| /* |
| * |
| * Copyright 2017 gRPC authors. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| * |
| */ |
| |
| #include "src/core/lib/support/arena.h" |
| #include <grpc/support/alloc.h> |
| #include <grpc/support/atm.h> |
| #include <grpc/support/log.h> |
| #include <grpc/support/useful.h> |
| |
| #define ROUND_UP_TO_ALIGNMENT_SIZE(x) \ |
| (((x) + GPR_MAX_ALIGNMENT - 1u) & ~(GPR_MAX_ALIGNMENT - 1u)) |
| |
| typedef struct zone { |
| size_t size_begin; |
| size_t size_end; |
| gpr_atm next_atm; |
| } zone; |
| |
| struct gpr_arena { |
| gpr_atm size_so_far; |
| zone initial_zone; |
| }; |
| |
| gpr_arena *gpr_arena_create(size_t initial_size) { |
| initial_size = ROUND_UP_TO_ALIGNMENT_SIZE(initial_size); |
| gpr_arena *a = (gpr_arena *)gpr_zalloc(sizeof(gpr_arena) + initial_size); |
| a->initial_zone.size_end = initial_size; |
| return a; |
| } |
| |
| size_t gpr_arena_destroy(gpr_arena *arena) { |
| gpr_atm size = gpr_atm_no_barrier_load(&arena->size_so_far); |
| zone *z = (zone *)gpr_atm_no_barrier_load(&arena->initial_zone.next_atm); |
| gpr_free(arena); |
| while (z) { |
| zone *next_z = (zone *)gpr_atm_no_barrier_load(&z->next_atm); |
| gpr_free(z); |
| z = next_z; |
| } |
| return (size_t)size; |
| } |
| |
| void *gpr_arena_alloc(gpr_arena *arena, size_t size) { |
| size = ROUND_UP_TO_ALIGNMENT_SIZE(size); |
| size_t start = |
| (size_t)gpr_atm_no_barrier_fetch_add(&arena->size_so_far, size); |
| zone *z = &arena->initial_zone; |
| while (start > z->size_end) { |
| zone *next_z = (zone *)gpr_atm_acq_load(&z->next_atm); |
| if (next_z == NULL) { |
| size_t next_z_size = (size_t)gpr_atm_no_barrier_load(&arena->size_so_far); |
| next_z = (zone *)gpr_zalloc(sizeof(zone) + next_z_size); |
| next_z->size_begin = z->size_end; |
| next_z->size_end = z->size_end + next_z_size; |
| if (!gpr_atm_rel_cas(&z->next_atm, (gpr_atm)NULL, (gpr_atm)next_z)) { |
| gpr_free(next_z); |
| next_z = (zone *)gpr_atm_acq_load(&z->next_atm); |
| } |
| } |
| z = next_z; |
| } |
| if (start + size > z->size_end) { |
| return gpr_arena_alloc(arena, size); |
| } |
| GPR_ASSERT(start >= z->size_begin); |
| GPR_ASSERT(start + size <= z->size_end); |
| return ((char *)(z + 1)) + start - z->size_begin; |
| } |