GODRIVER-3009 Fix concurrent panic in struct codec. #1477
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This reverts commit fc9fc3c.
prestonvasquez
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We need to add the following test case to TestRegistryBuilder/Register/Lookup:
{
"nil",
nil,
nil,
ErrNilType,
false,
},We might also add a test that captures the repro case in bson package:
func TestConcurrentEncoding(t *testing.T) {
t.Parallel()
wg := sync.WaitGroup{}
wg.Add(10_000)
for i := 0; i < 10_000; i++ {
go func() {
defer wg.Done()
Marshal(struct{ LastError error }{})
}()
}
wg.Wait()
}The latter might be caught by the race detector, but it couldn't hurt to have it around. What are your thoughts?
| @@ -388,6 +388,9 @@ func (r *Registry) RegisterTypeMapEntry(bt bsontype.Type, rt reflect.Type) { | |||
| // If no encoder is found, an error of type ErrNoEncoder is returned. LookupEncoder is safe for | |||
| // concurrent use by multiple goroutines after all codecs and encoders are registered. | |||
| func (r *Registry) LookupEncoder(valueType reflect.Type) (ValueEncoder, error) { | |||
| if valueType == nil { | |||
| return nil, ErrNoEncoder{Type: valueType} | |||
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The LookupEncoder and LookupDecoder return values should match when valueType is nil. I think it makes sense to return ErrNilType here rather than ErrNoEncoder
Suggested change
| return nil, ErrNoEncoder{Type: valueType} | |
| return nil, ErrNilType |
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I agree. However, it will be a breaking change. How do you think about filing a v2.0 ticket instead?
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The error message for ErrNilType is
"cannot perform a decoder lookup on <nil>"
We'll need to update the error message to make sense for either case.
prestonvasquez
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Nov 29, 2023
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Co-authored-by: Qingyang Hu <103950869+qingyang-hu@users.noreply.github.com>
matthewdale
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Co-authored-by: Qingyang Hu <103950869+qingyang-hu@users.noreply.github.com> (cherry picked from commit 3adad2b)
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GODRIVER-3009
Summary
Remove the unnecessary nil cache, so nil encoder/decoder will not be stored.
Background & Motivation
The original panic was:
from bson/bsoncodec/codec_cache.go:45
The root cause is at https://github.com/mongodb/mongo-go-driver/blob/master/bson/bsoncodec/struct_codec.go#L481