J. Nick KostonandJonathan Swoboda
ab45591507
Co-authored-by: Jonathan Swoboda <154711427+swoboda1337@users.noreply.github.com>
66 lines
3.2 KiB
C
66 lines
3.2 KiB
C
#pragma once
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// Fast socket monitoring for ESP32 and LibreTiny (LwIP >= 2.1.3)
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// Replaces lwip_select() with direct rcvevent reads and FreeRTOS task notifications.
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#include <stdbool.h>
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#include <stdint.h>
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// Forward declare lwip_sock for C++ callers that store cached pointers.
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// The full definition is only available in the .c file (lwip/priv/sockets_priv.h
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// conflicts with C++ compilation units).
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struct lwip_sock;
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// Byte offset of rcvevent (s16_t) within struct lwip_sock.
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// Verified at compile time in lwip_fast_select.c via _Static_assert.
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// Anonymous enum for a compile-time constant that works in both C and C++.
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enum { ESPHOME_LWIP_SOCK_RCVEVENT_OFFSET = 8 };
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#ifdef __cplusplus
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extern "C" {
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#endif
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/// Look up a LwIP socket struct from a file descriptor.
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/// Returns NULL if fd is invalid or the socket/netconn is not initialized.
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/// Use this at registration time to cache the pointer for esphome_lwip_socket_has_data().
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struct lwip_sock *esphome_lwip_get_sock(int fd);
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/// Check if a cached LwIP socket has data ready via unlocked hint read of rcvevent.
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/// This avoids lwIP core lock contention between the main loop (CPU0) and
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/// streaming/networking work (CPU1). Correctness is preserved because callers
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/// already handle EWOULDBLOCK on nonblocking sockets — a stale hint simply causes
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/// a harmless retry on the next loop iteration. In practice, stale reads have not
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/// been observed across multi-day testing, but the design does not depend on that.
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///
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/// The sock pointer must have been obtained from esphome_lwip_get_sock() and must
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/// remain valid (caller owns socket lifetime — no concurrent close).
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/// Hot path: inlined volatile 16-bit load — no function call overhead.
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/// Uses offset-based access because lwip/priv/sockets_priv.h conflicts with C++.
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/// The offset and size are verified at compile time in lwip_fast_select.c.
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static inline bool esphome_lwip_socket_has_data(struct lwip_sock *sock) {
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// Unlocked hint read — no lwIP core lock needed.
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// volatile prevents the compiler from caching/reordering this cross-thread read.
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// The write side (TCP/IP thread) commits via SYS_ARCH_UNPROTECT which releases a
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// FreeRTOS mutex (ESP32) or resumes the scheduler (LibreTiny), ensuring the value
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// is visible. Aligned 16-bit reads are single-instruction loads (L16SI/LH/LDRH) on
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// Xtensa/RISC-V/ARM and cannot produce torn values.
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return *(volatile int16_t *) ((char *) sock + (int) ESPHOME_LWIP_SOCK_RCVEVENT_OFFSET) > 0;
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}
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/// Hook a socket's netconn callback to notify the main loop task on receive events.
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/// Wraps the original event_callback with one that also calls xTaskNotifyGive().
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/// Must be called from the main loop after socket creation.
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/// The sock pointer must have been obtained from esphome_lwip_get_sock().
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void esphome_lwip_hook_socket(struct lwip_sock *sock);
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/// Set or clear TCP_NODELAY on a socket's tcp_pcb directly.
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/// Must be called with the TCPIP core lock held (LwIPLock in C++).
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/// This bypasses lwip_setsockopt() overhead (socket lookups, switch cascade,
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/// hooks, refcounting) — just a direct pcb->flags bit set/clear.
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/// Returns true if successful, false if sock/conn/pcb is NULL or the socket is not TCP.
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bool esphome_lwip_set_nodelay(struct lwip_sock *sock, bool enable);
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#ifdef __cplusplus
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}
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#endif
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