I've been reading the map internals in Go and came across into following structure in source code:
https://github.com/golang/go/blob/master/src/runtime/map.go#L150 // A bucket for a Go map. type bmap struct { // tophash generally contains the top byte of the hash value // for each key in this bucket. If tophash[0] < minTopHash, // tophash[0] is a bucket evacuation state instead. tophash [bucketCnt]uint8 // Followed by bucketCnt keys and then bucketCnt elems. // NOTE: packing all the keys together and then all the elems together makes the // code a bit more complicated than alternating key/elem/key/elem/... but it allows // us to eliminate padding which would be needed for, e.g., map[int64]int8. // Followed by an overflow pointer. } But if you scroll down the file and see the usage of this structure, actually it has the following structure: // NOT REAL type bmap struct { topbits [8]uint8 keys [8]keytype values [8]valuetype pad uintptr overflow uintptr } I can't find out the place in the source code where this structure is extended. In order to access those extra fields, authors do some pointer arithmetics: - https://github.com/golang/go/blob/master/src/runtime/map.go#L445 - https://github.com/golang/go/blob/master/src/runtime/map.go#L501 But in order to access those memory points, they needs to be allocated. Where does the allocation happen ? -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/08373fea-4e2b-4672-bc29-79825a1d3177n%40googlegroups.com.
