// Allocates a new block and updates core id => block mapping. 'old_block'
// points to the block that the caller thinks is attached to
// 'core_id'. 'old_block' may be NULL. Returns true if:
// - allocated a new block OR
// - 'core_id' => 'old_block' mapping changed (another thread allocated a
// block before lock was acquired).
static bool cl_allocate_core_local_block(uint32_t core_id,
cl_block* old_block) {
// Now that we have the lock, check if core-local mapping has changed.
cl_core_local_block* core_local_block = &g_log.core_local_blocks[core_id];
cl_block* block = cl_core_local_block_get_block(core_local_block);
if ((block != NULL) && (block != old_block)) {
return true;
}
if (block != NULL) {
cl_core_local_block_set_block(core_local_block, NULL);
cl_block_list_insert_at_tail(&g_log.dirty_block_list, block);
}
block = cl_allocate_block();
if (block == NULL) {
return false;
}
cl_core_local_block_set_block(core_local_block, block);
cl_block_enable_access(block);
return true;
}
/* Allocates a new block and updates core id => block mapping. 'old_block'
points to the block that the caller thinks is attached to
'core_id'. 'old_block' may be NULL. Returns non-zero if:
- allocated a new block OR
- 'core_id' => 'old_block' mapping changed (another thread allocated a
block before lock was acquired). */
static int cl_allocate_core_local_block(gpr_int32 core_id,
cl_block *old_block) {
/* Now that we have the lock, check if core-local mapping has changed. */
cl_core_local_block *core_local_block = &g_log.core_local_blocks[core_id];
cl_block *block = cl_core_local_block_get_block(core_local_block);
if ((block != NULL) && (block != old_block)) {
return 1;
}
if (block != NULL) {
cl_core_local_block_set_block(core_local_block, NULL);
cl_block_list_insert_at_tail(&g_log.dirty_block_list, block);
}
block = cl_allocate_block();
if (block == NULL) {
gpr_atm_rel_store(&g_log.is_full, 1);
return 0;
}
cl_core_local_block_set_block(core_local_block, block);
cl_block_enable_access(block);
return 1;
}
void *census_log_start_write(size_t size) {
/* Used to bound number of times block allocation is attempted. */
gpr_int32 attempts_remaining = g_log.num_blocks;
/* TODO(aveitch): move this inside the do loop when current_cpu is fixed */
gpr_int32 core_id = gpr_cpu_current_cpu();
GPR_ASSERT(g_log.initialized);
if (size > CENSUS_LOG_MAX_RECORD_SIZE) {
return NULL;
}
do {
int allocated;
void *record = NULL;
cl_block *block =
cl_core_local_block_get_block(&g_log.core_local_blocks[core_id]);
if (block && (record = cl_block_start_write(block, size))) {
return record;
}
/* Need to allocate a new block. We are here if:
- No block associated with the core OR
- Write in-progress on the block OR
- block is out of space */
if (gpr_atm_acq_load(&g_log.is_full)) {
gpr_atm_no_barrier_fetch_add(&g_log.out_of_space_count, 1);
return NULL;
}
gpr_mu_lock(&g_log.lock);
allocated = cl_allocate_core_local_block(core_id, block);
gpr_mu_unlock(&g_log.lock);
if (!allocated) {
gpr_atm_no_barrier_fetch_add(&g_log.out_of_space_count, 1);
return NULL;
}
} while (attempts_remaining--);
/* Give up. */
gpr_atm_no_barrier_fetch_add(&g_log.out_of_space_count, 1);
return NULL;
}
