emscripten/src/pthread-main.js at universal-python · JavaScriptIOT/emscripten · GitHub

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// 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.

// All pthreads share the same Emscripten HEAP as SharedArrayBuffer

// with the main execution thread.

var buffer;

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 tempDoublePtr = 0; // A temporary memory area for global float and double marshalling operations.

// Each thread has its own allocated stack space.

var STACK_BASE = 0;

var STACKTOP = 0;

var STACK_MAX = 0;

var ENVIRONMENT_IS_PTHREAD = true;

// 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 = {};

function threadPrint() {

var text = Array.prototype.slice.call(arguments).join(' ');

postMessage({cmd: 'print', text: text, threadId: selfThreadId});

}

function threadPrintErr() {

var text = Array.prototype.slice.call(arguments).join(' ');

postMessage({cmd: 'printErr', text: text, threadId: selfThreadId});

}

Module['print'] = threadPrint;

Module['printErr'] = threadPrintErr;

// Work around https://bugzilla.mozilla.org/show_bug.cgi?id=1049091

console = {

log: threadPrint,

error: threadPrintErr

};

this.onmessage = function(e) {

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

buffer = e.data.buffer;

tempDoublePtr = e.data.tempDoublePtr;

PthreadWorkerInit = e.data.PthreadWorkerInit;

importScripts(e.data.url);

FS.createStandardStreams();

postMessage({ cmd: 'loaded' });

} else if (e.data.cmd === 'run') { // This worker was idle, and now should start executing its pthread entry point.

threadInfoStruct = e.data.threadInfoStruct;

assert(threadInfoStruct);

selfThreadId = e.data.selfThreadId;

assert(selfThreadId);

// 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);

Runtime.establishStackSpace(e.data.stackBase, e.data.stackBase + e.data.stackSize);

var result = 0;

try {

// HACK: Some code in the wild has instead signatures of form 'void *ThreadMain()', which seems to be ok in native code.

// To emulate supporting both in test suites, use the following form. This is brittle!

if (typeof asm['dynCall_ii'] !== 'undefined') {

result = asm.dynCall_ii(e.data.start_routine, e.data.arg); // pthread entry points are always of signature 'void *ThreadMain(void *arg)'

} else {

result = asm.dynCall_i(e.data.start_routine); // as a hack, try signature 'i' as fallback.

}

} catch(e) {

if (e === 'Canceled!') {

PThread.threadCancel();

return;

} else {

Atomics.store(HEAPU32, (threadInfoStruct + 4 /*{{{ C_STRUCTS.pthread.threadExitCode }}}*/ ) >> 2, -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

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 {

Module['printErr']('pthread-main.js received unknown command ' + e.data.cmd);

}

emscripten/src/pthread-main.js at universal-python · JavaScriptIOT/emscripten · GitHub

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