pushprox refactored

client/app/src/main/java/com/birdthedeveloper/prometheus/android/prometheus/android/exporter/compose/PromViewModel.kt

@@ -99,15 +99,9 @@ class PromViewModel(): ViewModel() {
         when(_uiState.value.exporterState) {
             ExporterState.Running -> {
                 stopWorker()
-                _uiState.update { current ->
-                    current.copy(exporterState = ExporterState.NotRunning)
-                }
             }
             ExporterState.NotRunning -> {
                 startWorker()
-                _uiState.update { current ->
-                    current.copy(exporterState = ExporterState.Running)
-                }
             }
         }
     }
@@ -125,36 +119,53 @@ class PromViewModel(): ViewModel() {
         }
     }
 
+    private fun validatePromConfiguration() : Boolean{
+        //TODO implement this, on missing fields, e.g. not valid, display alert dialog in UI
+        return true
+    }
+
     private fun startWorker(){
-        Log.v(TAG, "Enqueuing work")
-        val workManagerInstance = WorkManager.getInstance(getContext())
+        if (validatePromConfiguration()){
+            Log.v(TAG, "Enqueuing work")
+            val workManagerInstance = WorkManager.getInstance(getContext())
 
-        // worker configuration
-        val inputData : Data = _uiState.value.promConfig.toWorkData()
+            // worker configuration
+            val inputData : Data = _uiState.value.promConfig.toWorkData()
 
-        // constraints
-        val constraints = Constraints.Builder()
-            .setRequiredNetworkType(NetworkType.NOT_REQUIRED)
-            .build()
+            // constraints
+            val constraints = Constraints.Builder()
+                .setRequiredNetworkType(NetworkType.NOT_REQUIRED)
+                .build()
 
-        // setup worker request
-        val workerRequest = OneTimeWorkRequestBuilder<PromWorker>()
-            .setInputData(inputData)
-            .setConstraints(constraints)
-            .setExpedited(OutOfQuotaPolicy.RUN_AS_NON_EXPEDITED_WORK_REQUEST)
-            .build()
+            // setup worker request
+            val workerRequest = OneTimeWorkRequestBuilder<PromWorker>()
+                .setInputData(inputData)
+                .setConstraints(constraints)
+                .setExpedited(OutOfQuotaPolicy.RUN_AS_NON_EXPEDITED_WORK_REQUEST)
+                .build()
 
-        // enqueue
-        workManagerInstance.beginUniqueWork(
-            PROM_UNIQUE_WORK,
-            ExistingWorkPolicy.KEEP,
-            workerRequest,
-        ).enqueue()
+            // enqueue
+            workManagerInstance.beginUniqueWork(
+                PROM_UNIQUE_WORK,
+                ExistingWorkPolicy.KEEP,
+                workerRequest,
+            ).enqueue()
+
+            // set UI state
+            _uiState.update { current ->
+                current.copy(exporterState = ExporterState.Running)
+            }
+        }
     }
 
     private fun stopWorker(){
         val workerManagerInstance = WorkManager.getInstance(getContext())
         workerManagerInstance.cancelUniqueWork(PROM_UNIQUE_WORK)
+
+        // update UI state
+        _uiState.update { current ->
+            current.copy(exporterState = ExporterState.NotRunning)
+        }
     }
 
     fun updatePromConfig(part : UpdatePromConfig, value : Any){

client/app/src/main/java/com/birdthedeveloper/prometheus/android/prometheus/android/exporter/worker/ExponentialBackoff.kt

@@ -0,0 +1,44 @@
+package com.birdthedeveloper.prometheus.android.prometheus.android.exporter.worker
+
+import kotlinx.coroutines.CancellationException
+import kotlinx.coroutines.delay
+import kotlin.math.pow
+
+class ExponentialBackoff{
+    companion object{
+        private const val multiplier : Double = 2.0
+        private const val initialDelay = 3.0 // seconds
+
+        suspend fun runWithBackoff(function : suspend () -> Unit, onException: () -> Unit){
+            var successfull : Boolean = false
+
+            var currentDelay = initialDelay
+            var currentExpIndex = -1
+
+            while(!successfull){
+                try {
+                    function()
+                    successfull = true
+                }catch (e : CancellationException){
+                    successfull = true
+                }
+                catch (e : Exception){
+                    // check for suppressed exceptions
+                    for(exception in e.suppressed){
+                        if(exception is CancellationException){
+                            successfull = true
+                        }
+                    }
+
+                    onException()
+
+                    // calculate new delay
+                    currentExpIndex++
+                    currentDelay = initialDelay + multiplier.pow(currentExpIndex)
+                }
+
+                delay(currentDelay.toLong())
+            }
+        }
+    }
+}

client/app/src/main/java/com/birdthedeveloper/prometheus/android/prometheus/android/exporter/worker/PromWorker.kt

@@ -27,9 +27,10 @@ class PromWorker(
     parameters : WorkerParameters,
 ) : CoroutineWorker(context, parameters) {
 
+    private val collectorRegistry = CollectorRegistry()
     private val metricsEngine : MetricsEngine = MetricsEngine(context)
-    private val pushProxClient = PushProxClient(::performScrape)
     private lateinit var androidCustomExporter : AndroidCustomExporter
+    private lateinit var pushProxClient : PushProxClient
 
     //TODO foreground notification
     private val notificationManager =
@@ -44,7 +45,7 @@ class PromWorker(
 
     private fun initializeWork(config : PromConfiguration){
         // initialize metrics
-        androidCustomExporter = AndroidCustomExporter(metricsEngine).register()
+        androidCustomExporter = AndroidCustomExporter(metricsEngine).register(collectorRegistry)
     }
 
     private suspend fun startServices(config : PromConfiguration){
@@ -54,13 +55,20 @@ class PromWorker(
                     PrometheusServer.start(
                         PrometheusServerConfig(config.prometheusServerPort, ::performScrape),
                     )
-                    Log.v(TAG, "Prometheus server started.")
                 }
             }
 
             if(config.pushproxEnabled){
+                pushProxClient = PushProxClient(
+                    PushProxConfig(
+                        pushProxUrl = config.pushproxProxyUrl,
+                        performScrape = ::performScrape,
+                        pushProxFqdn = config.pushproxFqdn,
+                        registry = collectorRegistry,
+                    )
+                )
                 launch {
-
+                    pushProxClient.start()
                 }
             }
 
@@ -81,7 +89,6 @@ class PromWorker(
         initializeWork(inputConfiguration)
         startServices(inputConfiguration)
 
-        //TODO implement this asap
         return Result.success()
     }
 

client/app/src/main/java/com/birdthedeveloper/prometheus/android/prometheus/android/exporter/worker/PushProxClient.kt

@@ -20,6 +20,7 @@ data class PushProxConfig(
     val pushProxUrl : String,
     val pushProxFqdn : String,
     val registry : CollectorRegistry,
+    val performScrape : () -> String,
 )
 
 /**
@@ -43,10 +44,10 @@ private class PushProxCounter(registry: CollectorRegistry) {
 
     fun scrapeError(){ scrapeErrorCounter.inc()}
     fun pushError(){ pushErrorCounter.inc() }
-    fun pollError(){ pollErrorCounter.inc() } //TODO use this thing
+    fun pollError(){ pollErrorCounter.inc() }
 }
 
-// Error in parsing HTTP header "Id" from HTTP request from Prometheus //TODO wtf
+// Error in parsing HTTP header "Id" from HTTP request from Prometheus
 class PushProxIdParseException(message: String) : Exception(message)
 
 // Context object for pushprox internal functions to avoid global variables
@@ -58,17 +59,17 @@ data class PushProxContext(
 )
 
 // This is a stripped down kotlin implementation of github.com/prometheus-community/PushProx client
-class PushProxClient(config: PushProxConfig) {
-    private val counters : PushProxCounter = PushProxCounter(config.registry)
+class PushProxClient(private val pushProxConfig: PushProxConfig) {
+    private val counters : PushProxCounter = PushProxCounter(pushProxConfig.registry)
 
     // Use this function to start exporting metrics to pushprox in the background
-    suspend fun start(config: PushProxConfig) {
+    suspend fun start() {
         Log.v(TAG, "Starting pushprox client")
 
         var client : HttpClient? = null
         try {
             client = HttpClient()
-            val context : PushProxContext = getPushProxContext(client, config)
+            val context : PushProxContext = getPushProxContext(client)
             loop(context)
         }finally {
             withContext(NonCancellable){
@@ -78,9 +79,8 @@ class PushProxClient(config: PushProxConfig) {
         }
     }
 
-
-    private fun getPushProxContext(client : HttpClient, config : PushProxConfig) : PushProxContext {
-        var modifiedProxyURL = config.pushProxUrl.trim('/')
+    private fun getPushProxContext(client : HttpClient) : PushProxContext {
+        var modifiedProxyURL = pushProxConfig.pushProxUrl.trim('/')
 
         if(
             !modifiedProxyURL.startsWith("http://") &&
@@ -96,23 +96,19 @@ class PushProxClient(config: PushProxConfig) {
             client,
             pollURL,
             pushURL,
-            config.pushProxFqdn,
+            pushProxConfig.pushProxFqdn,
         )
     }
 
-    //TODO refactor this function
-    // Continuous poll from android phone to pushprox gateway
+    // Continuously poll from pushprox gateway
     private suspend fun doPoll(context : PushProxContext){
-        log("poll", "polling now")
         val response : HttpResponse = context.client.post(context.pollUrl){
             setBody(context.fqdn)
         }
-        log("here", "here")
         val responseBody: String = response.body<String>()
         doPush(context, responseBody)
     }
 
-    //TODO refactor this function
     // get value of HTTP header "Id" from response body
     private fun getIdFromResponseBody(responseBody: String) : String {
 
@@ -124,7 +120,6 @@ class PushProxClient(config: PushProxConfig) {
         return id
     }
 
-    //TODO refactor this function
     private fun composeRequestBody(scrapedMetrics: String, id : String) : String {
         val httpHeaders = "HTTP/1.1 200 OK\r\n" +
             "Content-Type: text/plain; version=0.0.4; charset=utf-8\r\n" +
@@ -137,55 +132,39 @@ class PushProxClient(config: PushProxConfig) {
     // Parameter responseBody: response body of /poll request
     private suspend fun doPush(context : PushProxContext, pollResponseBody : String) {
         // perform scrape
-        lateinit var scrapedMetrics : String
-        try {
-            scrapedMetrics = performScrape()
-        }catch(e : Exception){
+        val scrapedMetrics : String = try {
+            pushProxConfig.performScrape()
+        }catch (e : Exception){
+            Log.v(TAG, "Scrape exception ${e.toString()}")
             counters.scrapeError()
-            log("scrape exception", e.toString())
-            return
+            ""
         }
 
+        // push metrics to pushprox
         try{
             val scrapeId : String = getIdFromResponseBody(pollResponseBody)
-            val pushResponseBody: String = composeRequestBody(scrapedMetrics, scrapeId)
+            val pushRequestBody: String = composeRequestBody(scrapedMetrics, scrapeId)
 
-            val response : HttpResponse = context.client.request(context.pushUrl) {
+            context.client.request(context.pushUrl) {
                 method = HttpMethod.Post
-                setBody(pushResponseBody)
+                setBody(pushRequestBody)
             }
-
         }catch(e : Exception){
             counters.pushError()
-            log("push exception", e.toString())
+            Log.v(TAG,"Push exception ${e.toString()}")
             return
         }
     }
 
-    //TODO migrate to work manager
     private suspend fun loop(context : PushProxContext) {
         while (true) {
             Log.v(TAG, "PushProxClient main loop start")
-            // register poll error using try-catch block
-            //TODO backoff strategy
-            //TODO asap
-//            var result = context.backoff.withRetries {
-//                try {
-//                    doPoll(context)
-//                }catch(e : CancellationException){
-//                    shouldContinue = false
-//                }
-//                catch (e: Exception) {
-//                    for(exception in e.suppressed){
-//                        if(exception is CancellationException){
-//                            shouldContinue = false
-//                        }
-//                    }
-//                    log("exception encountered!", e.toString())
-//                    counters.pollError()
-//                    throw e
-//                }
-//            }
+
+            ExponentialBackoff.runWithBackoff(
+                    function = { doPoll(context) },
+                    onException = { counters.pollError() }
+            )
+
             Log.v(TAG,"PushProxClient main loop end")
         }
     }