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/*
*
* Copyright 2014, 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>
/* 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();
grpc_mdctx *grpc_mdctx_create_with_seed(gpr_uint32 seed);
void grpc_mdctx_orphan(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);
/* 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);
#endif /* __GRPC_INTERNAL_TRANSPORT_METADATA_H__ */
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