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use a mutex to make requestJSONBufferLock / releaseJSONBufferLock robust

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similar to upstream https://github.com/wled/WLED/pull/4089,
but with slightly different "failure" logic.
This commit is contained in:
Frank
2025-12-23 00:05:16 +01:00
parent 9b5ae9fff9
commit d3076c43ec
1 changed files with 19 additions and 4 deletions
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23
wled00/util.cpp
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@@ -222,17 +222,31 @@ bool isAsterisksOnly(const char* str, byte maxLen)
//threading/network callback details: https://github.com/Aircoookie/WLED/pull/2336#discussion_r762276994
bool requestJSONBufferLock(uint8_t module)
{
unsigned long now = millis();
bool haveLock = false;
#ifdef ARDUINO_ARCH_ESP32
// We use a recursive mutex to prevent parallel JSON writes from parallel tasks.
// This also fixes hanging up for the full timeout interval in cases when the contention is from the same task.
// see https://github.com/wled/WLED/pull/4089 for more details.
if (esp32SemTake(jsonBufferLockMutex, 1800) == pdTRUE) haveLock = true; // WLEDMM must wait longer than suspendStripService timeout = 1500ms
#else
// 8266: only wait in case that can_yield() tells us we can yield and delay
if (can_yield()) {
unsigned long now = millis();
while (jsonBufferLock && millis()-now < 1800) delay(1); // wait for fraction for buffer lock // WLEDMM must wait longer than suspendStripService timeout = 1500ms
if (!jsonBufferLock) haveLock = true;
}
#endif
while (jsonBufferLock && millis()-now < 1100) delay(1); // wait for fraction for buffer lock
if (jsonBufferLock) {
if (jsonBufferLock || !haveLock) {
if (haveLock) esp32SemGive(jsonBufferLockMutex); // we got the mutex, but jsonBufferLock says the opposite -> give up
delay(10); // WLEDMM experimental: small extra wait, in case that esp32 cores temporarily disagree on the value of jsonBufferLock
USER_PRINT(F("ERROR: Locking JSON buffer failed! (still locked by "));
USER_PRINT(jsonBufferLock);
USER_PRINTLN(")");
return false; // waiting time-outed
}
// success - we keep holding the mutex until releaseJSONBufferLock()
jsonBufferLock = module ? module : 255;
DEBUG_PRINT(F("JSON buffer locked. ("));
DEBUG_PRINT(jsonBufferLock);
@@ -250,6 +264,7 @@ void releaseJSONBufferLock()
DEBUG_PRINTLN(")");
fileDoc = nullptr;
jsonBufferLock = 0;
esp32SemGive(jsonBufferLockMutex); // return the mutex
}