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This article will explain in detail what is the use of the LogEvent class in ceph. Xiaobian thinks it is quite practical, so share it with you as a reference. I hope you can gain something after reading this article.

LogEvent class description: (LogEvent class is the parent of all MDS Event classes)

class LogEvent {

EventType _type; Records the event type to which LogEvent belongs

uint64_t _start_off; Record the start position of LogEvent

utime_t stamp; Event stamp that records LogEvent

LogSegment *_segment; records a list of all LogSegments contained in a LogEvent

...

};

LogEvent class methods:

LogEvent::encode_with_header() serializes the LogEvent class object with header information as follows:

EVENT_NEW_ENCODING

1

_type

bufferlist

LogEvent::decode(bl) Parses serialized data streams to LogEvent class objects. Refer to encode_with_header() method

|__Parse type from bufferlist first

|__If type= EVENT_NEW_ENCODING indicates encode_with_header() function is used when encoding

|__Parses as encode_with_header()

|__decode_event()

|__if type!= EVENT_NEW_ENCODING

|__decode_event()

LogEvent::decode_event(bl, p, type)

|__Create different class objects according to the value of type ESubtreeMap/EExport/EImportStart/EImportFinish/EFragment/EResetJournal/ESession/EUpdate/ESlaveUpdate/EAssigned/ETableClient/ETableServer/ENoOp

|__Executes the decode() function of the created class object to parse bufferlist to class object, i.e.: le->decode(p)

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