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Add initial Ledger implementation.

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Add the ledger for an app's current balance and transactions. Writing to
and reading from disk will be added later.

Bug: 158300259
Test: Android builds
Change-Id: Ica9f5d5957f710538c9d8741555f0568fc0bc7ee
This commit is contained in:
Kweku Adams
2021-05-19 11:46:08 -07:00
parent 888996e278
commit 65e0ade151
3 changed files with 222 additions and 0 deletions
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120
apex/jobscheduler/service/java/com/android/server/tare/Ledger.java Normal file
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/*
* Copyright (C) 2021 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.server.tare;
import static android.text.format.DateUtils.HOUR_IN_MILLIS;
import static com.android.server.tare.TareUtils.narcToArc;
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.util.ArrayMap;
import android.util.IndentingPrintWriter;
import java.util.ArrayList;
import java.util.List;
/**
* Ledger to track the last recorded balance and recent activities of an app.
*/
class Ledger {
static class Transaction {
public final long startTimeMs;
public final long endTimeMs;
@NonNull
public final String reason;
@Nullable
public final String tag;
public final long delta;
Transaction(long startTimeMs, long endTimeMs,
@NonNull String reason, @Nullable String tag, long delta) {
this.startTimeMs = startTimeMs;
this.endTimeMs = endTimeMs;
this.reason = reason;
this.tag = tag;
this.delta = delta;
}
}
/** Last saved balance. This doesn't take currently ongoing events into account. */
private long mCurrentBalance = 0;
private final List<Transaction> mTransactions = new ArrayList<>();
private final ArrayMap<String, Long> mCumulativeDeltaPerReason = new ArrayMap<>();
private long mEarliestSumTime;
Ledger() {
}
long getCurrentBalance() {
return mCurrentBalance;
}
void recordTransaction(@NonNull Transaction transaction) {
mTransactions.add(transaction);
mCurrentBalance += transaction.delta;
Long sum = mCumulativeDeltaPerReason.get(transaction.reason);
if (sum == null) {
sum = 0L;
}
sum += transaction.delta;
mCumulativeDeltaPerReason.put(transaction.reason, sum);
mEarliestSumTime = Math.min(mEarliestSumTime, transaction.startTimeMs);
}
long get24HourSum(@NonNull String reason, final long now) {
final long windowStartTime = now - 24 * HOUR_IN_MILLIS;
if (mEarliestSumTime < windowStartTime) {
// Need to redo sums
mCumulativeDeltaPerReason.clear();
for (int i = mTransactions.size() - 1; i >= 0; --i) {
final Transaction transaction = mTransactions.get(i);
if (transaction.endTimeMs <= windowStartTime) {
break;
}
final Long sumObj = mCumulativeDeltaPerReason.get(transaction.reason);
long sum = sumObj == null ? 0 : sumObj;
if (transaction.startTimeMs >= windowStartTime) {
sum += transaction.delta;
} else {
// Pro-rate durationed deltas. Intentionally floor the result.
sum += (long) (1.0 * (transaction.endTimeMs - windowStartTime)
* transaction.delta)
/ (transaction.endTimeMs - transaction.startTimeMs);
}
mCumulativeDeltaPerReason.put(transaction.reason, sum);
}
mEarliestSumTime = windowStartTime;
}
Long sum = mCumulativeDeltaPerReason.get(reason);
if (sum == null) {
return 0;
}
return sum;
}
void dump(IndentingPrintWriter pw) {
pw.println("Ledger{");
pw.increaseIndent();
pw.print("cur balance", narcToArc(getCurrentBalance())).println();
pw.decreaseIndent();
pw.println("}");
}
}

27
apex/jobscheduler/service/java/com/android/server/tare/TareUtils.java Normal file
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/*
* Copyright (C) 2021 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.server.tare;
class TareUtils {
static long arcToNarc(int arcs) {
return arcs * 1_000_000_000L;
}
static int narcToArc(long narcs) {
return (int) (narcs / 1_000_000_000);
}
}

75
services/tests/servicestests/src/com/android/server/tare/LedgerTest.java Normal file
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/*
* Copyright (C) 2021 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.server.tare;
import static android.text.format.DateUtils.HOUR_IN_MILLIS;
import static android.text.format.DateUtils.MINUTE_IN_MILLIS;
import static org.junit.Assert.assertEquals;
import androidx.test.filters.SmallTest;
import androidx.test.runner.AndroidJUnit4;
import org.junit.Test;
import org.junit.runner.RunWith;
/** Test that the ledger records transactions correctly. */
@RunWith(AndroidJUnit4.class)
@SmallTest
public class LedgerTest {
@Test
public void testInitialState() {
final Ledger ledger = new Ledger();
assertEquals(0, ledger.getCurrentBalance());
assertEquals(0, ledger.get24HourSum("anything", 0));
}
@Test
public void testMultipleTransactions() {
final Ledger ledger = new Ledger();
ledger.recordTransaction(new Ledger.Transaction(0, 1000, "test", null, 5));
assertEquals(5, ledger.getCurrentBalance());
assertEquals(5, ledger.get24HourSum("test", 60_000));
ledger.recordTransaction(new Ledger.Transaction(2000, 2000, "test", null, 25));
assertEquals(30, ledger.getCurrentBalance());
assertEquals(30, ledger.get24HourSum("test", 60_000));
ledger.recordTransaction(new Ledger.Transaction(5000, 5500, "test", null, -10));
assertEquals(20, ledger.getCurrentBalance());
assertEquals(20, ledger.get24HourSum("test", 60_000));
}
@Test
public void test24HourSum() {
final Ledger ledger = new Ledger();
ledger.recordTransaction(new Ledger.Transaction(0, 1000, "test", null, 500));
assertEquals(500, ledger.get24HourSum("test", 24 * HOUR_IN_MILLIS));
ledger.recordTransaction(
new Ledger.Transaction(2 * HOUR_IN_MILLIS, 3 * HOUR_IN_MILLIS, "test", null, 2500));
assertEquals(3000, ledger.get24HourSum("test", 24 * HOUR_IN_MILLIS));
ledger.recordTransaction(
new Ledger.Transaction(4 * HOUR_IN_MILLIS, 4 * HOUR_IN_MILLIS, "test", null, 1));
assertEquals(3001, ledger.get24HourSum("test", 24 * HOUR_IN_MILLIS));
assertEquals(2501, ledger.get24HourSum("test", 25 * HOUR_IN_MILLIS));
assertEquals(2501, ledger.get24HourSum("test", 26 * HOUR_IN_MILLIS));
// Pro-rated as the second transaction phases out
assertEquals(1251,
ledger.get24HourSum("test", 26 * HOUR_IN_MILLIS + 30 * MINUTE_IN_MILLIS));
assertEquals(1, ledger.get24HourSum("test", 27 * HOUR_IN_MILLIS));
assertEquals(0, ledger.get24HourSum("test", 28 * HOUR_IN_MILLIS));
}
}