87 lines
No EOL
2.1 KiB
C++
87 lines
No EOL
2.1 KiB
C++
#include <iostream>
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#include <vector>
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#define HEAP_SIZE 65536 // Arbitrary for now, 2^16
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using namespace std;
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/* A simple mark and sweep algorithm */
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// Shouldn't be exposed. For now, it is
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struct ObjectHeader {
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size_t size = sizeof(this);
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bool marked = false;
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};
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struct Object : ObjectHeader {
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char name; // should be something like id, but for testing sake its char
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Object* child;
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// Object(char name_) {}
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Object(char name_, Object* child_) {
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name = name_;
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child = child_;
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}
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};
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// Representing the heap as a simple struct for now
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struct Heap {
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Object heap_space[HEAP_SIZE];
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};
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// For now it assumes that it is given root objects from the start, no root finding included
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class MarkSweep {
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public:
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void mark(Object* obj) {
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if (!markedBit(obj)) {
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markBit(obj);
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Object* ref = obj->child;
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if (ref != nullptr) {
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mark(ref);
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}
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}
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}
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void sweep(vector<Object*> worklist) {
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for (Object* obj: worklist) {
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if (!markedBit(obj) && obj != nullptr) {
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delete obj;
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}
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}
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}
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private:
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bool markedBit(Object* obj) {
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return obj->marked;
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}
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void markBit(Object* obj) {
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obj->marked = true;
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}
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};
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int main() {
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Object* b = new Object('B', nullptr);
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// b->name = 'B';
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// b->child = nullptr;
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Object* c = new Object('C', b);
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// c->name = 'C';
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// c->child = b; // c -> d
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Object* d = new Object('D', nullptr);
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// d->name = 'D';
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// d->child = nullptr;
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//Heap* heap = new Heap{*c, *b, *d};
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vector<Object*> worklist = {c, b, d};
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MarkSweep* gc = new MarkSweep();
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gc->mark(c);
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cout << "Expected 1, got: " << b->marked << '\n';
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cout << "Expected 1, got: " << c->marked << '\n';
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cout << "Expected 0, got: " << d->marked << '\n';
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gc->sweep(worklist);
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cout << b->name << '\n';
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cout << c->name << '\n';
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cout << d->name << '\n'; // The object at d is now deleted (freed)
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return 0;
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} |