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// onStep hooks on suspended Frames can keep Debuggers alive, even chaining them.
// The path through the heap we're building and testing here is:
// gen0 (generator object) -> frame1 (suspended Frame with .onStep) -> dbg1 (Debugger object)
// -> gen1 -> frame2 -> dbg2
// where everything after `gen1` is otherwise unreachable, and the edges
// `frame1 -> dbg1` and `frames2 -> dbg2` are due to the .onStep handlers, not
// strong refrences.
//
// There is no easy way to thread an event through this whole path; when we
// call gen0.next(), it will fire frame1.onStep(), but from there, making sure
// gen1.next() is called requires some minor heroics (see the WeakMap below).
var gen0;
var hits2 = 0;
var resuming2 = false;
function onStep2() {
if (resuming2) {
hits2++;
resuming2 = false;
}
}
function setup() {
let g1 = newGlobal({newCompartment: true});
g1.eval(`
function* gf1() {
debugger;
yield 1;
return 'done';
}
`);
gen0 = g1.gf1();
let g2 = newGlobal({newCompartment: true});
g2.eval(`
function* gf2() { debugger; yield 1; return 'done'; }
var resuming1 = false;
function makeOnStepHook1(dbg1) {
// We use this WeakMap as a weak reference from frame1.onStep to dbg1.
var weak = new WeakMap();
weak.set(dbg1, {});
return () => {
if (resuming1) {
var dbg1Arr = nondeterministicGetWeakMapKeys(weak);
assertEq(dbg1Arr.length, 1);
dbg1Arr[0].gen1.next();
resuming1 = false;
}
};
}
function test(g1, gen0) {
let dbg1 = Debugger(g1);
dbg1.onDebuggerStatement = frame1 => {
frame1.onStep = makeOnStepHook1(dbg1);
dbg1.onDebuggerStatement = undefined;
};
gen0.next(); // run to yield point, creating frame1 and setting its onStep hook
resuming1 = true;
dbg1.gen1 = gf2();
return dbg1.gen1;
}
`);
let dbg2 = Debugger(g2);
dbg2.onDebuggerStatement = frame2 => {
frame2.onStep = onStep2;
dbg2.onDebuggerStatement = undefined;
};
var gen1 = g2.test(g1, gen0);
gen1.next(); // run to yield point, creating frame2 and setting its onStep hook
resuming2 = true;
}
setup();
gc();
assertEq(hits2, 0);
gen0.next(); // fires frame1.onStep, which calls gen1.next(), which fires frame2.onStep
assertEq(hits2, 1);
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