go/sqlite3
1
0
Fork 0
mirror of https://github.com/ncruces/go-sqlite3.git synced 2026-01-11 21:49:13 +00:00
Code Issues Packages Projects Releases Wiki Activity

Bulk copies.

Browse Source
This commit is contained in:
Nuno Cruces
2025-11-24 13:42:12 +00:00
parent 0286e50e25
commit e6b2d2aef5
1 changed files with 64 additions and 29 deletions
Download Patch File Download Diff File Expand all files Collapse all files

89
vfs/shm_copy.go
View File

@@ -35,38 +35,44 @@ func (s *vfsShm) shmAcquire(errp *error) {
if errp != nil && *errp != nil {
return
}
if len(s.ptrs) == 0 || shmEqual(s.shadow[0][:], s.shared[0][:]) {
if len(s.ptrs) == 0 {
return
}
// Copies modified words from shared to private memory.
for id, p := range s.ptrs {
shared := shmPage(s.shared[id][:])
shadow := shmPage(s.shadow[id][:])
privat := shmPage(util.View(s.mod, p, _WALINDEX_PGSZ))
for i, shared := range shared {
if shadow[i] != shared {
shadow[i] = shared
privat[i] = shared
}
if !shmCopyHeader(
util.View(s.mod, s.ptrs[0], _WALINDEX_HDR_SIZE),
s.shadow[0][:],
s.shared[0][:]) {
return
}
skip := _WALINDEX_HDR_SIZE
for id := range s.ptrs {
shmCopyTables(
util.View(s.mod, s.ptrs[id], _WALINDEX_PGSZ)[skip:],
s.shadow[id][skip:],
s.shared[id][skip:])
skip = 0
}
}
func (s *vfsShm) shmRelease() {
if len(s.ptrs) == 0 || shmEqual(s.shadow[0][:], util.View(s.mod, s.ptrs[0], _WALINDEX_HDR_SIZE)) {
if len(s.ptrs) == 0 {
return
}
// Copies modified words from private to shared memory.
for id, p := range s.ptrs {
shared := shmPage(s.shared[id][:])
shadow := shmPage(s.shadow[id][:])
privat := shmPage(util.View(s.mod, p, _WALINDEX_PGSZ))
for i, privat := range privat {
if shadow[i] != privat {
shadow[i] = privat
shared[i] = privat
}
if !shmCopyHeader(
s.shared[0][:],
s.shadow[0][:],
util.View(s.mod, s.ptrs[0], _WALINDEX_HDR_SIZE)) {
return
}
skip := _WALINDEX_HDR_SIZE
for id := range s.ptrs {
shmCopyTables(
s.shared[id][skip:],
s.shadow[id][skip:],
util.View(s.mod, s.ptrs[id], _WALINDEX_PGSZ)[skip:])
skip = 0
}
}
@@ -77,11 +83,40 @@ func (s *vfsShm) shmBarrier() {
s.Unlock()
}
func shmPage(s []byte) *[_WALINDEX_PGSZ / 4]uint32 {
p := (*uint32)(unsafe.Pointer(unsafe.SliceData(s)))
return (*[_WALINDEX_PGSZ / 4]uint32)(unsafe.Slice(p, _WALINDEX_PGSZ/4))
func shmCopyTables(v1, v2, v3 []byte) {
if string(v2) != string(v3) {
copy(v1, v3)
copy(v2, v3)
}
}
func shmEqual(v1, v2 []byte) bool {
return *(*[_WALINDEX_HDR_SIZE]byte)(v1[:]) == *(*[_WALINDEX_HDR_SIZE]byte)(v2[:])
func shmCopyHeader(s1, s2, s3 []byte) (ret bool) {
// First copy of the WAL Index Information.
if string(s2[:48]) != string(s3[:48]) {
copy(s1, s3[:48])
copy(s2, s3[:48])
ret = true
}
// Second copy of the WAL Index Information.
if string(s2[48:][:48]) != string(s3[48:][:48]) {
copy(s1[48:], s3[48:][:48])
copy(s2[48:], s3[48:][:48])
ret = true
}
// Checkpoint Information and Locks.
i1 := shmCheckpointInfo(s1)
i2 := shmCheckpointInfo(s2)
for i, i3 := range shmCheckpointInfo(s3) {
if i2[i] != i3 {
i1[i] = i3
i2[i] = i3
ret = true
}
}
return
}
func shmCheckpointInfo(s []byte) *[10]uint32 {
p := (*uint32)(unsafe.Pointer(&s[96]))
return (*[10]uint32)(unsafe.Slice(p, 10))
}