1 files changed, 156 insertions, 0 deletions
diff --git a/searx/metrics/models.py b/searx/metrics/models.py
new file mode 100644
index 000000000..8936a51e3
--- /dev/null
+++ b/searx/metrics/models.py
@@ -0,0 +1,156 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
+import decimal
+import threading
+
+from searx import logger
+
+
+__all__ = ["Histogram", "HistogramStorage", "CounterStorage"]
+
+logger = logger.getChild('searx.metrics')
+
+
+class Histogram:
+
+    _slots__ = '_lock', '_size', '_sum', '_quartiles', '_count', '_width'
+
+    def __init__(self, width=10, size=200):
+        self._lock = threading.Lock()
+        self._width = width
+        self._size = size
+        self._quartiles = [0] * size
+        self._count = 0
+        self._sum = 0
+
+    def observe(self, value):
+        q = int(value / self._width)
+        if q < 0:
+            """Value below zero is ignored"""
+            q = 0
+        if q >= self._size:
+            """Value above the maximum is replaced by the maximum"""
+            q = self._size - 1
+        with self._lock:
+            self._quartiles[q] += 1
+            self._count += 1
+            self._sum += value
+
+    @property
+    def quartiles(self):
+        return list(self._quartiles)
+
+    @property
+    def count(self):
+        return self._count
+
+    @property
+    def sum(self):
+        return self._sum
+
+    @property
+    def average(self):
+        with self._lock:
+            if self._count != 0:
+                return self._sum / self._count
+            else:
+                return 0
+
+    @property
+    def quartile_percentage(self):
+        ''' Quartile in percentage '''
+        with self._lock:
+            if self._count > 0:
+                return [int(q * 100 / self._count) for q in self._quartiles]
+            else:
+                return self._quartiles
+
+    @property
+    def quartile_percentage_map(self):
+        result = {}
+        # use Decimal to avoid rounding errors
+        x = decimal.Decimal(0)
+        width = decimal.Decimal(self._width)
+        width_exponent = -width.as_tuple().exponent
+        with self._lock:
+            if self._count > 0:
+                for y in self._quartiles:
+                    yp = int(y * 100 / self._count)
+                    if yp != 0:
+                        result[round(float(x), width_exponent)] = yp
+                    x += width
+        return result
+
+    def percentage(self, percentage):
+        # use Decimal to avoid rounding errors
+        x = decimal.Decimal(0)
+        width = decimal.Decimal(self._width)
+        stop_at_value = decimal.Decimal(self._count) / 100 * percentage
+        sum_value = 0
+        with self._lock:
+            if self._count > 0:
+                for y in self._quartiles:
+                    sum_value += y
+                    if sum_value >= stop_at_value:
+                        return x
+                    x += width
+        return None
+
+    def __repr__(self):
+        return "Histogram<avg: " + str(self.average) + ", count: " + str(self._count) + ">"
+
+
+class HistogramStorage:
+
+    __slots__ = 'measures'
+
+    def __init__(self):
+        self.clear()
+
+    def clear(self):
+        self.measures = {}
+
+    def configure(self, width, size, *args):
+        measure = Histogram(width, size)
+        self.measures[args] = measure
+        return measure
+
+    def get(self, *args):
+        return self.measures.get(args, None)
+
+    def dump(self):
+        logger.debug("Histograms:")
+        ks = sorted(self.measures.keys(), key='/'.join)
+        for k in ks:
+            logger.debug("- %-60s %s", '|'.join(k), self.measures[k])
+
+
+class CounterStorage:
+
+    __slots__ = 'counters', 'lock'
+
+    def __init__(self):
+        self.lock = threading.Lock()
+        self.clear()
+
+    def clear(self):
+        with self.lock:
+            self.counters = {}
+
+    def configure(self, *args):
+        with self.lock:
+            self.counters[args] = 0
+
+    def get(self, *args):
+        return self.counters[args]
+
+    def add(self, value, *args):
+        with self.lock:
+            self.counters[args] += value
+
+    def dump(self):
+        with self.lock:
+            ks = sorted(self.counters.keys(), key='/'.join)
+        logger.debug("Counters:")
+        for k in ks:
+            logger.debug("- %-60s %s", '|'.join(k), self.counters[k])