            }
          }
          else
          {
            Module['PThread'].threadExit(-2);
            throw ex;
          }
        } else {
          // else e == 'unwind', and we should fall through here and keep the pthread alive for asynchronous events.
          err('Pthread 0x' + Module['_pthread_self']().toString(16) + ' completed its pthread main entry point with an unwind, keeping the pthread worker alive for asynchronous operation.');
        }
      }
    } else if (e.data.cmd === 'cancel') { // Main thread is asking for a pthread_cancel() on this thread.
      if (Module['_pthread_self']()) {
        Module['PThread'].threadCancel();
      }
    } else if (e.data.target === 'setimmediate') {
      // no-op
    } else if (e.data.cmd === 'processThreadQueue') {
      if (Module['_pthread_self']()) { // If this thread is actually running?
        Module['_emscripten_current_thread_process_queued_calls']();
      }
    } else {
      err('worker.js received unknown command ' + e.data.cmd);
      err(e.data);
    }
  } catch(ex) {
    err('worker.js onmessage() captured an uncaught exception: ' + ex);
    if (ex && ex.stack) err(ex.stack);
    throw ex;
  }
};