aboutsummaryrefslogtreecommitdiff
path: root/vendor/github.com/etcd-io/bbolt/freelist_hmap.go
diff options
context:
space:
mode:
Diffstat (limited to 'vendor/github.com/etcd-io/bbolt/freelist_hmap.go')
-rw-r--r--vendor/github.com/etcd-io/bbolt/freelist_hmap.go178
1 files changed, 178 insertions, 0 deletions
diff --git a/vendor/github.com/etcd-io/bbolt/freelist_hmap.go b/vendor/github.com/etcd-io/bbolt/freelist_hmap.go
new file mode 100644
index 000000000..6a03a6c3c
--- /dev/null
+++ b/vendor/github.com/etcd-io/bbolt/freelist_hmap.go
@@ -0,0 +1,178 @@
+package bbolt
+
+import "sort"
+
+// hashmapFreeCount returns count of free pages(hashmap version)
+func (f *freelist) hashmapFreeCount() int {
+ // use the forwardmap to get the total count
+ count := 0
+ for _, size := range f.forwardMap {
+ count += int(size)
+ }
+ return count
+}
+
+// hashmapAllocate serves the same purpose as arrayAllocate, but use hashmap as backend
+func (f *freelist) hashmapAllocate(txid txid, n int) pgid {
+ if n == 0 {
+ return 0
+ }
+
+ // if we have a exact size match just return short path
+ if bm, ok := f.freemaps[uint64(n)]; ok {
+ for pid := range bm {
+ // remove the span
+ f.delSpan(pid, uint64(n))
+
+ f.allocs[pid] = txid
+
+ for i := pgid(0); i < pgid(n); i++ {
+ delete(f.cache, pid+pgid(i))
+ }
+ return pid
+ }
+ }
+
+ // lookup the map to find larger span
+ for size, bm := range f.freemaps {
+ if size < uint64(n) {
+ continue
+ }
+
+ for pid := range bm {
+ // remove the initial
+ f.delSpan(pid, uint64(size))
+
+ f.allocs[pid] = txid
+
+ remain := size - uint64(n)
+
+ // add remain span
+ f.addSpan(pid+pgid(n), remain)
+
+ for i := pgid(0); i < pgid(n); i++ {
+ delete(f.cache, pid+pgid(i))
+ }
+ return pid
+ }
+ }
+
+ return 0
+}
+
+// hashmapReadIDs reads pgids as input an initial the freelist(hashmap version)
+func (f *freelist) hashmapReadIDs(pgids []pgid) {
+ f.init(pgids)
+
+ // Rebuild the page cache.
+ f.reindex()
+}
+
+// hashmapGetFreePageIDs returns the sorted free page ids
+func (f *freelist) hashmapGetFreePageIDs() []pgid {
+ count := f.free_count()
+ if count == 0 {
+ return nil
+ }
+
+ m := make([]pgid, 0, count)
+ for start, size := range f.forwardMap {
+ for i := 0; i < int(size); i++ {
+ m = append(m, start+pgid(i))
+ }
+ }
+ sort.Sort(pgids(m))
+
+ return m
+}
+
+// hashmapMergeSpans try to merge list of pages(represented by pgids) with existing spans
+func (f *freelist) hashmapMergeSpans(ids pgids) {
+ for _, id := range ids {
+ // try to see if we can merge and update
+ f.mergeWithExistingSpan(id)
+ }
+}
+
+// mergeWithExistingSpan merges pid to the existing free spans, try to merge it backward and forward
+func (f *freelist) mergeWithExistingSpan(pid pgid) {
+ prev := pid - 1
+ next := pid + 1
+
+ preSize, mergeWithPrev := f.backwardMap[prev]
+ nextSize, mergeWithNext := f.forwardMap[next]
+ newStart := pid
+ newSize := uint64(1)
+
+ if mergeWithPrev {
+ //merge with previous span
+ start := prev + 1 - pgid(preSize)
+ f.delSpan(start, preSize)
+
+ newStart -= pgid(preSize)
+ newSize += preSize
+ }
+
+ if mergeWithNext {
+ // merge with next span
+ f.delSpan(next, nextSize)
+ newSize += nextSize
+ }
+
+ f.addSpan(newStart, newSize)
+}
+
+func (f *freelist) addSpan(start pgid, size uint64) {
+ f.backwardMap[start-1+pgid(size)] = size
+ f.forwardMap[start] = size
+ if _, ok := f.freemaps[size]; !ok {
+ f.freemaps[size] = make(map[pgid]struct{})
+ }
+
+ f.freemaps[size][start] = struct{}{}
+}
+
+func (f *freelist) delSpan(start pgid, size uint64) {
+ delete(f.forwardMap, start)
+ delete(f.backwardMap, start+pgid(size-1))
+ delete(f.freemaps[size], start)
+ if len(f.freemaps[size]) == 0 {
+ delete(f.freemaps, size)
+ }
+}
+
+// initial from pgids using when use hashmap version
+// pgids must be sorted
+func (f *freelist) init(pgids []pgid) {
+ if len(pgids) == 0 {
+ return
+ }
+
+ size := uint64(1)
+ start := pgids[0]
+
+ if !sort.SliceIsSorted([]pgid(pgids), func(i, j int) bool { return pgids[i] < pgids[j] }) {
+ panic("pgids not sorted")
+ }
+
+ f.freemaps = make(map[uint64]pidSet)
+ f.forwardMap = make(map[pgid]uint64)
+ f.backwardMap = make(map[pgid]uint64)
+
+ for i := 1; i < len(pgids); i++ {
+ // continuous page
+ if pgids[i] == pgids[i-1]+1 {
+ size++
+ } else {
+ f.addSpan(start, size)
+
+ size = 1
+ start = pgids[i]
+ }
+ }
+
+ // init the tail
+ if size != 0 && start != 0 {
+ f.addSpan(start, size)
+ }
+}