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/*
*
* 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 <grpc/support/port_platform.h>
#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/gpr/murmur_hash.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/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 = static_cast<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 = static_cast<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((static_cast<char*>(p)) -
offsetof(interned_slice_refcount, sub));
}
static void interned_slice_sub_unref(void* p) {
interned_slice_unref((static_cast<char*>(p)) -
offsetof(interned_slice_refcount, sub));
}
static uint32_t interned_slice_hash(grpc_slice slice) {
interned_slice_refcount* s =
reinterpret_cast<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) {
GPR_TIMER_SCOPE("grow_strtab", 0);
size_t capacity = shard->capacity * 2;
size_t i;
interned_slice_refcount** strtab;
interned_slice_refcount *s, *next;
strtab = static_cast<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;
}
static grpc_slice materialize(interned_slice_refcount* s) {
grpc_slice slice;
slice.refcount = &s->base;
slice.data.refcounted.bytes = reinterpret_cast<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_SCOPE("grpc_slice_intern", 0);
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)) {
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);
return materialize(s);
}
}
}
/* not found: create a new string */
/* string data goes after the internal_string header */
s = static_cast<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);
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 = static_cast<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 = static_cast<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 = static_cast<uint32_t>(i);
if (j > max_static_metadata_hash_probe) {
max_static_metadata_hash_probe = static_cast<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);
}
}
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