package main
import (
"fmt"
"unsafe"
)
func str2bytes(s string) []byte {
ptr := (*[2]uintptr)(unsafe.Pointer(&s))
btr := [3]uintptr{ptr[0], ptr[1], ptr[1]}
return *(*[]byte)(unsafe.Pointer(&btr))
}
func bytes2str(b []byte) string {
return *(*string)(unsafe.Pointer(&b))
}
func main() {
s := "abcdefghi"
b := str2bytes(s)
s2 := bytes2str(b)
fmt.Println(s, b, s2)
}
Go Proverbs: A little copying is better than a little dependency. 对于一些短小的对象，复制成本远小于在堆上分配和回收操作。
{% pdf http://feiskyer.github.io/assets/ccs.pdf %}
SIG-Networking: Kubernetes Network Policy APIs Coming in 1.3
... ➦One problem many users have is that the open access network policy of Kubernetes is not suitable for applications that need more precise control over the traffic that accesses a pod or service. Today, this could be a multi-tier application where traffic is only allowed from a tier’s neighbor. But as new Cloud Native applications are built by composing microservices, the ability to control traffic as it flows among these services becomes even more critical.
runc is a CLI tool for spawning and running containers according to the OCI specification, while runV is a hypervisor-based runtime for OCI. Both of them are recommanded (implementations](https://github.com/opencontainers/runtime-spec/blob/master/implementations.md) of OCI.
Install runc:
yum install -y libseccomp-devel
mkdir -p $GOPATH/src/github.com/opencontainers
cd $GOPATH/src/github.com/opencontainers
git clone https://github.com/opencontainers/runc
cd runc
make
sudo make install
Run busybox:
$ docker pull busybox
$ mkdir rootfs
$ docker export $(docker create busybox) | tar -C rootfs -xvf -
$ runc spec .
$ runc start test
/ # ps
PID USER COMMAND
1 root sh
9 root ps
docker-containerd is installed togather with docker 1.11.
... ➦Docker v1.11正式集成了runc（终于支持OCI了），并将原来的一个二进制文件拆分为多个，同时还保持docker CLI和API不变：
Intel DPDK全称Intel Data Plane Development Kit，是intel提供的数据平面开发工具集，为Intel architecture（IA）处理器架构下用户空间高效的数据包处理提供库函数和驱动的支持，它不同于Linux系统以通用性设计为目的，而是专注于网络应用中数据包的高性能处理。DPDK应用程序是运行在用户空间上利用自身提供的数据平面库来收发数据包，绕过了Linux内核协议栈对数据包处理过程。Linux内核将DPDK应用程序看作是一个普通的用户态进程，包括它的编译、连接和加载方式和普通程序没有什么两样。DPDK程序启动后只能有一个主线程，然后创建一些子线程并绑定到指定CPU核心上运行。
... ➦cgo的一些tips
The standard C numeric types are available under the names C.char, C.schar (signed char), C.uchar (unsigned char), C.short, C.ushort (unsigned short), C.int, C.uint (unsigned int), C.long, C.ulong (unsigned long), C.longlong (long long), C.ulonglong (unsigned long long), C.float, C.double, C.complexfloat (complex float), and C.complexdouble (complex double). The C type void* is represented by Go’s unsafe.Pointer. The C types __int128_t and __uint128_t are represented by [16]byte.
... ➦The major change is the definition of rules for sharing Go pointers with C code, to ensure that such C code can coexist with Go’s garbage collector. Briefly, Go and C may share memory allocated by Go when a pointer to that memory is passed to C as part of a cgo call, provided that the memory itself contains no pointers to Go-allocated memory, and provided that C does not retain the pointer after the call returns. These rules are checked by the runtime during program execution: if the runtime detects a violation, it prints a diagnosis and crashes the program. The checks can be disabled by setting the environment variable GODEBUG=cgocheck=0, but note that the vast majority of code identified by the checks is subtly incompatible with garbage collection in one way or another. Disabling the checks will typically only lead to more mysterious failure modes. Fixing the code in question should be strongly preferred over turning off the checks.
终于耐不住要升级下kernel了，目前epel提供两个版本: kernel-lt (4.4)和kernel-ml (4.5):
升级到lt的步骤很简单：
... ➦Brendan Burns, Brian Grant等在Borg, Omega, and Kubernetes - Lessons learned from three container-management systems over a decade分享了Google在容器管理的经验教训。
在谷歌的历史上，开发了三种容器管理调度系统：
... ➦