make esp task yielding more consistent and reduce overhead

src/CMakeLists.txt

@@ -4,5 +4,5 @@
 FILE(GLOB_RECURSE app_sources ${CMAKE_SOURCE_DIR}/src/*.*)
 
 idf_component_register(SRCS ${app_sources}
-  PRIV_REQUIRES esp_wifi nvs_flash
+  PRIV_REQUIRES esp_wifi nvs_flash esp_timer
   INCLUDE_DIRS ".")

src/globals.c

@@ -5,6 +5,24 @@
 
 #include "globals.h"
 
+#ifdef ESP_PLATFORM
+  #include "esp_task_wdt.h"
+  #include "esp_timer.h"
+
+  // Time between vTaskDelay calls in microseconds
+  #define TASK_YIELD_INTERVAL 1000 * 1000
+  // How many ticks to delay for on each yield
+  #define TASK_YIELD_TICKS 1
+
+  int64_t last_yield = 0;
+  void task_yield () {
+    int64_t time_now = esp_timer_get_time();
+    if (time_now - last_yield < TASK_YIELD_INTERVAL) return;
+    vTaskDelay(TASK_YIELD_TICKS);
+    last_yield = time_now;
+  }
+#endif
+
 ssize_t recv_count;
 uint8_t recv_buffer[256] = {0};
 

src/main.c

@@ -16,6 +16,7 @@
   #include "esp_wifi.h"
   #include "esp_event.h"
   #include "esp_task_wdt.h"
+  #include "esp_timer.h"
   #include "lwip/sockets.h"
   #include "lwip/netdb.h"
 #else
@@ -97,7 +98,7 @@ void handlePacket (int client_fd, int length, int packet_id) {
 
         sc_synchronizePlayerPosition(client_fd, spawn_x, spawn_y, spawn_z, spawn_yaw, spawn_pitch);
 
-        wdt_reset();
+        task_yield();
 
         for (uint8_t i = 0; i < 41; i ++) {
           sc_setContainerSlot(client_fd, 0, serverSlotToClientSlot(0, i), player->inventory_count[i], player->inventory_items[i]);
@@ -115,7 +116,7 @@ void handlePacket (int client_fd, int length, int packet_id) {
         sc_startWaitingForChunks(client_fd);
         sc_setCenterChunk(client_fd, _x, _z);
 
-        wdt_reset();
+        task_yield();
 
         // Send spawn chunk first
         sc_chunkDataAndUpdateLight(client_fd, _x, _z);
@@ -128,7 +129,7 @@ void handlePacket (int client_fd, int length, int packet_id) {
         // Re-synchronize player position after all chunks have been sent
         sc_synchronizePlayerPosition(client_fd, spawn_x, spawn_y, spawn_z, spawn_yaw, spawn_pitch);
 
-        wdt_reset();
+        task_yield();
 
         // Register all existing players and spawn their entities, and broadcast
         // information about the joining player to all existing players.
@@ -398,7 +399,8 @@ int main () {
    * client connection.
    */
   while (true) {
-    if (client_count == 0) { wdt_reset(); }
+    // Check if it's time to yield to the idle task
+    task_yield();
 
     // Attempt to accept a new connection
     for (int i = 0; i < MAX_PLAYERS; i ++) {
@@ -473,8 +475,6 @@ int main () {
       disconnectClient(&clients[client_index], 4);
       continue;
     }
-    // Reset watchdog and yield between packets
-    wdt_reset();
 
   }
 
@@ -486,7 +486,6 @@ int main () {
 #ifdef ESP_PLATFORM
 
 void bareiron_main (void *pvParameters) {
-  esp_task_wdt_add(NULL);
   main();
   vTaskDelete(NULL);
 }
@@ -528,6 +527,7 @@ void wifi_init () {
 }
 
 void app_main () {
+  esp_timer_early_init();
   wifi_init();
 }
 

src/packets.c

@@ -308,8 +308,8 @@ int sc_chunkDataAndUpdateLight (int client_fd, int _x, int _z) {
     writeByte(client_fd, 0); // biome bits
     writeByte(client_fd, 0); // biome palette
   }
-  // reset watchdog and yield
-  wdt_reset();
+  // yield to idle task
+  task_yield();
 
   // send chunk sections
   for (int i = 0; i < 20; i ++) {
@@ -325,8 +325,8 @@ int sc_chunkDataAndUpdateLight (int client_fd, int _x, int _z) {
     // biome data
     writeByte(client_fd, 0); // bits per entry
     writeByte(client_fd, W_plains); // biome palette
-    // reset watchdog and yield
-    wdt_reset();
+    // yield to idle task
+    task_yield();
   }
 
   // send 8 chunk sections (up to Y=192) with no blocks
@@ -337,8 +337,8 @@ int sc_chunkDataAndUpdateLight (int client_fd, int _x, int _z) {
     writeByte(client_fd, 0); // biome bits
     writeByte(client_fd, 0); // biome palette
   }
-  // reset watchdog and yield
-  wdt_reset();
+  // yield to idle task
+  task_yield();
 
   writeVarInt(client_fd, 0); // omit block entities
 

src/tools.c

@@ -47,8 +47,7 @@ ssize_t recv_all (int client_fd, void *buf, size_t n, uint8_t require_first) {
     ssize_t r = recv(client_fd, p + total, n - total, 0);
     if (r < 0) {
       if (errno == EAGAIN || errno == EWOULDBLOCK) {
-        // spin until data arrives
-        wdt_reset();
+        task_yield();
         continue;
       } else {
         return -1; // real error
@@ -78,7 +77,7 @@ ssize_t send_all (int client_fd, const void *buf, size_t len) {
       return -1;
     }
     if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK) {
-      wdt_reset();
+      task_yield();
       continue;
     }
     return -1;