Async Logging (ISR-Safe)

Detailed Description

ISR-safe logging using ring buffers for deferred output.

Async logging enables safe logging from interrupt service routines (ISRs) by queueing messages in a ring buffer and draining them later from the main thread. This prevents watchdog timeouts caused by slow Serial I/O operations inside ISRs.

Automatic Servicing (Recommended): Async loggers are automatically serviced by fl::task system when using fl::delay(). No manual service calls required!

void IRAM_ATTR my_isr_handler() {
    FL_LOG_PARLIO_ASYNC_ISR("DMA complete");  // ISR-safe (const char* only)
}
 
void loop() {
    FL_LOG_PARLIO_ASYNC_MAIN("Processing batch " << batch_id);  // Main thread
    fl::delay(10);  // Loggers serviced automatically every 16ms (60fps)!
}

Manual Control (Optional): For fine-grained control, you can still manually service or flush loggers:

void loop() {
    fl::async_log_service();       // Manual service (for legacy timer-based flush)
    FL_LOG_PARLIO_ASYNC_FLUSH();   // Flush PARLIO immediately (all queued messages)
}

Custom Configuration (Optional): Configure service interval and messages-per-tick BEFORE first logger access:

void setup() {
    fl::configureAsyncLogService(50, 10);  // 50ms interval, 10 msgs/tick
    FL_LOG_PARLIO_ASYNC_MAIN("Setup complete");  // Task auto-instantiates here
}

Memory Footprint (Zero Heap Allocation):

• Each logger uses ~5KB static storage (128 descriptors + 4KB arena)
• Singletons instantiated lazily on first access (linker removes unused loggers)
• ISR messages: Stored as const char* (zero overhead, string literals only)
• Main thread messages: Stored as fl::string (arena-allocated, no heap)
• Ring buffer auto-evicts oldest messages when full (FIFO overflow)

Thread Safety:

• push() is ISR-safe (no locks, single-writer pattern)
• flush() must be called from main thread only

Namespaces
namespace	fl
	Base definition for an LED controller.

Macros
#define	FL_LOG_ASYNC(logger, X)
	Generic async logging macro (captures stream expression into string)
#define	FL_LOG_ASYNC_ISR(logger, msg)
#define	FL_LOG_AUDIO_ASYNC_FLUSH()
#define	FL_LOG_AUDIO_ASYNC_ISR(X)
#define	FL_LOG_AUDIO_ASYNC_MAIN(X)
#define	FL_LOG_FLEXIO_ASYNC_FLUSH()
#define	FL_LOG_FLEXIO_ASYNC_ISR(X)
#define	FL_LOG_FLEXIO_ASYNC_MAIN(X)
#define	FL_LOG_INTERRUPT_ASYNC_FLUSH()
#define	FL_LOG_INTERRUPT_ASYNC_ISR(X)
#define	FL_LOG_INTERRUPT_ASYNC_MAIN(X)
#define	FL_LOG_OBJECTFLED_ASYNC_FLUSH()
#define	FL_LOG_OBJECTFLED_ASYNC_ISR(X)
#define	FL_LOG_OBJECTFLED_ASYNC_MAIN(X)
#define	FL_LOG_PARLIO_ASYNC_FLUSH()
#define	FL_LOG_PARLIO_ASYNC_ISR(X)
#define	FL_LOG_PARLIO_ASYNC_MAIN(X)
#define	FL_LOG_RMT_ASYNC_FLUSH()
#define	FL_LOG_RMT_ASYNC_ISR(X)
#define	FL_LOG_RMT_ASYNC_MAIN(X)
#define	FL_LOG_SPI_ASYNC_FLUSH()
#define	FL_LOG_SPI_ASYNC_ISR(X)
#define	FL_LOG_SPI_ASYNC_MAIN(X)