Marshalling log messages by json-file and local drivers involved
serializing the message into a shared buffer. This caused a regression
resulting in log corruption with recent changes where Log may be called
from multiple goroutines at the same time.
Solution is to use a sync.Pool to manage the buffers used for the
serialization. Also removed the MarshalFunc, which the driver had to
expose to the LogFile so that it can marshal the message. This is now
moved entirely to the driver.
Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>
Before this change, if Decode() couldn't read a log record fully,
the subsequent invocation of Decode() would read the record's non-header part
as a header and cause a huge heap allocation.
This change prevents such a case by having the intermediate buffer in
the decoder struct.
Fixes#42125.
Signed-off-by: Kazuyoshi Kato <katokazu@amazon.com>
