fix: show the new-mail notification when the connection kept from the foreground has died #94

android/app/src/main/java/com/anonymous/bulwarkmobile/BulwarkMessagingService.kt

@@ -66,7 +66,12 @@ class BulwarkMessagingService : FirebaseMessagingService() {
         fun startTaskUnlessInForeground(context: Context, data: Map<String, String>, mail: Boolean) {
             val foreground = MainActivity.isInForeground
             Log.i(TAG, "Push: mail=$mail foreground=$foreground importance=${processImportance()}")
-            if (mail && !foreground) startHeadlessTask(context, data)
+            if (mail && !foreground) {
+                // The task opens its own connection rather than one left
+                // over from the foreground, which may be dead (#94).
+                HttpConnections.dropIdle()
+                startHeadlessTask(context, data)
+            }
         }
 
         /** For the log only. */

android/app/src/main/java/com/anonymous/bulwarkmobile/HttpConnections.kt

@@ -0,0 +1,41 @@
+package com.anonymous.bulwarkmobile
+
+import android.content.Context
+import com.facebook.react.modules.network.OkHttpClientFactory
+import com.facebook.react.modules.network.OkHttpClientProvider
+import okhttp3.ConnectionPool
+import okhttp3.OkHttpClient
+
+/**
+ * One connection pool for every OkHttp client React Native builds (fetch,
+ * XMLHttpRequest and the event stream on top of it), so the push path can
+ * drop the connections the app kept from the foreground.
+ *
+ * React Native's client has no connect or read timeout. A connection that
+ * died silently while the app was in the background (a mobile network's NAT
+ * forgot it, the server closed it and the FIN never arrived) stays in the
+ * pool, and the push task's first request was sent down it and waited until
+ * the task's 30 s timeout: no request reached the server and no
+ * notification appeared (#94). A fresh connection costs one TLS handshake.
+ */
+object HttpConnections {
+    private val pool = ConnectionPool()
+
+    /** Call before React Native creates its first network module. */
+    fun install(context: Context) {
+        val app = context.applicationContext
+        OkHttpClientProvider.setOkHttpClientFactory(
+            object : OkHttpClientFactory {
+                override fun createNewNetworkModuleClient(): OkHttpClient =
+                    OkHttpClientProvider.createClientBuilder(app)
+                        .connectionPool(pool)
+                        .build()
+            },
+        )
+    }
+
+    /** Closes every pooled connection no request is using. */
+    fun dropIdle() {
+        pool.evictAll()
+    }
+}

android/app/src/main/java/com/anonymous/bulwarkmobile/MainApplication.kt

@@ -40,6 +40,7 @@ class MainApplication : Application(), ReactApplication {
 
   override fun onCreate() {
     super.onCreate()
+    HttpConnections.install(this)
     DefaultNewArchitectureEntryPoint.releaseLevel = try {
       ReleaseLevel.valueOf(BuildConfig.REACT_NATIVE_RELEASE_LEVEL.uppercase())
     } catch (e: IllegalArgumentException) {