From c7265ede5924fdb69341bf18b445ca167510386c Mon Sep 17 00:00:00 2001
From: David Anderson <davea@ssl.berkeley.edu>
Date: Wed, 19 Jul 2023 15:06:16 -0700
Subject: [PATCH] client, Android: if suspend because of battery heat or
 charge, don't resume for at least 5 minutes. Avoid rapid start/stop when at
 threshold.

---
 client/client_state.h |  4 ++++
 client/cs_prefs.cpp   | 16 ++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/client/client_state.h b/client/client_state.h
index d1cd32306b..bce4b7650f 100644
--- a/client/client_state.h
+++ b/client/client_state.h
@@ -685,6 +685,10 @@ extern THREAD throttle_thread;
     // Android: if don't get a report_device_status() RPC from the GUI
     // in this interval, exit.
     // We rely on the GUI to report battery status.
+#define ANDROID_BATTERY_BACKOFF     300
+    // Android: if battery is overheated or undercharged,
+    // suspend for at least this long
+    // (avoid rapid start/stop)
 
 #ifndef ANDROID
 #define USE_NET_PREFS
diff --git a/client/cs_prefs.cpp b/client/cs_prefs.cpp
index b266d7dece..d73e497aa6 100644
--- a/client/cs_prefs.cpp
+++ b/client/cs_prefs.cpp
@@ -265,17 +265,28 @@ int CLIENT_STATE::check_suspend_processing() {
     }
 
 #ifdef ANDROID
+    // suspend if we haven't heard from the GUI in 30 sec
+    // (we rely on it for battery info)
+    //
     if (now > device_status_time + ANDROID_KEEPALIVE_TIMEOUT) {
         requested_exit = true;
         return SUSPEND_REASON_NO_GUI_KEEPALIVE;
     }
 
     // check for hot battery
+    // If suspend because of hot battery, don't resume for at least 5 min
+    // (crude hysteresis)
     //
+    static double battery_heat_resume_time=0;
+    if (now < battery_heat_resume_time) {
+        return SUSPEND_REASON_BATTERY_OVERHEATED;
+    }
     if (device_status.battery_state == BATTERY_STATE_OVERHEATED) {
+        battery_heat_resume_time = now + ANDROID_BATTERY_BACKOFF;
         return SUSPEND_REASON_BATTERY_OVERHEATED;
     }
     if (device_status.battery_temperature_celsius > global_prefs.battery_max_temperature) {
+        battery_heat_resume_time = now + ANDROID_BATTERY_BACKOFF;
         return SUSPEND_REASON_BATTERY_OVERHEATED;
     }
 
@@ -283,9 +294,14 @@ int CLIENT_STATE::check_suspend_processing() {
     // while it's recharging.
     // So compute only if 95% charged or more.
     //
+    static double battery_charge_resume_time=0;
+    if (now < battery_charge_resume_time) {
+        return SUSPEND_REASON_BATTERY_CHARGING;
+    }
     int cp = device_status.battery_charge_pct;
     if (cp >= 0) {
         if (cp < global_prefs.battery_charge_min_pct) {
+            battery_charge_resume_time = now + ANDROID_BATTERY_BACKOFF;
             return SUSPEND_REASON_BATTERY_CHARGING;
         }
     }