Feat/improve caching string cache mechanism

app/src/main/java/org/obd/graphs/activity/Receivers.kt

@@ -38,7 +38,6 @@ import org.obd.graphs.BACKUP_START
 import org.obd.graphs.BACKUP_SUCCESSFUL
 import org.obd.graphs.GOOGLE_SIGN_IN_GENERAL_FAILURE
 import org.obd.graphs.GOOGLE_SIGN_IN_NO_CREDENTIAL_FAILURE
-import org.obd.graphs.LOCATION_IS_DISABLED
 import org.obd.graphs.MODULES_LIST_CHANGED_EVENT
 import org.obd.graphs.Permissions
 import org.obd.graphs.PowerBroadcastReceiver
@@ -135,8 +134,6 @@ internal fun MainActivity.receive(intent: Intent?) {
         REQUEST_NOTIFICATION_PERMISSIONS -> Permissions.requestNotificationPermissions(this)
         REQUEST_LOCATION_PERMISSIONS -> Permissions.requestLocationPermissions(this)
 
-        LOCATION_IS_DISABLED -> toast(org.obd.graphs.commons.R.string.main_activity_toast_location_disabled)
-
         DATA_LOGGER_WIFI_NOT_CONNECTED -> {
             getContext()?.startActivity(Intent(Settings.ACTION_WIFI_SETTINGS))
             toast(org.obd.graphs.commons.R.string.main_activity_toast_connection_wifi_not_connected)
@@ -378,7 +375,6 @@ internal fun MainActivity.registerReceiver() {
         it.addAction(GOOGLE_SIGN_IN_NO_CREDENTIAL_FAILURE)
 
         it.addAction(REQUEST_NOTIFICATION_PERMISSIONS)
-        it.addAction(LOCATION_IS_DISABLED)
         it.addAction(NAVIGATION_BUTTONS_VISIBILITY_CHANGED)
         it.addAction(DATA_LOGGER_SCHEDULED_STOP_EVENT)
         it.addAction(PROFILE_NAME_CHANGED_EVENT)

app/src/main/res/values/strings.xml

@@ -91,7 +91,7 @@
     <string name="pref.adapter.query.view_individual.enabled_summary">Fetch from ECU only PIDs shown on current screen to boost performance—recommended for slow adapters. Note: this disables high/low freq PIDs polling.</string>
     <string name="pref.adapter.query.view_individual.dialog_disabled_warning">This setting is disabled because individual query strategy is enabled.</string>
 
-    <string name="pref.adapter.collect.gps.enabled_summary">Collect and log GPS coordinates alongside vehicle data</string>
+    <string name="pref.adapter.collect.gps.enabled_summary">Collect and log GPS coordinates alongside vehicle data. Note that <b>Location</b> services must be enabled for data collection to occur.</string>
     <string name="pref.adapter.collect.gps.enabled_title">Enable GPS Logging</string>
 
     <string name="pref.adapter.collect.gps.enabled.dialog_title">Enable GPS Logging?</string>

common/src/main/java/org/obd/graphs/Constants.kt

@@ -51,6 +51,4 @@ const val GOOGLE_SIGN_IN_NO_CREDENTIAL_FAILURE = "gdrive.authorization.no_creden
 
 const val REQUEST_NOTIFICATION_PERMISSIONS = "org.obd.graphs.logger.permissions.request_notifications"
 
-const val LOCATION_IS_DISABLED = "org.obd.graphs.logger.gps.LOCATION_IS_DISABLED.event"
-
 const val DATA_LOGGER_AUTO_CONNECT_EVENT = "data.logger.auto_connect.start"

common/src/main/java/org/obd/graphs/Formatter.kt

@@ -60,7 +60,7 @@ fun ObdMetric.toDouble(): Double = (toNumber() ?: 0).toDouble()
 
 fun ObdMetric.isNumber(): Boolean = this.value != null && this.value is Number
 
-private fun ObdMetric.toNumber(): Number? =
+fun ObdMetric.toNumber(): Number? =
     if (isNumber()) {
         value as Number
     } else {

common/src/main/java/org/obd/graphs/Notification.kt

@@ -0,0 +1,95 @@
+ /**
+ * Copyright 2019-2026, Tomasz Żebrowski
+ *
+ * <p>Licensed to the Apache Software Foundation (ASF) under one or more contributor license
+ * agreements. See the NOTICE file distributed with this work for additional information regarding
+ * copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the License. You may obtain a
+ * copy of the License at
+ *
+ * <p>http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * <p>Unless required by applicable law or agreed to in writing, software distributed under the
+ * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.obd.graphs
+
+import android.Manifest
+import android.app.Notification
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.PendingIntent
+import android.content.Context
+import android.content.pm.PackageManager
+import android.os.Build
+import android.util.Log
+import androidx.core.app.ActivityCompat
+import androidx.core.app.NotificationCompat
+import org.obd.graphs.commons.R
+
+const val NOTIFICATION_CHANNEL_ID = "data_logger_channel_v2"
+const val NOTIFICATION_ID = 12345
+
+private const val NOTIFICATION_TITLE = "Vehicle Telemetry Service"
+
+object Notification {
+    fun sendBasicNotification(
+        context: Context,
+        contentText: String,
+        pendingIntent: PendingIntent? = null,
+    ) {
+        try {
+            val notificationManager = context.getSystemService(NotificationManager::class.java)
+
+            val channelId = NOTIFICATION_CHANNEL_ID
+
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+                val channelName = NOTIFICATION_TITLE
+                val descriptionText = contentText
+                val importance = NotificationManager.IMPORTANCE_DEFAULT
+
+                val channel =
+                    NotificationChannel(channelId, channelName, importance).apply {
+                        description = descriptionText
+                    }
+
+                notificationManager.createNotificationChannel(channel)
+            }
+
+            val notification = notification(context, contentText, pendingIntent)
+
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
+                if (ActivityCompat.checkSelfPermission(
+                        context,
+                        Manifest.permission.POST_NOTIFICATIONS,
+                    ) == PackageManager.PERMISSION_GRANTED
+                ) {
+                    notificationManager.notify(NOTIFICATION_ID, notification)
+                }
+            } else {
+                notificationManager.notify(NOTIFICATION_ID, notification)
+            }
+        } catch (e: Throwable) {
+            Log.e("Notification", " Failed to send notification", e)
+        }
+    }
+
+    fun notification(
+        context: Context,
+        contentText: String,
+        pendingIntent: PendingIntent? = null,
+    ): Notification =
+        NotificationCompat
+            .Builder(context, NOTIFICATION_CHANNEL_ID)
+            .setContentTitle(NOTIFICATION_TITLE)
+            .setContentText(contentText)
+            .setSmallIcon(R.drawable.ic_mygiulia_logo)
+            .setPriority(NotificationCompat.PRIORITY_DEFAULT)
+            .apply {
+                pendingIntent?.let { setContentIntent(it) }
+            }.setOngoing(true)
+            .setAutoCancel(true)
+            .build()
+}

common/src/main/res/values/strings.xml

@@ -5,7 +5,6 @@
     <string name="main_activity.toast.connection.error">Error occurred during connection. Please try to connect again. If this does not help please check your connection settings.</string>
     <string name="main_activity.toast.connection.stopped">Connection with the device has been stopped.</string>
     <string name="main_activity.toast.connection.established">Connection to the device has been established.\n Start collecting data from ECU.</string>
-    <string name="main_activity.toast.location.disabled">Location is disabled. GPS data collection wont start.</string>
     <string name="main_activity.toast.connection.connecting">Connecting to the device.</string>
     <string name="main_activity.toast.connection.connect_error"> Error occurred during connection.\nPlease check your network settings.</string>
     <string name="main_activity.toast.connection.no_network">Network connection might be turned off.\n Please check your settings.</string>

datalogger/src/main/java/org/obd/graphs/bl/datalogger/DataLoggerService.kt

@@ -28,12 +28,12 @@ import android.os.Binder
 import android.os.Build
 import android.os.IBinder
 import android.util.Log
-import androidx.core.app.NotificationCompat
+import org.obd.graphs.NOTIFICATION_CHANNEL_ID
+import org.obd.graphs.NOTIFICATION_ID
 import org.obd.graphs.Permissions
 import org.obd.graphs.REQUEST_LOCATION_PERMISSIONS
 import org.obd.graphs.REQUEST_NOTIFICATION_PERMISSIONS
 import org.obd.graphs.bl.query.Query
-import org.obd.graphs.datalogger.R
 import org.obd.graphs.sendBroadcastEvent
 
 private const val ACTION_START = "org.obd.graphs.logger.START"
@@ -43,8 +43,6 @@ private const val UPDATE_QUERY = "org.obd.graphs.logger.UPDATE_QUERY"
 private const val QUERY = "org.obd.graphs.logger.QUERY"
 private const val EXECUTE_ROUTINE = "org.obd.graphs.logger.EXECUTE_ROUTINE"
 
-private const val NOTIFICATION_CHANNEL_ID = "data_logger_channel_v2"
-private const val NOTIFICATION_ID = 12345
 
 class DataLoggerService : Service() {
     private val binder = LocalBinder()
@@ -199,15 +197,9 @@ class DataLoggerService : Service() {
                 )
             }
 
-        return NotificationCompat
-            .Builder(this, NOTIFICATION_CHANNEL_ID)
-            .setContentTitle("Vehicle Telemetry Service")
-            .setContentText("Logging OBD & GPS data in background...")
-            .setSmallIcon(R.drawable.ic_mygiulia_logo)
-            .apply {
-                contentIntent?.let { setContentIntent(it) }
-            }.setOngoing(true)
-            .build()
+        return org.obd.graphs.Notification.notification(this,
+            "Logging OBD data in background...",
+            contentIntent)
     }
 
     private fun createNotificationChannel() {

datalogger/src/main/java/org/obd/graphs/bl/datalogger/Pid.kt

@@ -43,10 +43,6 @@ enum class Pid(val id: Long) {
     GAS_PID_ID(7007),
     OIL_DEGRADATION_PID_ID(7015),
     VEHICLE_STATUS_PID_ID(17091),
-    WCA_TEMP_PID_ID(17079),
-    PRE_IC_AIR_TEMP_PID_ID(7017),
-    SPARK_ADVANCE_PID_ID(7026),
-    CALCULATED_MAF_PID_ID(7041),
 
     GPS_LOCATION_PID_ID(9977774L)
 }

datalogger/src/main/java/org/obd/graphs/bl/gps/GpsMetricsEmitter.kt

@@ -28,14 +28,13 @@ import android.os.Handler
 import android.os.HandlerThread
 import android.os.Looper
 import android.util.Log
-import org.obd.graphs.LOCATION_IS_DISABLED
+import org.obd.graphs.Notification
 import org.obd.graphs.Permissions
 import org.obd.graphs.bl.datalogger.DataLoggerRepository
 import org.obd.graphs.bl.datalogger.MetricsProcessor
 import org.obd.graphs.bl.datalogger.Pid
 import org.obd.graphs.bl.datalogger.dataLoggerSettings
 import org.obd.graphs.getContext
-import org.obd.graphs.sendBroadcastEvent
 import org.obd.metrics.api.model.ObdMetric
 import org.obd.metrics.api.model.Reply
 import org.obd.metrics.api.model.ReplyObserver
@@ -82,10 +81,14 @@ internal class GpsMetricsEmitter : MetricsProcessor {
 
         // Guard Clauses
         if (!dataLoggerSettings.instance().adapter.gpsCollecetingEnabled) return
-        if (!Permissions.hasLocationPermissions(context)) return
+        if (!Permissions.hasLocationPermissions(context)){
+            Notification.sendBasicNotification(context,"Location permissions are not granted." +
+                    "GPS data won't be collected.")
+            return
+        }
         if (!Permissions.isLocationEnabled(context)) {
-            Log.w(TAG, "Location is disabled. Skipping")
-            sendBroadcastEvent(LOCATION_IS_DISABLED)
+            Notification.sendBasicNotification(context,"Location is not enabled. " +
+                    "GPS data won't be collected.")
             return
         }
 

profile/src/main/java/org/obd/graphs/profile/DefaultProfileService.kt

@@ -493,7 +493,6 @@ internal class DefaultProfileService :
 
             Prefs.updateString("pref.about.build_time", buildTime).commit()
             Prefs.updateString("pref.about.build_version", "$versionCode").commit()
-            Prefs.updateBoolean("pref.debug.logging.enabled", false).commit()
         }
     }
 }

screen_renderer/src/main/java/org/obd/graphs/renderer/cache/MetricStringCache.kt

@@ -20,23 +20,38 @@ import kotlin.math.abs
 
 internal class MetricStringCache(size: Int = 100) {
     private val pids = LongArray(size)
+
+    // Keep DoubleArray to prevent memory boxing and GC stuttering
     private val values = DoubleArray(size)
     private val strings = Array<String?>(size) { null }
     private var count = 0
 
     // Define a small epsilon for safe floating-point comparison
     private val EPSILON = 0.0001
 
-    inline fun get(pid: Long, value: Double, formatFallback: () -> String): String {
+    // Signature updated to accept Number?
+    inline fun get(pid: Long, value: Number?, formatFallback: () -> String): String {
+        // Convert any Number (Int, Float, etc.) to Double. Null stays null.
+        val doubleVal = value?.toDouble()
+
         for (i in 0 until count) {
             if (pids[i] == pid) {
-                if (abs(values[i] - value) < EPSILON && strings[i] != null) {
+                val cachedVal = values[i]
+
+                // Safely compare nulls and converted doubles
+                val isMatch = if (doubleVal == null) {
+                    cachedVal.isNaN() // We use NaN internally to represent null
+                } else {
+                    !cachedVal.isNaN() && abs(cachedVal - doubleVal) < EPSILON
+                }
+
+                if (isMatch && strings[i] != null) {
                     return strings[i]!!
                 }
 
                 // Cache miss (value changed), update it
                 val newStr = formatFallback()
-                values[i] = value
+                values[i] = doubleVal ?: Double.NaN
                 strings[i] = newStr
                 return newStr
             }
@@ -45,7 +60,7 @@ internal class MetricStringCache(size: Int = 100) {
         // PID not found in cache, add it if there's room
         if (count < pids.size) {
             pids[count] = pid
-            values[count] = value
+            values[count] = doubleVal ?: Double.NaN
             val newStr = formatFallback()
             strings[count] = newStr
             count++

screen_renderer/src/main/java/org/obd/graphs/renderer/gauge/GaugeDrawer.kt

@@ -41,8 +41,8 @@ import org.obd.graphs.renderer.cache.TextCache
 import org.obd.graphs.renderer.api.GaugeProgressBarType
 import org.obd.graphs.renderer.api.ScreenSettings
 import org.obd.graphs.round
-import org.obd.graphs.toDouble
 import org.obd.graphs.toFloat
+import org.obd.graphs.toNumber
 import org.obd.graphs.ui.common.COLOR_WHITE
 import org.obd.graphs.ui.common.color
 import kotlin.math.abs
@@ -496,7 +496,7 @@ internal class GaugeDrawer(
         val calculatedFontSize = calculateFontSize(multiplier = area.width() / 22f, fontSize = fontSize) * 3.8f
 
         val value =
-            textCache.value.get(metric.pid.id, metric.source.toDouble()) {
+            textCache.value.get(metric.pid.id, metric.source.toNumber()) {
                 metric.source.format(castToInt = false)
             }
 

screen_renderer/src/main/java/org/obd/graphs/renderer/giulia/GiuliaDrawer.kt

@@ -31,10 +31,10 @@ import org.obd.graphs.mapRange
 import org.obd.graphs.renderer.AbstractDrawer
 import org.obd.graphs.renderer.cache.TextCache
 import org.obd.graphs.renderer.api.ScreenSettings
-import org.obd.graphs.toDouble
 import org.obd.graphs.toFloat
 import kotlin.math.max
 import androidx.core.graphics.toColorInt
+import org.obd.graphs.toNumber
 
  private const val FOOTER_SIZE_RATIO = 1.3f
 const val MARGIN_END = 30
@@ -365,7 +365,7 @@ internal class GiuliaDrawer(
         valuePaint.textSize = textSize
         valuePaint.textAlign = Paint.Align.RIGHT
 
-        val value = textCache.value.get(metric.pid.id, metric.source.toDouble()) {
+        val value = textCache.value.get(metric.pid.id, metric.source.toNumber()) {
             metric.source.format(castToInt = castToInt)
         }