/**
* mds — A micro-display server
* Copyright © 2014, 2015, 2016, 2017 Mattias Andrée (maandree@kth.se)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef MDS_LIBMDSSERVER_HASH_LIST_H
#define MDS_LIBMDSSERVER_HASH_LIST_H
#include "macros.h"
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
/**
* The default initial capacity
*/
#ifndef HASH_LIST_DEFAULT_INITIAL_CAPACITY
# define HASH_LIST_DEFAULT_INITIAL_CAPACITY 128
#endif
/**
* It is encourage to run `hash_list_get` before
* `hash_list_put` and `hash_list_remove`. This
* way, you know exactly what is happening.
* There is an optimisation in place to let
* `hash_list_put` and `hash_list_remove` skip
* the search for the item (unless it is the first
* element) if `hash_list_get` was used directly
* prior to `hash_list_put` or `hash_list_remove`
* to find the element. This macro used to tell
* the compiler that position of the element is
* most likely already known but is not zero.
*
* If you however choose to not call `hash_list_get`
* before `hash_list_put` and `hash_list_remove`
* you should define this macro before including
* this header file, but with the `1` changed to
* a `0`. If you on the other hand do not know
* if you are going to call `hash_list_get` before
* `hash_list_put` and `hash_list_remove` you
* should define it to expand to the input verbatim,
* that is, have the value `__VA_ARGS__`.
*/
#ifndef HASH_LIST_EXPECTED
# define HASH_LIST_EXPECTED(...) __builtin_expect((__VA_ARGS__), 1)
#endif
#define HASH_LIST_HASH(key) (this->hasher ? this->hasher(key) : (size_t)key)
#define HASH_LIST_T_VERSION 0
/**
* Create a subclass of hash_list
*
* @param T The replacement text for `hash_list`
* @param KEY_T The datatype of the keys
* @param CKEY_T `const` version of `KEY_T`
* @param VALUE_T The datatype of the values
*/
#define CREATE_HASH_LIST_SUBCLASS(T, KEY_T, CKEY_T, VALUE_T)\
\
\
/**
* Slot for a value in a hash list
*/\
struct T##_entry;\
\
/**
* Slot for a value in a hash list
*/\
struct T;\
\
\
\
/**
* The datatype of the value
*/\
typedef VALUE_T T##_value_t;\
\
/**
* Function-type for the function responsible for freeing the key and value of an entry
*
* @param entry The entry, will never be `NULL`, any only used entries will be passed
*/\
typedef void T##_entry_free_func(struct T##_entry *entry);\
\
/**
* Function-type for the function responsible for hashing keys
*
* @param key The key, will never be `NULL`
* @return The hash of the key
*/\
typedef size_t T##_key_hash_func(CKEY_T key);\
\
\
\
/**
* Comparing keys
*
* @param key_a The first key, will never be `NULL`
* @param key_b The second key, will never be `NULL`
* @return Whether the keys are equal
*/\
__attribute__((pure, nonnull))\
static inline int T##_key_comparer(CKEY_T key_a, CKEY_T key_b);\
\
/**
* Determine the marshal-size of an entry's key and value
*
* @param entry The entry, will never be `NULL`, any only used entries will be passed
* @return The marshal-size of the entry's key and value
*/\
__attribute__((pure, nonnull))\
static inline size_t T##_submarshal_size(const struct T##_entry *entry);\
\
/**
* Marshal an entry's key and value
*
* @param entry The entry, will never be `NULL`, any only used entries will be passed
* @param data The buffer where the entry's key and value will be stored
* @return The marshal-size of the entry's key and value
*/\
__attribute__((pure, nonnull))\
static inline size_t T##_submarshal(const struct T##_entry *entry, char *restrict data);\
\
/**
* Unmarshal an entry's key and value
*
* @param entry The entry, will never be `NULL`, any only used entries will be passed
* @param data The buffer where the entry's key and value is stored
* @return The number of read bytes, zero on error
*/\
__attribute__((pure, nonnull))\
static inline size_t T##_subunmarshal(struct T##_entry *entry, char *restrict data);\
\
\
\
/**
* Slot for a value in a hash list
*/\
typedef struct T##_entry\
{\
/**
* The key of the entry, `NULL` if the slot is unused
*/\
KEY_T key;\
\
/**
* Hash of `key`, undefined but initialised if the slot is unused
*/\
size_t key_hash;\
\
/**
* The value of the entry
*/\
T##_value_t value;\
\
} T##_entry_t;\
\
\
/**
* The data structure of the hash list
*/\
typedef struct T\
{\
/**
* The number of allocated slots
*/\
size_t allocated;\
\
/**
* The number of unused slot that
* has previously be used
*/\
size_t unused;\
\
/**
* The number of slots that have
* been used, even if no longer used
*/\
size_t used;\
\
/**
* This variable is used for optimisation, any
* time `hash_list_get` finds an element, its
* will be stored, and it will be the first
* inspected element by `hash_list_put` and
* `hash_list_remove`
*/\
size_t last;\
\
/**
* The slots
*/\
T##_entry_t *slots;\
\
/**
* Function used to free keys and values of entries
*
* The freeing is not used if this function pointer is `NULL`
*
* Be aware, this variable cannot be marshalled
*/\
T##_entry_free_func *freer;\
\
/**
* Function used to calculate the hash of a key
*
* If this function pointer is `NULL`, the identity hash is used
*
* Be aware, this variable cannot be marshalled
*/\
T##_key_hash_func *hasher;\
\
} T##_t;\
\
\
\
/**
* Create a hash list
*
* @param this Memory slot in which to store the new hash list
* @param capacity The minimum initial capacity of the hash list, 0 for default
* @return Non-zero on error, `errno` will have been set accordingly
*/\
static inline int __attribute__((unused, nonnull))\
T##_create(T##_t *restrict this, size_t capacity)\
{\
if (!capacity)\
capacity = HASH_LIST_DEFAULT_INITIAL_CAPACITY;\
\
this->freer = NULL;\
this->hasher = NULL;\
this->allocated = 0;\
this->unused = 0;\
this->used = 0;\
this->last = 0;\
\
this->slots = malloc(capacity * sizeof(T##_t));\
if (!this->slots)\
return -1;\
\
this->allocated = capacity;\
return 0;\
}\
\
\
/**
* Release all resources in a hash list
*
* @param this The hash list
*/\
static inline void __attribute__((unused, nonnull))\
T##_destroy(T##_t *restrict this)\
{\
size_t i, n;\
if (this->freer)\
for (i = 0, n = this->used; i < n; i++)\
if (this->slots[i].key)\
this->freer(this->slots + i);\
this->used = 0;\
this->unused = 0;\
this->allocated = 0;\
this->last = 0;\
free(this->slots);\
this->slots = NULL;\
}\
\
\
/**
* Clone a hash list
*
* @param this The hash list to clone
* @param out Memory slot in which to store the new hash list
* @return Non-zero on error, `errno` will have been set accordingly
*/\
static inline int __attribute__((unused, nonnull))\
T##_clone(const T##_t *restrict this, T##_t *restrict out)\
{\
if (T##_create(out, this->allocated) < 0)\
return -1;\
out->used = this->used;\
out->unused = this->unused;\
out->last = this->last;\
memcpy(out->slots, this->slots, this->used * sizeof(T##_entry_t));\
}\
\
\
/**
* Pack the list so that there are no reusable
* positions, and reduce the capacity to the
* smallest capacity that can be used.
* This method has linear time complexity and
* constant memory complexity.
*
* @param this The list
* @return Non-zero on error, `errno` will have
* been set accordingly. Errors are non-fatal.
*/\
static inline int __attribute__((unused, nonnull))\
T##_pack(T##_t *restrict this)\
{\
size_t i, j, n;\
T##_entry_t *slots = this->slots;\
\
if (this->unused > 0) {\
for (i = 0, j = 0, n = this->used; i < n; i++)\
if (slots[i].key)\
slots[j++] = slots[i];\
\
this->used -= this->unused;\
this->unused = 0;\
this->last = 0;\
}\
\
if (this->used < this->allocated) {\
slots = realloc(slots, this->used * sizeof(T##_entry_t));\
if (!slots)\
return -1;\
this->slots = slots;\
this->allocated = this->used;\
}\
\
return 0;\
}\
\
\
/**
* Look up a value in a hash list
*
* @param this The hash list
* @param key The key associated with the value, must not be `NULL`
* @param value Output parameter for the value
* @return Whether the key was found, error is impossible
*/\
static inline int __attribute__((unused, nonnull))\
T##_get(T##_t *restrict this, CKEY_T key, T##_value_t *restrict value)\
{\
size_t i, n, hash = HASH_LIST_HASH(key);\
for (i = 0, n = this->used; i < n; i++)\
if (this->slots[i].key_hash == hash && this->slots[i].key)\
if (T##_key_comparer(this->slots[i].key, key))\
return *value = this->slots[this->last = i].value, 1;\
return this->last = 0, 0;\
}\
\
\
/**
* Remove an entry from a hash list
*
* @param this The hash list
* @param key The key of the entry to remove, must not be `NULL`
*/\
static inline void __attribute__((unused, nonnull))\
T##_remove(T##_t *restrict this, CKEY_T key)\
{\
size_t i = this->last, n, hash = HASH_LIST_HASH(key);\
T##_entry_t *slots = this->slots;\
\
/* First, try cached index. */\
if (HASH_LIST_EXPECTED(i && slots[i].key_hash == hash && slots[i].key))\
if (HASH_LIST_EXPECTED(T##_key_comparer(slots[i].key, key)))\
goto do_remove;\
/* It is discouraged to use put or remove without
* doing a get before it, otherwise you do not know
* what is happening. So we do not expect to get
* get to the next line. However, if do not expect to
* run get before put or remove, you should modify the
* `HASH_LIST_EXPECTED` macro. However, this is single
* case where will will get to the next line, when the
* index of the item is zero. */\
\
/* Then, search. */\
for (i = 0, n = this->used; i < n; i++)\
if (slots[i].key_hash == hash && slots[i].key)\
if (T##_key_comparer(slots[i].key, key))\
goto do_remove;\
\
return;\
do_remove:\
if (this->freer)\
this->freer(slots + i);\
slots[i].key = NULL;\
this->unused++;\
if (this->unused >> 1 >= this->used)\
T##_pack(this);\
this->last = 0;\
}\
\
\
/**
* Add an entry to a hash list
*
* @param this The hash list
* @param key The key of the entry to add, must not be `NULL`
* @param value Pointer to the value of the entry to add,
* `NULL` if the entry should be removed instead
* @return Non-zero on error, `errno` will have been set accordingly
*/\
static inline int __attribute__((unused, nonnull(1, 2)))\
T##_put(T##_t *restrict this, KEY_T key, const T##_value_t *restrict value)\
{\
size_t i = this->last, n, empty = this->used, hash;\
T##_entry_t* slots = this->slots;\
\
/* Remove entry if no value is passed. */\
if (!value) {\
T##_remove(this, key);\
return 0;\
}\
\
/* Hash the input key. */\
hash = HASH_LIST_HASH(key);\
\
/* Try cached index. */\
if (HASH_LIST_EXPECTED(i && slots[i].key))\
if (HASH_LIST_EXPECTED(slots[i].key_hash == hash))\
if (HASH_LIST_EXPECTED(T##_key_comparer(slots[i].key, key)))\
goto put;\
/* It is discouraged to use put or remove without
* doing a get before it, otherwise you do not know
* what is happening. So we do not expect to get
* get to the next line. However, if do not expect to
* run get before put or remove, you should modify the
* `HASH_LIST_EXPECTED` macro. However, this is single
* case where will will get to the next line, when the
* index of the item is zero. */\
\
/* Find an unused slot or the current slot. */\
for (i = 0, n = this->used; i < n; i++) {\
if (!slots[i].key) {\
empty = i;\
} else if (slots[i].key_hash == hash) {\
if (T##_key_comparer(slots[i].key, key))\
goto put;\
}\
}\
\
/* Grow slot allocation is required. */\
if (empty == this->allocated) {\
if (empty >= SIZE_MAX >> 1)\
return errno = ENOMEM, -1;\
slots = realloc(slots, (empty << 1) * sizeof(T##_entry_t));\
if (!slots)\
return -1;\
this->slots = slots;\
this->allocated <<= 1;\
}\
\
/* Store entry. */\
i = empty;\
goto put_no_free;\
put:\
if (this->freer)\
this->freer(slots + i);\
put_no_free:\
slots[i].key = key;\
slots[i].key_hash = hash;\
slots[i].value = *value;\
return 0;\
}\
\
\
/**
* Calculate the buffer size need to marshal a hash list
*
* @param this The hash table
* @return The number of bytes to allocate to the output buffer
*/\
static inline size_t __attribute__((unused, pure, nonnull))\
T##_marshal_size(const T##_t *restrict this)\
{\
size_t i, n = this->used;\
size_t rc = sizeof(int) + 4 * sizeof(size_t);\
for (i = 0; i < n; i++)\
if (this->slots[i].key)\
rc += T##_submarshal_size(this->slots + i);\
return rc + n * sizeof(char) + (n - this->unused) * sizeof(size_t);\
}\
\
\
/**
* Marshals a hash list
*
* @param this The hash list
* @param data Output buffer for the marshalled data
*/\
static inline void __attribute__((unused, nonnull))\
T##_marshal(const T##_t *restrict this, char *restrict data)\
{\
size_t wrote, i, n = this->used;\
\
buf_set_next(data, int, HASH_LIST_T_VERSION);\
buf_set_next(data, size_t, this->allocated);\
buf_set_next(data, size_t, this->unused);\
buf_set_next(data, size_t, this->used);\
buf_set_next(data, size_t, this->last);\
\
for (i = 0; i < n; i++) {\
if (this->slots[i].key) {\
buf_set_next(data, char, 1);\
buf_set_next(data, size_t, this->slots[i].key_hash);\
wrote = T##_submarshal(this->slots + i, data);\
data += wrote / sizeof(char);\
} else {\
buf_set_next(data, char, 0);\
}\
}\
}\
\
\
/**
* Unmarshals a hash list
*
* @param this Memory slot in which to store the new hash list
* @param data In buffer with the marshalled data
* @return Non-zero on error, `errno` will be set accordingly.
* Destroy the table on error.
*/\
static inline int __attribute__((unused, nonnull))\
T##_unmarshal(T##_t *restrict this, char *restrict data)\
{\
size_t i, n, got;\
char used;\
\
this->freer = NULL;\
this->hasher = NULL;\
\
/* buf_get(data, int, 0, HASH_LIST_T_VERSION); */\
buf_next(data, int, 1);\
\
buf_get_next(data, size_t, this->allocated);\
buf_get_next(data, size_t, this->unused);\
buf_get_next(data, size_t, this->used);\
buf_get_next(data, size_t, this->last);\
\
this->slots = calloc(this->allocated, sizeof(T##_entry_t));\
if (!this->slots)\
return -1;\
\
for (i = 0, n = this->used; i < n; i++) {\
buf_get_next(data, char, used);\
if (!used)\
continue;\
buf_set_next(data, size_t, this->slots[i].key_hash);\
got = T##_subunmarshal(this->slots + i, data);\
if (!got)\
return -1;\
data += got / sizeof(char);\
}\
\
return 0;\
}
/**
* Wrapper for `for` keyword that iterates over entry element in a hash list
*
* @param this:hash_list_t The hash lsit
* @param i:size_t The variable to store the buckey index in at each iteration
* @param entry:hash_list_enty_t* The variable to store the entry in at each iteration
*/
#define foreach_hash_list_entry(this, i, entry)\
for (i = 0; i < (this).used; i++)\
if ((entry = (this).slots)->key)
#endif
