From 063eeb8d1253990e4ff9e53793fbafd07b4bae6e Mon Sep 17 00:00:00 2001
From: Christien Rioux <chris@veilid.org>
Date: Mon, 12 May 2025 20:18:14 -0400
Subject: [PATCH] stats

---
 .../lib/dht_support/src/dht_record/stats.dart | 175 ++++++++++++++++++
 1 file changed, 175 insertions(+)
 create mode 100644 packages/veilid_support/lib/dht_support/src/dht_record/stats.dart

diff --git a/packages/veilid_support/lib/dht_support/src/dht_record/stats.dart b/packages/veilid_support/lib/dht_support/src/dht_record/stats.dart
new file mode 100644
index 0000000..6388f5c
--- /dev/null
+++ b/packages/veilid_support/lib/dht_support/src/dht_record/stats.dart
@@ -0,0 +1,175 @@
+import 'package:collection/collection.dart';
+import 'package:indent/indent.dart';
+
+import '../../../veilid_support.dart';
+
+const maxLatencySamples = 100;
+const timeoutDuration = 10;
+
+extension LatencyStatsExt on LatencyStats {
+  String debugString() => 'fast($fastest)/avg($average)/slow($slowest)/'
+      'tm90($tm90)/tm75($tm75)/p90($p90)/p75($p75)';
+}
+
+class LatencyStatsAccounting {
+  LatencyStatsAccounting({required this.maxSamples});
+
+  LatencyStats record(TimestampDuration dur) {
+    _samples.add(dur);
+    if (_samples.length > maxSamples) {
+      _samples.removeAt(0);
+    }
+
+    final sortedList = _samples.sorted();
+
+    final fastest = sortedList.first;
+    final slowest = sortedList.last;
+    final average = TimestampDuration(
+        value: sortedList.fold(BigInt.zero, (acc, x) => acc + x.value) ~/
+            BigInt.from(sortedList.length));
+
+    final tm90len = (sortedList.length * 90 + 99) ~/ 100;
+    final tm75len = (sortedList.length * 75 + 99) ~/ 100;
+    final tm90 = TimestampDuration(
+        value: sortedList
+                .sublist(0, tm90len)
+                .fold(BigInt.zero, (acc, x) => acc + x.value) ~/
+            BigInt.from(tm90len));
+    final tm75 = TimestampDuration(
+        value: sortedList
+                .sublist(0, tm75len)
+                .fold(BigInt.zero, (acc, x) => acc + x.value) ~/
+            BigInt.from(tm90len));
+    final p90 = sortedList[tm90len - 1];
+    final p75 = sortedList[tm75len - 1];
+
+    final ls = LatencyStats(
+        fastest: fastest,
+        slowest: slowest,
+        average: average,
+        tm90: tm90,
+        tm75: tm75,
+        p90: p90,
+        p75: p75);
+
+    return ls;
+  }
+
+  /////////////////////////////
+  final int maxSamples;
+  final _samples = <TimestampDuration>[];
+}
+
+class DHTCallStats {
+  void record(TimestampDuration dur, Exception? exc) {
+    final wasTimeout =
+        exc is VeilidAPIExceptionTimeout || dur.toSecs() >= timeoutDuration;
+
+    calls++;
+    if (wasTimeout) {
+      timeouts++;
+    } else {
+      successLatency = successLatencyAcct.record(dur);
+    }
+    latency = latencyAcct.record(dur);
+  }
+
+  String debugString() =>
+      ' timeouts/calls: $timeouts/$calls (${(timeouts * 100 / calls).toStringAsFixed(3)}%)\n'
+      'success latency: ${successLatency?.debugString()}\n'
+      '    all latency: ${latency?.debugString()}\n';
+
+  /////////////////////////////
+  int calls = 0;
+  int timeouts = 0;
+  LatencyStats? latency;
+  LatencyStats? successLatency;
+  final latencyAcct = LatencyStatsAccounting(maxSamples: maxLatencySamples);
+  final successLatencyAcct =
+      LatencyStatsAccounting(maxSamples: maxLatencySamples);
+}
+
+class DHTPerKeyStats {
+  DHTPerKeyStats(this.debugName);
+
+  void record(String func, TimestampDuration dur, Exception? exc) {
+    final keyFuncStats = _perFuncStats.putIfAbsent(func, DHTCallStats.new);
+
+    _stats.record(dur, exc);
+    keyFuncStats.record(dur, exc);
+  }
+
+  String debugString() {
+    //
+    final out = StringBuffer()
+      ..write('Name: $debugName\n')
+      ..write(_stats.debugString().indent(4))
+      ..writeln('Per-Function:');
+    for (final entry in _perFuncStats.entries) {
+      final funcName = entry.key;
+      final funcStats = entry.value.debugString().indent(4);
+      out.write('$funcName:\n$funcStats'.indent(4));
+    }
+
+    return out.toString();
+  }
+
+  //////////////////////////////
+
+  final String debugName;
+  final _stats = DHTCallStats();
+  final _perFuncStats = <String, DHTCallStats>{};
+}
+
+class DHTStats {
+  DHTStats();
+
+  Future<T> measure<T>(TypedKey key, String debugName, String func,
+      Future<T> Function() closure) async {
+    //
+    final start = Veilid.instance.now();
+    final keyStats =
+        _statsPerKey.putIfAbsent(key, () => DHTPerKeyStats(debugName));
+    final funcStats = _statsPerFunc.putIfAbsent(func, DHTCallStats.new);
+
+    VeilidAPIException? exc;
+
+    try {
+      final res = await closure();
+
+      return res;
+    } on VeilidAPIException catch (e) {
+      exc = e;
+      rethrow;
+    } finally {
+      final end = Veilid.instance.now();
+      final dur = end.diff(start);
+
+      keyStats.record(func, dur, exc);
+      funcStats.record(dur, exc);
+    }
+  }
+
+  String debugString() {
+    //
+    final out = StringBuffer()..writeln('Per-Function:');
+    for (final entry in _statsPerFunc.entries) {
+      final funcName = entry.key;
+      final funcStats = entry.value.debugString().indent(4);
+      out.write('$funcName:\n$funcStats\n'.indent(4));
+    }
+    out.writeln('Per-Key:');
+    for (final entry in _statsPerKey.entries) {
+      final keyName = entry.key;
+      final keyStats = entry.value.debugString().indent(4);
+      out.write('$keyName:\n$keyStats\n'.indent(4));
+    }
+
+    return out.toString();
+  }
+
+  //////////////////////////////
+
+  final _statsPerKey = <TypedKey, DHTPerKeyStats>{};
+  final _statsPerFunc = <String, DHTCallStats>{};
+}