Golang C.leveldb_free函數代碼示例

// GetApproximateSizes returns the approximate number of bytes of file system
// space used by one or more key ranges.
//
// The keys counted will begin at Range.Start and end on the key before
// Range.Limit.
func (db *DB) GetApproximateSizes(ranges []Range) []uint64 {
	starts := make([]*C.char, len(ranges))
	limits := make([]*C.char, len(ranges))
	startLens := make([]C.size_t, len(ranges))
	limitLens := make([]C.size_t, len(ranges))
	for i, r := range ranges {
		starts[i] = C.CString(string(r.Start))
		startLens[i] = C.size_t(len(r.Start))
		limits[i] = C.CString(string(r.Limit))
		limitLens[i] = C.size_t(len(r.Limit))
	}
	sizes := make([]uint64, len(ranges))
	numranges := C.int(len(ranges))
	startsPtr := &starts[0]
	limitsPtr := &limits[0]
	startLensPtr := &startLens[0]
	limitLensPtr := &limitLens[0]
	sizesPtr := (*C.uint64_t)(&sizes[0])
	C.go_leveldb_approximate_sizes(
		db.Ldb, numranges, startsPtr, startLensPtr,
		limitsPtr, limitLensPtr, sizesPtr)
	for i := range ranges {
		C.leveldb_free(unsafe.Pointer(starts[i]))
		C.leveldb_free(unsafe.Pointer(limits[i]))
	}
	return sizes
}

// DestroyDatabase removes a database entirely, removing everything from the
// filesystem.
func DestroyDatabase(dbname string, o *Options) error {
	var errStr *C.char
	ldbname := C.CString(dbname)
	defer C.leveldb_free(unsafe.Pointer(ldbname))

	C.leveldb_destroy_db(o.Opt, ldbname, &errStr)
	if errStr != nil {
		gs := C.GoString(errStr)
		C.leveldb_free(unsafe.Pointer(errStr))
		return DatabaseError(gs)
	}
	return nil
}

// Open opens a database.
//
// Creating a new database is done by calling SetCreateIfMissing(true) on the
// Options passed to Open.
//
// It is usually wise to set a Cache object on the Options with SetCache to
// keep recently used data from that database in memory.
func Open(dbname string, o *Options) (*DB, error) {
	var errStr *C.char
	ldbname := C.CString(dbname)
	defer C.leveldb_free(unsafe.Pointer(ldbname))

	leveldb := C.leveldb_open(o.Opt, ldbname, &errStr)
	if errStr != nil {
		gs := C.GoString(errStr)
		C.leveldb_free(unsafe.Pointer(errStr))
		return nil, DatabaseError(gs)
	}
	return &DB{leveldb}, nil
}

// Put writes data associated with a key to the database.
//
// If a nil []byte is passed in as value, it will be returned by Get
// as an zero-length slice. The WriteOptions passed in can be reused
// by multiple calls to this and if the WriteOptions is left unchanged.
//
// The key and value byte slices may be reused safely. Put takes a copy of
// them before returning.
func (db *DB) Put(wo *WriteOptions, key, value []byte) error {
	var errStr *C.char
	// leveldb_put, _get, and _delete call memcpy() (by way of Memtable::Add)
	// when called, so we do not need to worry about these []byte being
	// reclaimed by GC.
	var k, v *C.char
	if len(key) != 0 {
		k = (*C.char)(unsafe.Pointer(&key[0]))
	}
	if len(value) != 0 {
		v = (*C.char)(unsafe.Pointer(&value[0]))
	}

	lenk := len(key)
	lenv := len(value)
	C.leveldb_put(
		db.Ldb, wo.Opt, k, C.size_t(lenk), v, C.size_t(lenv), &errStr)

	if errStr != nil {
		gs := C.GoString(errStr)
		C.leveldb_free(unsafe.Pointer(errStr))
		return DatabaseError(gs)
	}
	return nil
}

func saveError(errStr *C.char) error {
	if errStr != nil {
		gs := C.GoString(errStr)
		C.leveldb_free(unsafe.Pointer(errStr))
		return fmt.Errorf(gs)
	}
	return nil
}

func (db *LevelDB) Delete(key string) (err error) {
	opt := C.leveldb_writeoptions_create() // write option
	defer C.leveldb_free(unsafe.Pointer(opt))

	k := C.CString(key) // copy
	defer C.leveldb_free(unsafe.Pointer(k))

	var cerr *C.char
	C.leveldb_delete(db.CLevelDB, opt, k, C.size_t(len(key)), &cerr)

	if cerr != nil {
		defer C.leveldb_free(unsafe.Pointer(cerr))
		return errors.New(C.GoString(cerr))
	}

	return
}

// Write atomically writes a WriteBatch to disk. The WriteOptions
// passed in can be reused by multiple calls to this and other methods.
func (db *DB) Write(wo *WriteOptions, w *WriteBatch) error {
	var errStr *C.char
	C.leveldb_write(db.Ldb, wo.Opt, w.wbatch, &errStr)
	if errStr != nil {
		gs := C.GoString(errStr)
		C.leveldb_free(unsafe.Pointer(errStr))
		return DatabaseError(gs)
	}
	return nil
}

// GetError returns an IteratorError from LevelDB if it had one during
// iteration.
//
// This method is safe to call when Valid returns false.
func (it *Iterator) GetError() error {
	var errStr *C.char
	C.leveldb_iter_get_error(it.Iter, &errStr)
	if errStr != nil {
		gs := C.GoString(errStr)
		C.leveldb_free(unsafe.Pointer(errStr))
		return IteratorError(gs)
	}
	return nil
}

// Open LevelDB with given name
func OpenLevelDB(path string) (leveldb *LevelDB, err error) {

	cpath := C.CString(path) // convert path to c string
	defer C.leveldb_free(unsafe.Pointer(cpath))

	// allocate LevelDB Option struct to open
	opt := C.leveldb_options_create()
	defer C.leveldb_free(unsafe.Pointer(opt))

	// set open option
	C.leveldb_options_set_create_if_missing(opt, C.uchar(1))

	// open leveldb
	var cerr *C.char
	cleveldb := C.leveldb_open(opt, cpath, &cerr)

	if cerr != nil {
		defer C.leveldb_free(unsafe.Pointer(cerr))
		return nil, errors.New(C.GoString(cerr))
	}

	return &LevelDB{cleveldb, path}, nil
}

func (db *DB) open() error {
	db.initOptions(db.cfg)

	var errStr *C.char
	ldbname := C.CString(db.path)
	defer C.leveldb_free(unsafe.Pointer(ldbname))

	db.db = C.leveldb_open(db.opts.Opt, ldbname, &errStr)
	if errStr != nil {
		db.db = nil
		return saveError(errStr)
	}
	return nil
}

// Get returns the data associated with the key from the database.
//
// If the key does not exist in the database, a nil []byte is returned. If the
// key does exist, but the data is zero-length in the database, a zero-length
// []byte will be returned.
//
// The key byte slice may be reused safely. Get takes a copy of
// them before returning.
func (db *DB) Get(ro *ReadOptions, key []byte) ([]byte, error) {
	var errStr *C.char
	var vallen C.size_t
	var k *C.char
	if len(key) != 0 {
		k = (*C.char)(unsafe.Pointer(&key[0]))
	}

	value := C.leveldb_get(
		db.Ldb, ro.Opt, k, C.size_t(len(key)), &vallen, &errStr)

	if errStr != nil {
		gs := C.GoString(errStr)
		C.leveldb_free(unsafe.Pointer(errStr))
		return nil, DatabaseError(gs)
	}

	if value == nil {
		return nil, nil
	}

	defer C.leveldb_free(unsafe.Pointer(value))
	return C.GoBytes(unsafe.Pointer(value), C.int(vallen)), nil
}

func (db *LevelDB) Get(key string) (value string, err error) {

	opt := C.leveldb_readoptions_create() // write option
	defer C.leveldb_free(unsafe.Pointer(opt))

	k := C.CString(key) // copy
	defer C.leveldb_free(unsafe.Pointer(k))

	var vallen C.size_t
	var cerr *C.char
	cvalue := C.leveldb_get(db.CLevelDB, opt, k, C.size_t(len(key)), &vallen, &cerr)

	if cerr != nil {
		defer C.leveldb_free(unsafe.Pointer(cerr))
		return "", errors.New(C.GoString(cerr))
	}

	if cvalue == nil {
		return "", nil
	}

	defer C.leveldb_free(unsafe.Pointer(cvalue))
	return C.GoString(cvalue), nil
}

func Get(k *string) (v string, err error) {
	var v_len C.size_t

	key := C.CString(*k)
	defer C.free(unsafe.Pointer(key))

	val := C.get(key, C.size_t(len(*k)), &v_len)
	if val == nil {
		err = NotExist
		return
	}
	defer C.leveldb_free(unsafe.Pointer(val))

	v = C.GoStringN(val, C.int(v_len))
	return
}

// Delete removes the data associated with the key from the database.
//
// The key byte slice may be reused safely. Delete takes a copy of
// them before returning. The WriteOptions passed in can be reused by
// multiple calls to this and if the WriteOptions is left unchanged.
func (db *DB) Delete(wo *WriteOptions, key []byte) error {
	var errStr *C.char
	var k *C.char
	if len(key) != 0 {
		k = (*C.char)(unsafe.Pointer(&key[0]))
	}

	C.leveldb_delete(
		db.Ldb, wo.Opt, k, C.size_t(len(key)), &errStr)

	if errStr != nil {
		gs := C.GoString(errStr)
		C.leveldb_free(unsafe.Pointer(errStr))
		return DatabaseError(gs)
	}
	return nil
}

func (db *DB) Destroy() error {
	path := db.cfg.Path

	db.Close()

	opts := NewOptions()
	defer opts.Close()

	var errStr *C.char
	ldbname := C.CString(path)
	defer C.leveldb_free(unsafe.Pointer(ldbname))

	C.leveldb_destroy_db(opts.Opt, ldbname, &errStr)
	if errStr != nil {
		return saveError(errStr)
	}
	return nil
}