summaryrefslogtreecommitdiffstats
path: root/lib/librte_hash/rte_fbk_hash.h
blob: a430961d0e4af7dd8239c092a68685261854ef56 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
/*-
 *   BSD LICENSE
 *
 *   Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
 *   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 Intel Corporation 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 _RTE_FBK_HASH_H_
#define _RTE_FBK_HASH_H_

/**
 * @file
 *
 * This is a hash table implementation for four byte keys (fbk).
 *
 * Note that the return value of the add function should always be checked as,
 * if a bucket is full, the key is not added even if there is space in other
 * buckets. This keeps the lookup function very simple and therefore fast.
 */

#include <stdint.h>
#include <errno.h>
#include <sys/queue.h>

#ifdef __cplusplus
extern "C" {
#endif

#include <string.h>

#ifndef RTE_FBK_HASH_FUNC_DEFAULT
#if defined(RTE_MACHINE_CPUFLAG_SSE4_2) || defined(RTE_MACHINE_CPUFLAG_CRC32)
#include <rte_hash_crc.h>
/** Default four-byte key hash function if none is specified. */
#define RTE_FBK_HASH_FUNC_DEFAULT		rte_hash_crc_4byte
#else
#include <rte_jhash.h>
#define RTE_FBK_HASH_FUNC_DEFAULT		rte_jhash_1word
#endif
#endif

#ifndef RTE_FBK_HASH_INIT_VAL_DEFAULT
/** Initialising value used when calculating hash. */
#define RTE_FBK_HASH_INIT_VAL_DEFAULT		0xFFFFFFFF
#endif

/** The maximum number of entries in the hash table that is supported. */
#define RTE_FBK_HASH_ENTRIES_MAX		(1 << 20)

/** The maximum number of entries in each bucket that is supported. */
#define RTE_FBK_HASH_ENTRIES_PER_BUCKET_MAX	256

/** Maximum size of string for naming the hash. */
#define RTE_FBK_HASH_NAMESIZE			32

/** Type of function that can be used for calculating the hash value. */
typedef uint32_t (*rte_fbk_hash_fn)(uint32_t key, uint32_t init_val);

/** Parameters used when creating four-byte key hash table. */
struct rte_fbk_hash_params {
	const char *name;		/**< Name of the hash table. */
	uint32_t entries;		/**< Total number of entries. */
	uint32_t entries_per_bucket;	/**< Number of entries in a bucket. */
	int socket_id;			/**< Socket to allocate memory on. */
	rte_fbk_hash_fn hash_func;	/**< The hash function. */
	uint32_t init_val;		/**< For initialising hash function. */
};

/** Individual entry in the four-byte key hash table. */
union rte_fbk_hash_entry {
	uint64_t whole_entry;		/**< For accessing entire entry. */
	struct {
		uint16_t is_entry;	/**< Non-zero if entry is active. */
		uint16_t value;		/**< Value returned by lookup. */
		uint32_t key;		/**< Key used to find value. */
	} entry;			/**< For accessing each entry part. */
};


/** The four-byte key hash table structure. */
struct rte_fbk_hash_table {
	char name[RTE_FBK_HASH_NAMESIZE];	/**< Name of the hash. */
	uint32_t entries;		/**< Total number of entries. */
	uint32_t entries_per_bucket;	/**< Number of entries in a bucket. */
	uint32_t used_entries;		/**< How many entries are used. */
	uint32_t bucket_mask;		/**< To find which bucket the key is in. */
	uint32_t bucket_shift;		/**< Convert bucket to table offset. */
	rte_fbk_hash_fn hash_func;	/**< The hash function. */
	uint32_t init_val;		/**< For initialising hash function. */

	/** A flat table of all buckets. */
	union rte_fbk_hash_entry t[0];
};

/**
 * Find the offset into hash table of the bucket containing a particular key.
 *
 * @param ht
 *   Pointer to hash table.
 * @param key
 *   Key to calculate bucket for.
 * @return
 *   Offset into hash table.
 */
static inline uint32_t
rte_fbk_hash_get_bucket(const struct rte_fbk_hash_table *ht, uint32_t key)
{
	return (ht->hash_func(key, ht->init_val) & ht->bucket_mask) <<
			ht->bucket_shift;
}

/**
 * Add a key to an existing hash table with bucket id.
 * This operation is not multi-thread safe
 * and should only be called from one thread.
 *
 * @param ht
 *   Hash table to add the key to.
 * @param key
 *   Key to add to the hash table.
 * @param value
 *   Value to associate with key.
 * @param bucket
 *   Bucket to associate with key.
 * @return
 *   0 if ok, or negative value on error.
 */
static inline int
rte_fbk_hash_add_key_with_bucket(struct rte_fbk_hash_table *ht,
			uint32_t key, uint16_t value, uint32_t bucket)
{
	/*
	 * The writing of a new value to the hash table is done as a single
	 * 64bit operation. This should help prevent individual entries being
	 * corrupted due to race conditions, but it's still possible to
	 * overwrite entries that have just been made valid.
	 */
	const uint64_t new_entry = ((uint64_t)(key) << 32) |
			((uint64_t)(value) << 16) |
			1;  /* 1 = is_entry bit. */
	uint32_t i;

	for (i = 0; i < ht->entries_per_bucket; i++) {
		/* Set entry if unused. */
		if (! ht->t[bucket + i].entry.is_entry) {
			ht->t[bucket + i].whole_entry = new_entry;
			ht->used_entries++;
			return 0;
		}
		/* Change value if key already exists. */
		if (ht->t[bucket + i].entry.key == key) {
			ht->t[bucket + i].entry.value = value;
			return 0;
		}
	}

	return -ENOSPC; /* No space in bucket. */
}

/**
 * Add a key to an existing hash table. This operation is not multi-thread safe
 * and should only be called from one thread.
 *
 * @param ht
 *   Hash table to add the key to.
 * @param key
 *   Key to add to the hash table.
 * @param value
 *   Value to associate with key.
 * @return
 *   0 if ok, or negative value on error.
 */
static inline int
rte_fbk_hash_add_key(struct rte_fbk_hash_table *ht,
			uint32_t key, uint16_t value)
{
	return rte_fbk_hash_add_key_with_bucket(ht,
				key, value, rte_fbk_hash_get_bucket(ht, key));
}

/**
 * Remove a key with a given bucket id from an existing hash table.
 * This operation is not multi-thread
 * safe and should only be called from one thread.
 *
 * @param ht
 *   Hash table to remove the key from.
 * @param key
 *   Key to remove from the hash table.
 * @param bucket
 *   Bucket id associate with key.
 * @return
 *   0 if ok, or negative value on error.
 */
static inline int
rte_fbk_hash_delete_key_with_bucket(struct rte_fbk_hash_table *ht,
					uint32_t key, uint32_t bucket)
{
	uint32_t last_entry = ht->entries_per_bucket - 1;
	uint32_t i, j;

	for (i = 0; i < ht->entries_per_bucket; i++) {
		if (ht->t[bucket + i].entry.key == key) {
			/* Find last key in bucket. */
			for (j = ht->entries_per_bucket - 1; j > i; j-- ) {
				if (! ht->t[bucket + j].entry.is_entry) {
					last_entry = j - 1;
				}
			}
			/*
			 * Move the last key to the deleted key's position, and
			 * delete the last key. lastEntry and i may be same but
			 * it doesn't matter.
			 */
			ht->t[bucket + i].whole_entry =
					ht->t[bucket + last_entry].whole_entry;
			ht->t[bucket + last_entry].whole_entry = 0;

			ht->used_entries--;
			return 0;
		}
	}

	return -ENOENT; /* Key didn't exist. */
}

/**
 * Remove a key from an existing hash table. This operation is not multi-thread
 * safe and should only be called from one thread.
 *
 * @param ht
 *   Hash table to remove the key from.
 * @param key
 *   Key to remove from the hash table.
 * @return
 *   0 if ok, or negative value on error.
 */
static inline int
rte_fbk_hash_delete_key(struct rte_fbk_hash_table *ht, uint32_t key)
{
	return rte_fbk_hash_delete_key_with_bucket(ht,
				key, rte_fbk_hash_get_bucket(ht, key));
}

/**
 * Find a key in the hash table with a given bucketid.
 * This operation is multi-thread safe.
 *
 * @param ht
 *   Hash table to look in.
 * @param key
 *   Key to find.
 * @param bucket
 *   Bucket associate to the key.
 * @return
 *   The value that was associated with the key, or negative value on error.
 */
static inline int
rte_fbk_hash_lookup_with_bucket(const struct rte_fbk_hash_table *ht,
				uint32_t key, uint32_t bucket)
{
	union rte_fbk_hash_entry current_entry;
	uint32_t i;

	for (i = 0; i < ht->entries_per_bucket; i++) {
		/* Single read of entry, which should be atomic. */
		current_entry.whole_entry = ht->t[bucket + i].whole_entry;
		if (! current_entry.entry.is_entry) {
			return -ENOENT; /* Error once we hit an empty field. */
		}
		if (current_entry.entry.key == key) {
			return current_entry.entry.value;
		}
	}
	return -ENOENT; /* Key didn't exist. */
}

/**
 * Find a key in the hash table. This operation is multi-thread safe.
 *
 * @param ht
 *   Hash table to look in.
 * @param key
 *   Key to find.
 * @return
 *   The value that was associated with the key, or negative value on error.
 */
static inline int
rte_fbk_hash_lookup(const struct rte_fbk_hash_table *ht, uint32_t key)
{
	return rte_fbk_hash_lookup_with_bucket(ht,
				key, rte_fbk_hash_get_bucket(ht, key));
}

/**
 * Delete all entries in a hash table. This operation is not multi-thread
 * safe and should only be called from one thread.
 *
 * @param ht
 *   Hash table to delete entries in.
 */
static inline void
rte_fbk_hash_clear_all(struct rte_fbk_hash_table *ht)
{
	memset(ht->t, 0, sizeof(ht->t[0]) * ht->entries);
	ht->used_entries = 0;
}

/**
 * Find what fraction of entries are being used.
 *
 * @param ht
 *   Hash table to find how many entries are being used in.
 * @return
 *   Load factor of the hash table, or negative value on error.
 */
static inline double
rte_fbk_hash_get_load_factor(struct rte_fbk_hash_table *ht)
{
	return (double)ht->used_entries / (double)ht->entries;
}

/**
 * Performs a lookup for an existing hash table, and returns a pointer to
 * the table if found.
 *
 * @param name
 *   Name of the hash table to find
 *
 * @return
 *   pointer to hash table structure or NULL on error with rte_errno
 *   set appropriately. Possible rte_errno values include:
 *    - ENOENT - required entry not available to return.
 */
struct rte_fbk_hash_table *rte_fbk_hash_find_existing(const char *name);

/**
 * Create a new hash table for use with four byte keys.
 *
 * @param params
 *   Parameters used in creation of hash table.
 *
 * @return
 *   Pointer to hash table structure that is used in future hash table
 *   operations, or NULL on error with rte_errno set appropriately.
 *   Possible rte_errno error values include:
 *    - E_RTE_NO_CONFIG - function could not get pointer to rte_config structure
 *    - E_RTE_SECONDARY - function was called from a secondary process instance
 *    - EINVAL - invalid parameter value passed to function
 *    - ENOSPC - the maximum number of memzones has already been allocated
 *    - EEXIST - a memzone with the same name already exists
 *    - ENOMEM - no appropriate memory area found in which to create memzone
 */
struct rte_fbk_hash_table * \
rte_fbk_hash_create(const struct rte_fbk_hash_params *params);

/**
 * Free all memory used by a hash table.
 * Has no effect on hash tables allocated in memory zones
 *
 * @param ht
 *   Hash table to deallocate.
 */
void rte_fbk_hash_free(struct rte_fbk_hash_table *ht);

#ifdef __cplusplus
}
#endif

#endif /* _RTE_FBK_HASH_H_ */