Restoring authorship annotation for Sergey Polovko <[email protected]>. Commit 2 of 2.

1 files changed, 428 insertions, 428 deletions

diff --git a/contrib/libs/hdr_histogram/src/hdr_histogram.h b/contrib/libs/hdr_histogram/src/hdr_histogram.h
index 3d124e8fe90..c4ba1a43f9b 100644
--- a/contrib/libs/hdr_histogram/src/hdr_histogram.h
+++ b/contrib/libs/hdr_histogram/src/hdr_histogram.h
@@ -1,428 +1,428 @@
-/** 
- * hdr_histogram.h 
- * Written by Michael Barker and released to the public domain, 
- * as explained at http://creativecommons.org/publicdomain/zero/1.0/ 
- * 
- * The source for the hdr_histogram utilises a few C99 constructs, specifically 
- * the use of stdint/stdbool and inline variable declaration. 
- */ 
- 
-#ifndef HDR_HISTOGRAM_H 
-#define HDR_HISTOGRAM_H 1 
- 
-#include <stdint.h> 
-#include <stdbool.h> 
-#include <stdio.h> 
- 
-struct hdr_histogram 
-{ 
-    int64_t lowest_trackable_value; 
-    int64_t highest_trackable_value; 
-    int32_t unit_magnitude; 
-    int32_t significant_figures; 
-    int32_t sub_bucket_half_count_magnitude; 
-    int32_t sub_bucket_half_count; 
-    int64_t sub_bucket_mask; 
-    int32_t sub_bucket_count; 
-    int32_t bucket_count; 
-    int64_t min_value; 
-    int64_t max_value; 
-    int32_t normalizing_index_offset; 
-    double conversion_ratio; 
-    int32_t counts_len; 
-    int64_t total_count; 
-    int64_t counts[0]; 
-}; 
- 
-#ifdef __cplusplus 
-extern "C" { 
-#endif 
- 
-/** 
- * Allocate the memory and initialise the hdr_histogram. 
- * 
- * Due to the size of the histogram being the result of some reasonably 
- * involved math on the input parameters this function it is tricky to stack allocate. 
- * The histogram is allocated in a single contigious block so can be delete via free, 
- * without any structure specific destructor. 
- * 
- * @param lowest_trackable_value The smallest possible value to be put into the 
- * histogram. 
- * @param highest_trackable_value The largest possible value to be put into the 
- * histogram. 
- * @param significant_figures The level of precision for this histogram, i.e. the number 
- * of figures in a decimal number that will be maintained.  E.g. a value of 3 will mean 
- * the results from the histogram will be accurate up to the first three digits.  Must 
- * be a value between 1 and 5 (inclusive). 
- * @param result Output parameter to capture allocated histogram. 
- * @return 0 on success, EINVAL if lowest_trackable_value is < 1 or the 
- * significant_figure value is outside of the allowed range, ENOMEM if malloc 
- * failed. 
- */ 
-int hdr_init( 
-    int64_t lowest_trackable_value, 
-    int64_t highest_trackable_value, 
-    int significant_figures, 
-    struct hdr_histogram** result); 
- 
-/** 
- * Allocate the memory and initialise the hdr_histogram.  This is the equivalent of calling 
- * hdr_init(1, highest_trackable_value, significant_figures, result); 
- * 
- * @deprecated use hdr_init. 
- */ 
-int hdr_alloc(int64_t highest_trackable_value, int significant_figures, struct hdr_histogram** result); 
- 
- 
-/** 
- * Reset a histogram to zero - empty out a histogram and re-initialise it 
- * 
- * If you want to re-use an existing histogram, but reset everything back to zero, this 
- * is the routine to use. 
- * 
- * @param h The histogram you want to reset to empty. 
- * 
- */ 
-void hdr_reset(struct hdr_histogram* h); 
- 
-/** 
- * Get the memory size of the hdr_histogram. 
- * 
- * @param h "This" pointer 
- * @return The amount of memory used by the hdr_histogram in bytes 
- */ 
-size_t hdr_get_memory_size(struct hdr_histogram* h); 
- 
-/** 
- * Records a value in the histogram, will round this value of to a precision at or better 
- * than the significant_figure specified at construction time. 
- * 
- * @param h "This" pointer 
- * @param value Value to add to the histogram 
- * @return false if the value is larger than the highest_trackable_value and can't be recorded, 
- * true otherwise. 
- */ 
-bool hdr_record_value(struct hdr_histogram* h, int64_t value); 
- 
-/** 
- * Records count values in the histogram, will round this value of to a 
- * precision at or better than the significant_figure specified at construction 
- * time. 
- * 
- * @param h "This" pointer 
- * @param value Value to add to the histogram 
- * @param count Number of 'value's to add to the histogram 
- * @return false if any value is larger than the highest_trackable_value and can't be recorded, 
- * true otherwise. 
- */ 
-bool hdr_record_values(struct hdr_histogram* h, int64_t value, int64_t count); 
- 
- 
-/** 
- * Record a value in the histogram and backfill based on an expected interval. 
- * 
- * Records a value in the histogram, will round this value of to a precision at or better 
- * than the significant_figure specified at contruction time.  This is specifically used 
- * for recording latency.  If the value is larger than the expected_interval then the 
- * latency recording system has experienced co-ordinated omission.  This method fills in the 
- * values that would have occured had the client providing the load not been blocked. 
- 
- * @param h "This" pointer 
- * @param value Value to add to the histogram 
- * @param expected_interval The delay between recording values. 
- * @return false if the value is larger than the highest_trackable_value and can't be recorded, 
- * true otherwise. 
- */ 
-bool hdr_record_corrected_value(struct hdr_histogram* h, int64_t value, int64_t expexcted_interval); 
-/** 
- * Record a value in the histogram 'count' times.  Applies the same correcting logic 
- * as 'hdr_record_corrected_value'. 
- * 
- * @param h "This" pointer 
- * @param value Value to add to the histogram 
- * @param count Number of 'value's to add to the histogram 
- * @param expected_interval The delay between recording values. 
- * @return false if the value is larger than the highest_trackable_value and can't be recorded, 
- * true otherwise. 
- */ 
-bool hdr_record_corrected_values(struct hdr_histogram* h, int64_t value, int64_t count, int64_t expected_interval); 
- 
-/** 
- * Adds all of the values from 'from' to 'this' histogram.  Will return the 
- * number of values that are dropped when copying.  Values will be dropped 
- * if they around outside of h.lowest_trackable_value and 
- * h.highest_trackable_value. 
- * 
- * @param h "This" pointer 
- * @param from Histogram to copy values from. 
- * @return The number of values dropped when copying. 
- */ 
-int64_t hdr_add(struct hdr_histogram* h, const struct hdr_histogram* from); 
- 
-/** 
- * Adds all of the values from 'from' to 'this' histogram.  Will return the 
- * number of values that are dropped when copying.  Values will be dropped 
- * if they around outside of h.lowest_trackable_value and 
- * h.highest_trackable_value. 
- * 
- * @param h "This" pointer 
- * @param from Histogram to copy values from. 
- * @return The number of values dropped when copying. 
- */ 
-int64_t hdr_add_while_correcting_for_coordinated_omission( 
-    struct hdr_histogram* h, struct hdr_histogram* from, int64_t expected_interval); 
- 
-/** 
- * Get minimum value from the histogram.  Will return 2^63-1 if the histogram 
- * is empty. 
- * 
- * @param h "This" pointer 
- */ 
-int64_t hdr_min(const struct hdr_histogram* h); 
- 
-/** 
- * Get maximum value from the histogram.  Will return 0 if the histogram 
- * is empty. 
- * 
- * @param h "This" pointer 
- */ 
-int64_t hdr_max(const struct hdr_histogram* h); 
- 
-/** 
- * Get the value at a specific percentile. 
- * 
- * @param h "This" pointer. 
- * @param percentile The percentile to get the value for 
- */ 
-int64_t hdr_value_at_percentile(const struct hdr_histogram* h, double percentile); 
- 
-/** 
- * Gets the standard deviation for the values in the histogram. 
- * 
- * @param h "This" pointer 
- * @return The standard deviation 
- */ 
-double hdr_stddev(const struct hdr_histogram* h); 
- 
-/** 
- * Gets the mean for the values in the histogram. 
- * 
- * @param h "This" pointer 
- * @return The mean 
- */ 
-double hdr_mean(const struct hdr_histogram* h); 
- 
-/** 
- * Determine if two values are equivalent with the histogram's resolution. 
- * Where "equivalent" means that value samples recorded for any two 
- * equivalent values are counted in a common total count. 
- * 
- * @param h "This" pointer 
- * @param a first value to compare 
- * @param b second value to compare 
- * @return 'true' if values are equivalent with the histogram's resolution. 
- */ 
-bool hdr_values_are_equivalent(const struct hdr_histogram* h, int64_t a, int64_t b); 
- 
-/** 
- * Get the lowest value that is equivalent to the given value within the histogram's resolution. 
- * Where "equivalent" means that value samples recorded for any two 
- * equivalent values are counted in a common total count. 
- * 
- * @param h "This" pointer 
- * @param value The given value 
- * @return The lowest value that is equivalent to the given value within the histogram's resolution. 
- */ 
-int64_t hdr_lowest_equivalent_value(const struct hdr_histogram* h, int64_t value); 
- 
-/** 
- * Get the count of recorded values at a specific value 
- * (to within the histogram resolution at the value level). 
- * 
- * @param h "This" pointer 
- * @param value The value for which to provide the recorded count 
- * @return The total count of values recorded in the histogram within the value range that is 
- * {@literal >=} lowestEquivalentValue(<i>value</i>) and {@literal <=} highestEquivalentValue(<i>value</i>) 
- */ 
-int64_t hdr_count_at_value(const struct hdr_histogram* h, int64_t value); 
- 
-int64_t hdr_count_at_index(const struct hdr_histogram* h, int32_t index); 
- 
-int64_t hdr_value_at_index(const struct hdr_histogram* h, int32_t index); 
- 
-struct hdr_iter_percentiles 
-{ 
-    bool seen_last_value; 
-    int32_t ticks_per_half_distance; 
-    double percentile_to_iterate_to; 
-    double percentile; 
-}; 
- 
-struct hdr_iter_recorded 
-{ 
-    int64_t count_added_in_this_iteration_step; 
-}; 
- 
-struct hdr_iter_linear 
-{ 
-    int64_t value_units_per_bucket; 
-    int64_t count_added_in_this_iteration_step; 
-    int64_t next_value_reporting_level; 
-    int64_t next_value_reporting_level_lowest_equivalent; 
-}; 
- 
-struct hdr_iter_log 
-{ 
-    double log_base; 
-    int64_t count_added_in_this_iteration_step; 
-    int64_t next_value_reporting_level; 
-    int64_t next_value_reporting_level_lowest_equivalent; 
-}; 
- 
-/** 
- * The basic iterator.  This is a generic structure 
- * that supports all of the types of iteration.  Use 
- * the appropriate initialiser to get the desired 
- * iteration. 
- * 
- * @ 
- */ 
-struct hdr_iter 
-{ 
-    const struct hdr_histogram* h; 
-    /** raw index into the counts array */ 
-    int32_t counts_index; 
-    /** snapshot of the length at the time the iterator is created */ 
-    int32_t total_count; 
-    /** value directly from array for the current counts_index */ 
-    int64_t count; 
-    /** sum of all of the counts up to and including the count at this index */ 
-    int64_t cumulative_count; 
-    /** The current value based on counts_index */ 
-    int64_t value; 
-    int64_t highest_equivalent_value; 
-    int64_t lowest_equivalent_value; 
-    int64_t median_equivalent_value; 
-    int64_t value_iterated_from; 
-    int64_t value_iterated_to; 
- 
-    union 
-    { 
-        struct hdr_iter_percentiles percentiles; 
-        struct hdr_iter_recorded recorded; 
-        struct hdr_iter_linear linear; 
-        struct hdr_iter_log log; 
-    } specifics; 
- 
-    bool (* _next_fp)(struct hdr_iter* iter); 
- 
-}; 
- 
-/** 
- * Initalises the basic iterator. 
- * 
- * @param itr 'This' pointer 
- * @param h The histogram to iterate over 
- */ 
-void hdr_iter_init(struct hdr_iter* iter, const struct hdr_histogram* h); 
- 
-/** 
- * Initialise the iterator for use with percentiles. 
- */ 
-void hdr_iter_percentile_init(struct hdr_iter* iter, const struct hdr_histogram* h, int32_t ticks_per_half_distance); 
- 
-/** 
- * Initialise the iterator for use with recorded values. 
- */ 
-void hdr_iter_recorded_init(struct hdr_iter* iter, const struct hdr_histogram* h); 
- 
-/** 
- * Initialise the iterator for use with linear values. 
- */ 
-void hdr_iter_linear_init( 
-    struct hdr_iter* iter, 
-    const struct hdr_histogram* h, 
-    int64_t value_units_per_bucket); 
- 
-/** 
- * Initialise the iterator for use with logarithmic values 
- */ 
-void hdr_iter_log_init( 
-    struct hdr_iter* iter, 
-    const struct hdr_histogram* h, 
-    int64_t value_units_first_bucket, 
-    double log_base); 
- 
-/** 
- * Iterate to the next value for the iterator.  If there are no more values 
- * available return faluse. 
- * 
- * @param itr 'This' pointer 
- * @return 'false' if there are no values remaining for this iterator. 
- */ 
-bool hdr_iter_next(struct hdr_iter* iter); 
- 
-typedef enum 
-{ 
-    CLASSIC, 
-    CSV 
-} format_type; 
- 
-/** 
- * Print out a percentile based histogram to the supplied stream.  Note that 
- * this call will not flush the FILE, this is left up to the user. 
- * 
- * @param h 'This' pointer 
- * @param stream The FILE to write the output to 
- * @param ticks_per_half_distance The number of iteration steps per half-distance to 100% 
- * @param value_scale Scale the output values by this amount 
- * @param format_type Format to use, e.g. CSV. 
- * @return 0 on success, error code on failure.  EIO if an error occurs writing 
- * the output. 
- */ 
-int hdr_percentiles_print( 
-    struct hdr_histogram* h, FILE* stream, int32_t ticks_per_half_distance, 
-    double value_scale, format_type format); 
- 
-/** 
-* Internal allocation methods, used by hdr_dbl_histogram. 
-*/ 
-struct hdr_histogram_bucket_config 
-{ 
-    int64_t lowest_trackable_value; 
-    int64_t highest_trackable_value; 
-    int64_t unit_magnitude; 
-    int64_t significant_figures; 
-    int32_t sub_bucket_half_count_magnitude; 
-    int32_t sub_bucket_half_count; 
-    int64_t sub_bucket_mask; 
-    int32_t sub_bucket_count; 
-    int32_t bucket_count; 
-    int32_t counts_len; 
-}; 
- 
-int hdr_calculate_bucket_config( 
-    int64_t lowest_trackable_value, 
-    int64_t highest_trackable_value, 
-    int significant_figures, 
-    struct hdr_histogram_bucket_config* cfg); 
- 
-void hdr_init_preallocated(struct hdr_histogram* h, struct hdr_histogram_bucket_config* cfg); 
- 
-int64_t hdr_size_of_equivalent_value_range(const struct hdr_histogram* h, int64_t value); 
- 
-int64_t hdr_next_non_equivalent_value(const struct hdr_histogram* h, int64_t value); 
- 
-int64_t hdr_median_equivalent_value(const struct hdr_histogram* h, int64_t value); 
- 
-/** 
- * Used to reset counters after importing data manuallying into the histogram, used by the logging code 
- * and other custom serialisation tools. 
- */ 
-void hdr_reset_internal_counters(struct hdr_histogram* h); 
- 
-#ifdef __cplusplus 
-} 
-#endif 
- 
-#endif 
+/**
+ * hdr_histogram.h
+ * Written by Michael Barker and released to the public domain,
+ * as explained at http://creativecommons.org/publicdomain/zero/1.0/
+ *
+ * The source for the hdr_histogram utilises a few C99 constructs, specifically
+ * the use of stdint/stdbool and inline variable declaration.
+ */
+
+#ifndef HDR_HISTOGRAM_H
+#define HDR_HISTOGRAM_H 1
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <stdio.h>
+
+struct hdr_histogram
+{
+    int64_t lowest_trackable_value;
+    int64_t highest_trackable_value;
+    int32_t unit_magnitude;
+    int32_t significant_figures;
+    int32_t sub_bucket_half_count_magnitude;
+    int32_t sub_bucket_half_count;
+    int64_t sub_bucket_mask;
+    int32_t sub_bucket_count;
+    int32_t bucket_count;
+    int64_t min_value;
+    int64_t max_value;
+    int32_t normalizing_index_offset;
+    double conversion_ratio;
+    int32_t counts_len;
+    int64_t total_count;
+    int64_t counts[0];
+};
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Allocate the memory and initialise the hdr_histogram.
+ *
+ * Due to the size of the histogram being the result of some reasonably
+ * involved math on the input parameters this function it is tricky to stack allocate.
+ * The histogram is allocated in a single contigious block so can be delete via free,
+ * without any structure specific destructor.
+ *
+ * @param lowest_trackable_value The smallest possible value to be put into the
+ * histogram.
+ * @param highest_trackable_value The largest possible value to be put into the
+ * histogram.
+ * @param significant_figures The level of precision for this histogram, i.e. the number
+ * of figures in a decimal number that will be maintained.  E.g. a value of 3 will mean
+ * the results from the histogram will be accurate up to the first three digits.  Must
+ * be a value between 1 and 5 (inclusive).
+ * @param result Output parameter to capture allocated histogram.
+ * @return 0 on success, EINVAL if lowest_trackable_value is < 1 or the
+ * significant_figure value is outside of the allowed range, ENOMEM if malloc
+ * failed.
+ */
+int hdr_init(
+    int64_t lowest_trackable_value,
+    int64_t highest_trackable_value,
+    int significant_figures,
+    struct hdr_histogram** result);
+
+/**
+ * Allocate the memory and initialise the hdr_histogram.  This is the equivalent of calling
+ * hdr_init(1, highest_trackable_value, significant_figures, result);
+ *
+ * @deprecated use hdr_init.
+ */
+int hdr_alloc(int64_t highest_trackable_value, int significant_figures, struct hdr_histogram** result);
+
+
+/**
+ * Reset a histogram to zero - empty out a histogram and re-initialise it
+ *
+ * If you want to re-use an existing histogram, but reset everything back to zero, this
+ * is the routine to use.
+ *
+ * @param h The histogram you want to reset to empty.
+ *
+ */
+void hdr_reset(struct hdr_histogram* h);
+
+/**
+ * Get the memory size of the hdr_histogram.
+ *
+ * @param h "This" pointer
+ * @return The amount of memory used by the hdr_histogram in bytes
+ */
+size_t hdr_get_memory_size(struct hdr_histogram* h);
+
+/**
+ * Records a value in the histogram, will round this value of to a precision at or better
+ * than the significant_figure specified at construction time.
+ *
+ * @param h "This" pointer
+ * @param value Value to add to the histogram
+ * @return false if the value is larger than the highest_trackable_value and can't be recorded,
+ * true otherwise.
+ */
+bool hdr_record_value(struct hdr_histogram* h, int64_t value);
+
+/**
+ * Records count values in the histogram, will round this value of to a
+ * precision at or better than the significant_figure specified at construction
+ * time.
+ *
+ * @param h "This" pointer
+ * @param value Value to add to the histogram
+ * @param count Number of 'value's to add to the histogram
+ * @return false if any value is larger than the highest_trackable_value and can't be recorded,
+ * true otherwise.
+ */
+bool hdr_record_values(struct hdr_histogram* h, int64_t value, int64_t count);
+
+
+/**
+ * Record a value in the histogram and backfill based on an expected interval.
+ *
+ * Records a value in the histogram, will round this value of to a precision at or better
+ * than the significant_figure specified at contruction time.  This is specifically used
+ * for recording latency.  If the value is larger than the expected_interval then the
+ * latency recording system has experienced co-ordinated omission.  This method fills in the
+ * values that would have occured had the client providing the load not been blocked.
+
+ * @param h "This" pointer
+ * @param value Value to add to the histogram
+ * @param expected_interval The delay between recording values.
+ * @return false if the value is larger than the highest_trackable_value and can't be recorded,
+ * true otherwise.
+ */
+bool hdr_record_corrected_value(struct hdr_histogram* h, int64_t value, int64_t expexcted_interval);
+/**
+ * Record a value in the histogram 'count' times.  Applies the same correcting logic
+ * as 'hdr_record_corrected_value'.
+ *
+ * @param h "This" pointer
+ * @param value Value to add to the histogram
+ * @param count Number of 'value's to add to the histogram
+ * @param expected_interval The delay between recording values.
+ * @return false if the value is larger than the highest_trackable_value and can't be recorded,
+ * true otherwise.
+ */
+bool hdr_record_corrected_values(struct hdr_histogram* h, int64_t value, int64_t count, int64_t expected_interval);
+
+/**
+ * Adds all of the values from 'from' to 'this' histogram.  Will return the
+ * number of values that are dropped when copying.  Values will be dropped
+ * if they around outside of h.lowest_trackable_value and
+ * h.highest_trackable_value.
+ *
+ * @param h "This" pointer
+ * @param from Histogram to copy values from.
+ * @return The number of values dropped when copying.
+ */
+int64_t hdr_add(struct hdr_histogram* h, const struct hdr_histogram* from);
+
+/**
+ * Adds all of the values from 'from' to 'this' histogram.  Will return the
+ * number of values that are dropped when copying.  Values will be dropped
+ * if they around outside of h.lowest_trackable_value and
+ * h.highest_trackable_value.
+ *
+ * @param h "This" pointer
+ * @param from Histogram to copy values from.
+ * @return The number of values dropped when copying.
+ */
+int64_t hdr_add_while_correcting_for_coordinated_omission(
+    struct hdr_histogram* h, struct hdr_histogram* from, int64_t expected_interval);
+
+/**
+ * Get minimum value from the histogram.  Will return 2^63-1 if the histogram
+ * is empty.
+ *
+ * @param h "This" pointer
+ */
+int64_t hdr_min(const struct hdr_histogram* h);
+
+/**
+ * Get maximum value from the histogram.  Will return 0 if the histogram
+ * is empty.
+ *
+ * @param h "This" pointer
+ */
+int64_t hdr_max(const struct hdr_histogram* h);
+
+/**
+ * Get the value at a specific percentile.
+ *
+ * @param h "This" pointer.
+ * @param percentile The percentile to get the value for
+ */
+int64_t hdr_value_at_percentile(const struct hdr_histogram* h, double percentile);
+
+/**
+ * Gets the standard deviation for the values in the histogram.
+ *
+ * @param h "This" pointer
+ * @return The standard deviation
+ */
+double hdr_stddev(const struct hdr_histogram* h);
+
+/**
+ * Gets the mean for the values in the histogram.
+ *
+ * @param h "This" pointer
+ * @return The mean
+ */
+double hdr_mean(const struct hdr_histogram* h);
+
+/**
+ * Determine if two values are equivalent with the histogram's resolution.
+ * Where "equivalent" means that value samples recorded for any two
+ * equivalent values are counted in a common total count.
+ *
+ * @param h "This" pointer
+ * @param a first value to compare
+ * @param b second value to compare
+ * @return 'true' if values are equivalent with the histogram's resolution.
+ */
+bool hdr_values_are_equivalent(const struct hdr_histogram* h, int64_t a, int64_t b);
+
+/**
+ * Get the lowest value that is equivalent to the given value within the histogram's resolution.
+ * Where "equivalent" means that value samples recorded for any two
+ * equivalent values are counted in a common total count.
+ *
+ * @param h "This" pointer
+ * @param value The given value
+ * @return The lowest value that is equivalent to the given value within the histogram's resolution.
+ */
+int64_t hdr_lowest_equivalent_value(const struct hdr_histogram* h, int64_t value);
+
+/**
+ * Get the count of recorded values at a specific value
+ * (to within the histogram resolution at the value level).
+ *
+ * @param h "This" pointer
+ * @param value The value for which to provide the recorded count
+ * @return The total count of values recorded in the histogram within the value range that is
+ * {@literal >=} lowestEquivalentValue(<i>value</i>) and {@literal <=} highestEquivalentValue(<i>value</i>)
+ */
+int64_t hdr_count_at_value(const struct hdr_histogram* h, int64_t value);
+
+int64_t hdr_count_at_index(const struct hdr_histogram* h, int32_t index);
+
+int64_t hdr_value_at_index(const struct hdr_histogram* h, int32_t index);
+
+struct hdr_iter_percentiles
+{
+    bool seen_last_value;
+    int32_t ticks_per_half_distance;
+    double percentile_to_iterate_to;
+    double percentile;
+};
+
+struct hdr_iter_recorded
+{
+    int64_t count_added_in_this_iteration_step;
+};
+
+struct hdr_iter_linear
+{
+    int64_t value_units_per_bucket;
+    int64_t count_added_in_this_iteration_step;
+    int64_t next_value_reporting_level;
+    int64_t next_value_reporting_level_lowest_equivalent;
+};
+
+struct hdr_iter_log
+{
+    double log_base;
+    int64_t count_added_in_this_iteration_step;
+    int64_t next_value_reporting_level;
+    int64_t next_value_reporting_level_lowest_equivalent;
+};
+
+/**
+ * The basic iterator.  This is a generic structure
+ * that supports all of the types of iteration.  Use
+ * the appropriate initialiser to get the desired
+ * iteration.
+ *
+ * @
+ */
+struct hdr_iter
+{
+    const struct hdr_histogram* h;
+    /** raw index into the counts array */
+    int32_t counts_index;
+    /** snapshot of the length at the time the iterator is created */
+    int32_t total_count;
+    /** value directly from array for the current counts_index */
+    int64_t count;
+    /** sum of all of the counts up to and including the count at this index */
+    int64_t cumulative_count;
+    /** The current value based on counts_index */
+    int64_t value;
+    int64_t highest_equivalent_value;
+    int64_t lowest_equivalent_value;
+    int64_t median_equivalent_value;
+    int64_t value_iterated_from;
+    int64_t value_iterated_to;
+
+    union
+    {
+        struct hdr_iter_percentiles percentiles;
+        struct hdr_iter_recorded recorded;
+        struct hdr_iter_linear linear;
+        struct hdr_iter_log log;
+    } specifics;
+
+    bool (* _next_fp)(struct hdr_iter* iter);
+
+};
+
+/**
+ * Initalises the basic iterator.
+ *
+ * @param itr 'This' pointer
+ * @param h The histogram to iterate over
+ */
+void hdr_iter_init(struct hdr_iter* iter, const struct hdr_histogram* h);
+
+/**
+ * Initialise the iterator for use with percentiles.
+ */
+void hdr_iter_percentile_init(struct hdr_iter* iter, const struct hdr_histogram* h, int32_t ticks_per_half_distance);
+
+/**
+ * Initialise the iterator for use with recorded values.
+ */
+void hdr_iter_recorded_init(struct hdr_iter* iter, const struct hdr_histogram* h);
+
+/**
+ * Initialise the iterator for use with linear values.
+ */
+void hdr_iter_linear_init(
+    struct hdr_iter* iter,
+    const struct hdr_histogram* h,
+    int64_t value_units_per_bucket);
+
+/**
+ * Initialise the iterator for use with logarithmic values
+ */
+void hdr_iter_log_init(
+    struct hdr_iter* iter,
+    const struct hdr_histogram* h,
+    int64_t value_units_first_bucket,
+    double log_base);
+
+/**
+ * Iterate to the next value for the iterator.  If there are no more values
+ * available return faluse.
+ *
+ * @param itr 'This' pointer
+ * @return 'false' if there are no values remaining for this iterator.
+ */
+bool hdr_iter_next(struct hdr_iter* iter);
+
+typedef enum
+{
+    CLASSIC,
+    CSV
+} format_type;
+
+/**
+ * Print out a percentile based histogram to the supplied stream.  Note that
+ * this call will not flush the FILE, this is left up to the user.
+ *
+ * @param h 'This' pointer
+ * @param stream The FILE to write the output to
+ * @param ticks_per_half_distance The number of iteration steps per half-distance to 100%
+ * @param value_scale Scale the output values by this amount
+ * @param format_type Format to use, e.g. CSV.
+ * @return 0 on success, error code on failure.  EIO if an error occurs writing
+ * the output.
+ */
+int hdr_percentiles_print(
+    struct hdr_histogram* h, FILE* stream, int32_t ticks_per_half_distance,
+    double value_scale, format_type format);
+
+/**
+* Internal allocation methods, used by hdr_dbl_histogram.
+*/
+struct hdr_histogram_bucket_config
+{
+    int64_t lowest_trackable_value;
+    int64_t highest_trackable_value;
+    int64_t unit_magnitude;
+    int64_t significant_figures;
+    int32_t sub_bucket_half_count_magnitude;
+    int32_t sub_bucket_half_count;
+    int64_t sub_bucket_mask;
+    int32_t sub_bucket_count;
+    int32_t bucket_count;
+    int32_t counts_len;
+};
+
+int hdr_calculate_bucket_config(
+    int64_t lowest_trackable_value,
+    int64_t highest_trackable_value,
+    int significant_figures,
+    struct hdr_histogram_bucket_config* cfg);
+
+void hdr_init_preallocated(struct hdr_histogram* h, struct hdr_histogram_bucket_config* cfg);
+
+int64_t hdr_size_of_equivalent_value_range(const struct hdr_histogram* h, int64_t value);
+
+int64_t hdr_next_non_equivalent_value(const struct hdr_histogram* h, int64_t value);
+
+int64_t hdr_median_equivalent_value(const struct hdr_histogram* h, int64_t value);
+
+/**
+ * Used to reset counters after importing data manuallying into the histogram, used by the logging code
+ * and other custom serialisation tools.
+ */
+void hdr_reset_internal_counters(struct hdr_histogram* h);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif