incorporate androidlib

app/src/main/java/com/geeksville/mesh/concurrent/SyncContinuation.kt

@@ -0,0 +1,82 @@
+package com.geeksville.mesh.concurrent
+
+import com.geeksville.mesh.android.Logging
+
+
+/**
+ * A deferred execution object (with various possible implementations)
+ */
+interface Continuation<in T> : Logging {
+    abstract fun resume(res: Result<T>)
+
+    // syntactic sugar
+
+    fun resumeSuccess(res: T) = resume(Result.success(res))
+    fun resumeWithException(ex: Throwable) = try {
+        resume(Result.failure(ex))
+    } catch (ex: Throwable) {
+        // errormsg("Ignoring $ex while resuming, because we are the ones who threw it")
+        throw ex
+    }
+}
+
+/**
+ * An async continuation that just calls a callback when the result is available
+ */
+class CallbackContinuation<in T>(private val cb: (Result<T>) -> Unit) : Continuation<T> {
+    override fun resume(res: Result<T>) = cb(res)
+}
+
+/**
+ * This is a blocking/threaded version of coroutine Continuation
+ *
+ * A little bit ugly, but the coroutine version has a nasty internal bug that showed up
+ * in my SyncBluetoothDevice so I needed a quick workaround.
+ */
+class SyncContinuation<T> : Continuation<T> {
+
+    private val mbox = java.lang.Object()
+    private var result: Result<T>? = null
+
+    override fun resume(res: Result<T>) {
+        synchronized(mbox) {
+            result = res
+            mbox.notify()
+        }
+    }
+
+    // Wait for the result (or throw an exception)
+    fun await(timeoutMsecs: Long = 0): T {
+        synchronized(mbox) {
+            val startT = System.currentTimeMillis()
+            while (result == null) {
+                mbox.wait(timeoutMsecs)
+
+                if (timeoutMsecs > 0 && ((System.currentTimeMillis() - startT) >= timeoutMsecs))
+                    throw Exception("SyncContinuation timeout")
+            }
+
+            val r = result
+            if (r != null)
+                return r.getOrThrow()
+            else
+                throw Exception("This shouldn't happen")
+        }
+    }
+}
+
+/**
+ * Calls an init function which is responsible for saving our continuation so that some
+ * other thread can call resume or resume with exception.
+ *
+ * Essentially this is a blocking version of the (buggy) coroutine suspendCoroutine
+ */
+fun <T> suspend(timeoutMsecs: Long = -1, initfn: (SyncContinuation<T>) -> Unit): T {
+    val cont = SyncContinuation<T>()
+
+    // First call the init funct
+    initfn(cont)
+
+    // Now wait for the continuation to finish
+    return cont.await(timeoutMsecs)
+}