symbols-as-weakmap-keys.js

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// |jit-test| --enable-symbols-as-weakmap-keys; skip-if: getBuildConfiguration("release_or_beta")

// Test weak maps with symbols keys where the symbols are referenced in

// different zones. Currently we require all participating zones plus the

// atoms zone to be collected to collect such weakmap entries.

gczeal(0);

gczeal('CheckHeapAfterGC');

function makeSymbol(name) {

  return Symbol(name);

function mapSize(wm) {

  return nondeterministicGetWeakMapSize(wm);

// Test weak map entry with a symbol key is removed when the symbol dies.

printErr("Test 1");

let wm = new WeakMap;

assertEq(mapSize(wm), 0);

let k = makeSymbol('test1');

wm.set(k, {});

assertEq(mapSize(wm), 1);

gc();

assertEq(mapSize(wm), 1);

k = undefined;

gc();

assertEq(mapSize(wm), 0);

wm = undefined;

gc();

// Repeat the test with the key held alive from a different zone.

printErr("Test 2");

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

keyZone.key = makeSymbol('test2');

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

mapZone.map = undefined;

mapZone.eval(`map = new WeakMap;`);

mapZone.map.set(keyZone.key, {});

assertEq(mapSize(mapZone.map), 1);

gc();

assertEq(mapSize(mapZone.map), 1);

keyZone.key = undefined;

gc();

assertEq(mapSize(mapZone.map), 0);

keyZone = undefined;

mapZone = undefined;

gc();

// Repeat the previous test with per zone GC.

printErr("Test 3");

keyZone = newGlobal({newCompartment: true});

mapZone = newGlobal({newCompartment: true});

keyZone.eval('var key = Symbol("test2");');

mapZone.eval(`var map = new WeakMap;`);

mapZone.keyZone = keyZone;

mapZone.eval('map.set(keyZone.key, {});');

mapZone.keyZone = undefined;

gc();

assertEq(mapSize(mapZone.map), 1);

printErr("  3.1 Setup");

keyZone.key = undefined;

printErr("  3.2 Collect only main zone");

gc(this);

assertEq(mapSize(mapZone.map), 1);

printErr("  3.3 Collect only map zone");

gc(mapZone);

assertEq(mapSize(mapZone.map), 1);

printErr("  3.4 Collect only key zone");

gc(keyZone);

// Bug 1410123: Perhaps we could stop marking the key atom in the key zone at

// this point if we refine the atom bitmaps without requiring the atoms zone

// to be collected.

assertEq(mapSize(mapZone.map), 1);

printErr("  3.5 Collect map zone and atoms zone (entry not removed)");

schedulezone(mapZone);

schedulezone('atoms');

gc('zone');

assertEq(mapSize(mapZone.map), 1);

printErr("  3.6 Collect key zone and atoms zone (key no longer referenced)");

schedulezone(keyZone);

schedulezone('atoms');

gc('zone');

assertEq(mapSize(mapZone.map), 1);

printErr("  3.7 Collect only atoms zone (nothing collected)");

schedulezone('atoms');

gc('zone');

assertEq(mapSize(mapZone.map), 1);

printErr("  3.8 Collect only map zone (nothing collected)");

gc(mapZone);

assertEq(mapSize(mapZone.map), 1);

printErr("  3.9 Collect map zone and atoms zone (entry collected)");

schedulezone(mapZone);

schedulezone('atoms');

gc('zone');

assertEq(mapSize(mapZone.map), 0);

printErr("  3.10 Collect all zones (nothing more collected)");

gc();

assertEq(mapSize(mapZone.map), 0);