mirror of
https://github.com/openvswitch/ovs
synced 2025-08-22 09:58:01 +00:00
421c94ee14
According to profiling data, converting UUIDs to strings is a frequent operation in some workloads. This typically results in a call to xasprintf(), which internally calls vsnprintf() twice, first to calculate the required buffer size, and then to format the string. This patch introduces specialized functions for printing UUIDs, which both reduces code duplication and improves performance. For example, on my laptop, 10,000,000 calls to the new uuid_to_string() function takes 1296 ms, while the same number of xasprintf() calls using UUID_FMT take 2498 ms. Signed-off-by: Dmitry Porokh <dporokh@nvidia.com> Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
108 lines
3.2 KiB
C
108 lines
3.2 KiB
C
/* Copyright (c) 2008, 2009, 2010, 2016, 2017 Nicira, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef UUID_H
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#define UUID_H 1
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#include "util.h"
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#include "openvswitch/uuid.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* An initializer or expression for an all-zero UUID. */
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#define UUID_ZERO ((struct uuid) { .parts = { 0, 0, 0, 0 } })
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/* Formats a UUID as a string, in the conventional format.
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*
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* Example:
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* struct uuid uuid = ...;
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* printf("This UUID is "UUID_FMT"\n", UUID_ARGS(&uuid));
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*
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*/
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#define UUID_LEN 36
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#define UUID_FMT "%08x-%04x-%04x-%04x-%04x%08x"
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#define UUID_ARGS(UUID) \
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((unsigned int) ((UUID)->parts[0])), \
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((unsigned int) ((UUID)->parts[1] >> 16)), \
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((unsigned int) ((UUID)->parts[1] & 0xffff)), \
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((unsigned int) ((UUID)->parts[2] >> 16)), \
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((unsigned int) ((UUID)->parts[2] & 0xffff)), \
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((unsigned int) ((UUID)->parts[3]))
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/* Returns a hash value for 'uuid'. This hash value is the same regardless of
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* whether we are running on a 32-bit or 64-bit or big-endian or little-endian
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* architecture. */
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static inline size_t
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uuid_hash(const struct uuid *uuid)
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{
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return uuid->parts[0];
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}
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/* Returns true if 'a == b', false otherwise. */
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static inline bool
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uuid_equals(const struct uuid *a, const struct uuid *b)
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{
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return (a->parts[0] == b->parts[0]
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&& a->parts[1] == b->parts[1]
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&& a->parts[2] == b->parts[2]
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&& a->parts[3] == b->parts[3]);
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}
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/* Returns the first 'n' hex digits of 'uuid', for 0 < 'n' <= 8.
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*
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* This is useful for displaying a few leading digits of the uuid, e.g. to
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* display 4 digits:
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* printf("%04x", uuid_prefix(uuid, 4));
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*/
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static inline unsigned int
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uuid_prefix(const struct uuid *uuid, int digits)
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{
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return (uuid->parts[0] >> (32 - 4 * digits));
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}
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/* Returns a string representation of a UUID.
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*
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* The string is allocated on the heap. Ownership of the string is
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* transferred to the caller.
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*/
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static inline char *
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uuid_to_string(const struct uuid *uuid)
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{
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char *data = xmalloc(UUID_LEN + 1);
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snprintf(data, UUID_LEN + 1, UUID_FMT, UUID_ARGS(uuid));
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return data;
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}
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void uuid_init(void);
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void uuid_generate(struct uuid *);
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struct uuid uuid_random(void);
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void uuid_zero(struct uuid *);
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bool uuid_is_zero(const struct uuid *);
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int uuid_compare_3way(const struct uuid *, const struct uuid *);
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bool uuid_from_string(struct uuid *, const char *);
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bool uuid_from_string_prefix(struct uuid *, const char *);
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int uuid_is_partial_string(const char *);
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int uuid_is_partial_match(const struct uuid *, const char *match);
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void uuid_set_bits_v4(struct uuid *);
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#ifdef __cplusplus
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}
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#endif
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#endif /* uuid.h */
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