Add distribution metrics

Makefile.am

@@ -426,6 +426,8 @@ libmetadata_la_SOURCES = \
 	src/utils/metadata/meta_data.h
 
 libmetric_la_SOURCES = \
+		       src/daemon/distribution.c \
+		       src/daemon/distribution.h \
 		       src/daemon/metric.c \
 		       src/daemon/metric.h
 libmetric_la_LIBADD = libmetadata.la $(COMMON_LIBS)

src/daemon/distribution.c

@@ -0,0 +1,291 @@
+/**
+ * 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>
+ */
+
+#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;
+};
+
+static bucket_t *bucket_new_linear(size_t num_buckets, double size) {
+  bucket_t *buckets = (bucket_t *)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 initial_size,
+                                        double factor) {
+  bucket_t *buckets = (bucket_t *)calloc(num_buckets, sizeof(bucket_t));
+
+  if (buckets == NULL) {
+    return NULL;
+  }
+
+  double multiplier = initial_size;
+
+  for (size_t i = 0; i < num_buckets - 1; ++i) {
+    buckets[i].max_boundary = factor * multiplier;
+    multiplier *= initial_size;
+  }
+
+  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 = (bucket_t *)calloc(num_boundaries + 1, sizeof(bucket_t));
+
+  if (buckets == NULL) {
+    return NULL;
+  }
+
+  if (custom_buckets_boundaries[0] <= 0) {
+    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 - 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) {
+  distribution_t *d = (distribution_t *)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 initial_size,
+                                             double factor) {
+  distribution_t *d = (distribution_t *)calloc(1, sizeof(distribution_t));
+
+  if (d == NULL) {
+    return NULL;
+  }
+
+  d->buckets = bucket_new_exponential(num_buckets, initial_size, 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 = (distribution_t *)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;
+  pthread_mutex_init(&d->mutex, NULL);
+
+  return d;
+}
+
+static void bucket_update(bucket_t *buckets, size_t num_buckets, double gauge) {
+  int ptr = (int)num_buckets - 1;
+
+  while (buckets[ptr].max_boundary > gauge && ptr >= 0) {
+    buckets[ptr].counter++;
+    ptr--;
+  }
+}
+
+void distribution_update(distribution_t *d, double gauge) {
+  if (d == NULL) {
+    errno = EINVAL;
+    return;
+  }
+
+  pthread_mutex_lock(&d->mutex);
+
+  bucket_update(d->buckets, d->num_buckets, gauge);
+
+  d->sum_gauges += gauge;
+  pthread_mutex_unlock(&d->mutex);
+}
+
+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) {
+      left = middle;
+    } else {
+      right = middle - 1;
+    }
+  }
+
+  return buckets[left].max_boundary;
+}
+
+double distribution_percentile(distribution_t *d, double percent) {
+  if (d == NULL || percent > 100.0) {
+    errno = EINVAL;
+    return NAN;
+  }
+
+  pthread_mutex_lock(&d->mutex);
+
+  uint64_t quantity =
+      (percent / 100.0) * 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);
+}

src/daemon/distribution.h

@@ -0,0 +1,94 @@
+/**
+ * collectd - src/daemon/distribution.h
+ * 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>
+ */
+
+#ifndef DISTRIBUTION_H
+#define DISTRIBUTION_H
+
+#include "collectd.h"
+
+struct distribution_s;
+typedef struct distribution_s distribution_t;
+
+/* function that create new distribution structure and initialize buckets using
+ * linear function
+ * it will return null if any error occurred, for example - num_buckets is zero
+ * or OS couldn't allocate the memory - then errno will contain the error code
+ */
+distribution_t *distribution_new_linear(size_t num_buckets, double size);
+/* function that create new distribution structure and initialize buckets using
+ * exponential function
+ * it will return null if any error occurred, for example - num_buckets is zero
+ * or OS couldn't allocate the memory - then errno will contain the error code
+ */
+distribution_t *distribution_new_exponential(size_t num_buckets,
+                                             double initial_size,
+                                             double factor);
+/* function that create new distribution structure and initialize buckets using
+ * custom buckets sizes given by the user
+ * It will return null if any error occurred, for example - num_boundaries is
+ * less than zero or OS couldn't allocate the memory - then errno will contain
+ * the error code There is also one case when the function can return with some
+ * error - if the custom buckets boundaries aren't in the ascending order or
+ * some boundaries are less than zero, then the function will return null and
+ * will set errno to EINVAL
+ */
+distribution_t *distribution_new_custom(size_t num_boundaries,
+                                        double *custom_buckets_boundaries);
+
+/* function for updating the buckets
+ * if the user will give the wrong argument, i.e. d will be null, then the
+ * function will return and the errno will be set to EINVAL*/
+void distribution_update(distribution_t *d, double gauge);
+
+/* function  for getting the percentile
+ * if the user will give the wrong argument, i.e. d will be null or percent
+ * will be greater than 100.0, then the function will return NaN and the errno
+ * will be set to EINVAL*/
+double distribution_percentile(distribution_t *d, double percent);
+
+/* function that calculates average of gauges
+ * if the user will pass the wrong argument to the function, i.e. d will be
+ * null, then the function will return NaN and the errno will be set to EINVAL
+ */
+double distribution_average(distribution_t *d);
+
+/* function that do the clone of distribution structure
+ * if the user will pass the wrong argument to this function, i.e. d will be
+ * null, then the function will return null and the errno will be set to EINVAL
+ * there is also the possibility that the user will pass the proper argument but
+ * the function will fail anyway, i.e. calloc will return null, then the
+ * function will return null and the errno will be set by calloc system call
+ */
+distribution_t *distribution_clone(distribution_t *d);
+
+/* function that do clean up and free all the memory
+ * if the user will pass the null as an argument to this function, then the
+ * function
+ * will return without setting any errno like the OS do it when have to free a
+ * null pointer */
+void distribution_destroy(distribution_t *d);
+
+#endif // DISTRIBUTION_H