Aled Sage created BROOKLYN-406:
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Summary: Coercion using fromMap(map) - exception thrown away, and
value not coerced
Key: BROOKLYN-406
URL: https://issues.apache.org/jira/browse/BROOKLYN-406
Project: Brooklyn
Issue Type: Bug
Reporter: Aled Sage
Fix For: 0.9.0
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.
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Digging into the underlying cause, the problem is in this stacktrace:
{noformat}
"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)
{noformat}
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.
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