[break] Fix MetricName comparator for tags, MetricName#safeTags() returns SortedMap #272

schlosna · 2019-05-24T20:37:09Z

Ensure MetricName#safeTags are compared in a total ordered fashion.

Ensure MetricName#safeTags are compared in a total ordered fashion.

schlosna · 2019-05-24T20:44:57Z

tritium-registry/src/main/java/com/palantir/tritium/metrics/registry/MetricName.java

@@ -65,7 +44,7 @@



Actually should make this:

@Value.NaturalOrder NavigableMap<String, String> safeTags();

That would do the trick, if we're okay with exposing NavigatableMap instead of Map

Why does MetricName need to be comparable? Are we better off removing that piece?

I mainly added it for convenience for the toString form when analyzing getMetrics output

carterkozak · 2019-05-24T21:02:45Z

tritium-registry/src/main/java/com/palantir/tritium/metrics/registry/MetricNames.java

+            Map.Entry.<String, String>comparingByKey()
+                    .thenComparing(Map.Entry.comparingByValue());
+
+    private static final Comparator<Map<String, String>> sizeComparator = Comparator.comparingInt(Map::size);


carterkozak · 2019-05-24T21:03:50Z

tritium-registry/src/main/java/com/palantir/tritium/metrics/registry/MetricName.java

@@ -61,11 +40,12 @@
     * <p>
     * All tags and keys must be {@link Safe} to log.
     */
-    Map<String, String> safeTags();
+    @Value.NaturalOrder
+    NavigableMap<String, String> safeTags();


Should we loosen this to SortedMap?

I'd prefer to just leave this as a NavigableMap as the underlying impl generated by immutables is a TreeMap either way with jdkOnly = true (though we could remove that since we already rely on Guava implementation dependency, created optional #273 for that).

I'd prefer the guava approach. We heavily rely on guava immutable collections, and they will avoid collection re-allocations when we attempt to re-wrap them.

I'm not sure any of the functionality provided by NavigableMap will be helpful for safeTags, where SortedMap provides clear advantages. Using the less specific type allows more freedom to change the implementation in the future. That said, I'm not actually aware of a SortedMap implementation which doesn't also implement NavigableMap, so I defer to your judgement.

ok, you convinced me, went with SortedMap for now

schlosna

Introducing a slight break since 0.12.5 by removing Comparable from MetricName, but I don't think that was actually necessary and was just something I had added for my own convenience when implementing the tagged cache metrics.

schlosna · 2019-05-25T01:22:00Z

tritium-registry/src/main/java/com/palantir/tritium/metrics/registry/MetricName.java

@@ -61,11 +40,12 @@
     * <p>
     * All tags and keys must be {@link Safe} to log.
     */
-    Map<String, String> safeTags();
+    @Value.NaturalOrder
+    NavigableMap<String, String> safeTags();


I'd prefer to just leave this as a NavigableMap as the underlying impl generated by immutables is a TreeMap either way with jdkOnly = true (though we could remove that since we already rely on Guava implementation dependency, created optional #273 for that).

…mpl (#273)

carterkozak · 2019-05-26T21:47:05Z

Thanks!

iamdanfox · 2019-05-28T13:53:43Z

As mentioned by @JacekLach, automatically upgrading to this version of tritium has caused NoSuchMethodErrors at runtime! It seems like changing Map -> SortedMap was API compatible but not ABI compatible!

We had some code in sls-logging, which did this:

        Map<String, String> tags = metricName.safeTags();

        if (metric instanceof Counter) {
            return Optional.of(MetricLogs.v1counter(name, (Counter) metric, tags));
        } else if (metric instanceof Meter) {
            ...

And it seems that first line triggers the exception:

java.lang.NoSuchMethodError: com.palantir.tritium.metrics.registry.MetricName.safeTags()Ljava/util/Map;
	at com.palantir.sls.logging.metric.ScheduledTaggedMetricLogReporter.metricLog(ScheduledTaggedMetricLogReporter.java:121)
	at com.palantir.sls.logging.metric.ScheduledTaggedMetricLogReporter.reportMetrics(ScheduledTaggedMetricLogReporter.java:102)
	at com.palantir.sls.logging.metric.ScheduledTaggedMetricLogReporter.lambda$report$2(ScheduledTaggedMetricLogReporter.java:91)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
	at com.palantir.tracing.DeferredTracer.withTrace(DeferredTracer.java:115)
	at com.palantir.tracing.Tracers$TracingAwareCallable.call(Tracers.java:343)
	at com.palantir.tracing.WrappingExecutorService.lambda$wrapTask$0(WrappingExecutorService.java:67)
	at com.codahale.metrics.InstrumentedExecutorService$InstrumentedRunnable.run(InstrumentedExecutorService.java:176)
	at com.palantir.tritium.metrics.TaggedMetricsExecutorService$TaggedMetricsRunnable.run(TaggedMetricsExecutorService.java:161)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at java.lang.Thread.run(Thread.java:834)

We worked around this by just releasing a new version of sls-logging.

schlosna · 2019-05-28T14:21:15Z

@iamdanfox sorry about that ABI break. I'm open to reverting that change if necessary and tagging a 0.13.1 (I'm half inclined to just remove immutables generation for MetricName as well so that I can fully control the generated implementation).

We should probably consider an actual 1.0.0 so that we can effectively do real API/ABI breaks and mark them as proper semver major version bumps.

carterkozak · 2019-05-28T14:37:58Z

I would support removing immutables since I've found a few places that subclass MetricName, I would prefer if we provided a concrete final implementation instead. interface -> class would be another ABI break though.

schlosna · 2019-05-28T14:41:19Z

I would probably leave MetricName as an interface, but provide an ABI compatible Immutable builder and simple static factory for just name & name+tags.

iamdanfox · 2019-05-28T14:52:27Z

Given how easy it was to workaround this, not sure it's worth reverting just yet, just wanted to flag because this is such a low level library that even tiny breaks can end up having quite far reaching consequences!

JacekLach · 2019-05-28T16:26:05Z

It was an easy workaround, but we only caught it in prod (when we noticed we were missing a subset of metrics for ~12h)! So there's a bit more to the tradeoff than just how difficult/easy the fix was.

Ensure `MetricName#safeTags` are compared in a total ordered fashion.

Fix MetricName comparator for tags

8435797

Ensure MetricName#safeTags are compared in a total ordered fashion.

schlosna requested a review from carterkozak May 24, 2019 20:37

schlosna commented May 24, 2019

View reviewed changes

Make MetricName#safeTags NavigableMap

28fba1b

carterkozak approved these changes May 24, 2019

View reviewed changes

[break] MetricName is no longer Comparable

6dfa869

schlosna commented May 25, 2019

View reviewed changes

schlosna and others added 2 commits May 25, 2019 12:15

Allow using Guava types in generated MetricName immutable builder & i…

a201e13

…mpl (#273)

Use SortedMap for safe tags

b1e527d

schlosna added the merge when ready label May 26, 2019

bulldozer-bot bot merged commit c2b1222 into develop May 26, 2019

bulldozer-bot bot deleted the ds/metric-name-tags-comparator branch May 26, 2019 21:46

iamdanfox changed the title ~~Fix MetricName comparator for tags~~ [break] Fix MetricName comparator for tags, MetricName#safeTags() returns SortedMap May 28, 2019

CRogers mentioned this pull request Sep 11, 2019

Demonstrate gradle-revapi finding ABI breaks #403

Closed

CRogers pushed a commit that referenced this pull request Sep 11, 2019

Rebase to remove tag: Fix MetricName comparator for tags (#272)

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Ensure `MetricName#safeTags` are compared in a total ordered fashion.

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[break] Fix MetricName comparator for tags, MetricName#safeTags() returns SortedMap #272

[break] Fix MetricName comparator for tags, MetricName#safeTags() returns SortedMap #272

schlosna commented May 24, 2019 •

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JacekLach commented May 28, 2019

[break] Fix MetricName comparator for tags, MetricName#safeTags() returns SortedMap #272

[break] Fix MetricName comparator for tags, MetricName#safeTags() returns SortedMap #272

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carterkozak commented May 26, 2019

iamdanfox commented May 28, 2019

schlosna commented May 28, 2019

carterkozak commented May 28, 2019

schlosna commented May 28, 2019

iamdanfox commented May 28, 2019

JacekLach commented May 28, 2019

schlosna commented May 24, 2019 •

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