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Diffstat (limited to 'src/core/lib/slice/slice_intern.c')
| -rw-r--r-- | src/core/lib/slice/slice_intern.c | 344 |
1 files changed, 344 insertions, 0 deletions
diff --git a/src/core/lib/slice/slice_intern.c b/src/core/lib/slice/slice_intern.c new file mode 100644 index 0000000000..7cbd17bffd --- /dev/null +++ b/src/core/lib/slice/slice_intern.c @@ -0,0 +1,344 @@ +/* + * + * Copyright 2016, Google Inc. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: + * + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above + * copyright notice, this list of conditions and the following disclaimer + * in the documentation and/or other materials provided with the + * distribution. + * * Neither the name of Google Inc. nor the names of its + * contributors may be used to endorse or promote products derived from + * this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + */ + +#include "src/core/lib/slice/slice_internal.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 = 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(grpc_exec_ctx *exec_ctx, void *p) { + interned_slice_refcount *s = 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(grpc_exec_ctx *exec_ctx, void *p) { + interned_slice_unref(exec_ctx, + ((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 = gpr_malloc(sizeof(interned_slice_refcount *) * capacity); + memset(strtab, 0, 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 == NULL ? 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) { + 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); + GPR_TIMER_END("grpc_mdstr_from_buffer", 0); + return materialize(s); + } + } + } + + /* not found: create a new string */ + /* string data goes after the internal_string header */ + s = 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 = (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 = gpr_malloc(sizeof(*shard->strs) * shard->capacity); + memset(shard->strs, 0, 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); + } +} |