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32 lines
1.3 KiB
Markdown
32 lines
1.3 KiB
Markdown
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# Asynchronous operations
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Node.js native add-ons often need to execute long running tasks and to avoid
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blocking the **event loop** they have to run them asynchronously from the
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**event loop**.
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In the Node.js model of execution the event loop thread represents the thread
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where JavaScript code is executing. The Node.js guidance is to avoid blocking
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other work queued on the event loop thread. Therefore, we need to do this work on
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another thread.
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All this means that native add-ons need to leverage async helpers from libuv as
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part of their implementation. This allows them to schedule work to be executed
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asynchronously so that their methods can return in advance of the work being
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completed.
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Node Addon API provides an interface to support functions that cover
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the most common asynchronous use cases. There is an abstract classes to implement
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asynchronous operations:
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- **[`Napi::AsyncWorker`](async_worker.md)**
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These class helps manage asynchronous operations through an abstraction
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of the concept of moving data between the **event loop** and **worker threads**.
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Also, the above class may not be appropriate for every scenario. When using any
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other asynchronous mechanism, the following API is necessary to ensure an
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asynchronous operation is properly tracked by the runtime:
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- **[AsyncContext](async_context.md)**
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- **[CallbackScope](callback_scope.md)**
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