v0.3.2-SNAPSHOT: added android-specific code and implementation, including defaultNamedStorage()

.gitignore

@@ -7,3 +7,4 @@
 .kotlin
 /.gigaide/gigaide.properties
 /java_pid40366.hprof
+/local.properties

build.gradle.kts

@@ -4,13 +4,15 @@ plugins {
     kotlin("multiplatform") version "2.2.21"
     kotlin("plugin.serialization") version "2.2.21"
     id("org.jetbrains.dokka") version "1.9.20"
+    id("com.android.library") version "8.7.2"
     `maven-publish`
 }
 
 group = "net.sergeych"
-version = "0.3.0"
+version = "0.3.2-SNAPSHOT"
 
 repositories {
+    google()
     mavenCentral()
     mavenLocal()
     maven("https://maven.universablockchain.com/")
@@ -19,6 +21,10 @@ repositories {
 kotlin {
     jvmToolchain(17)
     jvm()
+    androidTarget() {
+        // Ensure Android variant is published to Maven so consumers get androidMain APIs
+        publishLibraryVariants("release")
+    }
     js {
       browser()
       nodejs()
@@ -57,7 +63,7 @@ kotlin {
                 implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.10.2")
                 // this is actually a bug: we need only the core, but bare core causes strange errors
                 implementation("org.jetbrains.kotlinx:kotlinx-serialization-json:1.9.0")
-                api("net.sergeych:mp_stools:[1.5.2,)")
+                api("net.sergeych:mp_stools:[1.6.3,)")
                 implementation("org.jetbrains.kotlinx:kotlinx-datetime:0.7.1")
             }
         }
@@ -82,6 +88,11 @@ kotlin {
         }
         val jvmMain by getting
         val jvmTest by getting
+        val androidMain by getting {
+            dependencies {
+                // Android base64 and preferences are in the SDK; no extra deps required
+            }
+        }
         val jsMain by getting {
             dependencies {
             }
@@ -119,6 +130,26 @@ publishing {
     }
 }
 
+android {
+    namespace = "net.sergeych.bintools"
+    compileSdk = 34
+    defaultConfig {
+        minSdk = 21
+    }
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_17
+        targetCompatibility = JavaVersion.VERSION_17
+    }
+    // Publish only release variant of the Android target so consumers (Android apps)
+    // resolve the platform artifact instead of common metadata, which is required
+    // to access Android-only APIs like net.sergeych.bintools.AndroidKV
+    publishing {
+        singleVariant("release") {
+            withSourcesJar()
+        }
+    }
+}
+
 tasks.dokkaHtml.configure {
     outputDirectory.set(buildDir.resolve("dokka"))
     dokkaSourceSets {

settings.gradle.kts

@@ -1,3 +1,21 @@
 
+pluginManagement {
+    repositories {
+        google()
+        gradlePluginPortal()
+        mavenCentral()
+        mavenLocal()
+    }
+}
+
+dependencyResolutionManagement {
+    repositories {
+        google()
+        mavenCentral()
+        mavenLocal()
+        maven("https://maven.universablockchain.com/")
+    }
+}
+
 rootProject.name = "mp_bintools"
 

src/androidMain/kotlin/net.sergeych.bintools/KVStorage.android.kt

@@ -0,0 +1,65 @@
+package net.sergeych.bintools
+
+import android.content.Context
+import android.content.SharedPreferences
+import net.sergeych.bintools.AndroidKV.init
+import net.sergeych.mp_tools.decodeBase64Compact
+import net.sergeych.mp_tools.encodeToBase64Compact
+
+/**
+ * Simple holder to provide Application [Context] for this library.
+ *
+ * Call [init] from your app (e.g., in `Application.onCreate`) before using
+ * [defaultNamedStorage].
+ */
+object AndroidKV {
+    @Volatile
+    private var appContext: Context? = null
+
+    fun init(context: Context) {
+        appContext = context.applicationContext
+    }
+
+    internal fun requireContext(): Context =
+        appContext ?: error("AndroidKV is not initialized. Call AndroidKV.init(applicationContext) first.")
+}
+
+/**
+ * Implementation of [KVStorage] backed by [SharedPreferences].
+ * Values are stored as base64-encoded strings to fit preferences capabilities.
+ */
+class SharedPreferencesKVStorage(
+    private val prefs: SharedPreferences,
+    keyPrefix: String = ""
+) : KVStorage {
+    private val prefix = if (keyPrefix.isEmpty()) "" else "$keyPrefix:"
+
+    private fun k(key: String) = "$prefix$key"
+
+    override fun get(key: String): ByteArray? =
+        prefs.getString(k(key), null)?.decodeBase64Compact()
+
+    override fun set(key: String, value: ByteArray?) {
+        val e = prefs.edit()
+        val kk = k(key)
+        if (value == null) e.remove(kk)
+        else e.putString(kk, value.encodeToBase64Compact())
+        e.apply()
+    }
+
+    override val keys: Set<String>
+        get() {
+            val allKeys = prefs.all.keys
+            if (prefix.isEmpty()) return allKeys
+            return allKeys.filter { it.startsWith(prefix) }
+                .map { it.removePrefix(prefix) }
+                .toSet()
+        }
+}
+
+actual fun defaultNamedStorage(name: String): KVStorage {
+    val ctx = AndroidKV.requireContext()
+    val prefs = ctx.getSharedPreferences(name, Context.MODE_PRIVATE)
+    // We use separate preferences file per name, so prefix can be empty
+    return SharedPreferencesKVStorage(prefs)
+}

src/androidMain/kotlin/net/sergeych/synctools/ProtectedOp.android.kt

@@ -0,0 +1,17 @@
+package net.sergeych.synctools
+
+import java.util.concurrent.locks.ReentrantLock
+
+/**
+ * Android actual implementation mirrors JVM using [ReentrantLock].
+ */
+actual fun ProtectedOp(): ProtectedOpImplementation = object : ProtectedOpImplementation {
+    private val access = ReentrantLock()
+    override fun lock() {
+        access.lock()
+    }
+
+    override fun unlock() {
+        access.unlock()
+    }
+}

src/androidMain/kotlin/net/sergeych/synctools/WaitHandle.android.kt

@@ -0,0 +1,22 @@
+package net.sergeych.synctools
+
+@Suppress("EXPECT_ACTUAL_CLASSIFIERS_ARE_IN_BETA_WARNING")
+actual class WaitHandle {
+    @Suppress("PLATFORM_CLASS_MAPPED_TO_KOTLIN")
+    private val access = Object()
+
+    actual fun await(milliseconds: Long): Boolean {
+        return synchronized(access) {
+            try {
+                access.wait(milliseconds)
+                true
+            } catch (_: InterruptedException) {
+                false
+            }
+        }
+    }
+
+    actual fun wakeUp() {
+        synchronized(access) { access.notifyAll() }
+    }
+}

src/commonMain/kotlin/net.sergeych.bintools/KVStorage.kt

@@ -218,7 +218,19 @@ class MemoryKVStorage(copyFrom: KVStorage? = null) : KVStorage {
  *    - otherwise, the folder will be created in "`~/.local_storage`" parent directory
  *      (which also will be created if needed).
  *
- *  - For the native platorms it is not yet implemented (but will be soon).
+ *  - In Android (new!) it is implemented using preferences, but initializing is needed in
+ *      main activity `onCreate`, somewhat like:
+ *  ```kotlin
+ *       override fun onCreate(savedInstanceState: Bundle?) {
+ *          super.onCreate(savedInstanceState)
+ *          // set the Context which Preferences will be used for
+ *          // defaultNamedStorage
+ *          net.sergeych.bintools.AndroidKV.init(this)
+ *     }
+ *  ```
+ *  see also `AndroidKV` and `SharedPreferencesKVStorage` for Android
+ *
+ *  - For the native platforms it is not yet implemented (but will be soon).
  *
  *  See [DataKVStorage] and [DataProvider] to implement a KVStorage on filesystems and like,
  *  and `FileDataProvider` class on JVM target.