diff options
Diffstat (limited to 'src/core/lib/transport/mdstr_hash_table.c')
-rw-r--r-- | src/core/lib/transport/mdstr_hash_table.c | 118 |
1 files changed, 118 insertions, 0 deletions
diff --git a/src/core/lib/transport/mdstr_hash_table.c b/src/core/lib/transport/mdstr_hash_table.c new file mode 100644 index 0000000000..2791bf653b --- /dev/null +++ b/src/core/lib/transport/mdstr_hash_table.c @@ -0,0 +1,118 @@ +// +// 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/transport/mdstr_hash_table.h" + +#include <stdbool.h> +#include <string.h> + +#include <grpc/support/alloc.h> +#include <grpc/support/log.h> + +#include "src/core/lib/transport/metadata.h" + +struct grpc_mdstr_hash_table { + gpr_refcount refs; + size_t size; + grpc_mdstr_hash_table_entry* entries; +}; + +// Helper function for insert and get operations that performs quadratic +// probing (https://en.wikipedia.org/wiki/Quadratic_probing). +static size_t grpc_mdstr_hash_table_find_index( + const grpc_mdstr_hash_table* table, const grpc_mdstr* key, + bool find_empty) { + for (size_t i = 0; i < table->size; ++i) { + const size_t idx = (key->hash + i * i) % table->size; + if (table->entries[idx].key == NULL) return find_empty ? idx : table->size; + if (table->entries[idx].key == key) return idx; + } + return table->size; // Not found. +} + +static void grpc_mdstr_hash_table_add( + grpc_mdstr_hash_table* table, grpc_mdstr* key, void* value, + const grpc_mdstr_hash_table_vtable* vtable) { + GPR_ASSERT(value != NULL); + const size_t idx = + grpc_mdstr_hash_table_find_index(table, key, true /* find_empty */); + GPR_ASSERT(idx != table->size); // Table should never be full. + grpc_mdstr_hash_table_entry* entry = &table->entries[idx]; + entry->key = GRPC_MDSTR_REF(key); + entry->value = vtable->copy_value(value); + entry->vtable = vtable; +} + +grpc_mdstr_hash_table* grpc_mdstr_hash_table_create( + size_t num_entries, grpc_mdstr_hash_table_entry* entries) { + grpc_mdstr_hash_table* table = gpr_malloc(sizeof(*table)); + memset(table, 0, sizeof(*table)); + gpr_ref_init(&table->refs, 1); + // Quadratic probing gets best performance when the table is no more + // than half full. + table->size = num_entries * 2; + const size_t entry_size = sizeof(grpc_mdstr_hash_table_entry) * table->size; + table->entries = gpr_malloc(entry_size); + memset(table->entries, 0, entry_size); + for (size_t i = 0; i < num_entries; ++i) { + grpc_mdstr_hash_table_entry* entry = &entries[i]; + grpc_mdstr_hash_table_add(table, entry->key, entry->value, entry->vtable); + } + return table; +} + +grpc_mdstr_hash_table* grpc_mdstr_hash_table_ref(grpc_mdstr_hash_table* table) { + if (table != NULL) gpr_ref(&table->refs); + return table; +} + +void grpc_mdstr_hash_table_unref(grpc_exec_ctx* exec_ctx, + grpc_mdstr_hash_table* table) { + if (table != NULL && gpr_unref(&table->refs)) { + for (size_t i = 0; i < table->size; ++i) { + grpc_mdstr_hash_table_entry* entry = &table->entries[i]; + if (entry->key != NULL) { + GRPC_MDSTR_UNREF(exec_ctx, entry->key); + entry->vtable->destroy_value(exec_ctx, entry->value); + } + } + gpr_free(table->entries); + gpr_free(table); + } +} + +void* grpc_mdstr_hash_table_get(const grpc_mdstr_hash_table* table, + const grpc_mdstr* key) { + const size_t idx = + grpc_mdstr_hash_table_find_index(table, key, false /* find_empty */); + if (idx == table->size) return NULL; // Not found. + return table->entries[idx].value; +} |