| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include "core/conf.h" |
| #include "core/htrace.h" |
| #include "core/htracer.h" |
| #include "sampler/sampler.h" |
| #include "util/log.h" |
| #include "util/rand.h" |
| |
| #include <errno.h> |
| #include <inttypes.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <unistd.h> |
| |
| /** |
| * A sampler that fires with a certain chance. |
| */ |
| struct prob_sampler { |
| struct htrace_sampler base; |
| |
| /** |
| * A random source. |
| */ |
| struct random_src *rnd; |
| |
| /** |
| * The name of this probability sampler. |
| */ |
| char *name; |
| |
| /** |
| * The threshold at which we should sample. |
| */ |
| uint32_t threshold; |
| }; |
| |
| static double get_prob_sampler_threshold(struct htrace_log *lg, |
| const struct htrace_conf *conf); |
| static struct htrace_sampler *prob_sampler_create(struct htracer *tracer, |
| const struct htrace_conf *conf); |
| static const char *prob_sampler_to_str(struct htrace_sampler *s); |
| static int prob_sampler_next(struct htrace_sampler *s); |
| static void prob_sampler_free(struct htrace_sampler *s); |
| |
| const struct htrace_sampler_ty g_prob_sampler_ty = { |
| "prob", |
| prob_sampler_create, |
| prob_sampler_to_str, |
| prob_sampler_next, |
| prob_sampler_free, |
| }; |
| |
| static double get_prob_sampler_threshold(struct htrace_log *lg, |
| const struct htrace_conf *conf) |
| { |
| double fraction = |
| htrace_conf_get_double(lg, conf, HTRACE_PROB_SAMPLER_FRACTION_KEY); |
| if (fraction < 0) { |
| htrace_log(lg, "sampler_create: can't have a sampling fraction " |
| "less than 0. Setting fraction to 0.\n"); |
| fraction = 0.0; |
| } else if (fraction > 1.0) { |
| htrace_log(lg, "sampler_create: can't have a sampling fraction " |
| "greater than 1. Setting fraction to 1.\n"); |
| fraction = 1.0; |
| } |
| return fraction; |
| } |
| |
| static struct htrace_sampler *prob_sampler_create(struct htracer *tracer, |
| const struct htrace_conf *conf) |
| { |
| struct prob_sampler *smp; |
| double fraction; |
| |
| smp = calloc(1, sizeof(*smp)); |
| if (!smp) { |
| htrace_log(tracer->lg, "prob_sampler_create: OOM\n"); |
| return NULL; |
| } |
| smp->base.ty = &g_prob_sampler_ty; |
| smp->rnd = random_src_alloc(tracer->lg); |
| if (!smp->rnd) { |
| htrace_log(tracer->lg, "random_src_alloc failed.\n"); |
| free(smp); |
| return NULL; |
| } |
| fraction = get_prob_sampler_threshold(tracer->lg, conf); |
| smp->threshold = 0xffffffffLU * fraction; |
| if (asprintf(&smp->name, "ProbabilitySampler(fraction=%.03g)", |
| fraction) < 0) { |
| smp->name = NULL; |
| random_src_free(smp->rnd); |
| free(smp); |
| } |
| return (struct htrace_sampler *)smp; |
| } |
| |
| static const char *prob_sampler_to_str(struct htrace_sampler *s) |
| { |
| struct prob_sampler *smp = (struct prob_sampler *)s; |
| return smp->name; |
| } |
| |
| static int prob_sampler_next(struct htrace_sampler *s) |
| { |
| struct prob_sampler *smp = (struct prob_sampler *)s; |
| return random_u32(smp->rnd) < smp->threshold; |
| } |
| |
| static void prob_sampler_free(struct htrace_sampler *s) |
| { |
| struct prob_sampler *smp = (struct prob_sampler *)s; |
| random_src_free(smp->rnd); |
| free(smp->name); |
| free(smp); |
| } |
| |
| // vim: ts=4:sw=4:tw=79:et |