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git.proxmox.com Git - mirror_ovs.git/blob - lib/token-bucket.c
2 * Copyright (c) 2012 Nicira, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at:
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
19 #include "token-bucket.h"
21 #include "poll-loop.h"
26 /* Initializes 'tb' to accumulate 'rate' tokens per millisecond, with a
27 * maximum of 'burst' tokens.
29 * The token bucket is initially full.
31 * It may be more convenient to use TOKEN_BUCKET_INIT. */
33 token_bucket_init(struct token_bucket
*tb
,
34 unsigned int rate
, unsigned int burst
)
39 tb
->last_fill
= LLONG_MIN
;
42 /* Changes 'tb' to accumulate 'rate' tokens per millisecond, with a maximum of
45 * 'tb' must already have been initialized with TOKEN_BUCKET_INIT or
46 * token_bucket_init(). */
48 token_bucket_set(struct token_bucket
*tb
,
49 unsigned int rate
, unsigned int burst
)
53 if (burst
> tb
->tokens
) {
58 /* Attempts to remove 'n' tokens from 'tb'. Returns true if successful, false
59 * if 'tb' contained fewer than 'n' tokens (and thus 'n' tokens could not be
62 token_bucket_withdraw(struct token_bucket
*tb
, unsigned int n
)
65 long long int now
= time_msec();
66 if (now
> tb
->last_fill
) {
67 unsigned long long int elapsed_ull
68 = (unsigned long long int) now
- tb
->last_fill
;
69 unsigned int elapsed
= MIN(UINT_MAX
, elapsed_ull
);
70 unsigned int add
= sat_mul(tb
->rate
, elapsed
);
71 unsigned int tokens
= sat_add(tb
->tokens
, add
);
72 tb
->tokens
= MIN(tokens
, tb
->burst
);
85 /* Causes the poll loop to wake up when at least 'n' tokens will be available
86 * for withdrawal from 'tb'. */
88 token_bucket_wait(struct token_bucket
*tb
, unsigned int n
)
90 if (tb
->tokens
>= n
) {
91 poll_immediate_wake();
93 unsigned int need
= n
- tb
->tokens
;
94 poll_timer_wait_until(tb
->last_fill
+ need
/ tb
->rate
+ 1);