golang plugin插件的使用
Go 1.8 为我们提供了一个创建共享库的新工具,称为 Plugins!同时官方文档也提示了:Currently plugins are only supported on Linux and macOS 。其可以应用如下场景:
- 通过plugin我们可以很方便的对于不同功能加载相应的模块并调用相关的模块;
- 也可以针对不同语言(英文、汉语、德语……)加载不同的语言so文件,进行不同的输出;
- 还可以把编译出的文件给不同的编程语言用(如:c/java/python/lua等)。
一、go plugin示例
1、创建插件
创建一个插件方法aplugin.go:
package main func Add(x, y int) int { return x+y } func Subtract(x, y int) int { return x-y }
构建插件aplugin.so
go build -buildmode=plugin -o aplugin.so aplugin.go
2、插件调用
不同人类语言调用不同的模块示例,可以参考:https://github.com/vladimirvivien/go-plugin-example 。
二、cshared示例
除了上面提到的buildmode=plugin外,还有一种用法就是 buildmode=c-shared ,使用该参数时会生成出来两个文件,一个.so文件,一个.h头文件 ,使用起来就和使用c 生成的库文件和模块文件一样使用。具体使用如下:
1、awesome.go代码
package main import "C" import ( "fmt" "math" "sort" "sync" ) var count int var mtx sync.Mutex //export Add func Add(a, b int) int { return a + b } //export Cosine func Cosine(x float64) float64 { return math.Cos(x) } //export Sort func Sort(vals []int) { sort.Ints(vals) } //export Log func Log(msg string) int { mtx.Lock() defer mtx.Unlock() fmt.Println(msg) count++ return count } func main() {}
编译命令如下:
go build -o awesome.so -buildmode=c-shared awesome.go 编译后生成如下两个文件: awesome.h awesome.h
具体可以使用如下命令查看so文件:
file awesome.so nm awesome.so | grep -e "T Add" -e "T Cosine" -e "T Sort" -e "T Log"
其会输出为shared object文件,并exported 相关对像的symbols 。
2、c语言动态链接调用
#include <stdio.h> #include "awesome.h" int main() { //Call Add() - passing integer params, interger result GoInt a = 12; GoInt b = 99; printf("awesome.Add(12,99) = %d\n", Add(a, b)); //Call Cosine() - passing float param, float returned printf("awesome.Cosine(1) = %f\n", (float)(Cosine(1.0))); //Call Sort() - passing an array pointer GoInt data[6] = {77, 12, 5, 99, 28, 23}; GoSlice nums = {data, 6, 6}; Sort(nums); printf("awesome.Sort(77,12,5,99,28,23): "); for (int i = 0; i < 6; i++){ printf("%d,", ((GoInt *)nums.data)[i]); } printf("\n"); //Call Log() - passing string value GoString msg = {"Hello from C!", 13}; Log(msg); }
编译并调用
$> gcc -o client client1.c ./awesome.so $> ./client awesome.Add(12,99) = 111 awesome.Cosine(1) = 0.540302 awesome.Sort(77,12,5,99,28,23): 5,12,23,28,77,99, Hello from C!
3、c语言动态加载
#include <stdlib.h> #include <stdio.h> #include <dlfcn.h> // define types needed typedef long long go_int; typedef double go_float64; typedef struct{void *arr; go_int len; go_int cap;} go_slice; typedef struct{const char *p; go_int len;} go_str; int main(int argc, char **argv) { void *handle; char *error; // use dlopen to load shared object handle = dlopen ("./awesome.so", RTLD_LAZY); if (!handle) { fputs (dlerror(), stderr); exit(1); } // resolve Add symbol and assign to fn ptr go_int (*add)(go_int, go_int) = dlsym(handle, "Add"); if ((error = dlerror()) != NULL) { fputs(error, stderr); exit(1); } // call Add() go_int sum = (*add)(12, 99); printf("awesome.Add(12, 99) = %d\n", sum); // resolve Cosine symbol go_float64 (*cosine)(go_float64) = dlsym(handle, "Cosine"); if ((error = dlerror()) != NULL) { fputs(error, stderr); exit(1); } // Call Cosine go_float64 cos = (*cosine)(1.0); printf("awesome.Cosine(1) = %f\n", cos); // resolve Sort symbol void (*sort)(go_slice) = dlsym(handle, "Sort"); if ((error = dlerror()) != NULL) { fputs(error, stderr); exit(1); } // call Sort go_int data[5] = {44,23,7,66,2}; go_slice nums = {data, 5, 5}; sort(nums); printf("awesome.Sort(44,23,7,66,2): "); for (int i = 0; i < 5; i++){ printf("%d,", ((go_int *)data)[i]); } printf("\n"); // resolve Log symbol go_int (*log)(go_str) = dlsym(handle, "Log"); if ((error = dlerror()) != NULL) { fputs(error, stderr); exit(1); } // call Log go_str msg = {"Hello from C!", 13}; log(msg); // close file handle when done dlclose(handle); }
编译执行:
$> gcc -o client client2.c -ldl $> ./client awesome.Add(12, 99) = 111 awesome.Cosine(1) = 0.540302 awesome.Sort(44,23,7,66,2): 2,7,23,44,66, Hello from C!
4、python ctypes 方式调用
from ctypes import * lib = cdll.LoadLibrary("./awesome.so") # describe and invoke Add() lib.Add.argtypes = [c_longlong, c_longlong] lib.Add.restype = c_longlong print "awesome.Add(12,99) = %d" % lib.Add(12,99) # describe and invoke Cosine() lib.Cosine.argtypes = [c_double] lib.Cosine.restype = c_double print "awesome.Cosine(1) = %f" % lib.Cosine(1) # define class GoSlice to map to: # C type struct { void *data; GoInt len; GoInt cap; } class GoSlice(Structure): _fields_ = [("data", POINTER(c_void_p)), ("len", c_longlong), ("cap", c_longlong)] nums = GoSlice((c_void_p * 5)(74, 4, 122, 9, 12), 5, 5) # call Sort lib.Sort.argtypes = [GoSlice] lib.Sort.restype = None lib.Sort(nums) print "awesome.Sort(74,4,122,9,12) = [", for i in range(nums.len): print "%d "% nums.data[i], print "]" # define class GoString to map: # C type struct { const char *p; GoInt n; } class GoString(Structure): _fields_ = [("p", c_char_p), ("n", c_longlong)] # describe and call Log() lib.Log.argtypes = [GoString] lib.Log.restype = c_longlong msg = GoString(b"Hello Python!", 13) print "log id %d"% lib.Log(msg)
执行结果:
$> python client.py awesome.Add(12,99) = 111 awesome.Cosine(1) = 0.540302 awesome.Sort(74,4,122,9,12) = [ 4 9 12 74 122 ] Hello Python!
5、Python CFFI方式调用
from __future__ import print_function import sys from cffi import FFI is_64b = sys.maxsize > 2**32 ffi = FFI() if is_64b: ffi.cdef("typedef long GoInt;\n") else: ffi.cdef("typedef int GoInt;\n") ffi.cdef(""" typedef struct { void* data; GoInt len; GoInt cap; } GoSlice; typedef struct { const char *data; GoInt len; } GoString; GoInt Add(GoInt a, GoInt b); double Cosine(double v); void Sort(GoSlice values); GoInt Log(GoString str); """) lib = ffi.dlopen("./awesome.so") print("awesome.Add(12,99) = %d" % lib.Add(12,99)) print("awesome.Cosine(1) = %f" % lib.Cosine(1)) data = ffi.new("GoInt[]", [74,4,122,9,12]) nums = ffi.new("GoSlice*", {'data':data, 'len':5, 'cap':5}) lib.Sort(nums[0]) print("awesome.Sort(74,4,122,9,12) = %s" % [ ffi.cast("GoInt*", nums.data)[i] for i in range(nums.len)]) data = ffi.new("char[]", b"Hello Python!") msg = ffi.new("GoString*", {'data':data, 'len':13}) print("log id %d" % lib.Log(msg[0]))
6、java调用
import com.sun.jna.*; import java.util.*; import java.lang.Long; public class Client { public interface Awesome extends Library { // GoSlice class maps to: // C type struct { void *data; GoInt len; GoInt cap; } public class GoSlice extends Structure { public static class ByValue extends GoSlice implements Structure.ByValue {} public Pointer data; public long len; public long cap; protected List getFieldOrder(){ return Arrays.asList(new String[]{"data","len","cap"}); } } // GoString class maps to: // C type struct { const char *p; GoInt n; } public class GoString extends Structure { public static class ByValue extends GoString implements Structure.ByValue {} public String p; public long n; protected List getFieldOrder(){ return Arrays.asList(new String[]{"p","n"}); } } // Foreign functions public long Add(long a, long b); public double Cosine(double val); public void Sort(GoSlice.ByValue vals); public long Log(GoString.ByValue str); } static public void main(String argv[]) { Awesome awesome = (Awesome) Native.loadLibrary( "./awesome.so", Awesome.class); System.out.printf("awesome.Add(12, 99) = %s\n", awesome.Add(12, 99)); System.out.printf("awesome.Cosine(1.0) = %s\n", awesome.Cosine(1.0)); // Call Sort // First, prepare data array long[] nums = new long[]{53,11,5,2,88}; Memory arr = new Memory(nums.length * Native.getNativeSize(Long.TYPE)); arr.write(0, nums, 0, nums.length); // fill in the GoSlice class for type mapping Awesome.GoSlice.ByValue slice = new Awesome.GoSlice.ByValue(); slice.data = arr; slice.len = nums.length; slice.cap = nums.length; awesome.Sort(slice); System.out.print("awesome.Sort(53,11,5,2,88) = ["); long[] sorted = slice.data.getLongArray(0,nums.length); for(int i = 0; i < sorted.length; i++){ System.out.print(sorted[i] + " "); } System.out.println("]"); // Call Log Awesome.GoString.ByValue str = new Awesome.GoString.ByValue(); str.p = "Hello Java!"; str.n = str.p.length(); System.out.printf("msgid %d\n", awesome.Log(str)); } }
更多示例可以参考:https://github.com/vladimirvivien/go-cshared-examples
三、总结
除了上面提到的示例外,c-shared模式的golang模块还支持nodejs、lua、ruby、Julia等语言的调用。个人理解是大部分语言都是用C开发的,由于golang自身与 c 的亲缘性,所以其生成的模块都是支持其他语言去调用的。
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