Golang with rocksdb

[others...@gmail.com]

Hi,

  I am success to build rocksdb for golang windows.

  When i build project with import rocksdb, i got "gorocksdb(.text): rocksdb_backup_engine_close: not defined".

  I checked c.h/c.cc in rocksdb and fuction was there.

myEnv /cygdrive/c/mygo/src/gorocksdb

$ go install

myEnv /cygdrive/c/mygo/src/gorocksdb

$ go build

# _/C_/cygwin64/home/my/rocksdb/testRock

gorocksdb(.text): rocksdb_backup_engine_close: not defined

gorocksdb(.text): rocksdb_backup_engine_create_new_backup: not defined

gorocksdb(.text): rocksdb_backup_engine_get_backup_info: not defined

gorocksdb(.text): rocksdb_backup_engine_info_backup_id: not defined

gorocksdb(.text): rocksdb_backup_engine_info_count: not defined

gorocksdb(.text): rocksdb_backup_engine_info_destroy: not defined

gorocksdb(.text): rocksdb_backup_engine_info_number_files: not defined

gorocksdb(.text): rocksdb_backup_engine_info_size: not defined

gorocksdb(.text): rocksdb_backup_engine_info_timestamp: not defined

gorocksdb(.text): rocksdb_backup_engine_open: not defined

gorocksdb(.text): rocksdb_backup_engine_restore_db_from_latest_backup: not defined

gorocksdb(.text): rocksdb_restore_options_create: not defined

gorocksdb(.text): rocksdb_restore_options_destroy: not defined

gorocksdb(.text): rocksdb_restore_options_set_keep_log_files: not defined

gorocksdb(.text): rocksdb_cache_create_lru: not defined

gorocksdb(.text): rocksdb_cache_destroy: not defined

gorocksdb(.text): rocksdb_approximate_sizes: not defined

gorocksdb(.text): rocksdb_close: not defined

gorocksdb(.text): rocksdb_compact_range: not defined

gorocksdb(.text): rocksdb_create_iterator: not defined

gorocksdb(.text): rocksdb_create_snapshot: not defined

too many errors

Can you help me and how can i solve this?

Thanks,

[Ian Lance Taylor]

On Wed, Jun 17, 2015 at 12:52 PM, <others...@gmail.com> wrote:
>
> I am success to build rocksdb for golang windows.
> When i build project with import rocksdb, i got "gorocksdb(.text):
> rocksdb_backup_engine_close: not defined".
> I checked c.h/c.cc in rocksdb and fuction was there.
>
>
> myEnv /cygdrive/c/mygo/src/gorocksdb
> $ go install
>
> myEnv /cygdrive/c/mygo/src/gorocksdb
> $ go build
> # _/C_/cygwin64/home/my/rocksdb/testRock
> gorocksdb(.text): rocksdb_backup_engine_close: not defined

> Can you help me and how can i solve this?

I'm just guessing, but in the .go file that does import "C" you
probably need something like

#cgo LDFLAGS -lrocksdb

See http://golang.org/cmd/cgo for docs.

Ian

[others...@gmail.com]

Hi Ian,

  Thanks for quick response.

  Yes, I set "// #cgo LDFLAGS: -lrocksdb -lstdc++ -lm -lz -lbz2 -lsnappy" to .go file.

  It is issue when I import {/"github.com/tecbot/gorocksdb"} to other .go program.

//--------------------------------

package main

// #cgo LDFLAGS: -lrocksdb -lstdc++ -lm -lz -lbz2 -lsnappy 

import "C"

import (

                "fmt"

                "github.com/tecbot/gorocksdb" 

)

//----------------------------------------------------

Thanks,

Dong

[Dave Cheney]

Possibly related to your problem, you do not appear to have put your program inside $GOPATH/src. You can read about how to lay out our Go code here, http://golang.org/doc/code.html#Workspaces

[others...@gmail.com]

I tried to build new c lib and using import "C" and it work fine.

Now, i am trying to link to compiled rocksdb shared_lib  in cygwin but is is not success.

khoadong@DDKHLAP2 /cygdrive/c/mygo/src/gorocksdbTest

$ go build

# gorocksdbTest

gorocksdbTest(.text): rocksdb_destroy_db: not defined

gorocksdbTest(.text): rocksdb_options_create: not defined

gorocksdbTest(.text): rocksdb_options_set_create_if_missing: not defined

gorocksdbTest(.text): rocksdb_options_set_target_file_size_base: not defined

gorocksdbTest(.text): undefined: rocksdb_destroy_db

gorocksdbTest.text): undefined: rocksdb_options_create

gorocksdbTest(.text): undefined: rocksdb_options_set_create_if_missing

gorocksdbTest(.text): undefined: rocksdb_options_set_target_file_size_base

//-----This is my test ---// 

package main 

// #cgo CFLAGS: -I C:/cygwin64/usr/local/include

// #cgo LDFLAGS: -L C:/cygwin64/usr/local/lib -lrocksdb -lstdc++ -lm -lz -lbz2  

// #include "rocksdb/c.h"

// #include <stdlib.h>

import "C"  

import (

     "unsafe"

 "errors"

     "fmt"

     "path/filepath" 

)

//types and funs got from goRocksdb

type Options struct {

c *C.rocksdb_options_t

 

cmp  *Comparator

mo   *MergeOperator

env  *Env

st   *SliceTransform

cf   *CompactionFilter

bbto *BlockBasedTableOptions

 

ccmp *C.rocksdb_comparator_t

cmo  *C.rocksdb_mergeoperator_t

cst  *C.rocksdb_slicetransform_t

ccf  *C.rocksdb_compactionfilter_t

} 

 

type Comparator interface {

// Three-way comparison. Returns value:

//   < 0 iff "a" < "b",

//   == 0 iff "a" == "b",

//   > 0 iff "a" > "b"

Compare(a, b []byte) int

// The name of the comparator.

Name() string

} 

type MergeOperator interface { 

FullMerge(key, existingValue []byte, operands [][]byte) ([]byte, bool) 

PartialMerge(key, leftOperand, rightOperand []byte) ([]byte, bool) 

Name() string

}

// Env is a system call environment used by a database.

type Env struct {

c *C.rocksdb_env_t

}

// A SliceTransform can be used as a prefix extractor.

type SliceTransform interface {

// Transform a src in domain to a dst in the range.

Transform(src []byte) []byte

// Determine whether this is a valid src upon the function applies.

InDomain(src []byte) bool

// Determine whether dst=Transform(src) for some src.

InRange(src []byte) bool

// Return the name of this transformation.

Name() string

}

type CompactionFilter interface { 

Name() string 

Filter(level int, key, val []byte) (remove bool, newVal []byte)

}

 

type BlockBasedTableOptions struct {

c *C.rocksdb_block_based_table_options_t

// hold references for GC

cache      *Cache

comp_cache *Cache

fp         *FilterPolicy

// Hold on so memory can be freed in Destroy.

cfp *C.rocksdb_filterpolicy_t

}

 

type FilterPolicy interface { 

CreateFilter(keys [][]byte) []byte 

KeyMayMatch(key []byte, filter []byte) bool

// Return the name of this policy.

Name() string

}

 

type Cache struct {

c *C.rocksdb_cache_t

}

  

type BackupEngineInfo struct {

    c *C.rocksdb_backup_engine_info_t

}

 

type Slice struct {

data  *C.char

size  C.size_t

freed bool

}

// DB is a reusable handle to a RocksDB database on disk, created by Open.

type DB struct {

c    *C.rocksdb_t

name string

opts *Options

}

 

// NewDefaultOptions creates the default Options.

func NewDefaultOptions() *Options {

return NewNativeOptions(C.rocksdb_options_create())

}

func NewNativeOptions(c *C.rocksdb_options_t) *Options {

return &Options{c: c}

}

 

// If true, the database will be created if it is missing.

// Default: false

func (self *Options) SetCreateIfMissing(value bool) {

C.rocksdb_options_set_create_if_missing(self.c, boolToChar(value))

}

 

func (self *Options) SetTargetFileSizeBase(value uint64) {

C.rocksdb_options_set_target_file_size_base(self.c, C.uint64_t(value))

}

 

func DestroyDb(name string, opts *Options) error {

var cErr *C.char

cname := C.CString(name)

defer C.free(unsafe.Pointer(cname))

C.rocksdb_destroy_db(opts.c, cname, &cErr)

if cErr != nil {

defer C.free(unsafe.Pointer(cErr))

return errors.New(C.GoString(cErr))

}

return nil

}

 

/*func (self *BackupEngineInfo) Destroy() {

    C.rocksdb_backup_engine_info_destroy(self.c)

    self.c = nil

}

 

func (self *DB) Close() {

C.rocksdb_close(self.c)

}*/

//--utils

// boolToChar converts a bool value to C.uchar

func boolToChar(b bool) C.uchar {

if b {

return 1

}

return 0

}

//--slice

func (self *Slice) Free() {

if !self.freed {

C.free(unsafe.Pointer(self.data))

self.freed = true

}

}

var homePath string = "c:/"

func main() { 

                homePath := ""

                homePath = homePath + "/data/" 

                dbRocksDB_Name := "name" 

                dbMainName := dbDir(homePath, dbRocksDB_Name)

                options := NewDefaultOptions()

                options.SetTargetFileSizeBase(67108864) //64MB

                DestroyDb(dbMainName, options)  

}

 

func dbDir(home_path string, dbname string) string { 

                path := filepath.Join(home_path, dbname) 

                return path

} 

//-------------------------------------

Regards,

Dong

[others dong]

SOLVED

Because cgo is using dynamics/share library with extension *.a but rocksdb build static as *.a. I copied librocksdb.so.3.11.0 to librocksdb.a and go identified library.

Thanks,

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