Fix conditions that could cause SNTPClient.blockingEpochTime to block forever

README.md

@@ -41,13 +41,16 @@ Version numbers can be found under [Releases](https://github.com/tidal-music/net
 ## Usage
 
 Create your `SNTPClient` via its constructor. Its API allows you to toggle synchronization (starts
-off) and to retrieve the time based on the latest successful synchronization, if any.
+off) and to retrieve the time based on the latest successful synchronization.
 
-The property that retrieves the aforementioned time is nullable as it will return `null` if no
+The nullable property `epochTime` retrieves the aforementioned time will return `null` if no
 synchronization has occurred successfully during the lifetime of the process and no backup file has
 been specified for the `SNTPClient` instance or said file contains no valid prior synchronization
 data.
 
+As an alternative, the `blockingEpochTime` method can be used to suspend the caller until a valid
+synchronization or backup restoration occurs to avoid a nullable return type.
+
 ## networktime-singletons
 
 This is a tiny utility on top of the base artifact that extends the `SNTPClient` API by adding a new

changelog/1.1.1

@@ -0,0 +1 @@
+Fix bug when accessing SNTPClient.blockingEpoch time multiple times prior to a successful sync.

networktime/src/commonMain/kotlin/com/tidal/networktime/SNTPClient.kt

@@ -39,7 +39,8 @@ class SNTPClient(
   val epochTime by delegate::epochTime
 
   /**
-   * The calculated epoch time, blocking until it has been calculated at least once.
+   * The calculated epoch time. Suspends the caller until said time has been calculated at least
+   * once.
    */
   @ObjCName(name = "blockingEpochTimeMs")
   suspend fun blockingEpochTime() = delegate.blockingEpochTime()

networktime/src/commonMain/kotlin/com/tidal/networktime/internal/SNTPClientImpl.kt

@@ -42,7 +42,10 @@ constructor(
   suspend fun blockingEpochTime(): Duration {
     epochTime?.let { return it }
     synchronizationResultProcessor.firstSynchronizationLock
-      .lock()
+      .apply {
+        lock()
+        unlock()
+      }
     return epochTime!!
   }
 

networktime/src/commonMain/kotlin/com/tidal/networktime/internal/SynchronizationResultProcessor.kt

@@ -30,8 +30,11 @@ internal class SynchronizationResultProcessor(
       return value
     }
     set(value) {
+      val oldValue = mutableState.synchronizationResult
       mutableState.synchronizationResult = value
-      firstSynchronizationLock.unlock()
+      if (oldValue == null && value != null) {
+        firstSynchronizationLock.unlock()
+      }
       if (backupFilePath != null && value != null) {
         try {
           fileSystem.write(backupFilePath) {