forked from jmckaskill/gobdb
/
bdb.go
215 lines (176 loc) · 3.88 KB
/
bdb.go
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package bdb
import (
"fmt"
"runtime"
"sync"
"unsafe"
)
// #cgo LDFLAGS: -ldb
// #include <db.h>
// #include <stdlib.h>
// #include <fcntl.h>
//
// #if DB_VERSION_MAJOR+0 >= 3
// typedef struct {void* data; size_t size;} str;
// #define TNXID_ARG NULL,
// static DB* create(const char* path, int flags) {
// DB* db;
// int err = db_create(&db, NULL, 0);
// if (err) return NULL;
// err = db->open(db, NULL, path, NULL, DB_HASH, flags, 0666);
// if (err) {
// db->close(db, 0);
// return NULL;
// }
// return db;
// }
// static int db_close(DB* db) {
// return db->close(db, 0);
// }
//
// #else
// typedef DBT str;
// #define TNXID_ARG
// #define DB_CREATE (O_CREAT|O_RDWR)
// #define DB_RDONLY O_RDONLY
// #define DB_NOOVERWRITE R_NOOVERWRITE
// static DB* create(const char* path, int flags) {
// return dbopen(path, flags, 0666, DB_HASH, NULL);
// }
// static int db_close(DB* db) {
// return db->close(db);
// }
// #endif
//
// static int db_del(DB* db, str* key) {
// DBT k = {};
// k.data = key->data;
// k.size = key->size;
// return db->del(db, TNXID_ARG &k, 0);
// }
// static int db_get(DB* db, str* key, str* val) {
// int err;
// DBT k = {};
// DBT v = {};
// k.data = key->data;
// k.size = key->size;
// err = db->get(db, TNXID_ARG &k, &v, 0);
// if (err) return err;
// val->data = v.data;
// val->size = v.size;
// return 0;
// }
// static int db_put(DB* db, str* key, str* val, u_int flags) {
// DBT k = {};
// DBT v = {};
// k.data = key->data;
// k.size = key->size;
// v.data = val->data;
// v.size = val->size;
// return db->put(db, TNXID_ARG &k, &v, flags);
// }
// static int db_sync(DB* db) {
// return db->sync(db, 0);
// }
import "C"
type ErrKeyAlreadyExists string
type ErrKeyNotFound string
func (s ErrKeyAlreadyExists) Error() string {
return fmt.Sprintf("bdb: key '%s' already exists", string(s))
}
func (s ErrKeyNotFound) Error() string {
return fmt.Sprintf("bdb: key '%s' not found", string(s))
}
type DB struct {
db *C.DB
lk sync.Mutex
}
func Create(path string) (*DB, error) {
return create(path, C.DB_CREATE)
}
func Open(path string) (*DB, error) {
return create(path, C.DB_RDONLY)
}
func create(path string, flags int) (*DB, error) {
pstr := C.CString(path)
defer C.free(unsafe.Pointer(pstr))
db, err := C.create(pstr, C.int(flags))
if db == nil {
return nil, err
}
ret := &DB{db, sync.Mutex{}}
runtime.SetFinalizer(ret, destroy)
return ret, nil
}
func destroy(db *DB) {
db.Close()
}
func (db *DB) Close() error {
db.lk.Lock()
defer db.lk.Unlock()
if db.db == nil {
return nil
}
n, err := C.db_close(db.db)
db.db = nil
if n != 0 {
return err
}
return nil
}
func (db *DB) set(key, value []byte, flags int) error {
db.lk.Lock()
defer db.lk.Unlock()
k := C.str{unsafe.Pointer(&key[0]), C.size_t(len(key))}
v := C.str{unsafe.Pointer(&value[0]), C.size_t(len(value))}
n, err := C.db_put(db.db, &k, &v, C.u_int(flags))
switch {
case n < 0:
return err
case n > 0:
return ErrKeyAlreadyExists(string(key))
}
return nil
}
func (db *DB) Set(key, value []byte) error {
return db.set(key, value, 0)
}
func (db *DB) Add(key, value []byte) error {
return db.set(key, value, C.DB_NOOVERWRITE)
}
func (db *DB) Get(key []byte) ([]byte, error) {
db.lk.Lock()
defer db.lk.Unlock()
k := C.str{unsafe.Pointer(&key[0]), C.size_t(len(key))}
v := C.str{}
n, err := C.db_get(db.db, &k, &v)
switch {
case n < 0:
return []byte{}, err
case n > 0:
return []byte{}, ErrKeyNotFound(string(key))
}
return C.GoBytes(v.data, C.int(v.size)), nil
}
func (db *DB) Flush() error {
db.lk.Lock()
defer db.lk.Unlock()
n, err := C.db_sync(db.db)
if n < 0 {
return err
}
return nil
}
func (db *DB) Remove(key []byte) error {
db.lk.Lock()
defer db.lk.Unlock()
k := C.str{unsafe.Pointer(&key[0]), C.size_t(len(key))}
n, err := C.db_del(db.db, &k)
switch {
case n < 0:
return err
case n > 0:
return ErrKeyNotFound(string(key))
}
return nil
}