vm/gc.cpp

   1 #include "master.hpp"
   2
   3 namespace factor {
   4
   5 gc_event::gc_event(gc_op op, factor_vm* parent)
   6     : op(op),
   7       cards_scanned(0),
   8       decks_scanned(0),
   9       code_blocks_scanned(0),
  10       start_time(nano_count()),
  11       card_scan_time(0),
  12       code_scan_time(0),
  13       data_sweep_time(0),
  14       code_sweep_time(0),
  15       compaction_time(0) {
  16   data_heap_before = parent->data_room();
  17   code_heap_before = parent->code->allocator->as_allocator_room();
  18   start_time = nano_count();
  19 }
  20
  21 void gc_event::reset_timer() { temp_time = nano_count(); }
  22
  23 void gc_event::ended_card_scan(cell cards_scanned_, cell decks_scanned_) {
  24   cards_scanned += cards_scanned_;
  25   decks_scanned += decks_scanned_;
  26   card_scan_time = (cell)(nano_count() - temp_time);
  27 }
  28
  29 void gc_event::ended_code_scan(cell code_blocks_scanned_) {
  30   code_blocks_scanned += code_blocks_scanned_;
  31   code_scan_time = (cell)(nano_count() - temp_time);
  32 }
  33
  34 void gc_event::ended_data_sweep() {
  35   data_sweep_time = (cell)(nano_count() - temp_time);
  36 }
  37
  38 void gc_event::ended_code_sweep() {
  39   code_sweep_time = (cell)(nano_count() - temp_time);
  40 }
  41
  42 void gc_event::ended_compaction() {
  43   compaction_time = (cell)(nano_count() - temp_time);
  44 }
  45
  46 void gc_event::ended_gc(factor_vm* parent) {
  47   data_heap_after = parent->data_room();
  48   code_heap_after = parent->code->allocator->as_allocator_room();
  49   total_time = (cell)(nano_count() - start_time);
  50 }
  51
  52 gc_state::gc_state(gc_op op, factor_vm* parent) : op(op) {
  53   if (parent->gc_events) {
  54     event = new gc_event(op, parent);
  55     start_time = nano_count();
  56   } else
  57     event = NULL;
  58 }
  59
  60 gc_state::~gc_state() {
  61   if (event) {
  62     delete event;
  63     event = NULL;
  64   }
  65 }
  66
  67 void factor_vm::end_gc() {
  68   if (gc_events) {
  69     current_gc->event->ended_gc(this);
  70     gc_events->push_back(*current_gc->event);
  71   }
  72 }
  73
  74 void factor_vm::start_gc_again() {
  75   switch (current_gc->op) {
  76     case collect_nursery_op:
  77       // Nursery collection can fail if aging does not have enough
  78       // free space to fit all live objects from nursery.
  79       current_gc->op = collect_aging_op;
  80       break;
  81     case collect_aging_op:
  82       // Aging collection can fail if the aging semispace cannot fit
  83       // all the live objects from the other aging semispace and the
  84       // nursery.
  85       current_gc->op = collect_to_tenured_op;
  86       break;
  87     default:
  88       // Nothing else should fail mid-collection due to insufficient
  89       // space in the target generation.
  90       critical_error("in start_gc_again, bad GC op", current_gc->op);
  91       break;
  92   }
  93 }
  94
  95 void factor_vm::set_current_gc_op(gc_op op) {
  96   current_gc->op = op;
  97   if (gc_events)
  98     current_gc->event->op = op;
  99 }
 100
 101 void factor_vm::gc(gc_op op, cell requested_size) {
 102   FACTOR_ASSERT(!gc_off);
 103   FACTOR_ASSERT(!current_gc);
 104
 105   // Important invariant: tenured space must have enough contiguous free
 106   // space to fit the entire contents of the aging space and nursery. This is
 107   // because when doing a full collection, objects from younger generations
 108   // are promoted before any unreachable tenured objects are freed.
 109   FACTOR_ASSERT(!data->high_fragmentation_p());
 110
 111   current_gc = new gc_state(op, this);
 112   if (ctx)
 113     ctx->callstack_seg->set_border_locked(false);
 114   atomic::store(&current_gc_p, true);
 115
 116   // Keep trying to GC higher and higher generations until we don't run
 117   // out of space in the target generation.
 118   for (;;) {
 119     try {
 120       if (gc_events)
 121         current_gc->event->op = current_gc->op;
 122
 123       switch (current_gc->op) {
 124         case collect_nursery_op:
 125           collect_nursery();
 126           break;
 127         case collect_aging_op:
 128           // We end up here if the above fails.
 129           collect_aging();
 130           if (data->high_fragmentation_p()) {
 131             // Change GC op so that if we fail again, we crash.
 132             set_current_gc_op(collect_full_op);
 133             collect_full();
 134           }
 135           break;
 136         case collect_to_tenured_op:
 137           // We end up here if the above fails.
 138           collect_to_tenured();
 139           if (data->high_fragmentation_p()) {
 140             // Change GC op so that if we fail again, we crash.
 141             set_current_gc_op(collect_full_op);
 142             collect_full();
 143           }
 144           break;
 145         case collect_full_op:
 146           collect_full();
 147           break;
 148         case collect_compact_op:
 149           collect_compact();
 150           break;
 151         case collect_growing_heap_op:
 152           collect_growing_heap(requested_size);
 153           break;
 154         default:
 155           critical_error("in gc, bad GC op", current_gc->op);
 156           break;
 157       }
 158
 159       break;
 160     }
 161     catch (const must_start_gc_again&) {
 162       // We come back here if the target generation is full.
 163       start_gc_again();
 164       continue;
 165     }
 166   }
 167
 168   end_gc();
 169
 170   atomic::store(&current_gc_p, false);
 171   if (ctx)
 172     ctx->callstack_seg->set_border_locked(true);
 173   delete current_gc;
 174   current_gc = NULL;
 175
 176   // Check the invariant again, just in case.
 177   FACTOR_ASSERT(!data->high_fragmentation_p());
 178 }
 179
 180 void factor_vm::primitive_minor_gc() {
 181   gc(collect_nursery_op, 0);
 182 }
 183
 184 void factor_vm::primitive_full_gc() {
 185   gc(collect_full_op, 0);
 186 }
 187
 188 void factor_vm::primitive_compact_gc() {
 189   gc(collect_compact_op, 0);
 190 }
 191
 192 void factor_vm::primitive_enable_gc_events() {
 193   gc_events = new std::vector<gc_event>();
 194 }
 195
 196 // Allocates memory (byte_array_from_value, result.add)
 197 // XXX: Remember that growable_array has a data_root already
 198 void factor_vm::primitive_disable_gc_events() {
 199   if (gc_events) {
 200     growable_array result(this);
 201
 202     std::vector<gc_event>* gc_events = this->gc_events;
 203     this->gc_events = NULL;
 204
 205     FACTOR_FOR_EACH(*gc_events) {
 206       gc_event event = *iter;
 207       byte_array* obj = byte_array_from_value(&event);
 208       result.add(tag<byte_array>(obj));
 209     }
 210
 211     result.trim();
 212     ctx->push(result.elements.value());
 213
 214     delete this->gc_events;
 215   } else
 216     ctx->push(false_object);
 217 }
 218
 219 }