Merge "Add logic to persist jobs in separate files."
diff --git a/apex/jobscheduler/service/java/com/android/server/job/JobSchedulerService.java b/apex/jobscheduler/service/java/com/android/server/job/JobSchedulerService.java
index d9fb318..358f009 100644
--- a/apex/jobscheduler/service/java/com/android/server/job/JobSchedulerService.java
+++ b/apex/jobscheduler/service/java/com/android/server/job/JobSchedulerService.java
@@ -177,7 +177,7 @@
     @EnabledAfter(targetSdkVersion = Build.VERSION_CODES.TIRAMISU)
     private static final long REQUIRE_NETWORK_CONSTRAINT_FOR_NETWORK_JOB_WORK_ITEMS = 241104082L;
 
-    @VisibleForTesting
+    @VisibleForTesting(visibility = VisibleForTesting.Visibility.PACKAGE)
     public static Clock sSystemClock = Clock.systemUTC();
 
     private abstract static class MySimpleClock extends Clock {
@@ -454,6 +454,10 @@
                                 runtimeUpdated = true;
                             }
                             break;
+                        case Constants.KEY_PERSIST_IN_SPLIT_FILES:
+                            mConstants.updatePersistingConstantsLocked();
+                            mJobs.setUseSplitFiles(mConstants.PERSIST_IN_SPLIT_FILES);
+                            break;
                         default:
                             if (name.startsWith(JobConcurrencyManager.CONFIG_KEY_PREFIX_CONCURRENCY)
                                     && !concurrencyUpdated) {
@@ -537,6 +541,8 @@
         private static final String KEY_RUNTIME_MIN_HIGH_PRIORITY_GUARANTEE_MS =
                 "runtime_min_high_priority_guarantee_ms";
 
+        private static final String KEY_PERSIST_IN_SPLIT_FILES = "persist_in_split_files";
+
         private static final int DEFAULT_MIN_READY_NON_ACTIVE_JOBS_COUNT = 5;
         private static final long DEFAULT_MAX_NON_ACTIVE_JOB_BATCH_DELAY_MS = 31 * MINUTE_IN_MILLIS;
         private static final float DEFAULT_HEAVY_USE_FACTOR = .9f;
@@ -563,6 +569,7 @@
         public static final long DEFAULT_RUNTIME_MIN_EJ_GUARANTEE_MS = 3 * MINUTE_IN_MILLIS;
         @VisibleForTesting
         static final long DEFAULT_RUNTIME_MIN_HIGH_PRIORITY_GUARANTEE_MS = 5 * MINUTE_IN_MILLIS;
+        static final boolean DEFAULT_PERSIST_IN_SPLIT_FILES = false;
         private static final boolean DEFAULT_USE_TARE_POLICY = false;
 
         /**
@@ -678,6 +685,12 @@
                 DEFAULT_RUNTIME_MIN_HIGH_PRIORITY_GUARANTEE_MS;
 
         /**
+         * Whether to persist jobs in split files (by UID). If false, all persisted jobs will be
+         * saved in a single file.
+         */
+        public boolean PERSIST_IN_SPLIT_FILES = DEFAULT_PERSIST_IN_SPLIT_FILES;
+
+        /**
          * If true, use TARE policy for job limiting. If false, use quotas.
          */
         public boolean USE_TARE_POLICY = DEFAULT_USE_TARE_POLICY;
@@ -735,6 +748,11 @@
                     DEFAULT_CONN_LOW_SIGNAL_STRENGTH_RELAX_FRAC);
         }
 
+        private void updatePersistingConstantsLocked() {
+            PERSIST_IN_SPLIT_FILES = DeviceConfig.getBoolean(DeviceConfig.NAMESPACE_JOB_SCHEDULER,
+                    KEY_PERSIST_IN_SPLIT_FILES, DEFAULT_PERSIST_IN_SPLIT_FILES);
+        }
+
         private void updatePrefetchConstantsLocked() {
             PREFETCH_FORCE_BATCH_RELAX_THRESHOLD_MS = DeviceConfig.getLong(
                     DeviceConfig.NAMESPACE_JOB_SCHEDULER,
@@ -835,6 +853,8 @@
             pw.print(KEY_RUNTIME_FREE_QUOTA_MAX_LIMIT_MS, RUNTIME_FREE_QUOTA_MAX_LIMIT_MS)
                     .println();
 
+            pw.print(KEY_PERSIST_IN_SPLIT_FILES, PERSIST_IN_SPLIT_FILES).println();
+
             pw.print(Settings.Global.ENABLE_TARE, USE_TARE_POLICY).println();
 
             pw.decreaseIndent();
diff --git a/apex/jobscheduler/service/java/com/android/server/job/JobStore.java b/apex/jobscheduler/service/java/com/android/server/job/JobStore.java
index 68cb049..2f94705f 100644
--- a/apex/jobscheduler/service/java/com/android/server/job/JobStore.java
+++ b/apex/jobscheduler/service/java/com/android/server/job/JobStore.java
@@ -40,6 +40,7 @@
 import android.util.Pair;
 import android.util.Slog;
 import android.util.SparseArray;
+import android.util.SparseBooleanArray;
 import android.util.SystemConfigFileCommitEventLogger;
 import android.util.Xml;
 
@@ -89,6 +90,8 @@
 
     /** Threshold to adjust how often we want to write to the db. */
     private static final long JOB_PERSIST_DELAY = 2000L;
+    private static final String JOB_FILE_SPLIT_PREFIX = "jobs_";
+    private static final int ALL_UIDS = -1;
 
     final Object mLock;
     final Object mWriteScheduleLock;    // used solely for invariants around write scheduling
@@ -105,13 +108,20 @@
     @GuardedBy("mWriteScheduleLock")
     private boolean mWriteInProgress;
 
+    @GuardedBy("mWriteScheduleLock")
+    private boolean mSplitFileMigrationNeeded;
+
     private static final Object sSingletonLock = new Object();
     private final SystemConfigFileCommitEventLogger mEventLogger;
     private final AtomicFile mJobsFile;
+    private final File mJobFileDirectory;
+    private final SparseBooleanArray mPendingJobWriteUids = new SparseBooleanArray();
     /** Handler backed by IoThread for writing to disk. */
     private final Handler mIoHandler = IoThread.getHandler();
     private static JobStore sSingleton;
 
+    private boolean mUseSplitFiles = JobSchedulerService.Constants.DEFAULT_PERSIST_IN_SPLIT_FILES;
+
     private JobStorePersistStats mPersistInfo = new JobStorePersistStats();
 
     /** Used by the {@link JobSchedulerService} to instantiate the JobStore. */
@@ -144,10 +154,10 @@
         mContext = context;
 
         File systemDir = new File(dataDir, "system");
-        File jobDir = new File(systemDir, "job");
-        jobDir.mkdirs();
+        mJobFileDirectory = new File(systemDir, "job");
+        mJobFileDirectory.mkdirs();
         mEventLogger = new SystemConfigFileCommitEventLogger("jobs");
-        mJobsFile = new AtomicFile(new File(jobDir, "jobs.xml"), mEventLogger);
+        mJobsFile = createJobFile(new File(mJobFileDirectory, "jobs.xml"));
 
         mJobSet = new JobSet();
 
@@ -162,12 +172,21 @@
         // an incorrect historical timestamp.  That's fine; at worst we'll reboot with
         // a *correct* timestamp, see a bunch of overdue jobs, and run them; then
         // settle into normal operation.
-        mXmlTimestamp = mJobsFile.getLastModifiedTime();
+        mXmlTimestamp = mJobsFile.exists()
+                ? mJobsFile.getLastModifiedTime() : mJobFileDirectory.lastModified();
         mRtcGood = (sSystemClock.millis() > mXmlTimestamp);
 
         readJobMapFromDisk(mJobSet, mRtcGood);
     }
 
+    private AtomicFile createJobFile(String baseName) {
+        return createJobFile(new File(mJobFileDirectory, baseName + ".xml"));
+    }
+
+    private AtomicFile createJobFile(File file) {
+        return new AtomicFile(file, mEventLogger);
+    }
+
     public boolean jobTimesInflatedValid() {
         return mRtcGood;
     }
@@ -211,6 +230,7 @@
     public void add(JobStatus jobStatus) {
         mJobSet.add(jobStatus);
         if (jobStatus.isPersisted()) {
+            mPendingJobWriteUids.put(jobStatus.getUid(), true);
             maybeWriteStatusToDiskAsync();
         }
         if (DEBUG) {
@@ -224,6 +244,9 @@
     @VisibleForTesting
     public void addForTesting(JobStatus jobStatus) {
         mJobSet.add(jobStatus);
+        if (jobStatus.isPersisted()) {
+            mPendingJobWriteUids.put(jobStatus.getUid(), true);
+        }
     }
 
     boolean containsJob(JobStatus jobStatus) {
@@ -257,12 +280,24 @@
             return false;
         }
         if (removeFromPersisted && jobStatus.isPersisted()) {
+            mPendingJobWriteUids.put(jobStatus.getUid(), true);
             maybeWriteStatusToDiskAsync();
         }
         return removed;
     }
 
     /**
+     * Like {@link #remove(JobStatus, boolean)}, but doesn't schedule a disk write.
+     */
+    @VisibleForTesting
+    public void removeForTesting(JobStatus jobStatus) {
+        mJobSet.remove(jobStatus);
+        if (jobStatus.isPersisted()) {
+            mPendingJobWriteUids.put(jobStatus.getUid(), true);
+        }
+    }
+
+    /**
      * Remove the jobs of users not specified in the keepUserIds.
      * @param keepUserIds Array of User IDs whose jobs should be kept and not removed.
      */
@@ -273,6 +308,7 @@
     @VisibleForTesting
     public void clear() {
         mJobSet.clear();
+        mPendingJobWriteUids.put(ALL_UIDS, true);
         maybeWriteStatusToDiskAsync();
     }
 
@@ -282,6 +318,36 @@
     @VisibleForTesting
     public void clearForTesting() {
         mJobSet.clear();
+        mPendingJobWriteUids.put(ALL_UIDS, true);
+    }
+
+    void setUseSplitFiles(boolean useSplitFiles) {
+        synchronized (mLock) {
+            if (mUseSplitFiles != useSplitFiles) {
+                mUseSplitFiles = useSplitFiles;
+                migrateJobFilesAsync();
+            }
+        }
+    }
+
+    /**
+     * The same as above but does not schedule writing. This makes perf benchmarks more stable.
+     */
+    @VisibleForTesting
+    public void setUseSplitFilesForTesting(boolean useSplitFiles) {
+        final boolean changed;
+        synchronized (mLock) {
+            changed = mUseSplitFiles != useSplitFiles;
+            if (changed) {
+                mUseSplitFiles = useSplitFiles;
+                mPendingJobWriteUids.put(ALL_UIDS, true);
+            }
+        }
+        if (changed) {
+            synchronized (mWriteScheduleLock) {
+                mSplitFileMigrationNeeded = true;
+            }
+        }
     }
 
     /**
@@ -352,6 +418,16 @@
     private static final String XML_TAG_ONEOFF = "one-off";
     private static final String XML_TAG_EXTRAS = "extras";
 
+    private void migrateJobFilesAsync() {
+        synchronized (mLock) {
+            mPendingJobWriteUids.put(ALL_UIDS, true);
+        }
+        synchronized (mWriteScheduleLock) {
+            mSplitFileMigrationNeeded = true;
+            maybeWriteStatusToDiskAsync();
+        }
+    }
+
     /**
      * Every time the state changes we write all the jobs in one swath, instead of trying to
      * track incremental changes.
@@ -449,10 +525,38 @@
      * NOTE: This Runnable locks on mLock
      */
     private final Runnable mWriteRunnable = new Runnable() {
+        private final SparseArray<AtomicFile> mJobFiles = new SparseArray<>();
+        private final CopyConsumer mPersistedJobCopier = new CopyConsumer();
+
+        class CopyConsumer implements Consumer<JobStatus> {
+            private final SparseArray<List<JobStatus>> mJobStoreCopy = new SparseArray<>();
+            private boolean mCopyAllJobs;
+
+            private void prepare() {
+                mCopyAllJobs = !mUseSplitFiles || mPendingJobWriteUids.get(ALL_UIDS);
+            }
+
+            @Override
+            public void accept(JobStatus jobStatus) {
+                final int uid = mUseSplitFiles ? jobStatus.getUid() : ALL_UIDS;
+                if (jobStatus.isPersisted() && (mCopyAllJobs || mPendingJobWriteUids.get(uid))) {
+                    List<JobStatus> uidJobList = mJobStoreCopy.get(uid);
+                    if (uidJobList == null) {
+                        uidJobList = new ArrayList<>();
+                        mJobStoreCopy.put(uid, uidJobList);
+                    }
+                    uidJobList.add(new JobStatus(jobStatus));
+                }
+            }
+
+            private void reset() {
+                mJobStoreCopy.clear();
+            }
+        }
+
         @Override
         public void run() {
             final long startElapsed = sElapsedRealtimeClock.millis();
-            final List<JobStatus> storeCopy = new ArrayList<JobStatus>();
             // Intentionally allow new scheduling of a write operation *before* we clone
             // the job set.  If we reset it to false after cloning, there's a window in
             // which no new write will be scheduled but mLock is not held, i.e. a new
@@ -469,31 +573,73 @@
                 }
                 mWriteInProgress = true;
             }
+            final boolean useSplitFiles;
             synchronized (mLock) {
                 // Clone the jobs so we can release the lock before writing.
-                mJobSet.forEachJob(null, (job) -> {
-                    if (job.isPersisted()) {
-                        storeCopy.add(new JobStatus(job));
-                    }
-                });
+                useSplitFiles = mUseSplitFiles;
+                mPersistedJobCopier.prepare();
+                mJobSet.forEachJob(null, mPersistedJobCopier);
+                mPendingJobWriteUids.clear();
             }
-            writeJobsMapImpl(storeCopy);
+            mPersistInfo.countAllJobsSaved = 0;
+            mPersistInfo.countSystemServerJobsSaved = 0;
+            mPersistInfo.countSystemSyncManagerJobsSaved = 0;
+            for (int i = mPersistedJobCopier.mJobStoreCopy.size() - 1; i >= 0; --i) {
+                AtomicFile file;
+                if (useSplitFiles) {
+                    final int uid = mPersistedJobCopier.mJobStoreCopy.keyAt(i);
+                    file = mJobFiles.get(uid);
+                    if (file == null) {
+                        file = createJobFile(JOB_FILE_SPLIT_PREFIX + uid);
+                        mJobFiles.put(uid, file);
+                    }
+                } else {
+                    file = mJobsFile;
+                }
+                if (DEBUG) {
+                    Slog.d(TAG, "Writing for " + mPersistedJobCopier.mJobStoreCopy.keyAt(i)
+                            + " to " + file.getBaseFile().getName() + ": "
+                            + mPersistedJobCopier.mJobStoreCopy.valueAt(i).size() + " jobs");
+                }
+                writeJobsMapImpl(file, mPersistedJobCopier.mJobStoreCopy.valueAt(i));
+            }
             if (DEBUG) {
                 Slog.v(TAG, "Finished writing, took " + (sElapsedRealtimeClock.millis()
                         - startElapsed) + "ms");
             }
+            mPersistedJobCopier.reset();
+            if (!useSplitFiles) {
+                mJobFiles.clear();
+            }
+            // Update the last modified time of the directory to aid in RTC time verification
+            // (see the JobStore constructor).
+            mJobFileDirectory.setLastModified(sSystemClock.millis());
             synchronized (mWriteScheduleLock) {
+                if (mSplitFileMigrationNeeded) {
+                    final File[] files = mJobFileDirectory.listFiles();
+                    for (File file : files) {
+                        if (useSplitFiles) {
+                            if (!file.getName().startsWith(JOB_FILE_SPLIT_PREFIX)) {
+                                // Delete the now unused file so there's no confusion in the future.
+                                file.delete();
+                            }
+                        } else if (file.getName().startsWith(JOB_FILE_SPLIT_PREFIX)) {
+                            // Delete the now unused file so there's no confusion in the future.
+                            file.delete();
+                        }
+                    }
+                }
                 mWriteInProgress = false;
                 mWriteScheduleLock.notifyAll();
             }
         }
 
-        private void writeJobsMapImpl(List<JobStatus> jobList) {
+        private void writeJobsMapImpl(@NonNull AtomicFile file, @NonNull List<JobStatus> jobList) {
             int numJobs = 0;
             int numSystemJobs = 0;
             int numSyncJobs = 0;
             mEventLogger.setStartTime(SystemClock.uptimeMillis());
-            try (FileOutputStream fos = mJobsFile.startWrite()) {
+            try (FileOutputStream fos = file.startWrite()) {
                 TypedXmlSerializer out = Xml.resolveSerializer(fos);
                 out.startDocument(null, true);
                 out.setFeature("http://xmlpull.org/v1/doc/features.html#indent-output", true);
@@ -523,7 +669,7 @@
                 out.endTag(null, "job-info");
                 out.endDocument();
 
-                mJobsFile.finishWrite(fos);
+                file.finishWrite(fos);
             } catch (IOException e) {
                 if (DEBUG) {
                     Slog.v(TAG, "Error writing out job data.", e);
@@ -533,9 +679,9 @@
                     Slog.d(TAG, "Error persisting bundle.", e);
                 }
             } finally {
-                mPersistInfo.countAllJobsSaved = numJobs;
-                mPersistInfo.countSystemServerJobsSaved = numSystemJobs;
-                mPersistInfo.countSystemSyncManagerJobsSaved = numSyncJobs;
+                mPersistInfo.countAllJobsSaved += numJobs;
+                mPersistInfo.countSystemServerJobsSaved += numSystemJobs;
+                mPersistInfo.countSystemSyncManagerJobsSaved += numSyncJobs;
             }
         }
 
@@ -720,49 +866,82 @@
 
         @Override
         public void run() {
+            if (!mJobFileDirectory.isDirectory()) {
+                Slog.wtf(TAG, "jobs directory isn't a directory O.O");
+                mJobFileDirectory.mkdirs();
+                return;
+            }
+
             int numJobs = 0;
             int numSystemJobs = 0;
             int numSyncJobs = 0;
             List<JobStatus> jobs;
-            try (FileInputStream fis = mJobsFile.openRead()) {
-                synchronized (mLock) {
-                    jobs = readJobMapImpl(fis, rtcGood);
-                    if (jobs != null) {
-                        long now = sElapsedRealtimeClock.millis();
-                        for (int i=0; i<jobs.size(); i++) {
-                            JobStatus js = jobs.get(i);
-                            js.prepareLocked();
-                            js.enqueueTime = now;
-                            this.jobSet.add(js);
+            final File[] files;
+            try {
+                files = mJobFileDirectory.listFiles();
+            } catch (SecurityException e) {
+                Slog.wtf(TAG, "Not allowed to read job file directory", e);
+                return;
+            }
+            if (files == null) {
+                Slog.wtfStack(TAG, "Couldn't get job file list");
+                return;
+            }
+            boolean needFileMigration = false;
+            long now = sElapsedRealtimeClock.millis();
+            for (File file : files) {
+                final AtomicFile aFile = createJobFile(file);
+                try (FileInputStream fis = aFile.openRead()) {
+                    synchronized (mLock) {
+                        jobs = readJobMapImpl(fis, rtcGood);
+                        if (jobs != null) {
+                            for (int i = 0; i < jobs.size(); i++) {
+                                JobStatus js = jobs.get(i);
+                                js.prepareLocked();
+                                js.enqueueTime = now;
+                                this.jobSet.add(js);
 
-                            numJobs++;
-                            if (js.getUid() == Process.SYSTEM_UID) {
-                                numSystemJobs++;
-                                if (isSyncJob(js)) {
-                                    numSyncJobs++;
+                                numJobs++;
+                                if (js.getUid() == Process.SYSTEM_UID) {
+                                    numSystemJobs++;
+                                    if (isSyncJob(js)) {
+                                        numSyncJobs++;
+                                    }
                                 }
                             }
                         }
                     }
+                } catch (FileNotFoundException e) {
+                    // mJobFileDirectory.listFiles() gave us this file...why can't we find it???
+                    Slog.e(TAG, "Could not find jobs file: " + file.getName());
+                } catch (XmlPullParserException | IOException e) {
+                    Slog.wtf(TAG, "Error in " + file.getName(), e);
+                } catch (Exception e) {
+                    // Crashing at this point would result in a boot loop, so live with a general
+                    // Exception for system stability's sake.
+                    Slog.wtf(TAG, "Unexpected exception", e);
                 }
-            } catch (FileNotFoundException e) {
-                if (DEBUG) {
-                    Slog.d(TAG, "Could not find jobs file, probably there was nothing to load.");
-                }
-            } catch (XmlPullParserException | IOException e) {
-                Slog.wtf(TAG, "Error jobstore xml.", e);
-            } catch (Exception e) {
-                // Crashing at this point would result in a boot loop, so live with a general
-                // Exception for system stability's sake.
-                Slog.wtf(TAG, "Unexpected exception", e);
-            } finally {
-                if (mPersistInfo.countAllJobsLoaded < 0) { // Only set them once.
-                    mPersistInfo.countAllJobsLoaded = numJobs;
-                    mPersistInfo.countSystemServerJobsLoaded = numSystemJobs;
-                    mPersistInfo.countSystemSyncManagerJobsLoaded = numSyncJobs;
+                if (mUseSplitFiles) {
+                    if (!file.getName().startsWith(JOB_FILE_SPLIT_PREFIX)) {
+                        // We're supposed to be using the split file architecture, but we still have
+                        // the old job file around. Fully migrate and remove the old file.
+                        needFileMigration = true;
+                    }
+                } else if (file.getName().startsWith(JOB_FILE_SPLIT_PREFIX)) {
+                    // We're supposed to be using the legacy single file architecture, but we still
+                    // have some job split files around. Fully migrate and remove the split files.
+                    needFileMigration = true;
                 }
             }
+            if (mPersistInfo.countAllJobsLoaded < 0) { // Only set them once.
+                mPersistInfo.countAllJobsLoaded = numJobs;
+                mPersistInfo.countSystemServerJobsLoaded = numSystemJobs;
+                mPersistInfo.countSystemSyncManagerJobsLoaded = numSyncJobs;
+            }
             Slog.i(TAG, "Read " + numJobs + " jobs");
+            if (needFileMigration) {
+                migrateJobFilesAsync();
+            }
         }
 
         private List<JobStatus> readJobMapImpl(InputStream fis, boolean rtcIsGood)
diff --git a/services/tests/servicestests/src/com/android/server/job/JobStoreTest.java b/services/tests/servicestests/src/com/android/server/job/JobStoreTest.java
index f138311..808130a 100644
--- a/services/tests/servicestests/src/com/android/server/job/JobStoreTest.java
+++ b/services/tests/servicestests/src/com/android/server/job/JobStoreTest.java
@@ -155,7 +155,18 @@
     }
 
     @Test
-    public void testWritingTwoFilesToDisk() throws Exception {
+    public void testWritingTwoJobsToDisk_singleFile() throws Exception {
+        mTaskStoreUnderTest.setUseSplitFiles(false);
+        runWritingTwoJobsToDisk();
+    }
+
+    @Test
+    public void testWritingTwoJobsToDisk_splitFiles() throws Exception {
+        mTaskStoreUnderTest.setUseSplitFiles(true);
+        runWritingTwoJobsToDisk();
+    }
+
+    private void runWritingTwoJobsToDisk() throws Exception {
         final JobInfo task1 = new Builder(8, mComponent)
                 .setRequiresDeviceIdle(true)
                 .setPeriodic(10000L)
@@ -169,8 +180,10 @@
                 .setRequiredNetworkType(JobInfo.NETWORK_TYPE_UNMETERED)
                 .setPersisted(true)
                 .build();
-        final JobStatus taskStatus1 = JobStatus.createFromJobInfo(task1, SOME_UID, null, -1, null);
-        final JobStatus taskStatus2 = JobStatus.createFromJobInfo(task2, SOME_UID, null, -1, null);
+        final int uid1 = SOME_UID;
+        final int uid2 = uid1 + 1;
+        final JobStatus taskStatus1 = JobStatus.createFromJobInfo(task1, uid1, null, -1, null);
+        final JobStatus taskStatus2 = JobStatus.createFromJobInfo(task2, uid2, null, -1, null);
         mTaskStoreUnderTest.add(taskStatus1);
         mTaskStoreUnderTest.add(taskStatus2);
         waitForPendingIo();
diff --git a/tests/JobSchedulerPerfTests/src/com/android/frameworks/perftests/job/JobStorePerfTests.java b/tests/JobSchedulerPerfTests/src/com/android/frameworks/perftests/job/JobStorePerfTests.java
index dd9b294..afaeca1 100644
--- a/tests/JobSchedulerPerfTests/src/com/android/frameworks/perftests/job/JobStorePerfTests.java
+++ b/tests/JobSchedulerPerfTests/src/com/android/frameworks/perftests/job/JobStorePerfTests.java
@@ -15,7 +15,6 @@
  */
 package com.android.frameworks.perftests.job;
 
-
 import android.app.job.JobInfo;
 import android.content.ComponentName;
 import android.content.Context;
@@ -46,7 +45,8 @@
 public class JobStorePerfTests {
     private static final String SOURCE_PACKAGE = "com.android.frameworks.perftests.job";
     private static final int SOURCE_USER_ID = 0;
-    private static final int CALLING_UID = 10079;
+    private static final int BASE_CALLING_UID = 10079;
+    private static final int MAX_UID_COUNT = 10;
 
     private static Context sContext;
     private static File sTestDir;
@@ -65,10 +65,10 @@
         sJobStore = JobStore.initAndGetForTesting(sContext, sTestDir);
 
         for (int i = 0; i < 50; i++) {
-            sFewJobs.add(createJobStatus("fewJobs", i));
+            sFewJobs.add(createJobStatus("fewJobs", i, BASE_CALLING_UID + (i % MAX_UID_COUNT)));
         }
         for (int i = 0; i < 500; i++) {
-            sManyJobs.add(createJobStatus("manyJobs", i));
+            sManyJobs.add(createJobStatus("manyJobs", i, BASE_CALLING_UID + (i % MAX_UID_COUNT)));
         }
     }
 
@@ -104,6 +104,64 @@
         runPersistedJobWriting(sManyJobs);
     }
 
+    private void runPersistedJobWriting_delta(List<JobStatus> jobList,
+            List<JobStatus> jobAdditions, List<JobStatus> jobRemovals) {
+        final ManualBenchmarkState benchmarkState = mPerfManualStatusReporter.getBenchmarkState();
+
+        long elapsedTimeNs = 0;
+        while (benchmarkState.keepRunning(elapsedTimeNs)) {
+            sJobStore.clearForTesting();
+            for (JobStatus job : jobList) {
+                sJobStore.addForTesting(job);
+            }
+            sJobStore.writeStatusToDiskForTesting();
+
+            for (JobStatus job : jobAdditions) {
+                sJobStore.addForTesting(job);
+            }
+            for (JobStatus job : jobRemovals) {
+                sJobStore.removeForTesting(job);
+            }
+
+            final long startTime = SystemClock.elapsedRealtimeNanos();
+            sJobStore.writeStatusToDiskForTesting();
+            final long endTime = SystemClock.elapsedRealtimeNanos();
+            elapsedTimeNs = endTime - startTime;
+        }
+    }
+
+    @Test
+    public void testPersistedJobWriting_delta_fewJobs() {
+        List<JobStatus> additions = new ArrayList<>();
+        List<JobStatus> removals = new ArrayList<>();
+        final int numModifiedUids = MAX_UID_COUNT / 2;
+        for (int i = 0; i < sFewJobs.size() / 3; ++i) {
+            JobStatus job = createJobStatus("fewJobs", i, BASE_CALLING_UID + (i % numModifiedUids));
+            if (i % 2 == 0) {
+                additions.add(job);
+            } else {
+                removals.add(job);
+            }
+        }
+        runPersistedJobWriting_delta(sFewJobs, additions, removals);
+    }
+
+    @Test
+    public void testPersistedJobWriting_delta_manyJobs() {
+        List<JobStatus> additions = new ArrayList<>();
+        List<JobStatus> removals = new ArrayList<>();
+        final int numModifiedUids = MAX_UID_COUNT / 2;
+        for (int i = 0; i < sManyJobs.size() / 3; ++i) {
+            JobStatus job = createJobStatus("fewJobs", i, BASE_CALLING_UID + (i % numModifiedUids));
+            if (i % 2 == 0) {
+                additions.add(job);
+            } else {
+                removals.add(job);
+            }
+        }
+        runPersistedJobWriting_delta(sManyJobs, additions, removals);
+    }
+
     private void runPersistedJobReading(List<JobStatus> jobList, boolean rtcIsGood) {
         final ManualBenchmarkState benchmarkState = mPerfManualStatusReporter.getBenchmarkState();
 
@@ -144,12 +202,12 @@
         runPersistedJobReading(sManyJobs, false);
     }
 
-    private static JobStatus createJobStatus(String testTag, int jobId) {
+    private static JobStatus createJobStatus(String testTag, int jobId, int callingUid) {
         JobInfo jobInfo = new JobInfo.Builder(jobId,
                 new ComponentName(sContext, "JobStorePerfTestJobService"))
                 .setPersisted(true)
                 .build();
         return JobStatus.createFromJobInfo(
-                jobInfo, CALLING_UID, SOURCE_PACKAGE, SOURCE_USER_ID, testTag);
+                jobInfo, callingUid, SOURCE_PACKAGE, SOURCE_USER_ID, testTag);
     }
 }