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/*
*
* 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_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 = 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;
}
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