Add mutex to global race data.

include/config.h

@@ -12,3 +12,5 @@
 // Display resolution
 #define EPD_4IN2B_V2_WIDTH       400
 #define EPD_4IN2B_V2_HEIGHT      300
+
+#define MUTEX_TIMEOUT_TICKS      pdMS_TO_TICKS(150)

src/F1_api.h

@@ -4,8 +4,9 @@
 #include "task.h"
 #include "secrets.h"
 #include "ArduinoJson.h"
+#include "config.h"
 
-struct race_info {
+struct race_info_t {
     char session_name[50];
     char date_start[32];
     char circuit_short_name[50];
@@ -14,7 +15,8 @@ struct race_info {
     uint16_t circuit_key;
 };
 
-extern race_info next_race;
+extern race_info_t race_data;
+extern SemaphoreHandle_t dataMutex;
 
 static int get_race_query_url(char* target, size_t target_size) {
     if (target == NULL) return -1;
@@ -45,8 +47,43 @@ static int get_race_query_url(char* target, size_t target_size) {
 
 }
 
-int parse_session_json() {
+int parse_session_json(JsonArray sessions, race_info_t session) {
+    JsonObject nextRaceJson = sessions[0];
+    race_info_t localData;
 
+    const char* sessionName = nextRaceJson[F("session_name")];
+    const char* dateStart = nextRaceJson[F("date_start")];
+    const char* circuitName = nextRaceJson[F("circuit_short_name")];
+
+    localData.session_key = nextRaceJson[F("session_key")];
+    if (localData.session_key == 0) return -1;
+
+    localData.meeting_key = nextRaceJson[F("meeting_key")];
+    if (localData.meeting_key == 0) return -1;
+
+    localData.circuit_key = nextRaceJson[F("circuit_key")];
+    if (localData.circuit_key == 0) return -1;
+
+    if (sessionName != NULL) {
+        strlcpy(localData.session_name, sessionName, sizeof(localData.session_name));
+    } else return -1;
+    if (dateStart != NULL) {
+        strlcpy(localData.date_start, dateStart, sizeof(localData.date_start));
+    } else return -1;
+    if (circuitName != NULL) {
+        strlcpy(localData.circuit_short_name, circuitName, sizeof(localData.circuit_short_name));
+    } else return -1;
+
+    if (xSemaphoreTake(dataMutex, MUTEX_TIMEOUT_TICKS)) {
+        race_data = localData;
+        xSemaphoreGive(dataMutex);
+    } else {
+        Serial.print("");
+        Serial.println("Unable to acquire mutex, API loop.");
+        return -1;
+    }
+
+    return 0;
 }
 
 void get_next_race(void *pvParameters) {
@@ -62,9 +99,6 @@ void get_next_race(void *pvParameters) {
 
             char query_url[103];
             get_race_query_url(query_url, sizeof(query_url));
-            Serial.print("");
-            Serial.print("Query: ");
-            Serial.println(query_url);
 
             const bool requestReady = http.begin(query_url);
             if (!requestReady) {
@@ -81,30 +115,7 @@ void get_next_race(void *pvParameters) {
                     if (err == DeserializationError::Ok) {
                         JsonArray sessions = json.as<JsonArray>();
                         if (sessions.size() != 0) {
-                            JsonObject nextRaceJson = sessions[0];
+                            parse_session_json(sessions, race_data);
-                            const char* sessionName = nextRaceJson[F("session_name")];
-                            const char* dateStart = nextRaceJson[F("date_start")];
-                            const char* circuitName = nextRaceJson[F("circuit_short_name")];
-                            next_race.session_key = nextRaceJson[F("session_key")];
-                            next_race.meeting_key = nextRaceJson[F("meeting_key")];
-                            next_race.circuit_key = nextRaceJson[F("circuit_key")];
-                            if (sessionName != NULL) {
-                                strlcpy(next_race.session_name, sessionName, sizeof(next_race.session_name));
-                            }
-                            if (dateStart != NULL) {
-                                strlcpy(next_race.date_start, dateStart, sizeof(next_race.date_start));
-                            }
-                            if (circuitName != NULL) {
-                                strlcpy(next_race.circuit_short_name, circuitName, sizeof(next_race.circuit_short_name));
-                            }
-                            
-                            Serial.print("");
-                            Serial.print("Next race: ");
-                            Serial.print(next_race.session_name);
-                            Serial.print(" at ");
-                            Serial.print(next_race.circuit_short_name);
-                            Serial.print(" on ");
-                            Serial.println(next_race.date_start);
                         }
                     } else {
                         Serial.print("");

src/main.cpp

@@ -5,6 +5,7 @@
 #include "F1_api.h"
 #include "FreeRTOS.h"
 #include "task.h"
+#include <semphr.h>
 
 #include "config.h"
 
@@ -21,7 +22,9 @@ static constexpr UWORD COUNTER_HEIGHT = 24;
 static constexpr UWORD COUNTER_Y = 20;
 static UBYTE counterBuffer[(COUNTER_WIDTH / 8) * COUNTER_HEIGHT];
 static int counter = 0;
-race_info next_race;
+
+race_info_t race_data;
+SemaphoreHandle_t dataMutex;
 
 void wifi_connect() {
     WiFi.setHostname(DEVICE_HOSTNAME);
@@ -78,6 +81,7 @@ bool readLocalTime(struct tm* result) {
 }
 
 void display_loop(void *pvParameters) {
+    static race_info_t local_data;
     while (true) {
         static unsigned long lastRefresh = 0;
         static char counterStr[32];
@@ -91,12 +95,22 @@ void display_loop(void *pvParameters) {
 
         counter++;
 
-        if (next_race.session_key == 0) {
+        if (xSemaphoreTake(dataMutex, MUTEX_TIMEOUT_TICKS)) {
+            local_data = race_data;
+            xSemaphoreGive(dataMutex);
+            //Display will continue to use old data
+        } else {
+            Serial.print("");
+            Serial.println("Failed to acquire mutex in display thread!");
+        }
+
+
+        if (race_data.session_key == 0) {
             snprintf(counterStr, sizeof(counterStr), "Counter: %d", counter);
             Serial.print("");
             Serial.println(counterStr);
         } else {
-            snprintf(counterStr, sizeof(counterStr), "%s", next_race.circuit_short_name);
+            snprintf(counterStr, sizeof(counterStr), "%s", race_data.circuit_short_name);
         }
 
         Paint_Clear(WHITE);
@@ -116,6 +130,12 @@ void display_loop(void *pvParameters) {
 void setup() {
     Serial.begin(115200);
 
+    dataMutex = xSemaphoreCreateMutex();
+    if (dataMutex == NULL) {
+        Serial.println("Failed to create mutex!");
+        while(1);
+    }
+
     if (DEV_Module_Init() != 0) {
         Serial.println("Failed to initialize display module.");
         return;