6656: Allow capturing field values with path syntax

[tabjy]

This patch implements JMC-6656: Allow capturing field values with path syntax.

In the xml configuration, a field capture looks like:

<field>
  <name>a field value</name>
  <description>a field value capture with a path syntax</description>
  <expression>this.field.prop</expression>
</field>

See org/openjdk/jmc/agent/test/jfrprobes_template.xml for more examples.

There are currently two limitations to pay attention to:

1. Instrumentation point cannot be in synthesized classes:
   Instrumented classes are first loaded by obtaining the bytecode and inspected reflectively to resolve typing information. This fails if the class load is unable to provide the bytecode when ClassLoader.getResouce() is called. The cases where it might fail are unlikely to be for classes like proxies or auxiliaries for Java frameworks that have no visible equivalent.

2. Instrumentation is unable to access nestmates' private fields:
   Before nest-base access control was introduced in Java 11, accessing nestmates' private fields is, while lexically correct, forbidden by the JVM. The Java compiler works around by inserting synthetic getters/setters. However, it's not for a BCI agent since changing the class structure is not allowed during class transformation.

Please let me know your thoughts. Thank you very much!

Progress

• Commit message must refer to an issue
• Change must be properly reviewed

Issue

JMC-6656: Allow capturing field values with path syntax

Approvers

• Marcus Hirt (hirt - Reviewer)

[bridgekeeper]

👋 Welcome back kxu! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request (refresh this page to view it).

[tabjy]

/help

[openjdk]

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[edvbld]

Please ignore this comment, it is just for the bots to refresh their caches and re-evaluate this PR

[mlbridge]

Webrevs

• 09: Full - Incremental (a207b81)
• 08: Full (5dc43be)
• 07: Full (10e48d5)
• 06: Full (09abbb9)
• 06: Full (09abbb9)
• 05: Full (f7c3e52)
• 05: Full (0418566)
• 04: Full (4bb163b)
• 03: Full (c78ce94)
• 02: Full (c35788f)
• 01: Full (9782c75)
• 00: Full (caaa7e7)

[thegreystone]

First quick review. Will take a closer look as soon as I can find some more time.

[thegreystone]

All copyrights need to have 2020 added now, like so:

• Copyright (c) 2019, 2020, Oracle and/or its affiliates. All rights reserved.

Happy New Year! :)

[thegreystone]

Please ensure that the code is formatted with the Mission Control formatting settings. The agent isn't taking part in the automated formatting checks yet.

[thegreystone]

It's fine. I'll accept this, and open a new issue for getting the agent built, and the formatting applied, as part of the check in tests. Thanks for the contribution!

[openjdk]

@tabjy This change now passes all automated pre-integration checks. When the change also fulfills all project specific requirements, type /integrate in a new comment to proceed. After integration, the commit message will be:

6656: Allow capturing field values with path syntax

Reviewed-by: hirt

• If you would like to add a summary, use the /summary command.
• To credit additional contributors, use the /contributor command.
• To add additional solved issues, use the /solves command.

Since the source branch of this PR was last updated there have been 14 commits pushed to the master branch. Since there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid automatic rebasing, please merge master into your branch, and then specify the current head hash when integrating, like this: /integrate 7731ae960af49e9933a3adb15f1e270dd78aa143.

As you do not have Committer status in this project, an existing Committer must agree to sponsor your change. Possible candidates are the reviewers of this PR (@thegreystone) but any other Committer may sponsor as well.

➡️ To flag this PR as ready for integration with the above commit message, type /integrate in a new comment. (Afterwards, your sponsor types /sponsor in a new comment to perform the integration).

[tabjy]

/integrate

[openjdk]

@tabjy
Your change (at version a207b81) is now ready to be sponsored by a Committer.

[thegreystone]

/sponsor

[openjdk]

@thegreystone @tabjy The following commits have been pushed to master since your change was applied:

• 7731ae9: 6694: JDK8 RCP launch configurations should set -XX:+IgnoreUnrecognizedVMOptions
• ef91b05: 6693: Eclipse projects core/org.openjdk.jmc.jdp* should have the correct JRE target level
• ec4630f: 6687: Add icon to the flame view to render as icicle graph
• eb59321: 6684: Adding CONTRIBUTING.md file
• 490f619: 6677: Search to highlight cells in the flame view
• ef7f807: 6688: Adding project file for the 2019-12 platform
• 7485fad: 6686: Adding FAQ to wiki/readme
• c85d31b: 6685: Parse more fields directly to primitive values
• 6dd19dd: 6674: Optimize finding of first start time and first & last end times
• 875abcd: 6670: Harmonize ~ Unclassifiable ~ across Flame View and Stacktrace View
• 2dd271f: 6572: Make mbean functions protected by permission checks
• 1676ecc: 6673: Upgrading to Tycho 1.6.0
• e647a9d: 6661: Simplify Agent JMX tests
• c2134e2: 6672: JavaScript formatting template

Your commit was automatically rebased without conflicts.

Pushed as commit 689812b.

[mlbridge]

Mailing list message from Marcus Hirt on jmc-dev:

Changeset: 689812b
Author: Kangcheng Xu <kxu at openjdk.org>
Committer: Marcus Hirt <hirt at openjdk.org>
Date: 2020-02-13 15:37:19 +0000
URL: https://git.openjdk.java.net/jmc/commit/689812b0

6656: Allow capturing field values with path syntax

Reviewed-by: hirt

+ core/org.openjdk.jmc.agent/src/main/java/org/openjdk/jmc/agent/Attribute.java
+ core/org.openjdk.jmc.agent/src/main/java/org/openjdk/jmc/agent/Field.java
! core/org.openjdk.jmc.agent/src/main/java/org/openjdk/jmc/agent/Parameter.java
! core/org.openjdk.jmc.agent/src/main/java/org/openjdk/jmc/agent/ReturnValue.java
! core/org.openjdk.jmc.agent/src/main/java/org/openjdk/jmc/agent/TransformDescriptor.java
! core/org.openjdk.jmc.agent/src/main/java/org/openjdk/jmc/agent/Transformer.java
! core/org.openjdk.jmc.agent/src/main/java/org/openjdk/jmc/agent/impl/DefaultTransformRegistry.java
! core/org.openjdk.jmc.agent/src/main/java/org/openjdk/jmc/agent/jfr/JFRTransformDescriptor.java
! core/org.openjdk.jmc.agent/src/main/java/org/openjdk/jmc/agent/jfr/impl/JFRClassVisitor.java
! core/org.openjdk.jmc.agent/src/main/java/org/openjdk/jmc/agent/jfr/impl/JFREventClassGenerator.java
! core/org.openjdk.jmc.agent/src/main/java/org/openjdk/jmc/agent/jfr/impl/JFRMethodAdvisor.java
! core/org.openjdk.jmc.agent/src/main/java/org/openjdk/jmc/agent/jfrnext/impl/JFRNextClassVisitor.java
! core/org.openjdk.jmc.agent/src/main/java/org/openjdk/jmc/agent/jfrnext/impl/JFRNextEventClassGenerator.java
! core/org.openjdk.jmc.agent/src/main/java/org/openjdk/jmc/agent/jfrnext/impl/JFRNextMethodAdvisor.java
+ core/org.openjdk.jmc.agent/src/main/java/org/openjdk/jmc/agent/util/AccessUtils.java
+ core/org.openjdk.jmc.agent/src/main/java/org/openjdk/jmc/agent/util/InspectionClassLoader.java
! core/org.openjdk.jmc.agent/src/main/java/org/openjdk/jmc/agent/util/TypeUtils.java
+ core/org.openjdk.jmc.agent/src/main/java/org/openjdk/jmc/agent/util/expression/ExpressionResolver.java
+ core/org.openjdk.jmc.agent/src/main/java/org/openjdk/jmc/agent/util/expression/IllegalSyntaxException.java
+ core/org.openjdk.jmc.agent/src/main/java/org/openjdk/jmc/agent/util/expression/ReferenceChain.java
+ core/org.openjdk.jmc.agent/src/main/java/org/openjdk/jmc/agent/util/expression/ReferenceChainElement.java
! core/org.openjdk.jmc.agent/src/test/java/org/openjdk/jmc/agent/test/InstrumentMe.java
! core/org.openjdk.jmc.agent/src/test/java/org/openjdk/jmc/agent/test/TestDefineEventProbes.java
! core/org.openjdk.jmc.agent/src/test/resources/org/openjdk/jmc/agent/test/jfrprobes_template.xml