| /* |
| * |
| * Copyright 2015, 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. |
| * |
| */ |
| |
| #ifndef __GRPC_INTERNAL_TRANSPORT_METADATA_H__ |
| #define __GRPC_INTERNAL_TRANSPORT_METADATA_H__ |
| |
| #include <grpc/support/slice.h> |
| #include <grpc/support/useful.h> |
| |
| /* This file provides a mechanism for tracking metadata through the grpc stack. |
| It's not intended for consumption outside of the library. |
| |
| Metadata is tracked in the context of a grpc_mdctx. For the time being there |
| is one of these per-channel, avoiding cross channel interference with memory |
| use and lock contention. |
| |
| The context tracks unique strings (grpc_mdstr) and pairs of strings |
| (grpc_mdelem). Any of these objects can be checked for equality by comparing |
| their pointers. These objects are reference counted. |
| |
| grpc_mdelem can additionally store a (non-NULL) user data pointer. This |
| pointer is intended to be used to cache semantic meaning of a metadata |
| element. For example, an OAuth token may cache the credentials it represents |
| and the time at which it expires in the mdelem user data. |
| |
| Combining this metadata cache and the hpack compression table allows us to |
| simply lookup complete preparsed objects quickly, incurring a few atomic |
| ops per metadata element on the fast path. |
| |
| grpc_mdelem instances MAY live longer than their refcount implies, and are |
| garbage collected periodically, meaning cached data can easily outlive a |
| single request. */ |
| |
| /* Forward declarations */ |
| typedef struct grpc_mdctx grpc_mdctx; |
| typedef struct grpc_mdstr grpc_mdstr; |
| typedef struct grpc_mdelem grpc_mdelem; |
| |
| /* if changing this, make identical changes in internal_string in metadata.c */ |
| struct grpc_mdstr { |
| const gpr_slice slice; |
| const gpr_uint32 hash; |
| /* there is a private part to this in metadata.c */ |
| }; |
| |
| /* if changing this, make identical changes in internal_metadata in |
| metadata.c */ |
| struct grpc_mdelem { |
| grpc_mdstr *const key; |
| grpc_mdstr *const value; |
| /* there is a private part to this in metadata.c */ |
| }; |
| |
| /* Create/orphan a metadata context */ |
| grpc_mdctx *grpc_mdctx_create(void); |
| grpc_mdctx *grpc_mdctx_create_with_seed(gpr_uint32 seed); |
| void grpc_mdctx_ref(grpc_mdctx *mdctx); |
| void grpc_mdctx_unref(grpc_mdctx *mdctx); |
| |
| /* Test only accessors to internal state - only for testing this code - do not |
| rely on it outside of metadata_test.c */ |
| size_t grpc_mdctx_get_mdtab_capacity_test_only(grpc_mdctx *mdctx); |
| size_t grpc_mdctx_get_mdtab_count_test_only(grpc_mdctx *mdctx); |
| size_t grpc_mdctx_get_mdtab_free_test_only(grpc_mdctx *mdctx); |
| |
| /* Constructors for grpc_mdstr instances; take a variety of data types that |
| clients may have handy */ |
| grpc_mdstr *grpc_mdstr_from_string(grpc_mdctx *ctx, const char *str); |
| grpc_mdstr *grpc_mdstr_from_slice(grpc_mdctx *ctx, gpr_slice slice); |
| grpc_mdstr *grpc_mdstr_from_buffer(grpc_mdctx *ctx, const gpr_uint8 *str, |
| size_t length); |
| |
| /* Returns a borrowed slice from the mdstr with its contents base64 encoded |
| and huffman compressed */ |
| gpr_slice grpc_mdstr_as_base64_encoded_and_huffman_compressed(grpc_mdstr *str); |
| |
| /* Constructors for grpc_mdelem instances; take a variety of data types that |
| clients may have handy */ |
| grpc_mdelem *grpc_mdelem_from_metadata_strings(grpc_mdctx *ctx, grpc_mdstr *key, |
| grpc_mdstr *value); |
| grpc_mdelem *grpc_mdelem_from_strings(grpc_mdctx *ctx, const char *key, |
| const char *value); |
| grpc_mdelem *grpc_mdelem_from_slices(grpc_mdctx *ctx, gpr_slice key, |
| gpr_slice value); |
| grpc_mdelem *grpc_mdelem_from_string_and_buffer(grpc_mdctx *ctx, |
| const char *key, |
| const gpr_uint8 *value, |
| size_t value_length); |
| |
| /* Mutator and accessor for grpc_mdelem user data. The destructor function |
| is used as a type tag and is checked during user_data fetch. */ |
| void *grpc_mdelem_get_user_data(grpc_mdelem *md, |
| void (*if_destroy_func)(void *)); |
| void grpc_mdelem_set_user_data(grpc_mdelem *md, void (*destroy_func)(void *), |
| void *user_data); |
| |
| /* Reference counting */ |
| grpc_mdstr *grpc_mdstr_ref(grpc_mdstr *s); |
| void grpc_mdstr_unref(grpc_mdstr *s); |
| |
| grpc_mdelem *grpc_mdelem_ref(grpc_mdelem *md); |
| void grpc_mdelem_unref(grpc_mdelem *md); |
| |
| /* Recover a char* from a grpc_mdstr. The returned string is null terminated. |
| Does not promise that the returned string has no embedded nulls however. */ |
| const char *grpc_mdstr_as_c_string(grpc_mdstr *s); |
| |
| #define GRPC_MDSTR_KV_HASH(k_hash, v_hash) (GPR_ROTL((k_hash), 2) ^ (v_hash)) |
| |
| #endif /* __GRPC_INTERNAL_TRANSPORT_METADATA_H__ */ |