[BROOKLYN-406] Coercion using fromMap(map) - exception thrown away, and value not coerced

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.11.0
• Assignee: Unassigned
• Reporter: Aled Sage
• Created: 03/Dec/16 11:06
• Updated: 10/Jan/17 12:52
• Resolved: 10/Jan/17 12:52

Description

We had a ConfigKey<List<VolumeOptions>>, and were setting that in YAML using a map. We expected VolumeOptions.fromMap(map) to be called as part of getConfig(VOLUMES, val). This does indeed happen.

However, if VolumeOptions.fromMap(map) throws an exception (e.g. because the input data was malformed), it does not report any problems and instead the getConfig just returns a list containing uncoerced map objects. As a result, we subsequently got a ClassCastException in our entity code.

This was extremely hard to figure out - it involved attaching a debugger, breakpointing and stepping through the coercion code.

—
Digging into the underlying cause, the problem is in this stacktrace:

"brooklyn-execmanager-PRYA08PS-104" daemon prio=5 tid=0x00007f82096c7000 nid=0x14f0b runnable [0x0000700005eac000]
   java.lang.Thread.State: RUNNABLE
        at org.apache.brooklyn.util.javalang.coerce.TypeCoercerExtensible.tryCoerceWithFromMethod(TypeCoercerExtensible.java:204)
        at org.apache.brooklyn.util.javalang.coerce.TypeCoercerExtensible.tryCoerceInternal(TypeCoercerExtensible.java:135)
        at org.apache.brooklyn.util.javalang.coerce.TypeCoercerExtensible.tryCoerce(TypeCoercerExtensible.java:107)
        at org.apache.brooklyn.util.javalang.coerce.TypeCoercerExtensible.tryCoerceCollection(TypeCoercerExtensible.java:263)
        at org.apache.brooklyn.util.javalang.coerce.TypeCoercerExtensible.tryCoerceInternal(TypeCoercerExtensible.java:121)
        at org.apache.brooklyn.util.javalang.coerce.TypeCoercerExtensible.tryCoerce(TypeCoercerExtensible.java:107)
        at org.apache.brooklyn.util.javalang.coerce.TypeCoercerExtensible.coerce(TypeCoercerExtensible.java:97)
        at org.apache.brooklyn.util.core.flags.TypeCoercions.coerce(TypeCoercions.java:80)
        at org.apache.brooklyn.util.core.config.ConfigBag.coerceFirstNonNullKeyValue(ConfigBag.java:502)
        at org.apache.brooklyn.util.core.config.ConfigBag.get(ConfigBag.java:496)
        at org.apache.brooklyn.util.core.config.ConfigBag.get(ConfigBag.java:344)

The TypeCoercerExtensible.tryCoerceWithFromMethod accidentally throws away the exception! It is therefore treated as though there was no applicable coercion. However, because List<Map> can be cast to List then it returns it anyway.

Issue Links

• links to: GitHub Pull Request #477