# Context原理及其适用场景 随手记 李帅(飞雪无情) ___ ¥ 随手记 👨‍👩‍👧‍👦 卡牛 📸 随管家 ___ ## 大纲 常见并发模式 ■ Context实现原理 ☑ TLS VS Context ☑ 典型适用场景 ## Channel func add(a,b int) <-chan int{ sum:=make(chan int) go ## Context ● 一个任务，需要多个goroutine完成 ● 一个请求，会触发好多个goroutine做不同的事情 ● 如果我们的任务终止了，请求取消了，这些正在运行的goroutine怎么办？ ● 使用Context来简化这些操作 ## Context能做什么 ## ☑ 手动、定时、超时发出取消信号 ◆ 跨API传值 ☑ 控制生成Context树结构（Context链） func rootctx := context.Background() ctx, cancel := context.WithCancel(rootctx) go watch(ctx) go watch(ctx) time.Sleep(1 * time.Second) cancel() } func watch(ctx context.Context) { for

DeepSeek-V4: Towards Highly Efficient Million-Token Context Intelligence DeepSeek-AI research@deepseek.com Abstract We present a preview version of DeepSeek-V4 series, including two strong Mixture-of- parameters (49B activated) and DeepSeek-V4-Flash with 284B parameters (13B activated) both supporting a context length of one million tokens. DeepSeek-V4 series incorporate several key upgrades in architecture combines Compressed Sparse Attention (CSA) and Heavily Compressed Attention (HCA) to improve long-context efficiency; (2) Manifold- Constrained Hyper-Connections (mHC) that enhance conventional residual

Trace & Span   ## Trace & Span 例子 ![ span := opentracing.GlobalTracer().StartSpan("Root Span") defer span.Finish() }) (func() { span := span.Tracer().StartSpan("Child Span 1", opentracing.ChildOf(span.Context))) Context))) defer span.Finish() time.Sleep(time.Second) }) })( (func() { span := span.Tracer().StartSpan("Child Span 2", opentracing.ChildOf(span.Context())) defer span.Finish()

match beans with factory method / "factory-bean" definition Package org.springframework.context * added "alwaysUseMessageFormat" property to AbstractMessageSource, enforcing MessageFormat core * fixed ClassPathResource to fall back to its ClassLoader if none specified and no thread context ClassLoader available * deprecated ResourcePatternResolver's "CLASSPATH_URL_PREFIX" scenarios (with database access) from Countries sample application * revised all XML application context definition files to use Spring 1.2 shortcut attributes as far as possible Package org.springframework

for its data structures and algorithms to work properly. STL vocabulary types such as string_view, span, optional, expected etc., raise new questions regarding values types, whole-part semantics, copies analysis provides us some basis to evaluate non-owning reference parameters types (like string_view and span) in a practical fashion, without discarding Regular design. Let's go back to the roots... ## C++20 std::span Think "array view" as in std::string_view, but mutable on underlying data https://en.cppreference.com/w/cpp/container/span ## C++20 std::span A std::span does not manage

## placement new // accessor for an Vector called vs: Span vs() { return mbuf->vs; } flat type access type a Span is a range of elements  Flat::Span Message descriptor 000 lines of simple C++ ## • Flats support library • Vector, String, Optional, Variant, Array, Span, Span_ref, Uint32 • Minimal in-buffer representations • No pointers • ~500 lines of simple C++ “Programming

registers BeanFactoryAware as default ignored dependency interface Package org.springframework.context * AbstractApplicationContext registers MessageSourceAware/ApplicationContextAware/etc as ignored DefaultXmlBeanDefinitionParser to correctly parse null keys for XML map entries Package org.springframework.context * reworked LocaleContextHolder to use an InheritableThreadLocal, also exposing the thread-bound removed JndiBeanFactoryLocator, in favor of the existing default ContextJndiBeanFactoryLocator in the context package * deprecated SingletonBeanFactoryLocator's alias-through-String-bean feature, in favor

and their interoperability • When to use string_view • Using string_view safely • Intro to span • span vs. string_view • Case study of an optimization using string_view. ## Motivation • Consider destroyed at the end of the full-expression [-Wdangling] 15 | const auto sv = foo("hello"); ## span: Motivation ## Consider the following functions void foo(int* arr, int n) { for (int i = 0; these contiguous containers with a single interface? ## span: Motivation void foo(span s) { for (const auto i : s) { cout << i << ' ";

size away. For example span Can hold both C-Array and std::array. Of course, range-based forready. Cleaned up the code safely and with little overhead. ## bool Send(const span& data) 3 return return write(data.data(), data.size()); void Read(span data) int i = 1; // fill buffer with data for (auto& c : data) { c = i; ++i; } void Main() 18 std::arrayspan Can hold both C-Array and std::array. Of course, range-based forready. Cleaned up the code safely and with little overhead. C++20 Single Header Version of span: [2]. ## 1 template

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bean names for inner beans as well, with identity hashcode as suffix Package org.springframework.context * factored out AbstractApplicationEventMulticaster base class from * AbstractApplicationEventMulticaster scenarios (with database access) from Countries sample application * revised all XML application context definition files to use Spring 1.2 shortcut attributes as far as possible Package org.springframework registers BeanFactoryAware as default ignored dependency interface Package org.springframework.context * AbstractApplicationContext registers MessageSourceAware/ApplicationContextAware/etc as ignored