50 lines
1.5 KiB
Markdown
50 lines
1.5 KiB
Markdown
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# Threading
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*Smallest sequence of programmed instructions that can be managed independently by a [scheduler](https://en.wikipedia.org/wiki/Scheduling_(computing))*
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From <[https://en.wikipedia.org/wiki/Thread_(computing)](https://en.wikipedia.org/wiki/Thread_(computing))>
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- Instructions run independently by scheduler
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- Single address space
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- One thread blocked for I/O
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- Tasks run in other threads
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- Need locks and mutexes
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- Coordination between threads
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- Complicated
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- Deadlocks
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# Protothreads
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- Lightweight
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- Stack-less
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- Interruptible tasks for event-based
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- Conditional blocking statement
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- Blocks until given statement is true
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- Use timer to manage
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- Invoked whenever process receives message from another process or timer
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# Events
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*Action or occurrence recognized by software, often originating asynchronously from the external environment, that may be [handled](https://en.wikipedia.org/wiki/Event_handler) by the software*
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From <[https://en.wikipedia.org/wiki/Event_(computing)](https://en.wikipedia.org/wiki/Event_(computing))>
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- Event loop
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- Waits for events
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- Inputs
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- On event
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- Collects info
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- Dispatches to call-back
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- Register handlers with OS scheduler
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- Kernel usually runs loop to poll for events
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- Blocking operation
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- Register call-back
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- Return control to scheduler
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# Radio Sleep
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- Energy efficiency
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- Congestion
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## Event-based
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## Thread-based
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- Less complex
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- Faster
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- Pointer-based
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