建议日志 slog 改换 tracing(金庆的专栏 2021.11)slog 不是立即写盘，最后的几行日志会丢失tracing 不会丢日志slog 不支持运行中动态更改日志等级tracingwith_filter_reloading()examples/tower-loadslog 不支持不同包设置不同日志等级tracing 可单独打开某个模块的日志发现一次 slog panic:panicked at 'slog::Fuse Drain: Fatal(Custom { kind: BrokenPipe, error: "The logger thread terminated" })'搜到相同错误：https://github.com/mimblewimble/grin/issues/946别人的解决方法是: 不用slog了slog 主页10月添加推荐使用 tracingslog 按线程保存上下文，tracing 按协程保存上下文tracing github star 1.9K > slog 1.2Ktracing crates 下载 21M > sloggers 0.4M, slog-scope 2.6M, slog-stdlog 1.9Mtracing vs slog:https://www.reddit.com/r/rust/comments/kdo29n/slog_vs ...继续阅读 (12)

Named parameters in Rust(Jin Qing's Column, Nov. 18, 2021)There is no "named function parameters" in Rust, but there is an idiom for this case. If a function needs many parameters, we can define a type with all these parameters as fields, and implementDefaulttrait for this type. Then we can input this type as the function parameter, with some of the fields specified and others using default.foo(Config { a: 123, b: bool, ...Default::default(), });金庆2021-11-18 13:14发表评论 ...继续阅读 (28)

Rust traits act as generic constraints(Jin Qing's Column, Nov. 18, 2021)Rust traits are different from interfaces of C++/Java/Go.See:https://stevedonovan.github.io/rustifications/2018/09/08/common-rust-traits.htmlRust traits are mechanism for adding behavior to types.Traits have 2 modes. One is interface as Java.Another is generic constraint. Generic functions are defined over types that implemented specific traits.The "complie-time duck typing" in C++ templates is avoided in Rust. Rust will reject a type with quack() method as a Duck type. We must pass a type which implements Duck trait. But ...继续阅读 (25)

GLIBC_2.29 not found(Jin Qing's Column, Nov. 4, 2021)My Rust program failed when running in docker:root@a26b49c91efb:/myapp# ldd libmyapp_py.so ./libmyapp_py.so: /lib/x86_64-linux-gnu/libm.so.6: version `GLIBC_2.29' not found (required by ./libmyapp_py.so)The problem is because I build in "rust:1.56", and run in "debian:buster-slim" which is quite old. Rundpkg -l libc-binshows the libc version is 2.28:C:\Users\jinqing01>docker run debian:buster-slim dpkg -l libc-bin Unable to find image 'debian:buster-slim' locally buster-slim: Pulling from library/debian b380bbd43752: Already exists Digest: s ...继续阅读 (23)

Clustering provider in Orleans(Jin Qing's Column, Nov. 3, 2021)When deployed to a cluster of nodes, Orleans internally implements a protocol to manage it's silos, including discovery, failure and reconfigure, which is called cluster membership management.Orleans has clustering membership providers for: Azure, SQL server, Zookeeper.Clustering provider is one of key aspects of silo configuration.Orleans.Clustering.KubernetesOrleansContrib/Orleans.Clustering.Kubernetesis a clustering provider for running Orleans cluster on Kubernetes.Tell silo to use Kubernetes as the Cluster Membership Provide ...继续阅读 (29)

Why Orleans' actor is virutal(Jin Qing's Column, Nov. 2, 2021)Virtual Actor is a concept invented by Microsoft Orleans, which is a framework of distributed actor.Orleans: Distributed Virtual Actors for Programmability and Scalabilitydescribes the virtual programming model.The virtual actor is analogous to virtual memory. Virtual actors are mapped to physical arctors instances in the running servers. Virtualization of actors in Orleans has 4 facets:Perpetual existenceActors always exist, virtuallyActors can not be created or destroied explicitlyServer failure does not affect the actors' existen ...继续阅读 (24)

What comes after microservice?(Jin Qing's Column, Oct. 25, 2021)Reading "The Evolution of Distributed Systems on Kubernetes" from Bilgin Ibryam.https://www.infoq.com/articles/distributed-systems-kubernetes/What are the purpose of projects like Dapr, Istio, Knative? How can they change the world?Modern distributed systemsThe needs of distributed systems:Business logicOtherLifecycle: deploy, rollback, upgrade, scale, stop, isolate, configNetwork: connect, circuit break, retry, timeout, load balance, discover, security, traceResource binding: to API, protocol, message, data formatState: stateless ...继续阅读 (21)

Display Non-UTF-8 output(Jin Qing's Column, Oct. 27, 2021)Cargo build output Non-UTF-8. Use python to decode it as gbk and print.```C:\Users\jinqing01>python>>> s = b'Non-UTF-8 output: \xd5\xfd\xd4\xda\xb4\xb4\xbd\xa8\xbf\xe2 E:\\gitlab\\myproj\\target\\debug\\deps\\pyext.dll.lib \xba\xcd\xb6\xd4\xcf\xf3 E:\\gitlab\\myproj\\target\\debug\\deps\\pyext.dll.exp\r\npyext.2rtvxajnfydf6uo2.rcgu.o : error LNK2019: \xce\xde\xb7\xa8\xbd\xe2\xce\xf6\xb5\xc4\xcd\xe2\xb2\xbf\xb7\xfb\xba\xc5 __imp_PyUnicode_AsUTF8\xa3\xac\xba\xaf\xca\xfd _ZN116_$LT$pyext..script..pyext..py_object_proxy..PyNonTxnStates$u2 ...继续阅读 (16)

Advice for library writersIdioms for Rust libraries are still forming, but if your library needs to report custom errors, then you should probably define your own error type. It’s up to you whether or not to expose its representation (like ErrorKind) or keep it hidden (like ParseIntError). Regardless of how you do it, it’s usually good practice to at least provide some information about the error beyond just its String representation. But certainly, this will vary depending on use cases.At a minimum, you should probably implement the Error trait. This will give users of your librar ...继续阅读 (23)

# How to show the first few errors of rustc(Jin Qing's Column, Sep. 1, 2021)When using VS Code to develop Rust, "cargo check" output maybe thousands of lines.Use "cargo check --color=always 2>&1 | head -n100" to limit the output.1. Change powershell terminal to cmd, because powershell fails to use pipe * Terminal -> New Terminal to open a terminal * Open the dropdown list by click the down arrow of "+" on the top-left of terminal * Select "Command Prompt"2. Type and run command: `cargo test 2>&1 --color always | "d:\Program Files\Git\usr\bin\head.exe" -n100` * You should change the ...继续阅读 (19)

# &'a mut self is restrictiveFrom https://github.com/pretzelhammer/rust-blog/blob/master/posts/common-rust-lifetime-misconceptions.md#5-if-it-compiles-then-my-lifetime-annotations-are-correct```#[derive(Debug)]struct NumRef<'a>(&'a i32);impl<'a> NumRef<'a> { // my struct is generic over 'a so that means I need to annotate // my self parameters with 'a too, right? (answer: no, not right) fn some_method(&'a mut self) {}}fn main() { let mut num_ref = NumRef(&5); num_ref.some_method(); // mutably borrows num_ref for the rest of its lifetime num_ref.some_method(); // ❌ println! ...继续阅读 (23)

# Rust callback idiomCode is from: https://stackoverflow.com/questions/41081240/idiomatic-callbacks-in-rustandhttps://morestina.net/blog/793/closure-lifetimes-in-rust```struct Processor<'a> { callback: Box,}impl<'a> Processor<'a> { fn new() -> Processor<'a> { Processor { callback: Box::new(|| ()), } } fn set_callback(&mut; self, c: impl FnMut() + 'a) { self.callback = Box::new(c); } fn process_events(&mut; self) { (self.callback)(); }}fn simple_callback() { println!("hello");}fn main() { let _ = Processor::new(); let mut ...继续阅读 (36)

# Rust variable rebinding for closureFrom: https://rust-unofficial.github.io/patterns/idioms/pass-var-to-closure.htmlRust closure captures variables by reference by default.You can use "move" keyword to change to move variables.In most cases, some variables are moved, and some are referenced.We can rebind variables in a separate scope before move to the closure.```use std::rc::Rc;let num1 = Rc::new(1);let num2 = Rc::new(2);let num3 = Rc::new(3);let closure = { // `num1` is moved let num2 = num2.clone(); // `num2` is cloned let num3 = num3.as_ref(); // `num3` is borrowed move || { ...继续阅读 (28)

# Rust Deref coercion examplehttps://doc.rust-lang.org/std/ops/trait.Deref.html```use std::ops::Deref;struct DerefExample{ value: T}implDeref for DerefExample{ type Target = T; fn deref(&self;) -> &Self;::Target { &self.value; }}let x = DerefExample { value: 'a' };assert_eq!('a', *x);```Deref coercion can be used in newtype:```struct MyI32(i32)impl Deref for MyI32 { type Target = i32; fn deref(&self;) -> &Self;::Target { &self.0; }}```金庆2021-08-22 12:31发表评论 ...继续阅读 (27)

Error Return Check PolicyNever use unwrap on Result. If the type is Err, it will panic and crash the program. The only exception is if it has already been checked for error previously or in test code.Never use unwrap on Option for the same reason if the type is None as Result is Err.金庆2021-08-09 17:08发表评论 ...继续阅读 (22)

From: Visibility and privacy - The Rust Reference (rust-lang.org)pub(in path), pub(crate), pub(super), and pub(self)In addition to public and private, Rust allows users to declare an item as visible only within a given scope. The rules for pub restrictions are as follows:pub(in path) makes an item visible within the provided path. path must be an ancestor module of the item whose visibility is being declared.pub(crate) makes an item visible within the current crate.pub(super) makes an item visible to the parent module. This is equivalent to pub(in super).pub(self) makes an item visible to the ...继续阅读 (30)

# Why does Rust check borrow even in single thread(Jin Qing's Column, Aug. 7, 2021)The Rust book says borrow checking is to prevent data race.But the borrow checker forbids multiply mutable borrows even in the same thread.Is there data race in single thread?Why does the borrow checker forbid it in the same thread?[The Problem With Single-threaded Shared Mutability](https://manishearth.github.io/blog/2015/05/17/the-problem-with-shared-mutability/)answers this question.It gaves 2 cases that shared mutability causes prolem.One is Rust enum variable, which can has different inner type.If the inner ...继续阅读 (27)

# Multiple Event BeginPlay(金庆的专栏 2021.7)How to do multiple actions on Event BeginPlay in UE4 Blueprints?Sams-Teach-Yourself-Unreal-Engine-4-Game-Development-in-24-Hours says:```Q. When I try to add a second event node, BeginPlay, the Editor shows me the first one alreadyplaced in the Event Graph. Why does this happen?A. Some events, such as Event Tick and the BeginPlay event, can have only one instance perBlueprint.```https://forums.unrealengine.com/t/do-multiple-things-on-event-begin-play/411/10```The Sequence node allows for a single execution pulse to trigger a series of events in order. Th ...继续阅读 (15)

# Visual Studio 2019 Compiler Hangs(金庆的专栏 2021.7)Discovered by my colleague Shen Yichai:```Share a interesting MS Build bug:For file a.cpp, enable optimization for Win64 or XSX.The MSBuild always compiling without error and ending (infinite compile).The PS5 (clang) does not have this issue.```The simplified code:```struct Tag{ int v;};void Goo(Tag* r, Tag* a){ r->v = a->v;}void Foo(Tag* pos0, Tag* pos){ for (int j = 0; j < 4; j++) { if (j == 0) { for (int i = 0; i < 8; i++) { Goo(pos0++, pos); Goo(pos0++, pos); } } ...继续阅读 (15)

# Fbx File Format Identifier(金庆的专栏 2021.5)Print the list of FBX file format identifiers.FBX SDK FbxExporter can set the file format identifier which is an int parameter.The commnet says: User does not need to specify it by default.If not specified, plugin will detect the file format according to file suffix automatically.FBX SDK 2020 automatically set it to the latest binary format, which can not be parsed by "Autodesk FBX Converter 2013".We need to specify the format identifier for FBX Converter 2013.But there is no specification of this parameter.We use the following code to display all the ...继续阅读 (28)

# 第9代游戏主机原文：[Ninth generation of video game consoles](https://en.wikipedia.org/wiki/Ninth_generation_of_video_game_consoles)2020.11，微软(MS) Xbox Series X/S 和 Sony PlayStation 5 (PS5) 发布，标志着游戏主机进入第9代。和前代的 Xbox One 和 PS4 相比，新一代主机有可观的性能提升，支持实时光线跟踪，4K分辨率，目标帧率为60。内部都使用了固态硬盘(SSD)。低配版没有光驱，仅支持网络和USB。定位上要胜过任天堂Switch和云游戏服务如 Stadia 和 Amazon Luna.## 背景第8代时间较长。因为摩尔定律，过去几代一般每代为5年时间，但是 MS 和 Sony 出了中间代产品 Xbox One X 和 PS4 Pro.2020.3 开始的 COVID-19 疫情影响也使新一代主机的发布延后了。## 主要主机### PS5有2个机型，基本型和数字型，数字型没有光驱较便宜，其他一样。PS5和PS4的游戏兼容，只有少量游戏不支持，但是可以通过 PS Now 云游戏服务玩 PS4 游戏。### Xbox Series X/SMS 延继了双主机模式：高端的X系列和低端的S系列。S系列没有光驱。两者 ...继续阅读 (24)

Canvas Scaler 的3种模式(金庆的专栏 2021.3)参考：https://wenku.baidu.com/view/83991090336c1eb91b375db8.htmlUnity Canvas 有个 Canvas Scaler 组件，用来决定 Canvas 的 Scale(缩放)值。Scale 有 X,Y,Z 3个分量，都是同一值，即在各个方向上都是同倍率缩放的。它有3种Scale Mode。因为设计时的宽高比与目标机型宽高比不同，Canvas 需要先增减为目标高宽比，然后再缩放。Canvas 缩放并不影响UI元素的相互位置，只是同比缩放。但是高宽比调整时会造成UI元素的相对位置变化，如宽度增大后，UI元素会在宽度方向上相互散开。可以在 Unity Editor Game 页左上角分辨率下拉菜单中创建几个低分辨率屏，用来测试屏幕大小切换。测试界面可放置2个按钮，一个锚定到左上，位于左上，一个锚定到右下，位于右下，不要strech。3种模式如下。## Constance Pixel SizeConstance Pixel Size 模式下，Scale 总是为1。目标机上的 Canvas 就是其分辨率大小。因为设计时分辨率与实际分辨率不同，显示会不同。但是图片和按钮的大小保持固定像素大小。如果屏幕变大，UI元素就会相互散开，变小则聚拢。如果需要缩放，只能通过程序调节 ...继续阅读 (15)

# C#异步方法返回void和Task的区别(金庆的专栏 2021.2)如果异步(async关键字)方法有返回值，返回类型为T时，返回类型必然是 `Task`。但是如果没有返回值，异步方法的返回类型有2种，一个是返回 Task, 一个是返回 void：``` public async Task CountDownAsync(int count) { for (int i = count; i >= 0; i--) { await Task.Delay(1000); } } public async void CountDown(int count) { for (int i = count; i >= 0; i--) { await Task.Delay(1000); } }```调用时，如果返回 Task, 但返回值被忽略时，VS 会用绿色波浪线警告：``` CountDownAsync(3); ~~~~~~~~~~~~~~~~~```信息为：```(awaitable) Task AsyncExample.CountDownAsync(int count)Usage: await CountDownAsy ...继续阅读 (22)

net.LookupSRV()查询k8s无头服务(金庆的专栏 2021.2)如下创建 StatefulSet 和 Headless Service: test.yaml```apiVersion: v1kind: Servicemetadata: name: headless-svc labels: app: headless-svcspec: ports: - port: 80 name: aaaa - port: 20080 name: bbbb selector: app: headless-pod clusterIP: None ---apiVersion: apps/v1kind: StatefulSetmetadata: name: statefulset-testspec: serviceName: headless-svc replicas: 3 selector: matchLabels: app: headless-pod template: metadata: labels: app: headless-pod spec: containers: - name: myhttpd image: httpd ports ...继续阅读 (31)

std::hash实现太简单分布不匀(金庆的专栏 2017.5)#include#includeusing namespace std;int main(){ std::hashhasher; cout << hasher(2) << endl; cout << hasher(3) << endl; cout << hasher(4) << endl; return 0;}输出为jinqing@server:~/test$ g++ main.cpp -std=c++11jinqing@server:~/test$ ./a.out234查看实现，/usr/include/c++/5/bits/functional_hash.h operator()(_Tp __val) const noexcept \ { return static_cast(__val); } \所以对分布有要求的，应该使用自己的hash, 不要使用 std::hash.boost::hash 的实现也是简单取值，boost_1_60_0/boost/functional/hash/hash.hpp templatetypename boost::hash_detail::basic_numbers::type ...继续阅读 (11)

用preload加载Lua导出模块(金庆的专栏 2017.5)参考：How to make exported module non-global?https://github.com/SteveKChiu/lua-intf/issues/135动态库可以这样导出模块： extern "C" #if defined(_MSC_VER) || defined(__BORLANDC__) || defined(__CODEGEARC__) __declspec(dllexport) #endif int luaopen_modname(lua_State* L) { LuaRef mod = LuaRef::createTable(L); LuaBinding(mod) ...; mod.pushToStack(); return 1; }如果不是动态库，可以这样导出全局模块 c_util：int main(){ ... LuaBinding(L).beginModule("c_util") .addFunction("foo", []() { return 123; }) .endModule(); ...}如果不想让它成为全局模 ...继续阅读 (18)

grpc++不支持异步多次写入(金庆的专栏 2017.5)见：Multi ClientAsyncWriter::Write() calls will crash. #7659https://github.com/grpc/grpc/issues/7659why the continuous write to async streaming crash? #4007https://github.com/grpc/grpc/issues/4007write stream error:GRPC_CALL_ERROR_ALREADY_INVOKEDhttps://github.com/grpc/grpc/issues/3953grpc_cb 支持真正的异步写。https://github.com/jinq0123/grpc_cb金庆2017-05-07 10:38发表评论 ...继续阅读 (39)

网游开发目录结构(金庆的专栏 2017.4)合理设置网游开发目录结构，可以方便目录权限设置。以前分为3大块，分别对应美术，程序，策划的目录。ArtCodeDesign也有可能是分成3个SVN库。个人倾向于分成多个库，SVN应该只保存文本文件。对于U3d开发，美术和策划需要更改客户端开发目录。ArtDesignClientServerCommon金庆2017-04-27 10:01发表评论 ...继续阅读 (35)

支持 proto3 的 lua 绑定库LuaPbIntf(金庆的专栏 2017.4)protobuf的lua绑定库之前一直用 pbc，但是该库已经不更新了。想要添加 proto3 的 map , 还有支持 service, 发现代码太高深，无法下手。pbc因为用c代码实现了 protobuf 的功能，所以代码量很大。而对于 c++ 来说，只需要利用 protobuf 库中动态消息就可以实现 lua 所需功能。luapb 就是直接用 protobuf 库封装后导出lua实现的。该库仅支持 proto2.在 luapb 基础上实现对 proto3 的支持，就是LuaPbIntf库。LuaPbIntf 库利用了 lua-intf 库来实现 c++ 与 lua 绑定，所以代码量比 luapb 又少了许多，并且可读性大大增强，更改添加新功能也就更方便了。与 pbc, lubpb 一样，LuaPbIntf 也是动态加载 proto 文件，不需要代码生成。LuaPbIntf 采用 lua table 来表示 pb 消息，不是 pbc 中的代理表，而只是普通表。项目地址：https://github.com/jinq0123/LuaPbIntf示例：local pb = require("luapbintf")pb.import_proto_file("test.proto")local msg ...继续阅读 (37)

建议proto文件按包名分子目录(金庆的专栏 2017.4)服务器客户端之间的protobuf协议定义在客户端与服务器公共目录下，包名为rpc.服务器内部协议定义在服务器目录下，包名为svr.rpc.EmptyMsg 和 svr.EmptyMsg 分别定义在各自的根目录，文件名都是 empty_msg.proto.运行时就会报错：[libprotobuf ERROR E:\deps\protobuf-3.2.0\protobuf-3.2.0\src\google\protobuf\descriptor_database.cc:57] File already exists in database : empty_msg.proto[libprotobuf FATAL E:\deps\protobuf-3.2.0\protobuf-3.2.0\src\google\protobuf\descriptor.cc:1275] CHECK failed: generated_database_->Add(encoded_file_descriptor, size):原因为试图用同一个文件名"empty_msg.proto"往descriptor_database添加descriptor。如果按包名分子目录，文件名就可以分开为 "rpc/empty_msg.proto" 和 "svr/emp ...继续阅读 (36)