Go语言中Levigo库的安装与常见CGO链接问题解决

/home/fun/workspace/study/leveldb/test/libleveldb.a(env_posix.o): In function `leveldb::(anonymous namespace)::StartThreadWrapper(void*)':
env_posix.cc:(.text+0x1e): undefined reference to `operator delete(void*)'
/home/fun/workspace/study/leveldb/test/libleveldb.a(env_posix.o): In function `leveldb::(anonymous namespace)::PosixEnv::NewLogger(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, leveldb::Logger**)':
env_posix.cc:(.text+0x10c): undefined reference to `operator new(unsigned long)'
...

CGO_CFLAGS="-I/path/to/leveldb/include" CGO_LDFLAGS="-L/path/to/leveldb/lib" go get github.com/jmhodges/levigo

sudo apt-get update
sudo apt-get install libleveldb-dev

go get -v github.com/jmhodges/levigo

package main

import (
    "fmt"
    "log"
    "os"

    "github.com/jmhodges/levigo"
)

func main() {
    // 定义数据库路径
    dbPath := "/tmp/my_leveldb_test"

    // 确保数据库路径不存在，以便每次运行都是全新开始
    _ = os.RemoveAll(dbPath)

    // 配置LevelDB选项
    opts := levigo.NewOptions()
    defer opts.Close() // 确保选项资源被释放
    opts.SetCreateIfMissing(true) // 如果数据库不存在则创建

    // 打开数据库
    db, err := levigo.Open(dbPath, opts)
    if err != nil {
        log.Fatalf("无法打开LevelDB数据库: %v", err)
    }
    defer db.Close() // 确保数据库连接被关闭

    fmt.Println("LevelDB数据库已成功打开。")

    // 写入数据
    wo := levigo.NewWriteOptions()
    defer wo.Close()
    key1 := []byte("name")
    value1 := []byte("Alice")
    err = db.Put(wo, key1, value1)
    if err != nil {
        log.Fatalf("写入数据失败: %v", err)
    }
    fmt.Printf("已写入: %s -> %s\n", key1, value1)

    key2 := []byte("age")
    value2 := []byte("30")
    err = db.Put(wo, key2, value2)
    if err != nil {
        log.Fatalf("写入数据失败: %v", err)
    }
    fmt.Printf("已写入: %s -> %s\n", key2, value2)

    // 读取数据
    ro := levigo.NewReadOptions()
    defer ro.Close()
    readVal1, err := db.Get(ro, key1)
    if err != nil {
        log.Fatalf("读取数据失败: %v", err)
    }
    fmt.Printf("已读取: %s -> %s\n", key1, readVal1)

    readVal2, err := db.Get(ro, key2)
    if err != nil {
        log.Fatalf("读取数据失败: %v", err)
    }
    fmt.Printf("已读取: %s -> %s\n", key2, readVal2)

    // 尝试读取不存在的键
    key3 := []byte("city")
    readVal3, err := db.Get(ro, key3)
    if err != nil {
        // LevelDB在键不存在时会返回nil和特定的错误，这里简单处理
        fmt.Printf("读取键 '%s' 失败或不存在: %v\n", key3, err)
    } else {
        fmt.Printf("已读取: %s -> %s\n", key3, readVal3)
    }

    // 删除数据
    err = db.Delete(wo, key1)
    if err != nil {
        log.Fatalf("删除数据失败: %v", err)
    }
    fmt.Printf("已删除: %s\n", key1)

    // 再次读取被删除的键
    readVal1AfterDelete, err := db.Get(ro, key1)
    if err != nil {
        fmt.Printf("删除后读取键 '%s' 失败或不存在: %v\n", key1, err)
    } else {
        fmt.Printf("删除后读取: %s -> %s\n", key1, readVal1AfterDelete)
    }

    fmt.Println("示例程序执行完毕。")
}