From 64c795f2331c63e55a2cc4342f9f5f6c63036ceb Mon Sep 17 00:00:00 2001
From: Mikhail <misha_mst@mail.ru>
Date: Fri, 15 May 2026 13:34:54 +0300
Subject: [PATCH] Make Android VPN watchdog conservative under load

---
 clients/android/app/build.gradle              |  4 +--
 .../java/su/cin/rapvpn/RapVpnService.java     | 31 +++++++++++++++++++
 2 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/clients/android/app/build.gradle b/clients/android/app/build.gradle
index 3c2c11a..c5c0321 100644
--- a/clients/android/app/build.gradle
+++ b/clients/android/app/build.gradle
@@ -30,8 +30,8 @@ android {
         applicationId "su.cin.rapvpn"
         minSdk 26
         targetSdk 35
-        versionCode 194
-        versionName "0.2.194"
+        versionCode 195
+        versionName "0.2.195"
         buildConfigField "String", "DEFAULT_BACKEND_URL", "\"${normalizeGradleString(defaultBackendUrl)}\""
         buildConfigField "String", "DEFAULT_CLUSTER_ID", "\"${normalizeGradleString(defaultClusterId)}\""
         buildConfigField "String", "DEFAULT_ORGANIZATION_ID", "\"${normalizeGradleString(defaultOrganizationId)}\""
diff --git a/clients/android/app/src/main/java/su/cin/rapvpn/RapVpnService.java b/clients/android/app/src/main/java/su/cin/rapvpn/RapVpnService.java
index 21403c7..e42b326 100644
--- a/clients/android/app/src/main/java/su/cin/rapvpn/RapVpnService.java
+++ b/clients/android/app/src/main/java/su/cin/rapvpn/RapVpnService.java
@@ -78,6 +78,9 @@ public class RapVpnService extends VpnService {
     private static final int RUNTIME_STATUS_INTERVAL_MS = 500;
     private static final int RUNTIME_WATCHDOG_INTERVAL_MS = 2000;
     private static final int RUNTIME_WATCHDOG_STALE_SYNACK_MS = 7000;
+    private static final int RUNTIME_WATCHDOG_STALE_ROUNDS_BEFORE_RECOVERY = 3;
+    private static final int RUNTIME_WATCHDOG_STALE_SYNACKS_BEFORE_RECOVERY = 4;
+    private static final int RUNTIME_WATCHDOG_MAX_STALE_ROUNDS_BEFORE_RECOVERY = 6;
     private static final int RUNTIME_WATCHDOG_RECOVERY_COOLDOWN_MS = 20000;
     private static final int RUNTIME_WATCHDOG_HARD_RESTART_COOLDOWN_MS = 60000;
     private static final int DIAGNOSTIC_WATCHDOG_INTERVAL_MS = 5000;
@@ -218,6 +221,9 @@ public class RapVpnService extends VpnService {
     private volatile String shutdownReason = "service destroyed";
     private volatile long lastRuntimeWatchdogRecoveryAt;
     private volatile long lastRuntimeWatchdogHardRestartAt;
+    private volatile long lastRuntimeWatchdogDownlinkPackets;
+    private volatile long lastRuntimeWatchdogUplinkPackets;
+    private volatile int runtimeWatchdogStaleRounds;
     private volatile long lastDiagnosticEnsureAt;
     private volatile long lastDiagnosticStatusEnsureAt;
     private volatile long lastDiagnosticRestartAt;
@@ -1360,6 +1366,11 @@ public class RapVpnService extends VpnService {
         tcpHandshakeStalls.set(0);
         runtimeWatchdogHardRestarts.set(0);
         hardRuntimeRestartInProgress.set(false);
+        lastRuntimeWatchdogRecoveryAt = 0;
+        lastRuntimeWatchdogHardRestartAt = 0;
+        lastRuntimeWatchdogDownlinkPackets = 0;
+        lastRuntimeWatchdogUplinkPackets = 0;
+        runtimeWatchdogStaleRounds = 0;
         downlinkDroppedPackets.set(0);
         downlinkDroppedBytes.set(0);
         downlinkTransportChecksumRepairs.set(0);
@@ -1539,12 +1550,32 @@ public class RapVpnService extends VpnService {
                 }
                 long now = System.currentTimeMillis();
                 int stale = staleTCPHandshakeCount();
+                long downlinkPackets = downlinkReceivedPackets.get();
+                long uplinkPackets = uplinkSentPackets.get();
+                boolean downlinkProgressed = downlinkPackets > lastRuntimeWatchdogDownlinkPackets;
+                boolean uplinkProgressed = uplinkPackets > lastRuntimeWatchdogUplinkPackets;
+                lastRuntimeWatchdogDownlinkPackets = downlinkPackets;
+                lastRuntimeWatchdogUplinkPackets = uplinkPackets;
                 if (stale <= 0) {
+                    runtimeWatchdogStaleRounds = 0;
+                    continue;
+                }
+                if (downlinkProgressed) {
+                    runtimeWatchdogStaleRounds = 0;
+                    writeRuntimeDetail("watchdog_observed_downlink", "stale=" + stale + " downlink_progress=true uplink_progress=" + uplinkProgressed, "watchdog", runtimeWatchdogRecoveries.get(), tcpHandshakeStalls.get(), "", -1);
+                    continue;
+                }
+                runtimeWatchdogStaleRounds++;
+                if (runtimeWatchdogStaleRounds < RUNTIME_WATCHDOG_STALE_ROUNDS_BEFORE_RECOVERY
+                        || (stale < RUNTIME_WATCHDOG_STALE_SYNACKS_BEFORE_RECOVERY
+                        && runtimeWatchdogStaleRounds < RUNTIME_WATCHDOG_MAX_STALE_ROUNDS_BEFORE_RECOVERY)) {
+                    writeRuntimeDetail("watchdog_waiting", "stale=" + stale + " rounds=" + runtimeWatchdogStaleRounds + " uplink_progress=" + uplinkProgressed, "watchdog", runtimeWatchdogRecoveries.get(), tcpHandshakeStalls.get(), "", -1);
                     continue;
                 }
                 if (now - lastRuntimeWatchdogRecoveryAt < RUNTIME_WATCHDOG_RECOVERY_COOLDOWN_MS) {
                     continue;
                 }
+                runtimeWatchdogStaleRounds = 0;
                 tcpHandshakeStalls.addAndGet(stale);
                 runtimeWatchdogRecoveries.incrementAndGet();
                 lastRuntimeWatchdogRecoveryAt = now;