1 files changed, 89 insertions, 0 deletions
diff --git a/src/metrics/statistics.py b/src/metrics/statistics.py
new file mode 100644
index 0000000..9ad7bf0
--- /dev/null
+++ b/src/metrics/statistics.py
@@ -0,0 +1,89 @@
+import copy
+
+class Stats(dict):
+
+    def __init__(self, count=0, total=0.0, min=0.0, max=0.0,
+            sum_of_squares=0.0):
+
+        # Attribute names here must not change as this is what
+        # New Relic uses. Easier to adopt that convention rather
+        # than something slightly different.
+
+        self.count = count
+        self.total = total
+        self.min = min
+        self.max = max
+        self.sum_of_squares = sum_of_squares
+
+    def __setattr__(self, name, value):
+        self[name] = value
+
+    def __getattr__(self, name):
+        return self[name]
+
+    def merge_stats(self, other):
+        self.total += other.total
+        self.min = self.count and min(self.min, other.min) or other.min
+        self.max = max(self.max, other.max)
+        self.sum_of_squares += other.sum_of_squares
+        self.count += other.count
+
+    def merge_value(self, value):
+        self.total += value
+        self.min = self.count and min(self.min, value) or value
+        self.max = max(self.max, value)
+        self.sum_of_squares += value ** 2
+        self.count += 1
+
+class Metrics(object):
+
+    def __init__(self):
+        self.metrics = {}
+
+    def __iter__(self):
+        return iter(self.metrics.items())
+
+    def __len__(self):
+        return len(self.metrics)
+
+    def assign_value(self, name, value):
+        if isinstance(value, Stats):
+            sample = copy.copy(value)
+            self.metrics[name] = sample
+        else:
+            sample = Stats()
+            self.metrics[name] = sample
+            sample.merge_value(value)
+
+        return sample
+
+    def merge_value(self, name, value):
+        sample = self.fetch_stats(name)
+
+        if isinstance(value, Stats):
+            sample.merge_stats(value)
+        else:
+            sample.merge_value(value)
+
+        return sample
+
+    def fetch_stats(self, name):
+        sample = self.metrics.get(name)
+
+        if sample is None:
+            sample = Stats()
+            self.metrics[name] = sample
+
+        return sample
+
+    def merge_metrics(self, metrics):
+        for name, stats in metrics:
+            self.merge_value(name, stats)
+
+    def assign_metrics(self, metrics):
+        for name, stats in metrics:
+            self.assign_value(name, stats)
+
+    def clear_metrics(self):
+        self.metrics.clear()
+