OtaDexopt: Downgrade apps when low on space

When running low on space, attempt to "downgrade" apps to lower
states in the optimization flow to free up space before starting
the OTA.

Bug: 31347757
Change-Id: I3a44b106b83d86d7290f4c557267b319f28de12a
diff --git a/services/core/java/com/android/server/pm/OtaDexoptService.java b/services/core/java/com/android/server/pm/OtaDexoptService.java
index bff6d2d..756ba5e 100644
--- a/services/core/java/com/android/server/pm/OtaDexoptService.java
+++ b/services/core/java/com/android/server/pm/OtaDexoptService.java
@@ -53,6 +53,10 @@
     // The synthetic library dependencies denoting "no checks."
     private final static String[] NO_LIBRARIES = new String[] { "&" };
 
+    // The amount of "available" (free - low threshold) space necessary at the start of an OTA to
+    // not bulk-delete unused apps' odex files.
+    private final static long BULK_DELETE_THRESHOLD = 1024 * 1024 * 1024;  // 1GB.
+
     private final Context mContext;
     private final PackageManagerService mPackageManagerService;
 
@@ -128,6 +132,14 @@
                     generatePackageDexopts(p, PackageManagerService.REASON_FIRST_BOOT));
         }
         completeSize = mDexoptCommands.size();
+
+        if (getAvailableSpace() < BULK_DELETE_THRESHOLD) {
+            Log.i(TAG, "Low on space, deleting oat files in an attempt to free up space: "
+                    + PackageManagerServiceUtils.packagesToString(others));
+            for (PackageParser.Package pkg : others) {
+                deleteOatArtifactsOfPackage(pkg);
+            }
+        }
     }
 
     @Override
@@ -169,28 +181,65 @@
 
         String next = mDexoptCommands.remove(0);
 
-        if (IsFreeSpaceAvailable()) {
+        if (getAvailableSpace() > 0) {
             return next;
         } else {
+            if (DEBUG_DEXOPT) {
+                Log.w(TAG, "Not enough space for OTA dexopt, stopping with "
+                        + (mDexoptCommands.size() + 1) + " commands left.");
+            }
             mDexoptCommands.clear();
             return "(no free space)";
         }
     }
 
-    /**
-     * Check for low space. Returns true if there's space left.
-     */
-    private boolean IsFreeSpaceAvailable() {
-        // TODO: If apps are not installed in the internal /data partition, we should compare
-        //       against that storage's free capacity.
+    private long getMainLowSpaceThreshold() {
         File dataDir = Environment.getDataDirectory();
         @SuppressWarnings("deprecation")
         long lowThreshold = StorageManager.from(mContext).getStorageLowBytes(dataDir);
         if (lowThreshold == 0) {
             throw new IllegalStateException("Invalid low memory threshold");
         }
+        return lowThreshold;
+    }
+
+    /**
+     * Returns the difference of free space to the low-storage-space threshold. Positive values
+     * indicate free bytes.
+     */
+    private long getAvailableSpace() {
+        // TODO: If apps are not installed in the internal /data partition, we should compare
+        //       against that storage's free capacity.
+        long lowThreshold = getMainLowSpaceThreshold();
+
+        File dataDir = Environment.getDataDirectory();
         long usableSpace = dataDir.getUsableSpace();
-        return (usableSpace >= lowThreshold);
+
+        return usableSpace - lowThreshold;
+    }
+
+    private static String getOatDir(PackageParser.Package pkg) {
+        if (!pkg.canHaveOatDir()) {
+            return null;
+        }
+        File codePath = new File(pkg.codePath);
+        if (codePath.isDirectory()) {
+            return PackageDexOptimizer.getOatDir(codePath).getAbsolutePath();
+        }
+        return null;
+    }
+
+    private void deleteOatArtifactsOfPackage(PackageParser.Package pkg) {
+        String[] instructionSets = getAppDexInstructionSets(pkg.applicationInfo);
+        for (String codePath : pkg.getAllCodePaths()) {
+            for (String isa : instructionSets) {
+                try {
+                    mPackageManagerService.mInstaller.deleteOdex(codePath, isa, getOatDir(pkg));
+                } catch (InstallerException e) {
+                    Log.e(TAG, "Failed deleting oat files for " + codePath, e);
+                }
+            }
+        }
     }
 
     /**
diff --git a/services/core/java/com/android/server/pm/PackageManagerServiceUtils.java b/services/core/java/com/android/server/pm/PackageManagerServiceUtils.java
index 9a8ebed..cfd0af7 100644
--- a/services/core/java/com/android/server/pm/PackageManagerServiceUtils.java
+++ b/services/core/java/com/android/server/pm/PackageManagerServiceUtils.java
@@ -168,23 +168,8 @@
                 packageManagerService);
 
         if (DEBUG_DEXOPT) {
-            StringBuilder sb = new StringBuilder();
-            for (PackageParser.Package pkg : result) {
-                if (sb.length() > 0) {
-                    sb.append(", ");
-                }
-                sb.append(pkg.packageName);
-            }
-            Log.i(TAG, "Packages to be dexopted: " + sb.toString());
-
-            sb.setLength(0);
-            for (PackageParser.Package pkg : remainingPkgs) {
-                if (sb.length() > 0) {
-                    sb.append(", ");
-                }
-                sb.append(pkg.packageName);
-            }
-            Log.i(TAG, "Packages skipped from dexopt: " + sb.toString());
+            Log.i(TAG, "Packages to be dexopted: " + packagesToString(result));
+            Log.i(TAG, "Packages skipped from dexopt: " + packagesToString(remainingPkgs));
         }
 
         return result;
@@ -201,4 +186,15 @@
             throw ee.rethrowAsIOException();
         }
     }
+
+    public static String packagesToString(Collection<PackageParser.Package> c) {
+        StringBuilder sb = new StringBuilder();
+        for (PackageParser.Package pkg : c) {
+            if (sb.length() > 0) {
+                sb.append(", ");
+            }
+            sb.append(pkg.packageName);
+        }
+        return sb.toString();
+    }
 }