// Gets the next block to read and tries to free 'prev' block (if not NULL).
// Returns NULL if reached the end.
static cl_block* cl_next_block_to_read(cl_block* prev) {
cl_block* block = NULL;
if (g_log.read_iterator_state == g_log.num_cores) {
// We are traversing dirty list; find the next dirty block.
if (prev != NULL) {
// Try to free the previous block if there is no unread data. This
// block
// may have unread data if previously incomplete record completed
// between
// read_next() calls.
block = prev->link.next->block;
if (cl_block_try_disable_access(prev, 0 /* do not discard data */)) {
cl_block_list_remove(&g_log.dirty_block_list, prev);
cl_block_list_insert_at_head(&g_log.free_block_list, prev);
}
} else {
block = cl_block_list_head(&g_log.dirty_block_list);
}
if (block != NULL) {
return block;
}
// We are done with the dirty list; moving on to core-local blocks.
}
while (g_log.read_iterator_state > 0) {
g_log.read_iterator_state--;
block = cl_core_local_block_get_block(
&g_log.core_local_blocks[g_log.read_iterator_state]);
if (block != NULL) {
return block;
}
}
return NULL;
}
// Allocates a new free block (or recycles an available dirty block if log is
// configured to discard old records). Returns NULL if out-of-space.
static cl_block* cl_allocate_block(void) {
cl_block* block = cl_block_list_head(&g_log.free_block_list);
if (block != NULL) {
cl_block_list_remove(&g_log.free_block_list, block);
return block;
}
if (!g_log.discard_old_records) {
// No free block and log is configured to keep old records.
return NULL;
}
// Recycle dirty block. Start from the oldest.
for (block = cl_block_list_head(&g_log.dirty_block_list); block != NULL;
block = block->link.next->block) {
if (cl_block_try_disable_access(block, 1 /* discard data */)) {
cl_block_list_remove(&g_log.dirty_block_list, block);
return block;
}
}
return NULL;
}
// External functions: primary stats_log interface
void census_log_initialize(size_t size_in_mb, int discard_old_records) {
// Check cacheline alignment.
GPR_ASSERT(sizeof(cl_block) % GPR_CACHELINE_SIZE == 0);
GPR_ASSERT(sizeof(cl_core_local_block) % GPR_CACHELINE_SIZE == 0);
GPR_ASSERT(!g_log.initialized);
g_log.discard_old_records = discard_old_records;
g_log.num_cores = gpr_cpu_num_cores();
// Ensure that we will not get any overflow in calaculating num_blocks
GPR_ASSERT(CL_LOG_2_MB >= CENSUS_LOG_2_MAX_RECORD_SIZE);
GPR_ASSERT(size_in_mb < 1000);
// Ensure at least 2x as many blocks as there are cores.
g_log.num_blocks =
(uint32_t)GPR_MAX(2 * g_log.num_cores, (size_in_mb << CL_LOG_2_MB) >>
CENSUS_LOG_2_MAX_RECORD_SIZE);
gpr_mu_init(&g_log.lock);
g_log.read_iterator_state = 0;
g_log.block_being_read = NULL;
g_log.core_local_blocks = (cl_core_local_block*)gpr_malloc_aligned(
g_log.num_cores * sizeof(cl_core_local_block), GPR_CACHELINE_SIZE_LOG);
memset(g_log.core_local_blocks, 0,
g_log.num_cores * sizeof(cl_core_local_block));
g_log.blocks = (cl_block*)gpr_malloc_aligned(
g_log.num_blocks * sizeof(cl_block), GPR_CACHELINE_SIZE_LOG);
memset(g_log.blocks, 0, g_log.num_blocks * sizeof(cl_block));
g_log.buffer = gpr_malloc(g_log.num_blocks * CENSUS_LOG_MAX_RECORD_SIZE);
memset(g_log.buffer, 0, g_log.num_blocks * CENSUS_LOG_MAX_RECORD_SIZE);
cl_block_list_initialize(&g_log.free_block_list);
cl_block_list_initialize(&g_log.dirty_block_list);
for (uint32_t i = 0; i < g_log.num_blocks; ++i) {
cl_block* block = g_log.blocks + i;
cl_block_initialize(block, g_log.buffer + (CENSUS_LOG_MAX_RECORD_SIZE * i));
cl_block_try_disable_access(block, 1 /* discard data */);
cl_block_list_insert_at_tail(&g_log.free_block_list, block);
}
gpr_atm_rel_store(&g_log.out_of_space_count, 0);
g_log.initialized = 1;
}
/* External functions: primary stats_log interface */
void census_log_initialize(size_t size_in_mb, int discard_old_records) {
gpr_int32 ix;
/* Check cacheline alignment. */
GPR_ASSERT(sizeof(cl_block) % GPR_CACHELINE_SIZE == 0);
GPR_ASSERT(sizeof(cl_core_local_block) % GPR_CACHELINE_SIZE == 0);
GPR_ASSERT(!g_log.initialized);
g_log.discard_old_records = discard_old_records;
g_log.num_cores = gpr_cpu_num_cores();
/* Ensure at least as many blocks as there are cores. */
g_log.num_blocks = GPR_MAX(
g_log.num_cores, (size_in_mb << 20) >> CENSUS_LOG_2_MAX_RECORD_SIZE);
gpr_mu_init(&g_log.lock);
g_log.read_iterator_state = 0;
g_log.block_being_read = NULL;
gpr_atm_rel_store(&g_log.is_full, 0);
g_log.core_local_blocks = (cl_core_local_block *)gpr_malloc_aligned(
g_log.num_cores * sizeof(cl_core_local_block), GPR_CACHELINE_SIZE_LOG);
memset(g_log.core_local_blocks, 0,
g_log.num_cores * sizeof(cl_core_local_block));
g_log.blocks = (cl_block *)gpr_malloc_aligned(
g_log.num_blocks * sizeof(cl_block), GPR_CACHELINE_SIZE_LOG);
memset(g_log.blocks, 0, g_log.num_blocks * sizeof(cl_block));
g_log.buffer = gpr_malloc(g_log.num_blocks * CENSUS_LOG_MAX_RECORD_SIZE);
memset(g_log.buffer, 0, g_log.num_blocks * CENSUS_LOG_MAX_RECORD_SIZE);
cl_block_list_initialize(&g_log.free_block_list);
cl_block_list_initialize(&g_log.dirty_block_list);
for (ix = 0; ix < g_log.num_blocks; ++ix) {
cl_block *block = g_log.blocks + ix;
cl_block_initialize(block,
g_log.buffer + (CENSUS_LOG_MAX_RECORD_SIZE * ix));
cl_block_try_disable_access(block, 1 /* discard data */);
cl_block_list_insert_at_tail(&g_log.free_block_list, block);
}
gpr_atm_rel_store(&g_log.out_of_space_count, 0);
g_log.initialized = 1;
}
