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Don't throw exceptions during DocumentField serialization #95673

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merged 4 commits into from
May 2, 2023
Merged

Don't throw exceptions during DocumentField serialization #95673

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7e3daf2
Don't throw exceptions during DocumentField serialization
romseygeek Apr 28, 2023
17323e1
spotless
romseygeek Apr 28, 2023
f40d158
rest compat
romseygeek Apr 28, 2023
e25980a
Merge branch 'main' into documentfield/xcontent-validation
elasticmachine May 2, 2023
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10 changes: 6 additions & 4 deletions server/src/main/java/org/elasticsearch/common/document/DocumentField.java
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Original file line number Diff line number Diff line change
Expand Up @@ -135,10 +135,12 @@ public ToXContentFragment getValidValuesWriter() {
return (builder, params) -> {
builder.startArray(name);
for (Object value : values) {
// This call doesn't really need to support writing any kind of object, since the values
// here are always serializable to xContent. Each value could be a leaf types like a string,
// number, or boolean, a list of such values, or a map of such values with string keys.
builder.value(value);
try {
builder.value(value);
} catch (RuntimeException e) {
// if the value cannot be serialized, we catch here and return a placeholder value
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@quux00 quux00 Apr 28, 2023 •
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Since we are catching a generic RuntimeException, we don't know if this was an intentional error (UnsupportedOperationException) or unintentional (NPE or other type of unexpected error, possibly indicating a code bug). Should we inspect the error and log it if it is not UnsupportedOperationException?

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We could make the placeholder value more explicit by including the exception message maybe? I'm not sure how frequent this issue actually is, or how useful an error message would be for something like a script field.

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I'd vote for logging to help find rare bugs and avoid "swallowing" unexpected errors, but I'm still ramping up on standard practices here and don't have much context on this issue yet :-)
But this is just optional feedback.

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Having thought about this, I think I'd like to leave it as it is for now - really the only useful information we could return here would be a stack trace, which isn't really very user friendly. It shouldn't be too difficult to reproduce a problem if it comes up as we will have the document source.

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this reminded me of Strings#toString, but there we catch IOException which is a checked exception. What are the exceptions that can happen in practice? I see that XContentBuilder#value may throw IllegalArgumentException. We could make the builder print out a more user-friendly error?

builder.value("<unserializable>");
}
}
builder.endArray();
return builder;
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10 changes: 10 additions & 0 deletions server/src/test/java/org/elasticsearch/index/get/DocumentFieldTests.java
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Expand Up @@ -43,6 +43,16 @@ public void testToXContent() {
assertEquals("{\"field\":[\"ignored1\",\"ignored2\"]}", ignoredOutput);
}

public void testUnserializableXContent() {
DocumentField df = new DocumentField(
"field",
List.of((ToXContent) (builder, params) -> { throw new UnsupportedOperationException(); })
);
String output = Strings.toString(df.getValidValuesWriter());
assertEquals("""
{"field":["<unserializable>"]}""", output);
}

public void testEqualsAndHashcode() {
checkEqualsAndHashCode(
randomDocumentField(XContentType.JSON).v1(),
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1 change: 1 addition & 0 deletions x-pack/plugin/build.gradle
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Expand Up @@ -154,6 +154,7 @@ tasks.named("yamlRestTestV7CompatTransform").configure { task ->
task.skipTest("sql/translate/Translate SQL", "query folding changed in v 8.5, added track_total_hits: -1")
task.skipTest("service_accounts/10_basic/Test get service accounts", "new service accounts are added")
task.skipTest("spatial/70_script_doc_values/diagonal length", "precision changed in 8.4.0")
task.skipTest("spatial/70_script_doc_values/geoshape value", "error message changed in 8.9.0")

task.replaceValueInMatch("_type", "_doc")
task.addAllowedWarningRegex("\\[types removal\\].*")
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13 changes: 7 additions & 6 deletions x-pack/plugin/src/yamlRestTest/resources/rest-api-spec/test/spatial/70_script_doc_values.yml
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Expand Up @@ -93,8 +93,11 @@ setup:

---
"geoshape value":
- skip:
version: " - 8.8.99"
reason: output changed in 8.9

- do:
catch: /illegal_argument_exception/
search:
rest_total_hits_as_int: true
body:
Expand All @@ -103,10 +106,9 @@ setup:
script:
source: "doc['geo_shape'].get(0)"

- match: { error.root_cause.0.reason: "cannot write xcontent for geo_shape doc value" }
- match: { hits.hits.0.fields.type.0: '<unserializable>' }

- do:
catch: /illegal_argument_exception/
search:
rest_total_hits_as_int: true
body:
Expand All @@ -115,10 +117,9 @@ setup:
script:
source: "field('geo_shape').get(null)"

- match: { error.root_cause.0.reason: "cannot write xcontent for geo_shape doc value" }
- match: { hits.hits.0.fields.type.0: '<unserializable>' }

- do:
catch: /illegal_argument_exception/
search:
rest_total_hits_as_int: true
body:
Expand All @@ -127,7 +128,7 @@ setup:
script:
source: "/* avoid yaml stash */ $('geo_shape', null)"

- match: { error.root_cause.0.reason: "cannot write xcontent for geo_shape doc value" }
- match: { hits.hits.0.fields.type.0: '<unserializable>' }

---
"diagonal length":
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