source: src/examples/gc_no_raii/src/internal/state.c@ 1b5c81ed

#include "state.h"

#include <stdlib>

//general purpouse includes
#include "tools.h"

//platform abstraction includes
#include "allocate-pool.h"

//gc internal includes
#include "collector.h"
#include "globals.h"
#include "memory_pool.h"
#include "object_header.h"
#include "tools/worklist.h"

void gc_state_swap(gc_state *const this);
void gc_state_sweep_roots(gc_state *const this, worklist_t* worklist);
void gc_state_clear(gc_state *const this);
void gc_state_calc_usage(gc_state *const this);

#if DEBUG
        bool gc_state_roots_match(gc_state *const this);
        bool gc_state_no_from_space_ref(gc_state *const this);
#endif

static gc_state s;

gc_state* gc_get_state()
{
        if(!s.is_initialized) ctor(&s);
        return &s;
}

void ctor(gc_state *const this)
{
        this->from_code = 0;
        this->to_space = NULL;
        this->from_space = NULL;
        this->total_space = 0;
        this->used_space = 0;
        ctor(&this->pools_table);

        gc_allocate_pool(this);

        this->is_initialized = true;
}

void dtor(gc_state *const this)
{
        dtor(&this->pools_table);
        this->is_initialized = false;
}

bool gc_is_in_heap(const gc_state* const this, const void* const address)
{
        gc_memory_pool* target_pool = gc_pool_of(address);

        gc_memory_pool** first = cbegin(&this->pools_table);
        gc_memory_pool** last = cend(&this->pools_table);
        gc_memory_pool** result = find(first, &last, target_pool);
        return result != last && gc_pool_is_from_space(*result);
}

bool gc_is_in_to_space(const gc_state* const this, const void* const address)
{
        gc_memory_pool* target_pool = gc_pool_of(address);

        gc_memory_pool** first = cbegin(&this->pools_table);
        gc_memory_pool** last = cend(&this->pools_table);
        gc_memory_pool** result = find(first, &last, target_pool);
        return result != last && !gc_pool_is_from_space(*result);
}

gc_object_header* gc_get_object_for_ref(gc_state* state, void* member)
{
        intptr_t target = ((intptr_t)member);
        if(!gc_is_in_heap(state, member)) return NULL;

        gc_memory_pool* pool = gc_pool_of(member);
        gc_pool_object_iterator it = gc_pool_iterator_for(pool, member);
        gc_pool_object_iterator end = end(pool);

        while(it != end)
        {
                gc_object_header* object = *it;
                {
                        intptr_t start = ((intptr_t)object);
                        intptr_t end = ((intptr_t)start + object->size);
                        if(start < target && end > target)
                        {
                                return object;
                        }
                }
                ++it;
        }

        checkf(false, "is_in_heap() and iterator_for() return inconsistent data");
        abort();
        return NULL;
}

void* gc_try_allocate(gc_state* const this, size_t size)
{
        gc_memory_pool* pool = this->from_space;
        while(pool != (gc_memory_pool*)0)
        {
                if(gc_pool_size_left(pool) > size)
                {
                        return gc_pool_allocate(pool, size, true);
                }
                pool = pool->next;
        }

        return (void*)0;
}

void gc_allocate_pool(gc_state *const this)
{
        gc_memory_pool* old_from_space = this->from_space;
      gc_memory_pool* old_to_space = this->to_space;

      this->from_space = (gc_memory_pool*)(pal_allocPool(POOL_SIZE_BYTES, 1));
      this->to_space = (gc_memory_pool*)(pal_allocPool(POOL_SIZE_BYTES, 1));

      ctor(this->from_space, POOL_SIZE_BYTES, old_from_space, this->to_space,   this->from_code);
      ctor(this->to_space,   POOL_SIZE_BYTES, old_to_space,   this->from_space, (~this->from_code) & 0x01);

        this->total_space += gc_pool_size_used(this->from_space);

        push_back(&this->pools_table, this->from_space);
        push_back(&this->pools_table, this->to_space);
}

void gc_collect(gc_state* const this)
{
        // DEBUG("collecting");
        // DEBUG("previous usage " << this->used_space << " / " << this->total_space);

        worklist_t worklist;
        ctor(&worklist);
        gc_state_sweep_roots(this, &worklist);

        while(!empty(&worklist))
        {
                intptr_t* ref = back(&worklist);
                pop_back(&worklist);
                gc_process_reference((void**)ref, &worklist);
        }

        check(gc_state_roots_match(this));
        check(gc_state_no_from_space_ref(this));

        gc_state_swap(this);

        gc_state_calc_usage(this);

        if(gc_needs_collect(this)) gc_allocate_pool(this);

        // DEBUG("done");
        dtor(&worklist);
}

void gc_state_swap(gc_state* const this)
{
        swap(&this->from_space, &this->to_space);

        gc_memory_pool* pool = this->to_space;
        while(pool)
        {
                gc_reset_pool(pool);
                pool = pool->next;
        }

        this->from_code = (~this->from_code) & 0x01;

        #if _DEBUG
                {
                        gc_memory_pool* pool = this->from_space;
                        while(pool)
                        {
                                check(gc_pool_is_from_space(pool));
                                pool = pool->next;
                        }

                        pool = this->to_space;
                        while(pool)
                        {
                                check(!gc_pool_is_from_space(pool));
                                pool = pool->next;
                        }
                }
        #endif
}

void gc_state_sweep_roots(gc_state* const this, worklist_t* worklist)
{
        gc_memory_pool* pool = this->from_space;
        while(pool)
        {
                gc_pool_object_iterator it = begin(pool);
                gc_pool_object_iterator end = end(pool);
                for(;it != end; ++it)
                {
                        gc_object_header* object = *it;
                        if(!object->root_chain) continue;

                        gc_copy_object(object);

                        gc_scan_object(object->forward, worklist);
                }

                pool = pool->next;
        }
}

void gc_state_clear(gc_state* const this)
{
        gc_memory_pool* pool = this->from_space;
        while(pool)
        {
                gc_reset_pool(pool);
                pool = pool->next;
        }

        pool = this->to_space;
        while(pool)
        {
                gc_reset_pool(pool);
                pool = pool->next;
        }
}

void gc_state_calc_usage(gc_state* const this)
{
        this->total_space = 0;
        this->used_space = 0;

        gc_memory_pool* pool = this->from_space;
        while(pool)
        {
                size_t size = gc_pool_size_total(pool);
                size_t used = gc_pool_size_used(pool);
                check(used <= size);
                this->total_space += size;
                this->used_space += used;

                pool = pool->next;
        }
}

#if _DEBUG
        bool gc_state_roots_match(gc_state* const this)
        {
                gc_memory_pool* pool = this->to_space;
                while(pool)
                {
                        size_t size = 0;
                        gc_pool_object_iterator it = begin(pool);
                        gc_pool_object_iterator end = end(pool);
                        for(;it != end; ++it)
                        {
                                gc_object_header* object = *it;
                                size += object->size;

                                gcpointer_base* ptr = object->root_chain;
                                while(ptr)
                                {
                                        check(get_object_ptr(ptr->m_ptr) == object);
                                        ptr = ptr->m_next;
                                }
                        }

                        check(size + gc_pool_size_used(pool) == gc_pool_size_total(pool));

                        pool = pool->next;
                }

                return true;
        }

        bool gc_state_no_from_space_ref(gc_state* const this)
        {
                gc_memory_pool* pool = this->to_space;
                while(pool)
                {
                        void** potential_ref = (void**)pool->m_start;
                        while(potential_ref < (void**)pool->m_free)
                        {
                                check(!gc_is_in_heap(this, *potential_ref));
                                potential_ref++;
                        }

                        pool = pool->next;
                }

                return true;
        }
#endif