add bkjg implementation

diff --git a/distbench/bkjg.c b/distbench/bkjg.c
index cccdc4f4e2ef2bb5c5dd167f086c22f6b8226feb..51ebada30d9726be5f5913c48528a814a7a6d06a 100644 (file)
--- a/distbench/bkjg.c
+++ b/distbench/bkjg.c
@@ -1,3 +1,403 @@
-int counter = 0; // Just an example
+/**
+ * collectd - src/daemon/distribution.c
+ * Copyright (C) 2020       Google LLC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * Authors:
+ *   Barbara bkjg Kaczorowska <bkjg at google.com>
+ */
 
-int my_function() { return ++counter; }
+#include "distribution.h"
+#include <math.h>
+#include <pthread.h>
+
+typedef struct {
+  double max_boundary;
+  uint64_t counter;
+} bucket_t;
+
+struct distribution_s {
+  bucket_t *buckets;
+  double sum_gauges;
+  size_t num_buckets;
+  pthread_mutex_t mutex;
+};
+
+double *distribution_get_buckets_boundaries(distribution_t *d) {
+  if (d == NULL) {
+    errno = EINVAL;
+    return NULL;
+  }
+
+  double *boundaries = calloc(d->num_buckets, sizeof(double));
+
+  if (boundaries == NULL) {
+    return NULL;
+  }
+
+  /* boundaries won't change, so we don't have to lock the mutex */
+  for (size_t i = 0; i < d->num_buckets; ++i) {
+    boundaries[i] = d->buckets[i].max_boundary;
+  }
+
+  return boundaries;
+}
+
+uint64_t *distribution_get_buckets_counters(distribution_t *d) {
+  if (d == NULL) {
+    errno = EINVAL;
+    return NULL;
+  }
+
+  uint64_t *counters = calloc(d->num_buckets, sizeof(uint64_t));
+
+  if (counters == NULL) {
+    return NULL;
+  }
+
+  pthread_mutex_lock(&d->mutex);
+  for (size_t i = 0; i < d->num_buckets; ++i) {
+    counters[i] = d->buckets[i].counter;
+  }
+  pthread_mutex_unlock(&d->mutex);
+
+  return counters;
+}
+
+size_t distribution_get_num_buckets(distribution_t *d) {
+  if (d == NULL) {
+    errno = EINVAL;
+    return 0;
+  }
+
+  return d->num_buckets;
+}
+
+double distribution_get_sum_gauges(distribution_t *d) {
+  if (d == NULL) {
+    errno = EINVAL;
+    return NAN;
+  }
+
+  return d->sum_gauges;
+}
+
+bool distribution_check_equal(distribution_t *d1, distribution_t *d2) {
+  if ((d1 == NULL && d2 != NULL) || (d1 != NULL && d2 == NULL)) {
+    return false;
+  }
+
+  /* thanks to previous condition we know that if d1 is NULL then d2 is NULL too
+   */
+  if (d1 == NULL) {
+    return true;
+  }
+
+  pthread_mutex_lock(&d1->mutex);
+  pthread_mutex_lock(&d2->mutex);
+
+  if (d1->sum_gauges != d2->sum_gauges) {
+    return false;
+  }
+
+  if (d1->num_buckets != d2->num_buckets) {
+    return false;
+  }
+
+  for (size_t i = 0; i < d1->num_buckets; ++i) {
+    if (d1->buckets[i].max_boundary != d2->buckets[i].max_boundary ||
+        d1->buckets[i].counter != d2->buckets[i].counter) {
+      return false;
+    }
+  }
+
+  pthread_mutex_unlock(&d2->mutex);
+  pthread_mutex_unlock(&d1->mutex);
+
+  return true;
+}
+
+static bucket_t *bucket_new_linear(size_t num_buckets, double size) {
+  bucket_t *buckets = calloc(num_buckets, sizeof(bucket_t));
+
+  if (buckets == NULL) {
+    return NULL;
+  }
+
+  for (size_t i = 0; i < num_buckets - 1; ++i) {
+    buckets[i].max_boundary = (double)(i + 1) * size;
+  }
+
+  buckets[num_buckets - 1].max_boundary = INFINITY;
+
+  return buckets;
+}
+
+static bucket_t *bucket_new_exponential(size_t num_buckets, double base,
+                                        double factor) {
+  bucket_t *buckets = calloc(num_buckets, sizeof(bucket_t));
+
+  if (buckets == NULL) {
+    return NULL;
+  }
+
+  double multiplier = 1.0;
+
+  for (size_t i = 0; i < num_buckets - 1; ++i) {
+    buckets[i].max_boundary = factor * multiplier;
+    multiplier *= base;
+  }
+
+  buckets[num_buckets - 1].max_boundary = INFINITY;
+
+  return buckets;
+}
+
+static bucket_t *bucket_new_custom(size_t num_boundaries,
+                                   const double *custom_buckets_boundaries) {
+  bucket_t *buckets = calloc(num_boundaries + 1, sizeof(bucket_t));
+
+  if (buckets == NULL) {
+    return NULL;
+  }
+
+  if (num_boundaries > 0) {
+    if (custom_buckets_boundaries[0] <= 0 ||
+        custom_buckets_boundaries[0] == INFINITY) {
+      free(buckets);
+      errno = EINVAL;
+      return NULL;
+    }
+
+    buckets[0].max_boundary = custom_buckets_boundaries[0];
+
+    for (size_t i = 1; i < num_boundaries; ++i) {
+      if (custom_buckets_boundaries[i] <= 0 ||
+          custom_buckets_boundaries[i] == INFINITY ||
+          custom_buckets_boundaries[i - 1] >= custom_buckets_boundaries[i]) {
+        free(buckets);
+        errno = EINVAL;
+        return NULL;
+      }
+
+      buckets[i].max_boundary = custom_buckets_boundaries[i];
+    }
+  }
+
+  buckets[num_boundaries].max_boundary = INFINITY;
+
+  return buckets;
+}
+
+distribution_t *distribution_new_linear(size_t num_buckets, double size) {
+  if (num_buckets == 0 || size <= 0) {
+    errno = EINVAL;
+    return NULL;
+  }
+
+  distribution_t *d = calloc(1, sizeof(distribution_t));
+
+  if (d == NULL) {
+    return NULL;
+  }
+
+  d->buckets = bucket_new_linear(num_buckets, size);
+
+  if (d->buckets == NULL) {
+    free(d);
+    return NULL;
+  }
+
+  d->num_buckets = num_buckets;
+  pthread_mutex_init(&d->mutex, NULL);
+
+  return d;
+}
+
+distribution_t *distribution_new_exponential(size_t num_buckets, double base,
+                                             double factor) {
+  if (num_buckets == 0 || base <= 1 || factor <= 0) {
+    errno = EINVAL;
+    return NULL;
+  }
+
+  distribution_t *d = calloc(1, sizeof(distribution_t));
+
+  if (d == NULL) {
+    return NULL;
+  }
+
+  /* as in distribution_new_linear: it would be nice to check if base
+   * and factor are greater than zero, for consideration: one of them also
+   * greater than one */
+  d->buckets = bucket_new_exponential(num_buckets, base, factor);
+
+  if (d->buckets == NULL) {
+    free(d);
+    return NULL;
+  }
+
+  d->num_buckets = num_buckets;
+  pthread_mutex_init(&d->mutex, NULL);
+
+  return d;
+}
+
+distribution_t *distribution_new_custom(size_t num_boundaries,
+                                        double *custom_buckets_boundaries) {
+  distribution_t *d = calloc(1, sizeof(distribution_t));
+
+  if (d == NULL) {
+    return NULL;
+  }
+
+  d->buckets = bucket_new_custom(num_boundaries, custom_buckets_boundaries);
+
+  if (d->buckets == NULL) {
+    free(d);
+    return NULL;
+  }
+
+  d->num_buckets = num_boundaries + 1;
+  pthread_mutex_init(&d->mutex, NULL);
+
+  return d;
+}
+
+static void bucket_update(bucket_t *buckets, size_t num_buckets, double gauge) {
+  int idx = (int)num_buckets - 1;
+
+  while (idx >= 0 && buckets[idx].max_boundary > gauge) {
+    buckets[idx].counter++;
+    idx--;
+  }
+}
+
+int distribution_update(distribution_t *d, double gauge) {
+  if (d == NULL || gauge < 0) {
+    errno = EINVAL;
+    return EXIT_FAILURE;
+  }
+
+  pthread_mutex_lock(&d->mutex);
+
+  bucket_update(d->buckets, d->num_buckets, gauge);
+
+  d->sum_gauges += gauge;
+  pthread_mutex_unlock(&d->mutex);
+
+  return EXIT_SUCCESS;
+}
+
+static double find_percentile(bucket_t *buckets, size_t num_buckets,
+                              uint64_t quantity) {
+  size_t left = 0;
+  size_t right = num_buckets - 1;
+  size_t middle;
+
+  while (left < right) {
+    middle = (left + right) / 2;
+
+    if (buckets[middle].counter >= quantity) {
+      right = middle;
+    } else {
+      left = middle + 1;
+    }
+  }
+
+  return buckets[left].max_boundary;
+}
+
+double distribution_percentile(distribution_t *d, double percent) {
+  if (d == NULL || percent > 100.0 || percent < 0) {
+    errno = EINVAL;
+    return NAN;
+  }
+
+  pthread_mutex_lock(&d->mutex);
+
+  uint64_t quantity = (uint64_t)(
+      (percent / 100.0) * (double)d->buckets[d->num_buckets - 1].counter);
+
+  percent = find_percentile(d->buckets, d->num_buckets, quantity);
+
+  pthread_mutex_unlock(&d->mutex);
+  return percent;
+}
+
+double distribution_average(distribution_t *d) {
+  if (d == NULL) {
+    errno = EINVAL;
+    return NAN;
+  }
+
+  pthread_mutex_lock(&d->mutex);
+
+  double average =
+      d->sum_gauges / (double)d->buckets[d->num_buckets - 1].counter;
+
+  pthread_mutex_unlock(&d->mutex);
+
+  return average;
+}
+
+distribution_t *distribution_clone(distribution_t *d) {
+  if (d == NULL) {
+    errno = EINVAL;
+    return NULL;
+  }
+
+  distribution_t *distribution = calloc(1, sizeof(distribution_t));
+
+  if (distribution == NULL) {
+    return NULL;
+  }
+
+  pthread_mutex_lock(&d->mutex);
+
+  distribution->sum_gauges = d->sum_gauges;
+  distribution->num_buckets = d->num_buckets;
+
+  distribution->buckets = calloc(d->num_buckets, sizeof(bucket_t));
+
+  if (distribution->buckets == NULL) {
+    free(distribution);
+    pthread_mutex_unlock(&d->mutex);
+    return NULL;
+  }
+
+  memcpy(distribution->buckets, d->buckets, d->num_buckets * sizeof(bucket_t));
+
+  pthread_mutex_init(&distribution->mutex, NULL);
+
+  pthread_mutex_unlock(&d->mutex);
+
+  return distribution;
+}
+
+void distribution_destroy(distribution_t *d) {
+  if (d == NULL) {
+    return;
+  }
+
+  pthread_mutex_destroy(&d->mutex);
+  free(d->buckets);
+  free(d);
+}