1 files changed, 121 insertions, 0 deletions
diff --git a/src/common/perf_histogram.cc b/src/common/perf_histogram.cc
new file mode 100644
index 00000000..13528764
--- /dev/null
+++ b/src/common/perf_histogram.cc
@@ -0,0 +1,121 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * Copyright (C) 2017 OVH
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software
+ * Foundation.  See file COPYING.
+ *
+ */
+
+#include "common/perf_histogram.h"
+
+#include <limits>
+
+void PerfHistogramCommon::dump_formatted_axis(
+    ceph::Formatter *f, const PerfHistogramCommon::axis_config_d &ac) {
+  f->open_object_section("axis");
+
+  // Dump axis configuration
+  f->dump_string("name", ac.m_name);
+  f->dump_int("min", ac.m_min);
+  f->dump_int("quant_size", ac.m_quant_size);
+  f->dump_int("buckets", ac.m_buckets);
+  switch (ac.m_scale_type) {
+    case SCALE_LINEAR:
+      f->dump_string("scale_type", "linear");
+      break;
+    case SCALE_LOG2:
+      f->dump_string("scale_type", "log2");
+      break;
+    default:
+      ceph_assert(false && "Invalid scale type");
+  }
+
+  {
+    // Dump concrete ranges for axis buckets
+    f->open_array_section("ranges");
+    auto ranges = get_axis_bucket_ranges(ac);
+    for (int i = 0; i < ac.m_buckets; ++i) {
+      f->open_object_section("bucket");
+      if (i > 0) {
+        f->dump_int("min", ranges[i].first);
+      }
+      if (i < ac.m_buckets - 1) {
+        f->dump_int("max", ranges[i].second);
+      }
+      f->close_section();
+    }
+    f->close_section();
+  }
+
+  f->close_section();
+}
+
+int64_t get_quants(int64_t i, PerfHistogramCommon::scale_type_d st) {
+  switch (st) {
+    case PerfHistogramCommon::SCALE_LINEAR:
+      return i;
+    case PerfHistogramCommon::SCALE_LOG2:
+      return int64_t(1) << (i - 1);
+  }
+  ceph_assert(false && "Invalid scale type");
+}
+
+int64_t PerfHistogramCommon::get_bucket_for_axis(
+    int64_t value, const PerfHistogramCommon::axis_config_d &ac) {
+  if (value < ac.m_min) {
+    return 0;
+  }
+
+  value -= ac.m_min;
+  value /= ac.m_quant_size;
+
+  switch (ac.m_scale_type) {
+    case SCALE_LINEAR:
+      return std::min<int64_t>(value + 1, ac.m_buckets - 1);
+
+    case SCALE_LOG2:
+      for (int64_t i = 1; i < ac.m_buckets; ++i) {
+        if (value < get_quants(i, SCALE_LOG2)) {
+          return i;
+        }
+      }
+      return ac.m_buckets - 1;
+  }
+  ceph_assert(false && "Invalid scale type");
+}
+
+std::vector<std::pair<int64_t, int64_t>>
+PerfHistogramCommon::get_axis_bucket_ranges(
+    const PerfHistogramCommon::axis_config_d &ac) {
+  std::vector<std::pair<int64_t, int64_t>> ret;
+  ret.resize(ac.m_buckets);
+
+  // First bucket is for value < min
+  int64_t min = ac.m_min;
+  for (int64_t i = 1; i < ac.m_buckets - 1; i++) {
+    int64_t max_exclusive =
+        ac.m_min + get_quants(i, ac.m_scale_type) * ac.m_quant_size;
+
+    // Dump bucket range
+    ret[i].first = min;
+    ret[i].second = max_exclusive - 1;
+
+    // Shift min to next bucket
+    min = max_exclusive;
+  }
+
+  // Fill up first and last element, note that in case m_buckets == 1
+  // those will point to the same element, the order is important here
+  ret.front().second = ac.m_min - 1;
+  ret.back().first = min;
+
+  ret.front().first = std::numeric_limits<int64_t>::min();
+  ret.back().second = std::numeric_limits<int64_t>::max();
+  return ret;
+}