/*---------------------------------------------------------------------------*/
static void
collect_garbage(int mode)
{
uint16_t sector;
struct sector_status stats;
coffee_page_t first_page, isolation_count;
COFFEE_WATCHDOG_STOP();
PRINTF("Coffee: Running the file system garbage collector in %s mode\n",
mode == GC_RELUCTANT ? "reluctant" : "greedy");
/*
* The garbage collector erases as many sectors as possible. A sector is
* erasable if there are only free or obsolete pages in it.
*/
for(sector = 0; sector < COFFEE_SECTOR_COUNT; sector++) {
isolation_count = get_sector_status(sector, &stats);
PRINTF("Coffee: Sector %u has %u active, %u obsolete, and %u free pages.\n",
sector, (unsigned)stats.active,
(unsigned)stats.obsolete, (unsigned)stats.free);
if(stats.active > 0) {
continue;
}
if((mode == GC_RELUCTANT && stats.free == 0) ||
(mode == GC_GREEDY && stats.obsolete > 0)) {
first_page = sector * COFFEE_PAGES_PER_SECTOR;
if(first_page < *next_free) {
*next_free = first_page;
}
if(isolation_count > 0) {
isolate_pages(first_page + COFFEE_PAGES_PER_SECTOR, isolation_count);
}
COFFEE_ERASE(sector);
PRINTF("Coffee: Erased sector %d!\n", sector);
if(mode == GC_RELUCTANT && isolation_count > 0) {
break;
}
}
}
COFFEE_WATCHDOG_START();
}
/*---------------------------------------------------------------------------*/
static int
cfs_garbage_collect(void)
{
uint16_t sector;
uint16_t active_pages, free_pages, obsolete_pages;
uint8_t sectors_in_row, longest_row;
watchdog_stop();
PRINTF("Coffee: Running the file system garbage collector...\n");
sectors_in_row = longest_row = 0;
/*
* The garbage collector erases as many sectors as possible. A sector is
* erasable if there are only free or obsolete pages in it.
*/
for(sector = 0; sector < COFFEE_SIZE / COFFEE_SECTOR_SIZE; sector++) {
get_sector_status(sector, &active_pages, &free_pages, &obsolete_pages);
PRINTF("Coffee: Sector %u has %u active, %u free, and %u obsolete pages.\n",
sector, active_pages, free_pages, obsolete_pages);
if(active_pages == 0 && obsolete_pages > 0) {
COFFEE_ERASE(sector);
PRINTF("Coffee: Erased sector %d!\n", sector);
++sectors_in_row;
if(sectors_in_row > longest_row) {
longest_row = sectors_in_row;
}
} else {
sectors_in_row = 0;
}
}
watchdog_start();
return longest_row * COFFEE_PAGES_PER_SECTOR;
}
