Exclude from a report a part of bytecode that compiler generates for a try-with-resources #500

Godin · 2017-03-16T23:31:33Z

https://github.com/jacoco/jacoco/wiki/filtering-JAVAC.TRYWITH

marchof · 2017-03-17T15:06:14Z

@Godin Count me deeply impressed!!! And I'm very sorry that I couldn't immediately jump into both PRs. So+Mo are travel dates, so I hope to study it in detail then.

Godin · 2017-03-17T15:18:01Z

@marchof no worry, will be cool to get all this on board, but no need to rush - let's do a proper careful review and testing. Slowly, but at least we are progressing on this big subject. And I personally start to see the light at the end of the tunnel, which wasn't the case few months ago.

FYI next week I'm also kind of traveling - will attend DevoxxUS, and hope to not be offline all the time.

bjkail · 2017-03-17T16:31:01Z

@Godin It would be useful if the members of Pattern had high-level descriptions of the code being matched and which conditions cause the compiler to generate that pattern. It would be good to have a test of t-w-r with custom finally block (try (...) { ... } finally { nop() }) to be sure it doesn't cause problems for the analyses. It would also be good to have tests with nested t-w-r nested in the try, catch, and finally blocks (e.g., try (...) { ... } finally { try (...) { ... } catch (...) { ... } finally { ... } }, etc.).

Godin · 2017-03-17T16:57:26Z

@bjkail Hey, glad to see you here! Actually was about to ask if you're interested in this subject and if so maybe you could leave some valuable comments as before 😉 And here they are 😋

You are right on all points - let's cleanup and harden this PoC. Also wondering WDTY about approach in general? About it we'd better add explanatory comments also. As well as estimate impact on performance of analysis - can imagine some optimizations... but traded them on the correctness and attempt to keep relative simplicity of code for now.

Anyway thank you! we really appreciate your help 👍

bjkail · 2017-03-17T20:52:34Z

@Godin The overall approach seems reasonable to me of skipping ignored instructions in MethodAnalyzer.visitEnd and matching bytecode sequences in TryWithResourcesMatcher.

Last time I thought about t-w-r, I was thinking to require the t-w-r close sequence be replicated at the end of the try block and each catch block (including Throwable) to ensure it was either written by a compiler or fully correctly hand-written. My motivation was to avoid filtering out a badly hand-written close sequence (e.g., at the end of try block only but not all catch blocks or missing Throwable block, etc.), but the algorithm to do the rigid matching seemed quite complex, especially for custom finally blocks and nested t-w-r (thus my suggested testcases). However, I am now thinking your approach is fine. There is some risk of false positive (matching a hand-written close sequence), but the risk is low since the close sequence is relatively complex, and we can leave detecting badly hand-written close sequences (like missing close sequence on some possible code path) to static analyzers like FindBugs.

bjkail · 2017-03-17T21:21:40Z

As an anecdote, last time I investigated t-w-r was because we kept regressing coverage in classes that use t-w-r heavily because drops go unnoticed due to all the uncovered generated code. I tried forcing all the generate code paths to be executed (our code/tests made it easy to force all the conditions: null resource, exception with null resource, exception with non-null resource, close exception, exception and close exception), but I ultimately gave up when I discovered javac emits completely dead code:

if (#primaryExc) != null) is always false in the try block and is always true in the catch blocks.
if (Identifier != null) can be always false in the try block. JDK-7020499 improves that for Java 9, but I wish it also had "effectively non-null" analysis like the "effectively final" analysis that would elide the check.

So, I think this will be a great feature to have in JaCoCo :-).

Godin · 2017-04-20T17:06:59Z

org.jacoco.core/src/org/jacoco/core/internal/analysis/filter/TryWithResourcesJavacFilter.java

+	 * initialized using <code>new</code></li>
+	 * <li>synthetic method <code>$closeResource</code> containing
+	 * <code>null</code> check of primaryExc and calls to methods
+	 * <code>addSuppressed</code> and <code>close</code> is used when numbers of


typo - numbers instead of number

Godin · 2017-04-21T19:25:39Z

@marchof I scanned bigger subset of Maven Central - latest versions of some artifacts within group org. This was not easy, because not counting time that were spent to download - some jars with sources should be excluded as they are incomplete, contain more than jars with classes, contain templates for generation of sources, etc...

Nevertheless 9753 try-with-resources statements were filtered correctly from ≈20 Gb of JAR files with classes. And this time ECJ filter was triggered quite a good amount of times.

Case that was already presented in our tests and not filtered - when body of try-with-resources is empty

try (Resource r = new Resource()) {
}

was encountered in

org/apache/cassandra/cassandra-all/3.10
org/apache/cayenne/modeler/cayenne-modeler/4.0.M5
org/apache/reef/reef-runtime-hdinsight/0.15.0
org/apache/tomcat/embed/tomcat-embed-jasper/9.0.0.M19
org/apache/tomcat/tomcat-jasper/9.0.0.M19
org/apache/solr/solr-core/6.5.0
org/eclipse/scout/sdk/deps/org.eclipse.jdt.launching/3.8.100.v20160505-0636
org/integratedmodelling/klab-common/0.9.10
org/jboss/arquillian/container/arquillian-gae-common/1.0.0.Beta10
org/jboss/cdi/tck/cdi-tck-impl/2.0.0.CR1
org/neo4j/app/neo4j-server/3.2.0-alpha07
org/neo4j/neo4j-ha/3.2.0-alpha07
org/neo4j/neo4j-ogm/1.1.6
org/sonatype/nexus/bundles/org.sonatype.nexus.bundles.elasticsearch/3.2.1-01
org/sonarsource/sonarqube/sonar-process/6.3
org/simplericity/jettyconsole/jetty-console-core/1.60
org/vesalainen/comm/1.0.3
org/qi4j/core/org.qi4j.core.testsupport/2.1

Another funny case that was already presented in our tests and not filtered - when try-with-resources contains only throw statement

try (Resource r = new Resource()) {
  throw new Exception();
}

was encountered in

org/apache/nifi/nifi-framework-core/1.1.2
org/apache/reef/reef-common/0.15.0
org/codelibs/fess/fess-crawler/1.1.0
org/tentackle/tentackle-persistence/2.0.7
org/sonatype/nexus/bundles/org.sonatype.nexus.bundles.elasticsearch/3.2.1-01

Not explicitly presented in out tests, but a kind of variation of previous and not filtered - when there is no non-exceptional path from a body as for example

try (Resource r = new Resource()) {
  while (true) {
    read(r);
  }
} catch (EOFException e) {
}

was encountered in

org/apache/cassandra/cassandra-all/3.10
org/apache/fluo/fluo-accumulo/1.0.0-incubating
org/github/evenjn/knit/0.6.0
org/infinispan/infinispan-embedded/9.0.0.Final
org/jgroups/jgroups/4.0.1.Final
org/kohsuke/elb-dns/1.1

An interesting case where source code contains try-with-resources, but retrolambda removes call to Throwable.addSuppressed and so not filtered, was encountered in

org/ansj/ansj_seg/5.1.1

An interesting case where AspectJ adds try-with-resources into bytecode was encountered in

org/no-hope/aspectj/metrics-aspectj-el/1.7

All in all: I satisfied by results and would like to merge this PR. We can deal with cases of an empty body and absence of non-exceptional path in a separate PR. If you agree I'll squash and merge into master.

marchof · 2017-04-22T05:16:18Z

@Godin Awesome work, Evgeny! I'm absolutly curious about the exact test setup. And yes, we can add corner cases later.

I was already about to ask about the performance of the new, way more readable matching code. As there is no negative impact -> yes, please merge this!

romani · 2017-06-29T17:34:48Z

@Godin , when do you plan to release this ?
Checkstyle project plan to give jacoco another try this summer, this feature could be a good stimulus to switch to jacoco for coverage.
jacoco is already 5month without release with bunch of good fixes.

Godin · 2017-06-29T17:45:13Z

@romani please see already existing answers on such question:
https://groups.google.com/forum/#!msg/jacoco/gd8xD30TDNo/SHj-hEq1AAAJ
https://groups.google.com/forum/#!msg/jacoco/-MmsVzC6szM/Q9sPTbAeBAAJ

Godin added component: core.filters type: enhancement labels Mar 16, 2017

Godin added this to TODO in Filtering Mar 16, 2017

Godin added this to IN PROGRESS in Current work items Mar 16, 2017

Godin force-pushed the issue-500 branch from 0d7a711 to cea277a Compare March 16, 2017 23:39

Godin self-assigned this Mar 16, 2017

Godin requested a review from marchof March 16, 2017 23:59

Godin mentioned this pull request Mar 17, 2017

Exclude from a report a part of bytecode that ECJ generates for a String in switch statement and that is hard to cover by tests #496

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Godin force-pushed the issue-500 branch 16 times, most recently from 50d98bc to 1adc2d1 Compare March 25, 2017 15:55

Godin force-pushed the issue-500 branch from f2dec3c to 96bc5d4 Compare April 4, 2017 08:58

Merge branch 'master'

96bc5d4

Godin mentioned this pull request Apr 10, 2017

Exclude methods annotated with @lombok.Generated #513

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marchof approved these changes Apr 11, 2017

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Godin force-pushed the issue-500 branch from edff741 to 79cacf3 Compare April 11, 2017 22:25

(wip) get rid of TODO in test

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Godin force-pushed the issue-500 branch from 79cacf3 to df07579 Compare April 11, 2017 22:50

Godin added 2 commits April 12, 2017 00:51

(wip) get rid of TODO

2240661

(wip) add comments to TryWithResourcesEcjFilterTest

2929ed7

Godin force-pushed the issue-500 branch from fd9bb95 to 2929ed7 Compare April 12, 2017 19:15

Godin added 3 commits April 12, 2017 22:38

(wip) add comments to TryWithResourcesJavacFilterTest

c9b3c28

(wip) add comments to TryWithResourcesJavacFilter

020a850

(wip) make more declarative

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Godin force-pushed the issue-500 branch from a3a9f9a to 61cf25f Compare April 13, 2017 13:13

(wip) add missing unit test

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Godin commented Apr 20, 2017

View reviewed changes

Godin added 3 commits April 21, 2017 19:30

(wip) fix typo

da3b6e3

(wip) make test less fragile

297c45d

(wip) improve test

e29ec72

Godin merged commit e93053e into master Apr 22, 2017

Godin deleted the issue-500 branch April 22, 2017 10:39

Godin removed this from IN PROGRESS in Current work items Apr 22, 2017

Godin moved this from IN PROGRESS to DONE in Filtering Apr 22, 2017

fdaugan mentioned this pull request Nov 5, 2017

Update "jacoco 0.7.10" before "commons-io 2.6" ligoj/bootstrap#8

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Godin added the language: Java label Oct 12, 2023

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Exclude from a report a part of bytecode that compiler generates for a try-with-resources #500

Exclude from a report a part of bytecode that compiler generates for a try-with-resources #500

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Exclude from a report a part of bytecode that compiler generates for a try-with-resources #500

Exclude from a report a part of bytecode that compiler generates for a try-with-resources #500

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