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|
//go:build (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !sqlite3_dotlk
package vfs
import (
"context"
"io"
"os"
"sync"
"syscall"
"time"
"github.com/tetratelabs/wazero/api"
"golang.org/x/sys/windows"
"github.com/ncruces/go-sqlite3/internal/util"
"github.com/ncruces/go-sqlite3/util/osutil"
)
type vfsShm struct {
*os.File
mod api.Module
alloc api.Function
free api.Function
path string
regions []*util.MappedRegion
shared [][]byte
shadow [][_WALINDEX_PGSZ]byte
ptrs []ptr_t
stack [1]stk_t
fileLock bool
blocking bool
sync.Mutex
}
var _ blockingSharedMemory = &vfsShm{}
func (s *vfsShm) Close() error {
// Unmap regions.
for _, r := range s.regions {
r.Unmap()
}
s.regions = nil
// Close the file.
return s.File.Close()
}
func (s *vfsShm) shmOpen() _ErrorCode {
if s.File == nil {
f, err := osutil.OpenFile(s.path,
os.O_RDWR|os.O_CREATE|syscall.O_NONBLOCK, 0666)
if err != nil {
return _CANTOPEN
}
s.File = f
}
if s.fileLock {
return _OK
}
// Dead man's switch.
if rc := osWriteLock(s.File, _SHM_DMS, 1, 0); rc == _OK {
err := s.Truncate(0)
osUnlock(s.File, _SHM_DMS, 1)
if err != nil {
return _IOERR_SHMOPEN
}
}
rc := osReadLock(s.File, _SHM_DMS, 1, time.Millisecond)
s.fileLock = rc == _OK
return rc
}
func (s *vfsShm) shmMap(ctx context.Context, mod api.Module, id, size int32, extend bool) (_ ptr_t, rc _ErrorCode) {
// Ensure size is a multiple of the OS page size.
if size != _WALINDEX_PGSZ || (windows.Getpagesize()-1)&_WALINDEX_PGSZ != 0 {
return 0, _IOERR_SHMMAP
}
if s.mod == nil {
s.mod = mod
s.free = mod.ExportedFunction("sqlite3_free")
s.alloc = mod.ExportedFunction("sqlite3_malloc64")
}
if rc := s.shmOpen(); rc != _OK {
return 0, rc
}
defer s.shmAcquire(&rc)
// Check if file is big enough.
o, err := s.Seek(0, io.SeekEnd)
if err != nil {
return 0, _IOERR_SHMSIZE
}
if n := (int64(id) + 1) * int64(size); n > o {
if !extend {
return 0, _OK
}
if osAllocate(s.File, n) != nil {
return 0, _IOERR_SHMSIZE
}
}
// Maps regions into memory.
for int(id) >= len(s.shared) {
r, err := util.MapRegion(ctx, mod, s.File, int64(id)*int64(size), size)
if err != nil {
return 0, _IOERR_SHMMAP
}
s.regions = append(s.regions, r)
s.shared = append(s.shared, r.Data)
}
// Allocate shadow memory.
if int(id) >= len(s.shadow) {
s.shadow = append(s.shadow, make([][_WALINDEX_PGSZ]byte, int(id)-len(s.shadow)+1)...)
}
// Allocate local memory.
for int(id) >= len(s.ptrs) {
s.stack[0] = stk_t(size)
if err := s.alloc.CallWithStack(ctx, s.stack[:]); err != nil {
panic(err)
}
if s.stack[0] == 0 {
panic(util.OOMErr)
}
clear(util.View(s.mod, ptr_t(s.stack[0]), _WALINDEX_PGSZ))
s.ptrs = append(s.ptrs, ptr_t(s.stack[0]))
}
s.shadow[0][4] = 1
return s.ptrs[id], _OK
}
func (s *vfsShm) shmLock(offset, n int32, flags _ShmFlag) (rc _ErrorCode) {
var timeout time.Duration
if s.blocking {
timeout = time.Millisecond
}
switch {
case flags&_SHM_LOCK != 0:
defer s.shmAcquire(&rc)
case flags&_SHM_EXCLUSIVE != 0:
s.shmRelease()
}
switch {
case flags&_SHM_UNLOCK != 0:
return osUnlock(s.File, _SHM_BASE+uint32(offset), uint32(n))
case flags&_SHM_SHARED != 0:
return osReadLock(s.File, _SHM_BASE+uint32(offset), uint32(n), timeout)
case flags&_SHM_EXCLUSIVE != 0:
return osWriteLock(s.File, _SHM_BASE+uint32(offset), uint32(n), timeout)
default:
panic(util.AssertErr())
}
}
func (s *vfsShm) shmUnmap(delete bool) {
if s.File == nil {
return
}
s.shmRelease()
// Free local memory.
for _, p := range s.ptrs {
s.stack[0] = stk_t(p)
if err := s.free.CallWithStack(context.Background(), s.stack[:]); err != nil {
panic(err)
}
}
s.ptrs = nil
s.shadow = nil
s.shared = nil
// Close the file.
s.Close()
s.File = nil
if delete {
os.Remove(s.path)
}
}
func (s *vfsShm) shmEnableBlocking(block bool) {
s.blocking = block
}
|
