| /* |
| * |
| * Copyright 2016 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/slice/slice_internal.h" |
| |
| #include <inttypes.h> |
| #include <string.h> |
| |
| #include <grpc/support/alloc.h> |
| #include <grpc/support/log.h> |
| |
| #include "src/core/lib/iomgr/iomgr_internal.h" /* for iomgr_abort_on_leaks() */ |
| #include "src/core/lib/profiling/timers.h" |
| #include "src/core/lib/slice/slice_string_helpers.h" |
| #include "src/core/lib/support/murmur_hash.h" |
| #include "src/core/lib/transport/static_metadata.h" |
| |
| #define LOG2_SHARD_COUNT 5 |
| #define SHARD_COUNT (1 << LOG2_SHARD_COUNT) |
| #define INITIAL_SHARD_CAPACITY 8 |
| |
| #define TABLE_IDX(hash, capacity) (((hash) >> LOG2_SHARD_COUNT) % (capacity)) |
| #define SHARD_IDX(hash) ((hash) & ((1 << LOG2_SHARD_COUNT) - 1)) |
| |
| typedef struct interned_slice_refcount { |
| grpc_slice_refcount base; |
| grpc_slice_refcount sub; |
| size_t length; |
| gpr_atm refcnt; |
| uint32_t hash; |
| struct interned_slice_refcount* bucket_next; |
| } interned_slice_refcount; |
| |
| typedef struct slice_shard { |
| gpr_mu mu; |
| interned_slice_refcount** strs; |
| size_t count; |
| size_t capacity; |
| } slice_shard; |
| |
| /* hash seed: decided at initialization time */ |
| static uint32_t g_hash_seed; |
| static int g_forced_hash_seed = 0; |
| |
| static slice_shard g_shards[SHARD_COUNT]; |
| |
| typedef struct { |
| uint32_t hash; |
| uint32_t idx; |
| } static_metadata_hash_ent; |
| |
| static static_metadata_hash_ent |
| static_metadata_hash[4 * GRPC_STATIC_MDSTR_COUNT]; |
| static uint32_t max_static_metadata_hash_probe; |
| static uint32_t static_metadata_hash_values[GRPC_STATIC_MDSTR_COUNT]; |
| |
| static void interned_slice_ref(void* p) { |
| interned_slice_refcount* s = (interned_slice_refcount*)p; |
| GPR_ASSERT(gpr_atm_no_barrier_fetch_add(&s->refcnt, 1) > 0); |
| } |
| |
| static void interned_slice_destroy(interned_slice_refcount* s) { |
| slice_shard* shard = &g_shards[SHARD_IDX(s->hash)]; |
| gpr_mu_lock(&shard->mu); |
| GPR_ASSERT(0 == gpr_atm_no_barrier_load(&s->refcnt)); |
| interned_slice_refcount** prev_next; |
| interned_slice_refcount* cur; |
| for (prev_next = &shard->strs[TABLE_IDX(s->hash, shard->capacity)], |
| cur = *prev_next; |
| cur != s; prev_next = &cur->bucket_next, cur = cur->bucket_next) |
| ; |
| *prev_next = cur->bucket_next; |
| shard->count--; |
| gpr_free(s); |
| gpr_mu_unlock(&shard->mu); |
| } |
| |
| static void interned_slice_unref(void* p) { |
| interned_slice_refcount* s = (interned_slice_refcount*)p; |
| if (1 == gpr_atm_full_fetch_add(&s->refcnt, -1)) { |
| interned_slice_destroy(s); |
| } |
| } |
| |
| static void interned_slice_sub_ref(void* p) { |
| interned_slice_ref(((char*)p) - offsetof(interned_slice_refcount, sub)); |
| } |
| |
| static void interned_slice_sub_unref(void* p) { |
| interned_slice_unref(((char*)p) - offsetof(interned_slice_refcount, sub)); |
| } |
| |
| static uint32_t interned_slice_hash(grpc_slice slice) { |
| interned_slice_refcount* s = (interned_slice_refcount*)slice.refcount; |
| return s->hash; |
| } |
| |
| static int interned_slice_eq(grpc_slice a, grpc_slice b) { |
| return a.refcount == b.refcount; |
| } |
| |
| static const grpc_slice_refcount_vtable interned_slice_vtable = { |
| interned_slice_ref, interned_slice_unref, interned_slice_eq, |
| interned_slice_hash}; |
| static const grpc_slice_refcount_vtable interned_slice_sub_vtable = { |
| interned_slice_sub_ref, interned_slice_sub_unref, |
| grpc_slice_default_eq_impl, grpc_slice_default_hash_impl}; |
| |
| static void grow_shard(slice_shard* shard) { |
| size_t capacity = shard->capacity * 2; |
| size_t i; |
| interned_slice_refcount** strtab; |
| interned_slice_refcount *s, *next; |
| |
| GPR_TIMER_BEGIN("grow_strtab", 0); |
| |
| strtab = (interned_slice_refcount**)gpr_zalloc( |
| sizeof(interned_slice_refcount*) * capacity); |
| |
| for (i = 0; i < shard->capacity; i++) { |
| for (s = shard->strs[i]; s; s = next) { |
| size_t idx = TABLE_IDX(s->hash, capacity); |
| next = s->bucket_next; |
| s->bucket_next = strtab[idx]; |
| strtab[idx] = s; |
| } |
| } |
| |
| gpr_free(shard->strs); |
| shard->strs = strtab; |
| shard->capacity = capacity; |
| |
| GPR_TIMER_END("grow_strtab", 0); |
| } |
| |
| static grpc_slice materialize(interned_slice_refcount* s) { |
| grpc_slice slice; |
| slice.refcount = &s->base; |
| slice.data.refcounted.bytes = (uint8_t*)(s + 1); |
| slice.data.refcounted.length = s->length; |
| return slice; |
| } |
| |
| uint32_t grpc_slice_default_hash_impl(grpc_slice s) { |
| return gpr_murmur_hash3(GRPC_SLICE_START_PTR(s), GRPC_SLICE_LENGTH(s), |
| g_hash_seed); |
| } |
| |
| uint32_t grpc_static_slice_hash(grpc_slice s) { |
| return static_metadata_hash_values[GRPC_STATIC_METADATA_INDEX(s)]; |
| } |
| |
| int grpc_static_slice_eq(grpc_slice a, grpc_slice b) { |
| return GRPC_STATIC_METADATA_INDEX(a) == GRPC_STATIC_METADATA_INDEX(b); |
| } |
| |
| uint32_t grpc_slice_hash(grpc_slice s) { |
| return s.refcount == nullptr ? grpc_slice_default_hash_impl(s) |
| : s.refcount->vtable->hash(s); |
| } |
| |
| grpc_slice grpc_slice_maybe_static_intern(grpc_slice slice, |
| bool* returned_slice_is_different) { |
| if (GRPC_IS_STATIC_METADATA_STRING(slice)) { |
| return slice; |
| } |
| |
| uint32_t hash = grpc_slice_hash(slice); |
| for (uint32_t i = 0; i <= max_static_metadata_hash_probe; i++) { |
| static_metadata_hash_ent ent = |
| static_metadata_hash[(hash + i) % GPR_ARRAY_SIZE(static_metadata_hash)]; |
| if (ent.hash == hash && ent.idx < GRPC_STATIC_MDSTR_COUNT && |
| grpc_slice_eq(grpc_static_slice_table[ent.idx], slice)) { |
| *returned_slice_is_different = true; |
| return grpc_static_slice_table[ent.idx]; |
| } |
| } |
| |
| return slice; |
| } |
| |
| bool grpc_slice_is_interned(grpc_slice slice) { |
| return (slice.refcount && slice.refcount->vtable == &interned_slice_vtable) || |
| GRPC_IS_STATIC_METADATA_STRING(slice); |
| } |
| |
| grpc_slice grpc_slice_intern(grpc_slice slice) { |
| GPR_TIMER_BEGIN("grpc_slice_intern", 0); |
| if (GRPC_IS_STATIC_METADATA_STRING(slice)) { |
| GPR_TIMER_END("grpc_slice_intern", 0); |
| return slice; |
| } |
| |
| uint32_t hash = grpc_slice_hash(slice); |
| for (uint32_t i = 0; i <= max_static_metadata_hash_probe; i++) { |
| static_metadata_hash_ent ent = |
| static_metadata_hash[(hash + i) % GPR_ARRAY_SIZE(static_metadata_hash)]; |
| if (ent.hash == hash && ent.idx < GRPC_STATIC_MDSTR_COUNT && |
| grpc_slice_eq(grpc_static_slice_table[ent.idx], slice)) { |
| GPR_TIMER_END("grpc_slice_intern", 0); |
| return grpc_static_slice_table[ent.idx]; |
| } |
| } |
| |
| interned_slice_refcount* s; |
| slice_shard* shard = &g_shards[SHARD_IDX(hash)]; |
| |
| gpr_mu_lock(&shard->mu); |
| |
| /* search for an existing string */ |
| size_t idx = TABLE_IDX(hash, shard->capacity); |
| for (s = shard->strs[idx]; s; s = s->bucket_next) { |
| if (s->hash == hash && grpc_slice_eq(slice, materialize(s))) { |
| if (gpr_atm_no_barrier_fetch_add(&s->refcnt, 1) == 0) { |
| /* If we get here, we've added a ref to something that was about to |
| * die - drop it immediately. |
| * The *only* possible path here (given the shard mutex) should be to |
| * drop from one ref back to zero - assert that with a CAS */ |
| GPR_ASSERT(gpr_atm_rel_cas(&s->refcnt, 1, 0)); |
| /* and treat this as if we were never here... sshhh */ |
| } else { |
| gpr_mu_unlock(&shard->mu); |
| GPR_TIMER_END("grpc_slice_intern", 0); |
| return materialize(s); |
| } |
| } |
| } |
| |
| /* not found: create a new string */ |
| /* string data goes after the internal_string header */ |
| s = (interned_slice_refcount*)gpr_malloc(sizeof(*s) + |
| GRPC_SLICE_LENGTH(slice)); |
| gpr_atm_rel_store(&s->refcnt, 1); |
| s->length = GRPC_SLICE_LENGTH(slice); |
| s->hash = hash; |
| s->base.vtable = &interned_slice_vtable; |
| s->base.sub_refcount = &s->sub; |
| s->sub.vtable = &interned_slice_sub_vtable; |
| s->sub.sub_refcount = &s->sub; |
| s->bucket_next = shard->strs[idx]; |
| shard->strs[idx] = s; |
| memcpy(s + 1, GRPC_SLICE_START_PTR(slice), GRPC_SLICE_LENGTH(slice)); |
| |
| shard->count++; |
| |
| if (shard->count > shard->capacity * 2) { |
| grow_shard(shard); |
| } |
| |
| gpr_mu_unlock(&shard->mu); |
| |
| GPR_TIMER_END("grpc_slice_intern", 0); |
| return materialize(s); |
| } |
| |
| void grpc_test_only_set_slice_hash_seed(uint32_t seed) { |
| g_hash_seed = seed; |
| g_forced_hash_seed = 1; |
| } |
| |
| void grpc_slice_intern_init(void) { |
| if (!g_forced_hash_seed) { |
| g_hash_seed = (uint32_t)gpr_now(GPR_CLOCK_REALTIME).tv_nsec; |
| } |
| for (size_t i = 0; i < SHARD_COUNT; i++) { |
| slice_shard* shard = &g_shards[i]; |
| gpr_mu_init(&shard->mu); |
| shard->count = 0; |
| shard->capacity = INITIAL_SHARD_CAPACITY; |
| shard->strs = (interned_slice_refcount**)gpr_zalloc(sizeof(*shard->strs) * |
| shard->capacity); |
| } |
| for (size_t i = 0; i < GPR_ARRAY_SIZE(static_metadata_hash); i++) { |
| static_metadata_hash[i].hash = 0; |
| static_metadata_hash[i].idx = GRPC_STATIC_MDSTR_COUNT; |
| } |
| max_static_metadata_hash_probe = 0; |
| for (size_t i = 0; i < GRPC_STATIC_MDSTR_COUNT; i++) { |
| static_metadata_hash_values[i] = |
| grpc_slice_default_hash_impl(grpc_static_slice_table[i]); |
| for (size_t j = 0; j < GPR_ARRAY_SIZE(static_metadata_hash); j++) { |
| size_t slot = (static_metadata_hash_values[i] + j) % |
| GPR_ARRAY_SIZE(static_metadata_hash); |
| if (static_metadata_hash[slot].idx == GRPC_STATIC_MDSTR_COUNT) { |
| static_metadata_hash[slot].hash = static_metadata_hash_values[i]; |
| static_metadata_hash[slot].idx = (uint32_t)i; |
| if (j > max_static_metadata_hash_probe) { |
| max_static_metadata_hash_probe = (uint32_t)j; |
| } |
| break; |
| } |
| } |
| } |
| } |
| |
| void grpc_slice_intern_shutdown(void) { |
| for (size_t i = 0; i < SHARD_COUNT; i++) { |
| slice_shard* shard = &g_shards[i]; |
| gpr_mu_destroy(&shard->mu); |
| /* TODO(ctiller): GPR_ASSERT(shard->count == 0); */ |
| if (shard->count != 0) { |
| gpr_log(GPR_DEBUG, "WARNING: %" PRIuPTR " metadata strings were leaked", |
| shard->count); |
| for (size_t j = 0; j < shard->capacity; j++) { |
| for (interned_slice_refcount* s = shard->strs[j]; s; |
| s = s->bucket_next) { |
| char* text = |
| grpc_dump_slice(materialize(s), GPR_DUMP_HEX | GPR_DUMP_ASCII); |
| gpr_log(GPR_DEBUG, "LEAKED: %s", text); |
| gpr_free(text); |
| } |
| } |
| if (grpc_iomgr_abort_on_leaks()) { |
| abort(); |
| } |
| } |
| gpr_free(shard->strs); |
| } |
| } |