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executable file 360 lines (305 sloc) 7.876 kb
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#include "master.hpp"

namespace factor
{

gc_event::gc_event(gc_op op_, factor_vm *parent) :
op(op_),
cards_scanned(0),
decks_scanned(0),
code_blocks_scanned(0),
start_time(nano_count()),
card_scan_time(0),
code_scan_time(0),
data_sweep_time(0),
code_sweep_time(0),
compaction_time(0)
{
data_heap_before = parent->data_room();
code_heap_before = parent->code_room();
start_time = nano_count();
}

void gc_event::started_card_scan()
{
temp_time = nano_count();
}

void gc_event::ended_card_scan(cell cards_scanned_, cell decks_scanned_)
{
cards_scanned += cards_scanned_;
decks_scanned += decks_scanned_;
card_scan_time = (cell)(nano_count() - temp_time);
}

void gc_event::started_code_scan()
{
temp_time = nano_count();
}

void gc_event::ended_code_scan(cell code_blocks_scanned_)
{
code_blocks_scanned += code_blocks_scanned_;
code_scan_time = (cell)(nano_count() - temp_time);
}

void gc_event::started_data_sweep()
{
temp_time = nano_count();
}

void gc_event::ended_data_sweep()
{
data_sweep_time = (cell)(nano_count() - temp_time);
}

void gc_event::started_code_sweep()
{
temp_time = nano_count();
}

void gc_event::ended_code_sweep()
{
code_sweep_time = (cell)(nano_count() - temp_time);
}

void gc_event::started_compaction()
{
temp_time = nano_count();
}

void gc_event::ended_compaction()
{
compaction_time = (cell)(nano_count() - temp_time);
}

void gc_event::ended_gc(factor_vm *parent)
{
data_heap_after = parent->data_room();
code_heap_after = parent->code_room();
total_time = (cell)(nano_count() - start_time);
}

gc_state::gc_state(gc_op op_, factor_vm *parent) : op(op_)
{
if(parent->gc_events)
{
event = new gc_event(op,parent);
start_time = nano_count();
}
else
event = NULL;
}

gc_state::~gc_state()
{
if(event)
{
delete event;
event = NULL;
}
}

void factor_vm::end_gc()
{
if(gc_events)
{
current_gc->event->ended_gc(this);
gc_events->push_back(*current_gc->event);
}
}

void factor_vm::start_gc_again()
{
end_gc();

switch(current_gc->op)
{
case collect_nursery_op:
/* Nursery collection can fail if aging does not have enough
free space to fit all live objects from nursery. */
current_gc->op = collect_aging_op;
break;
case collect_aging_op:
/* Aging collection can fail if the aging semispace cannot fit
all the live objects from the other aging semispace and the
nursery. */
current_gc->op = collect_to_tenured_op;
break;
default:
/* Nothing else should fail mid-collection due to insufficient
space in the target generation. */
critical_error("Bad GC op",current_gc->op);
break;
}

if(gc_events)
current_gc->event = new gc_event(current_gc->op,this);
}

void factor_vm::set_current_gc_op(gc_op op)
{
current_gc->op = op;
if(gc_events) current_gc->event->op = op;
}

void factor_vm::gc(gc_op op, cell requested_size, bool trace_contexts_p)
{
FACTOR_ASSERT(!gc_off);
FACTOR_ASSERT(!current_gc);

/* Important invariant: tenured space must have enough contiguous free
space to fit the entire contents of the aging space and nursery. This is
because when doing a full collection, objects from younger generations
are promoted before any unreachable tenured objects are freed. */
FACTOR_ASSERT(!data->high_fragmentation_p());

current_gc = new gc_state(op,this);
atomic::store(&current_gc_p, true);

/* Keep trying to GC higher and higher generations until we don't run
out of space in the target generation. */
for(;;)
{
try
{
if(gc_events) current_gc->event->op = current_gc->op;

switch(current_gc->op)
{
case collect_nursery_op:
collect_nursery();
break;
case collect_aging_op:
/* We end up here if the above fails. */
collect_aging();
if(data->high_fragmentation_p())
{
/* Change GC op so that if we fail again,
we crash. */
set_current_gc_op(collect_full_op);
collect_full(trace_contexts_p);
}
break;
case collect_to_tenured_op:
/* We end up here if the above fails. */
collect_to_tenured();
if(data->high_fragmentation_p())
{
/* Change GC op so that if we fail again,
we crash. */
set_current_gc_op(collect_full_op);
collect_full(trace_contexts_p);
}
break;
case collect_full_op:
collect_full(trace_contexts_p);
break;
case collect_compact_op:
collect_compact(trace_contexts_p);
break;
case collect_growing_heap_op:
collect_growing_heap(requested_size,trace_contexts_p);
break;
default:
critical_error("Bad GC op",current_gc->op);
break;
}

break;
}
catch(const must_start_gc_again &)
{
/* We come back here if the target generation is full. */
start_gc_again();
continue;
}
}

end_gc();

atomic::store(&current_gc_p, false);
delete current_gc;
current_gc = NULL;

/* Check the invariant again, just in case. */
FACTOR_ASSERT(!data->high_fragmentation_p());
}

/* primitive_minor_gc() is invoked by inline GC checks, and it needs to fill in
uninitialized stack locations before actually calling the GC. See the comment
in compiler.cfg.stacks.uninitialized for details. */

struct call_frame_scrubber {
factor_vm *parent;
context *ctx;

explicit call_frame_scrubber(factor_vm *parent_, context *ctx_) :
parent(parent_), ctx(ctx_) {}

void operator()(void *frame_top, cell frame_size, code_block *owner, void *addr)
{
cell return_address = owner->offset(addr);

gc_info *info = owner->block_gc_info();

FACTOR_ASSERT(return_address < owner->size());
cell index = info->return_address_index(return_address);
if(index != (cell)-1)
ctx->scrub_stacks(info,index);
}
};

void factor_vm::scrub_context(context *ctx)
{
call_frame_scrubber scrubber(this,ctx);
iterate_callstack(ctx,scrubber);
}

void factor_vm::scrub_contexts()
{
std::set<context *>::const_iterator begin = active_contexts.begin();
std::set<context *>::const_iterator end = active_contexts.end();
while(begin != end)
{
scrub_context(*begin);
begin++;
}
}

void factor_vm::primitive_minor_gc()
{
scrub_contexts();

gc(collect_nursery_op,
0, /* requested size */
true /* trace contexts? */);
}

void factor_vm::primitive_full_gc()
{
gc(collect_full_op,
0, /* requested size */
true /* trace contexts? */);
}

void factor_vm::primitive_compact_gc()
{
gc(collect_compact_op,
0, /* requested size */
true /* trace contexts? */);
}

/* Allocates memory */
/*
* It is up to the caller to fill in the object's fields in a meaningful
* fashion!
*/
object *factor_vm::allot_large_object(cell type, cell size)
{
/* If tenured space does not have enough room, collect and compact */
cell requested_size = size + data->high_water_mark();
if(!data->tenured->can_allot_p(requested_size))
{
primitive_compact_gc();

/* If it still won't fit, grow the heap */
if(!data->tenured->can_allot_p(requested_size))
{
gc(collect_growing_heap_op,
size, /* requested size */
true /* trace contexts? */);
}
}

object *obj = data->tenured->allot(size);

/* Allows initialization code to store old->new pointers
without hitting the write barrier in the common case of
a nursery allocation */
write_barrier(obj,size);

obj->initialize(type);
return obj;
}

void factor_vm::primitive_enable_gc_events()
{
gc_events = new std::vector<gc_event>();
}

void factor_vm::primitive_disable_gc_events()
{
if(gc_events)
{
growable_array result(this);

std::vector<gc_event> *gc_events = this->gc_events;
this->gc_events = NULL;

std::vector<gc_event>::const_iterator iter = gc_events->begin();
std::vector<gc_event>::const_iterator end = gc_events->end();

for(; iter != end; iter++)
{
gc_event event = *iter;
byte_array *obj = byte_array_from_value(&event);
result.add(tag<byte_array>(obj));
}

result.trim();
ctx->push(result.elements.value());

delete this->gc_events;
}
else
ctx->push(false_object);
}

}
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