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Experimental file control opcode for write transaction (#339)

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Nuno Cruces
2025-11-21 12:48:31 +00:00
committed by GitHub
parent 8ac10eb8b4
commit 0286e50e25
3 changed files with 18 additions and 4 deletions
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21
vfs/mvcc/mvcc.go
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@@ -90,6 +90,7 @@ type mvccFile struct {
data *wbt.Tree[int64, string]
lock vfs.LockLevel
readOnly bool
wrflag bool
}
var (
@@ -212,6 +213,14 @@ func (m *mvccFile) Truncate(size int64) error {
return nil
}
func (m *mvccFile) Pragma(name, value string) (string, error) {
// notest // https://sqlite.org/forum/forumpost/c4ca8e7f4a887aa4
if name == "experimental_pragma_20251114" {
m.wrflag = true
}
return "", sqlite3.NOTFOUND
}
func (m *mvccFile) Lock(lock vfs.LockLevel) error {
if m.lock >= lock {
return nil
@@ -225,7 +234,7 @@ func (m *mvccFile) Lock(lock vfs.LockLevel) error {
defer m.mtx.Unlock()
// Take a snapshot of the database.
if lock == vfs.LOCK_SHARED {
if lock == vfs.LOCK_SHARED && !m.wrflag {
m.data = m.mvccDB.data
m.lock = lock
return nil
@@ -244,7 +253,7 @@ func (m *mvccFile) Lock(lock vfs.LockLevel) error {
defer time.AfterFunc(time.Millisecond, m.waiter.Broadcast).Stop()
for m.owner != nil {
// Our snapshot is invalid.
if m.data != m.mvccDB.data {
if m.data != nil && m.data != m.mvccDB.data {
return sqlite3.BUSY_SNAPSHOT
}
if time.Since(before) > time.Millisecond {
@@ -253,11 +262,15 @@ func (m *mvccFile) Lock(lock vfs.LockLevel) error {
m.waiter.Wait()
}
}
// Our snapshot is invalid.
if m.data != m.mvccDB.data {
switch {
case m.data == nil:
m.data = m.mvccDB.data
case m.data != m.mvccDB.data:
// Our snapshot is invalid.
return sqlite3.BUSY_SNAPSHOT
}
// Take ownership.
m.wrflag = false
m.lock = lock
m.owner = m
return nil