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xlog_page_header.go
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xlog_page_header.go
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package walparser
const (
// info flags
/* When record crosses page boundary, set this flag in new page's header */
XlpFirstIsContRecord = 0x0001
/* This flag indicates a "long" page header */
XlpLongHeader = 0x0002
/* This flag indicates backup blocks starting in this page are optional */
XlpBkpRemovable = 0x0004
/* All defined flag bits in xlp_info (used for validity checking of header) */
XlpAllFlags = 0x0007
)
/* This struct corresponds to postgres struct XLogPageHeaderData.
* For clarification you can find it in postgres:
* src/include/access/xlog_internal.h
*/
type XLogPageHeader struct {
Magic uint16
Info uint16
TimeLineID TimeLineID
PageAddress XLogRecordPtr
RemainingDataLen uint32
}
func (pageHeader *XLogPageHeader) IsLong() bool {
return (pageHeader.Info & XlpLongHeader) != 0
}
func (pageHeader *XLogPageHeader) HasContinuationRecord() bool {
return (pageHeader.Info & XlpFirstIsContRecord) != 0
}
func (pageHeader *XLogPageHeader) IsValid() bool {
return pageHeader.hasValidFlags() &&
pageHeader.hasConsistentRemainingDataLen()
}
func (pageHeader *XLogPageHeader) isZero() bool {
return pageHeader.Magic == 0 &&
pageHeader.Info == 0 &&
pageHeader.TimeLineID == 0 &&
pageHeader.PageAddress == 0 &&
pageHeader.RemainingDataLen == 0
}
func (pageHeader *XLogPageHeader) hasValidFlags() bool {
return (pageHeader.Info &^ XlpAllFlags) == 0
}
func (pageHeader *XLogPageHeader) hasConsistentRemainingDataLen() bool {
if pageHeader.HasContinuationRecord() {
if pageHeader.RemainingDataLen == 0 {
return false
}
} else {
if pageHeader.RemainingDataLen != 0 {
return false
}
}
return true
}