8370175: State engine terminates when throwing self-caused exception

[sormuras]

Please review this change to prevent an engine termination in jshell in a self-causation exception scenario.

Prior to the fix, a non-null cause exception was unconditionally converted and used. Now, a set with identity equalitiy semantics is guarding the process, by breaking a recursive chains when a reference cycle is detected. The guard implementation is inspired by the one used in java.base/java.lang.Throwable

Note that a direct self-causation state is already prevented at the Throwable::initCause method level:

jshell> var t = new Throwable() t ==> java.lang.Throwable jshell> t.initCause(t) | Exception java.lang.IllegalArgumentException: Self-causation not permitted | at Throwable.initCause (Throwable.java:492) | at (#8:1) | Caused by: java.lang.Throwable | at do_it$Aux (#7:1) | at (#7:1) 

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Progress

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Issue

• JDK-8370175: State engine terminates when throwing self-caused exception (Bug - P4)

Reviewers

• Jan Lahoda (@lahodaj - Reviewer)
• Francesco Andreuzzi (@fandreuz - Author)

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@sormuras This change now passes all automated pre-integration checks.

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8370175: State engine terminates when throwing self-caused exception Reviewed-by: jlahoda, fandreuzzi 

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At the time when this comment was updated there had been 22 new commits pushed to the master branch:

• 20bcf0e: 6400876: (bf) Remove sun.nio.ByteBuffered and related obsolete code
• c97d50d: 8369508: Type annotations on anonymous new class creation expressions can't be retrieved
• 0687f12: 8368199: Add @AOTSafeClassInitializer to jdk.internal.access.SharedSecrets
• ... and 19 more: https://git.openjdk.org/jdk/compare/d5ce66698d2f15c5f8316110a6118a10baa4013d...master

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[mlbridge]

Webrevs

• 00: Full (6fc81a31)

[lahodaj]

Looks reasonable to me.

[pavelrappo]

As a reporter, thanks for taking care of this. One note is that Throwable.printStackTrace also takes care of cycles in suppressed trees. JShell does not seem to print suppressed exceptions, but if it ever does, we will need to treat them the same way.

jshell> var e1 = new Error(); ...> var e2 = new Error(); ...> e1.addSuppressed(e2); ...> e2.addSuppressed(e1); ...> e1.printStackTrace(); e1 ==> java.lang.Error e2 ==> java.lang.Error java.lang.Error	at REPL.$JShell$2.do_it$Aux($JShell$2.java:6)	at REPL.$JShell$2.do_it$($JShell$2.java:11)	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)	at java.base/java.lang.reflect.Method.invoke(Method.java:565)	at jdk.jshell/jdk.jshell.execution.DirectExecutionControl.invoke(DirectExecutionControl.java:227)	at jdk.jshell/jdk.jshell.execution.RemoteExecutionControl.invoke(RemoteExecutionControl.java:121)	at jdk.jshell/jdk.jshell.execution.DirectExecutionControl.invoke(DirectExecutionControl.java:125)	at jdk.jshell/jdk.jshell.execution.ExecutionControlForwarder.processCommand(ExecutionControlForwarder.java:148)	at jdk.jshell/jdk.jshell.execution.ExecutionControlForwarder.commandLoop(ExecutionControlForwarder.java:266)	at jdk.jshell/jdk.jshell.execution.Util.forwardExecutionControl(Util.java:78)	at jdk.jshell/jdk.jshell.execution.Util.forwardExecutionControlAndIO(Util.java:148)	at jdk.jshell/jdk.jshell.execution.RemoteExecutionControl.main(RemoteExecutionControl.java:74)	Suppressed: java.lang.Error	at REPL.$JShell$3.do_it$Aux($JShell$3.java:6)	at REPL.$JShell$3.do_it$($JShell$3.java:11)	... 10 more	Suppressed: [CIRCULAR REFERENCE: java.lang.Error] jshell> throw e1 | Exception java.lang.Error | at do_it$Aux (#1:1) | at (#1:1) 

Btw, why doesn't JShell print suppressed exceptions? Seems helpful in try-with-resources blocks.

[sormuras]

As a reporter, thanks for taking care of this.

Welcome, Pavel!

[...]
Btw, why doesn't JShell print suppressed exceptions? Seems helpful in try-with-resources blocks.

Should be discussed in a dedicated JBS issue or thread on the appropriated mailing list. As kulla-dev is archived, please send a mail to compiler-dev instead.