Be increasingly aggressive about fstrim if it isn't being run

The current heuristics depend on devices being alive at midnight+ in
order to run periodic background fstrim operations.  This unfortunately
means that people who routinely turn their devices off overnight wind
up with their devices *never* running fstrim, and this causes major
performance and disk-life problems.

We now backstop this very-friendly schedule with an increasingly
aggressive one.  If the device goes a defined time without a background
fstrim, we then force the fstrim at the next reboot.  Once the
device hits the midnight+ idle fstrim request time, then we already
aggressively attempt to fstrim at the first available moment
thereafter, even if it's days/weeks later without a reboot.

'Available' here means charging + device idle.  If the device never
becomes idle then we can't do much without rendering an in-use device
inoperable for some number of minutes -- but we have no evidence of
devices ever failing to run fstrim due to this usage pattern.

A new Settings.Global element (type 'long', called
"fstrim_mandatory_interval") is the source of the backstop time.  If
this element is zero or negative, no mandatory boot-time fstrim will
ever be performed.  If the element is not supplied on a given device,
the default backstop is 3 days.

Adds a new string to display in the upgrading dialog when doing
the fstrim.  Note it is too late for this to be localized, but since
this operation can take a long time it is probably better to have
it show *something* even if not localized, rather than just sit there.

Bug 18486922

Change-Id: I5b265ca0a65570fb8931251aa1ac37b530635a2c

2 files changed, 70 insertions, 0 deletions

diff --git a/core/java/android/os/storage/IMountService.java b/core/java/android/os/storage/IMountService.java
index cf407f401844..116110eba74d 100644
--- a/core/java/android/os/storage/IMountService.java
+++ b/core/java/android/os/storage/IMountService.java
@@ -856,6 +856,38 @@ public interface IMountService extends IInterface {
                 }
                 return _result;
             }
+
+            @Override
+            public long lastMaintenance() throws RemoteException {
+                Parcel _data = Parcel.obtain();
+                Parcel _reply = Parcel.obtain();
+                long _result;
+                try {
+                    _data.writeInterfaceToken(DESCRIPTOR);
+                    mRemote.transact(Stub.TRANSACTION_lastMaintenance, _data, _reply, 0);
+                    _reply.readException();
+                    _result = _reply.readLong();
+                } finally {
+                    _reply.recycle();
+                    _data.recycle();
+                }
+                return _result;
+            }
+
+            @Override
+            public void runMaintenance() throws RemoteException {
+                Parcel _data = Parcel.obtain();
+                Parcel _reply = Parcel.obtain();
+                try {
+                    _data.writeInterfaceToken(DESCRIPTOR);
+                    mRemote.transact(Stub.TRANSACTION_runMaintenance, _data, _reply, 0);
+                    _reply.readException();
+                } finally {
+                    _reply.recycle();
+                    _data.recycle();
+                }
+                return;
+            }
         }
 
         private static final String DESCRIPTOR = "IMountService";
@@ -942,6 +974,10 @@ public interface IMountService extends IInterface {
 
         static final int TRANSACTION_resizeSecureContainer = IBinder.FIRST_CALL_TRANSACTION + 40;
 
+        static final int TRANSACTION_lastMaintenance = IBinder.FIRST_CALL_TRANSACTION + 41;
+
+        static final int TRANSACTION_runMaintenance = IBinder.FIRST_CALL_TRANSACTION + 42;
+
         /**
          * Cast an IBinder object into an IMountService interface, generating a
          * proxy if needed.
@@ -1347,6 +1383,19 @@ public interface IMountService extends IInterface {
                     reply.writeInt(resultCode);
                     return true;
                 }
+                case TRANSACTION_lastMaintenance: {
+                    data.enforceInterface(DESCRIPTOR);
+                    long lastMaintenance = lastMaintenance();
+                    reply.writeNoException();
+                    reply.writeLong(lastMaintenance);
+                    return true;
+                }
+                case TRANSACTION_runMaintenance: {
+                    data.enforceInterface(DESCRIPTOR);
+                    runMaintenance();
+                    reply.writeNoException();
+                    return true;
+                }
             }
             return super.onTransact(code, data, reply, flags);
         }
@@ -1617,4 +1666,18 @@ public interface IMountService extends IInterface {
     public String getField(String field) throws RemoteException;
 
     public int resizeSecureContainer(String id, int sizeMb, String key) throws RemoteException;
+
+    /**
+     * Report the time of the last maintenance operation such as fstrim.
+     * @return Timestamp of the last maintenance operation, in the
+     *     System.currentTimeMillis() time base
+     * @throws RemoteException
+     */
+    public long lastMaintenance() throws RemoteException;
+
+    /**
+     * Kick off an immediate maintenance operation
+     * @throws RemoteException
+     */
+    public void runMaintenance() throws RemoteException;
 }
diff --git a/core/java/android/provider/Settings.java b/core/java/android/provider/Settings.java
index 79e84d959109..73c7cc38af49 100644
--- a/core/java/android/provider/Settings.java
+++ b/core/java/android/provider/Settings.java
@@ -5544,6 +5544,13 @@ public final class Settings {
        public static final String PACKAGE_VERIFIER_INCLUDE_ADB = "verifier_verify_adb_installs";
 
        /**
+        * Time since last fstrim (milliseconds) after which we force one to happen
+        * during device startup.  If unset, the default is 3 days.
+        * @hide
+        */
+       public static final String FSTRIM_MANDATORY_INTERVAL = "fstrim_mandatory_interval";
+
+       /**
         * The interval in milliseconds at which to check packet counts on the
         * mobile data interface when screen is on, to detect possible data
         * connection problems.