src/core/lib/transport/mdstr_hash_table.h

/*
 * Copyright 2016, Google Inc.
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 * modification, are permitted provided that the following conditions are
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 *
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 * notice, this list of conditions and the following disclaimer.
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 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
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 * 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
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#ifndef GRPC_CORE_LIB_TRANSPORT_MDSTR_HASH_TABLE_H
#define GRPC_CORE_LIB_TRANSPORT_MDSTR_HASH_TABLE_H

#include "src/core/lib/transport/metadata.h"

/** Hash table implementation.
 *
 * This implementation uses open addressing
 * (https://en.wikipedia.org/wiki/Open_addressing) with quadratic
 * probing (https://en.wikipedia.org/wiki/Quadratic_probing).
 *
 * The keys are \a grpc_mdstr objects.  The values are arbitrary pointers
 * with a common vtable.
 *
 * Hash tables are intentionally immutable, to avoid the need for locking.
 */

typedef struct grpc_mdstr_hash_table grpc_mdstr_hash_table;

typedef struct grpc_mdstr_hash_table_vtable {
  void (*destroy_value)(void* value);
  void* (*copy_value)(void* value);
  int (*compare_value)(void* value1, void* value2);
} grpc_mdstr_hash_table_vtable;

typedef struct grpc_mdstr_hash_table_entry {
  grpc_mdstr* key;
  void* value; /* Must not be NULL. */
  const grpc_mdstr_hash_table_vtable* vtable;
} grpc_mdstr_hash_table_entry;

/** Creates a new hash table of containing \a entries, which is an array
    of length \a num_entries.
    Creates its own copy of all keys and values from \a entries. */
grpc_mdstr_hash_table* grpc_mdstr_hash_table_create(
    size_t num_entries, grpc_mdstr_hash_table_entry* entries);

grpc_mdstr_hash_table* grpc_mdstr_hash_table_ref(grpc_mdstr_hash_table* table);
/** Returns 1 when \a table is destroyed. */
int grpc_mdstr_hash_table_unref(grpc_mdstr_hash_table* table);

/** Returns the number of entries in \a table. */
size_t grpc_mdstr_hash_table_num_entries(const grpc_mdstr_hash_table* table);

/** Returns the value from \a table associated with \a key.
    Returns NULL if \a key is not found. */
void* grpc_mdstr_hash_table_get(const grpc_mdstr_hash_table* table,
                                const grpc_mdstr* key);

/** Compares two hash tables.
    The sort order is stable but undefined. */
int grpc_mdstr_hash_table_cmp(const grpc_mdstr_hash_table* table1,
                              const grpc_mdstr_hash_table* table2);

/** Iterates over the entries in \a table, calling \a func for each entry. */
void grpc_mdstr_hash_table_iterate(
    const grpc_mdstr_hash_table* table,
    void (*func)(const grpc_mdstr_hash_table_entry* entry, void* user_data),
    void* user_data);

#endif /* GRPC_CORE_LIB_TRANSPORT_MDSTR_HASH_TABLE_H */