gray-unmarking.js - mozsearch

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// Test interaction of gray marking / cross zone pointers / aborted GC marking.

gczeal(0);

gc();

assertEq(grayBitsValid(), true);

// Create some globals in different zones.

let g1 = newGlobal({newCompartment: true});

let g2 = newGlobal({newCompartment: true});

let g3 = newGlobal({newCompartment: true});

// Set up a linked list of objects in different zones: a --> b --> c

g1.eval('var a = {}');

g2.eval('var b = {}');

g3.eval('var c = {}');

g1.a.next = g2.b;

g2.b.next = g3.c;

// Observe mark state of the objects and remove extra references from the globals.

g1.eval('addMarkObservers([a])');

g2.eval('addMarkObservers([b])');

g3.eval('addMarkObservers([c])');

g2.b = undefined;

g3.c = undefined;

function checkMarks(a, b, c) {

  assertEq(getMarks().join(", "), [a, b, c].join(", "));

// Check GC initially marks everything black.

gc();

checkMarks("black", "black", "black");

// Replace root with a gray one and check GC marks everything gray.

g1.eval('grayRoot()[0] = a');

g1.a = undefined;

gc();

checkMarks("gray", "gray", "gray");

// Read the gray root and check gray unmarking marks everything black again.

g1.eval('grayRoot()[0]');

checkMarks("black", "black", "black");

// Reset everything to gray.

gc();

checkMarks("gray", "gray", "gray");

// Start marking zone 2.

schedulezone(g2);

startgc(10);

while (gcstate() === "Prepare" || gcstate() === "MarkRoots") {

  gcslice(10);

assertEq(gcstate(), "Mark");

assertEq(gcstate(g1), "NoGC");

assertEq(gcstate(g2), "MarkBlackOnly");

assertEq(gcstate(g3), "NoGC");

// Check zone 2's mark bits have been cleared.

checkMarks("gray", "unmarked", "gray");

// Gray unmarking stops at the zone that is being mraked

g1.eval('grayRoot()[0]');

checkMarks("black", "black", "gray");

// GC marking handles the gray unmarking by propagaing b's mark state.

finishgc();

assertEq(grayBitsValid(), true);

checkMarks("black", "black", "black");

// Reset everything to gray.

gc();

checkMarks("gray", "gray", "gray");

// Repeat the previous test but abort marking after unmarking a. c is

// left as 'gray' (incorrect) but the gray marking state is marked as invalid.

schedulezone(g2);

startgc(10);

while (gcstate() === "Prepare" || gcstate() === "MarkRoots") {

  gcslice(10);

assertEq(gcstate(), "Mark");

checkMarks("gray", "unmarked", "gray");

g1.eval('grayRoot()[0]');

assertEq(grayBitsValid(), true);

abortgc();

assertEq(grayBitsValid(), false);

checkMarks("black", "black", "gray");

gc();

checkMarks("gray", "gray", "gray");