68 lines
2.1 KiB
C
68 lines
2.1 KiB
C
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/*
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* Copyright (c) 2016 Cisco and/or its affiliates.
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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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/*
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* vlib provides lock-free counters but those
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* - Have 16bits per-CPU counter, which may overflow.
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* - Would only increment.
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*
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* This is very similar to vlib counters, but may be used to count reference.
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* Such a counter includes an arbitrary number of counters. Each counter
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* is identified by its index. This is used to aggregate per-cpu memory.
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*
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* Warning:
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* This reference counter is lock-free but is not race-condition free.
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* The counting result is approximate and another mechanism needs to be used
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* in order to ensure that an object may be freed.
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*
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*/
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#include <vnet/vnet.h>
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typedef struct {
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u32 *counters;
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u32 length;
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u32 *reader_lengths;
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CLIB_CACHE_LINE_ALIGN_MARK(o);
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} vlib_refcount_per_cpu_t;
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typedef struct {
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vlib_refcount_per_cpu_t *per_cpu;
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} vlib_refcount_t;
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void __vlib_refcount_resize(vlib_refcount_per_cpu_t *per_cpu, u32 size);
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static_always_inline
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void vlib_refcount_add(vlib_refcount_t *r, u32 cpu_index, u32 counter_index, i32 v)
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{
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vlib_refcount_per_cpu_t *per_cpu = &r->per_cpu[cpu_index];
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if (PREDICT_FALSE(counter_index >= per_cpu->length))
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__vlib_refcount_resize(per_cpu, clib_max(counter_index + 16, per_cpu->length * 2));
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per_cpu->counters[counter_index] += v;
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}
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u64 vlib_refcount_get(vlib_refcount_t *r, u32 index);
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static_always_inline
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void vlib_refcount_init(vlib_refcount_t *r)
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{
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vlib_thread_main_t *tm = vlib_get_thread_main ();
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r->per_cpu = 0;
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vec_validate (r->per_cpu, tm->n_vlib_mains - 1);
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}
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