Atomics Futex API

src/harmony-atomics.js

Index: src/harmony-atomics.js
diff --git a/src/harmony-atomics.js b/src/harmony-atomics.js
index aa81822d1e2f877f4de933f02d269b81775eea11..0eb496dae1d49fc0c1e4ebf110d49351983088d3 100644
--- a/src/harmony-atomics.js
+++ b/src/harmony-atomics.js
@@ -13,6 +13,12 @@
 
 var GlobalObject = global.Object;
 
+var MathMax;
+
+utils.Import(function(from) {
+  MathMax = from.MathMax;
+});
+
 // -------------------------------------------------------------------
 
 
@@ -28,6 +34,13 @@ function CheckSharedIntegerTypedArray(ia) {
   }
 }
 
+function CheckSharedInteger32TypedArray(ia) {
+  CheckSharedIntegerTypedArray(ia);
+  if (%_ClassOf(ia) !== 'Int32Array') {
+    throw MakeTypeError(kNotInt32SharedTypedArray, ia);
+  }
+}
+
 //-------------------------------------------------------------------
 
 function AtomicsCompareExchangeJS(sta, index, oldValue, newValue) {
@@ -115,6 +128,49 @@ function AtomicsIsLockFreeJS(size) {
   return %_AtomicsIsLockFree(size);
 }
 
+// Futexes
+
+function AtomicsFutexWaitJS(ia, index, value, timeout) {
+  CheckSharedInteger32TypedArray(ia);
+  index = $toInteger(index);
+  if (index < 0 || index >= ia.length) {
+    return UNDEFINED;
+  }
+  if (IS_UNDEFINED(timeout)) {
+    timeout = INFINITY;
+  } else {
+    timeout = $toNumber(timeout);
+    if (NUMBER_IS_NAN(timeout)) {
+      timeout = INFINITY;
+    } else {
+      timeout = MathMax(0, timeout);
+    }
+  }
+  return %_AtomicsFutexWait(ia, index, value, timeout);

[Michael Starzinger, 2015/07/08 17:54:20]

The %_FooBar syntax is used to indicate that at least one compiler inlines this
as an intrinsic. Since there are only runtime function backing this so far, I
would for using plain %FooBar instead, to not confuse people about the expected
overhead. Likewise below.

[binji, 2015/07/08 18:05:29]

Done.

+}
+
+function AtomicsFutexWakeJS(ia, index, count) {
+  CheckSharedInteger32TypedArray(ia);
+  index = $toInteger(index);
+  if (index < 0 || index >= ia.length) {
+    return UNDEFINED;
+  }
+  count = MathMax(0, $toInteger(count));
+  return %_AtomicsFutexWake(ia, index, count);
+}
+
+function AtomicsFutexWakeOrRequeueJS(ia, index1, count, value, index2) {
+  CheckSharedInteger32TypedArray(ia);
+  index1 = $toInteger(index1);
+  count = MathMax(0, $toInteger(count));
+  value = $toInt32(value);
+  index2 = $toInteger(index2);
+  if (index1 < 0 || index1 >= ia.length || index2 < 0 || index2 >= ia.length) {
+    return UNDEFINED;
+  }
+  return %_AtomicsFutexWakeOrRequeue(ia, index1, count, value, index2);
+}
+
 // -------------------------------------------------------------------
 
 function AtomicsConstructor() {}
@@ -127,6 +183,13 @@ var Atomics = new AtomicsConstructor();
 
 %AddNamedProperty(Atomics, symbolToStringTag, "Atomics", READ_ONLY | DONT_ENUM);
 
+// These must match the values in src/futex-emulation.h
+utils.InstallConstants(Atomics, [
+  "OK", 0,
+  "NOTEQUAL", -1,
+  "TIMEDOUT", -2,
+]);
+
 utils.InstallFunctions(Atomics, DONT_ENUM, [
   "compareExchange", AtomicsCompareExchangeJS,
   "load", AtomicsLoadJS,
@@ -138,6 +201,9 @@ utils.InstallFunctions(Atomics, DONT_ENUM, [
   "xor", AtomicsXorJS,
   "exchange", AtomicsExchangeJS,
   "isLockFree", AtomicsIsLockFreeJS,
+  "futexWait", AtomicsFutexWaitJS,
+  "futexWake", AtomicsFutexWakeJS,
+  "futexWakeOrRequeue", AtomicsFutexWakeOrRequeueJS,
 ]);
 
 })