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149 lines
4.7 KiB
Plaintext
149 lines
4.7 KiB
Plaintext
queue_spsc_atomic
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A fixed capacity single-producer, single-consumer queue for multi-threaded and interrupt driven systems.
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The queue may be used to transfer data to or from two threads or an ISR.
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The queue makes use of etl::atomic_size_t
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etl::queue_spsc_atomic<typename T,
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const size_t SIZE,
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const size_t MEMORY_MODEL = etl::memory_model::MEMORY_MODEL_LARGE>
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Inherits from etl::iqueue_spsc_atomic<T>
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etl::iqueue_spsc_atomic may be used as a size independent pointer or reference type for any etl::queue_spsc_atomic instance of the same implementation.
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The memory model determines the type used internally for indexes and size, to allow for the most efficient implementation for the application.
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Maximum queue sizes:
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MEMORY_MODEL_SMALL 255
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MEMORY_MODEL_MEDIUM 65535
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MEMORY_MODEL_LARGE 2147483647
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MEMORY_MODEL_HUGE 9223372036854775807
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See memory_model.h
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____________________________________________________________________________________________________
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Member types
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value_type T
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size_type <based on memory model>
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pointer value_type*
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const_pointer const value_type*
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reference value_type&
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const_reference const value_type&
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____________________________________________________________________________________________________
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Constructor
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queue_spsc_atomic();
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____________________________________________________________________________________________________
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Capacity
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bool empty() const
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Returns true if the size of the queue is zero, otherwise false.
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Accurate from the 'pop' thread.
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'Not empty' is a guess from the 'push' thread.
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____________________________________________________________________________________________________
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bool full() const
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Returns true if the size of the queue is SIZE, otherwise false.
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Accurate from the 'push' thread.
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'Not full' is a guess from the 'pop' thread.
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____________________________________________________________________________________________________
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size_t size() const
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Returns the size of the queue.
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Due to concurrency, this is a guess.
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____________________________________________________________________________________________________
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size_t available() const
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Returns the remaining available capacity in the queue.
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Due to concurrency, this is a guess.
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____________________________________________________________________________________________________
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ETL_CONSTEXPR size_t max_size() const
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Returns the maximum possible size of the queue.
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____________________________________________________________________________________________________
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ETL_CONSTEXPR size_t capacity() const
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Returns the maximum possible size of the queue.
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____________________________________________________________________________________________________
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Modifiers
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bool push(const T& value);
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bool push(T&& value);
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Pushes a value to the back of the queue.
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Returns true if successful, otherwise false.
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____________________________________________________________________________________________________
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bool pop();
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Pop a value from the front of the list.
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Returns true if successful, otherwise false.
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____________________________________________________________________________________________________
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bool pop(T& value);
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bool pop(T&& value);
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Pop a value from the front of the list and place it in value.
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Returns true if successful, otherwise false.
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____________________________________________________________________________________________________
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void clear();
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Clears the queue to a size of zero.
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Must be called from thread that pops the queue or when there is no possibility of concurrent access.
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____________________________________________________________________________________________________
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C++03
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bool emplace(const T1& value1);
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bool emplace(const T1& value1, const T2& value2);
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bool emplace(const T1& value1, const T2& value2, const T3& value3);
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bool emplace(const T1& value1, const T2& value2, const T3& value3, const T4& value4);
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C++11
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bool emplace(Args&&… args);
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Constructs an item in the the queue 'in place'.
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C++03: Supports up to four constructor parameters.
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____________________________________________________________________________________________________
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Notes
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Remember that thread context switches may occur between calls to the access protected functions. For example, a call to empty() may return true, but a subsequent call to pop() may succeed if a context switch occurred between the two and pushed a new value.
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____________________________________________________________________________________________________
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Example
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etl::queue_spsc_atomic<char, 10> queue;
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int main()
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{
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while (true)
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{
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char c;
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if (queue.pop(c))
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{
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Print(c);
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}
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}
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}
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void Thread()
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{
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while (true)
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{
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queue.push('A');
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}
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}
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