Memory-takeCensus-02.js

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// Debugger.Memory.prototype.takeCensus behaves plausibly as we allocate objects.

// Exact object counts vary in ways we can't predict. For example,

// BaselineScripts can hold onto "template objects", which exist only to hold

// the shape and type for newly created objects. When BaselineScripts are

// discarded, these template objects go with them.

//

// So instead of expecting precise counts, we expect counts that are at least as

// many as we would expect given the object graph we've built.

load(libdir + 'census.js');

// A Debugger with no debuggees had better not find anything.

var dbg = new Debugger;

var census0 = dbg.memory.takeCensus();

Census.walkCensus(census0, "census0", Census.assertAllZeros);

function newGlobalWithDefs() {

  var g = newGlobal({newCompartment: true});

  g.eval(`

         function times(n, fn) {

           var a=[];

           for (var i = 0; i<n; i++)

             a.push(fn());

           return a;

         }`);

  return g;

// Allocate a large number of various types of objects, and check that census

// finds them.

var g = newGlobalWithDefs();

dbg.addDebuggee(g);

g.eval('var objs = times(100, () => ({}));');

g.eval('var rxs  = times(200, () => /foo/);');

g.eval('var ars  = times(400, () => []);');

g.eval('var fns  = times(800, () => () => {});');

var census1 = dbg.memory.takeCensus();

Census.walkCensus(census1, "census1",

                  Census.assertAllNotLessThan(

                    { 'objects':

                      { 'Object':   { count: 100 },

                        'RegExp':   { count: 200 },

                        'Array':    { count: 400 },

                        'Function': { count: 800 }

                    }));