Merge pull request #5340 from k9mail/imap_folder_pusher

Add ImapFolderPusher to listen for changes to an IMAP folder

backend/imap/src/main/java/com/fsck/k9/backend/imap/ImapFolderPusher.kt

@@ -0,0 +1,85 @@
+package com.fsck.k9.backend.imap
+
+import com.fsck.k9.mail.power.PowerManager
+import com.fsck.k9.mail.store.imap.IdleRefreshManager
+import com.fsck.k9.mail.store.imap.IdleResult
+import com.fsck.k9.mail.store.imap.ImapFolderIdler
+import com.fsck.k9.mail.store.imap.ImapStore
+import kotlin.concurrent.thread
+import timber.log.Timber
+
+/**
+ * Listens for changes to an IMAP folder in a dedicated thread.
+ */
+class ImapFolderPusher(
+    private val imapStore: ImapStore,
+    private val powerManager: PowerManager,
+    private val idleRefreshManager: IdleRefreshManager,
+    private val callback: ImapPusherCallback,
+    private val accountName: String,
+    private val folderServerId: String,
+    private val idleRefreshTimeoutMs: Long
+) {
+    @Volatile
+    private var folderIdler: ImapFolderIdler? = null
+
+    @Volatile
+    private var stopPushing = false
+
+    fun start() {
+        Timber.v("Starting ImapFolderPusher for %s / %s", accountName, folderServerId)
+
+        thread(name = "ImapFolderPusher-$accountName-$folderServerId") {
+            Timber.v("Starting ImapFolderPusher thread for %s / %s", accountName, folderServerId)
+
+            runPushLoop()
+
+            Timber.v("Exiting ImapFolderPusher thread for %s / %s", accountName, folderServerId)
+        }
+    }
+
+    fun stop() {
+        Timber.v("Stopping ImapFolderPusher for %s / %s", accountName, folderServerId)
+
+        stopPushing = true
+        folderIdler?.stop()
+    }
+
+    private fun runPushLoop() {
+        val wakeLock = powerManager.newWakeLock("ImapFolderPusher-$accountName-$folderServerId")
+        wakeLock.acquire()
+
+        performInitialSync()
+
+        val folderIdler = ImapFolderIdler.create(
+            idleRefreshManager,
+            wakeLock,
+            imapStore,
+            folderServerId,
+            idleRefreshTimeoutMs
+        ).also {
+            folderIdler = it
+        }
+
+        try {
+            while (!stopPushing) {
+                val idleResult = folderIdler.idle()
+
+                if (idleResult == IdleResult.SYNC) {
+                    callback.onPushEvent(folderServerId)
+                }
+            }
+        } catch (e: Exception) {
+            Timber.v(e, "Exception in ImapFolderPusher")
+
+            this.folderIdler = null
+            callback.onPushError(folderServerId, e)
+        }
+
+        wakeLock.release()
+    }
+
+    private fun performInitialSync() {
+        callback.onPushEvent(folderServerId)
+    }
+}

backend/imap/src/main/java/com/fsck/k9/backend/imap/ImapPusherCallback.kt

@@ -0,0 +1,6 @@
+package com.fsck.k9.backend.imap
+
+interface ImapPusherCallback {
+    fun onPushEvent(folderServerId: String)
+    fun onPushError(folderServerId: String, exception: Exception)
+}

mail/protocols/imap/src/main/java/com/fsck/k9/mail/store/imap/ImapFolderIdler.kt

@@ -1,9 +1,37 @@
 package com.fsck.k9.mail.store.imap
 
+import com.fsck.k9.mail.power.WakeLock
+
 interface ImapFolderIdler {
     fun idle(): IdleResult
 
     fun stop()
+
+    companion object {
+        private val connectionProvider = object : ImapConnectionProvider {
+            override fun getConnection(folder: ImapFolder): ImapConnection? {
+                require(folder is RealImapFolder)
+                return folder.connection
+            }
+        }
+
+        fun create(
+            idleRefreshManager: IdleRefreshManager,
+            wakeLock: WakeLock,
+            imapStore: ImapStore,
+            folderServerId: String,
+            idleRefreshTimeoutMs: Long
+        ): ImapFolderIdler {
+            return RealImapFolderIdler(
+                idleRefreshManager,
+                wakeLock,
+                imapStore,
+                connectionProvider,
+                folderServerId,
+                idleRefreshTimeoutMs
+            )
+        }
+    }
 }
 
 enum class IdleResult {