User avatar Bstran

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The detection function above is suitably generic and targeted in focus that it may be used as a building block to create higher level abstractions. Our goal is to create a ['stream algorithm]: a function which is invoked with a stream, that reads or writes (or both) to achieve a purpose. In this case, to detect the TLS client handshake. Stream algorithms may be synchronous or asynchronous. Because synchronous algorithms are easier to write, we start there. Then we build the asynchronous version, trying to model it similarly to make reasoning about it easier.
The detection function above is suitably generic and targeted in focus that it may be used as a building block to create higher level abstractions. Our goal is to create a ['stream algorithm]: a function which is invoked with a stream, that reads or writes (or both) to achieve a purpose. In this case, to detect the TLS client handshake. Stream algorithms may be synchronous or asynchronous. Because synchronous algorithms are easier to write, we start there. Then we build the asynchronous version, trying to model it similarly to make reasoning about it easier.上述检测函数足够通用，且目标明确，可以作为基础模块来构建更高级的抽象。接下来要创建一个流算法：该算法接收一个流作为参数，通过执行读写操作来达到特定目的，这里就是检测 TLS 客户端握手。流算法可以是同步的，也可以是异步的。同步算法更容易编写，因此先实现同步版本，再在此基础上构建异步版本，并尽量让两者风格相似，便于理解。
06/12/2026
User avatar Bstran

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The algorithm examines the buffer starting from the beginning, and performs a series of qualifying checks against the TLS specification. When not enough data exists to be certain, the returned value of `boost::indeterminate` informs the caller to read more data into the buffer. The function definition for the declaration above follows:
The algorithm examines the buffer starting from the beginning, and performs a series of qualifying checks against the TLS specification. When not enough data exists to be certain, the returned value of `boost::indeterminate` informs the caller to read more data into the buffer. The function definition for the declaration above follows:该算法从缓冲区开头开始检查，并按照 TLS 规范进行一系列验证。如果数据不足，无法确定结果，则返回 `boost::indeterminate`，通知调用方继续向缓冲区读入更多数据。上面声明的函数，其定义如下：
06/12/2026
User avatar Bstran

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Here is the declaration for a function template to detect the SSL client handshake. The function accepts any object whose type meets the requirements of __ConstBufferSequence__. This gives callers flexibility to use a buffer object whose behavior is appropriate to the task.
Here is the declaration for a function template to detect the SSL client handshake. The function accepts any object whose type meets the requirements of __ConstBufferSequence__. This gives callers flexibility to use a buffer object whose behavior is appropriate to the task.以下函数模板声明用于检测 SSL 客户端握手。该函数接受任何满足 __ConstBufferSequence__ 概念要求的对象，从而使调用方能够根据任务需要灵活选择合适的缓冲区对象。
06/12/2026
User avatar Bstran

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In this example we will build a simple function to detect the presence of the [@https://tools.ietf.org/html/rfc2246#section-7.4 TLS client handshake] given an input buffer sequence. Then we build on the example by adding a synchronous stream algorithm. Finally, we implement an asynchronous detection function using a composed operation. This SSL detector may be used to allow a server to accept both TLS and plain (unencrypted) connections at the same port.
In this example we will build a simple function to detect the presence of the [@https://tools.ietf.org/html/rfc2246#section-7.4 TLS client handshake] given an input buffer sequence. Then we build on the example by adding a synchronous stream algorithm. Finally, we implement an asynchronous detection function using a composed operation. This SSL detector may be used to allow a server to accept both TLS and plain (unencrypted) connections at the same port.本示例将构建一个简单函数，用于检测输入缓冲区序列中是否存在 TLS 客户端握手协议。然后在该示例的基础上，添加一个同步流算法。最后，通过组合操作实现异步检测函数。该 SSL 检测器可用于让服务器在同一端口上同时接受 TLS 和明文（未加密）连接。
06/12/2026
User avatar Bstran

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Detect SSL __example__
Detect检测 SSL __example示例__
06/12/2026
User avatar Bstran

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The listing for a complete, runnable version of this example is in [path_link example/echo-op/echo_op.cpp echo_op.cpp].
The listing for a complete, runnable version of this example is in该示例的完整可运行代码参见 [path_link example/echo-op/echo_op.cpp echo_op.cpp].。
06/12/2026
User avatar Bstran

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* For operations which complete immediately (i.e. without calling an
* For operations which complete immediately (i.e. without calling an对于立即完成的操作（即无需调用异步发起函数即可完成的操作），
06/12/2026
User avatar Bstran

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* Forgetting to provide `executor_type` and `get_executor` for the
* 忘记提供 `executor_type` 和 `get_executor` 成员（为组合操作提供）。
06/12/2026
User avatar Bstran

Translation changed
* Forgetting to create an object of type __executor_work_guard__ with the
* Forgetting to create an object of type忘记创建 __executor_work_guard__ with the对象（使用执行器来创建）。
06/12/2026
User avatar Bstran

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* Forgetting to provide `executor_type` and `get_executor` for the
* Forgetting to provide忘记提供 `executor_type` and和 `get_executor` for the成员（为）。
06/12/2026
User avatar Bstran

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* Calling a synchronous function by accident. In general composed
* Calling a synchronous function by accident. In general composed意外调用同步函数。通常情况下，
06/12/2026
User avatar Bstran

Translation changed
* Forgetting to include a return statement after calling an
* Forgetting to include a return statement after calling an调用异步发起函数后忘记包含 return 语句
06/12/2026
User avatar Bstran

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* Type erasing the final handler. This will cause undefined behavior.
* Type erasing the final handler. This will cause undefined behavior.对最终处理器进行类型擦除，该操作会导致未定义行为。
06/12/2026
User avatar Bstran

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There are some common mistakes that should be avoided when writing composed operations:
当编写组合操作时，需要避免以下几种常见错误：
06/12/2026
User avatar Bstran

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There are some common mistakes that should be avoided when writing composed operations:
There are some common mistakes that should be avoided when writing composed operations:编写组合操作时，需要避免以下几种常见错误：
06/12/2026
User avatar Bstran

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The implementation strategy is to make the composed object meet the requirements of a completion handler by being movable, and by making it invocable so it can be used as a continuation for the asynchronous operations it launches. Rather than using `std::bind` or `boost::bind`, which destroys the type information and therefore breaks the associators, we will simply pass `std::move(*this)` as the completion handler parameter for any operations that we initiate. For the move to work correctly, care must be taken to ensure that no access to data members are made after the move takes place. Here is the complete implementation of our composed operation:
The implementation strategy is to make the composed object meet the requirements of a completion handler by being movable, and by making it invocable so it can be used as a continuation for the asynchronous operations it launches. Rather than using实现策略是让组合对象满足完成处理器的要求：一方面要支持移动语义，另一方面要使其可调用，这样它就能作为其发起的异步操作的后续回调来使用。我们不使用 `std::bind` or或 `boost::bind`, which destroys the type information and therefore breaks the associators, we will simply pass `std::move(*this)` as the completion handler parameter for any operations that we initiate. For the move to work correctly, care must be taken to ensure that no access to data members are made after the move takes place. Here is the complete implementation of our composed operation:，因为它们会丢失类型信息，从而破坏关联器。相反，我们会直接把 `std::move(*this)` 作为完成处理器参数，传递给所发起的每个异步操作。为确保移动操作能正确工作，需要注意在移动发生之后，不能再访问任何数据成员。以下是该组合操作的完整实现：
06/12/2026
User avatar Bstran

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The initiating function contains a few relatively simple parts. There is the customization of the return value type, static type checking, building the return value type using the helper, and creating and launching the `echo_op` composed operation object.
The initiating function contains a few relatively simple parts. There is the customization of the return value type, static type checking, building the return value type using the helper, and creating and launching the `echo_op` composed operation object.发起函数包含几个相对简单的部分：定制返回值类型、静态类型检查、使用辅助工具构建返回值类型，以及创建并启动 `echo_op` 组合操作对象。
06/12/2026
User avatar Bstran

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Now that we have a declaration, we will define the body of the function. We want to achieve the following goals: perform static type checking on the input parameters, set up the return value as per __N3747__, and launch the composed operation by constructing an intermediate, stateful completion handler and invoking it.
Now that we have a declaration, we will define the body of the function. We want to achieve the following goals: perform static type checking on the input parameters, set up the return value as per __N3747__, and launch the composed operation by constructing an intermediate, stateful completion handler and invoking it.完成函数声明后，我们再对该函数的实现部分进行定义。实现过程中需要满足以下几个目标：对输入参数执行静态类型检查，按照 __N3747__ 规范设定返回值类型，同时构造一个带有状态的中间完成处理器并调用该处理器，以此启动组合操作。
06/12/2026
User avatar Bstran

Translation changed
This example develops an initiating function called [*echo]. The operation will read up to the first newline on a stream, and then write the same line including the newline back on the stream. First we define the input parameters and results, then declare our initiation function. For our echo operation the only inputs are the stream and the completion token. The output is the error code which is usually included in all completion handler signatures.
该示例用于开发名为 [*echo] 的启动函数。该操作从流中读取数据，直到遇到第一个换行符为止，然后将读取的内容（包含该换行符）写回流中。

实现步骤如下：首先定义输入参数与返回结果，然后声明启动函数。该回显操作的输入参数仅为流对象与完成令牌，返回结果为错误码。该错误码通常包含在所有完成处理器的签名中。
06/12/2026
User avatar Bstran

Translation changed
This example develops an initiating function called [*echo]. The operation will read up to the first newline on a stream, and then write the same line including the newline back on the stream. First we define the input parameters and results, then declare our initiation function. For our echo operation the only inputs are the stream and the completion token. The output is the error code which is usually included in all completion handler signatures.
This example develops an initiating function called [*echo]. The operation will read up to the first newline on a stream, and then write the same line including the newline back on the stream. First we define the input parameters and results, then declare our initiation function. For our echo operation the only inputs are the stream and the completion token. The output is the error code which is usually included in all completion handler signatures.该示例用于开发名为 [*echo] 的启动函数。该操作从流中读取数据，直到遇到第一个换行符为止，然后将读取的内容（包含该换行符）写回流中。

实现步骤如下：首先定义输入参数与返回结果，然后声明启动函数。该回显操作的输入参数仅为流对象与完成令牌，返回结果为错误码。该错误码通常包含在所有完成处理器的签名中。
06/12/2026

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