feature: add StatsCollector for basic metrics aggregation#16
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feature: add StatsCollector for basic metrics aggregation#16
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devcrocod
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Mar 20, 2026
| private final LongAccumulator maxLatencyMs = new LongAccumulator(Math::max, Long.MIN_VALUE); | ||
| private final LongAccumulator minLatencyMs = new LongAccumulator(Math::min, Long.MAX_VALUE); | ||
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| public void record(int statusCode, long latencyMs) throws IllegalArgumentException { |
Collaborator
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Please keep in mind that this code is not thread-safe, so errorCount may end up becoming negative
| private final LongAccumulator maxLatencyMs = new LongAccumulator(Math::max, Long.MIN_VALUE); | ||
| private final LongAccumulator minLatencyMs = new LongAccumulator(Math::min, Long.MAX_VALUE); | ||
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| public void record(int statusCode, long latencyMs) throws IllegalArgumentException { |
Collaborator
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IllegalArgumentException is unchecked exception
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| totalRequests.increment(); | ||
| if (200 <= statusCode && statusCode < 300) { | ||
| successCount.increment(); |
Collaborator
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Are 1xx or 3xx statuses as errors?
Comment on lines
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| public StatsSnapshot getSnapshot() { | ||
| long snapshotTotalRequests = totalRequests.sum(); | ||
| long snapshotSuccessCount = successCount.sum(); | ||
| long snapshotTotalLatencyMs = totalLatencyMs.sum(); | ||
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| long snapshotMinLatencyMs = (snapshotTotalRequests == 0 ? 0 : minLatencyMs.get()); | ||
| long snapshotMaxLatencyMs = (snapshotTotalRequests == 0 ? 0 : maxLatencyMs.get()); | ||
| long snapshotAvgLatencyMs = | ||
| (snapshotTotalRequests == 0 ? 0 : snapshotTotalLatencyMs / snapshotTotalRequests); | ||
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| return new StatsSnapshot( | ||
| snapshotTotalRequests, | ||
| snapshotSuccessCount, | ||
| snapshotTotalRequests - snapshotSuccessCount, | ||
| snapshotAvgLatencyMs, | ||
| snapshotMinLatencyMs, | ||
| snapshotMaxLatencyMs); | ||
| } | ||
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| public void reset() { | ||
| totalRequests.reset(); | ||
| successCount.reset(); | ||
| totalLatencyMs.reset(); | ||
| minLatencyMs.reset(); | ||
| maxLatencyMs.reset(); | ||
| } |
Collaborator
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add method getSnapshotAndReset()
| long snapshotMinLatencyMs = (snapshotTotalRequests == 0 ? 0 : minLatencyMs.get()); | ||
| long snapshotMaxLatencyMs = (snapshotTotalRequests == 0 ? 0 : maxLatencyMs.get()); | ||
| long snapshotAvgLatencyMs = | ||
| (snapshotTotalRequests == 0 ? 0 : snapshotTotalLatencyMs / snapshotTotalRequests); |
Collaborator
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Try to use double-precision arithmetic where possible. Integer arithmetic can introduce significant error
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What
Thread-safe StatsCollector for aggregating per-request metrics.
Collects status codes and latencies, provides snapshot with
total/success/error counts, avg/min/max latency.
Uses LongAdder and LongAccumulator for lock-free concurrency.
How to verify
./mvnw test
Closes #11