| /* |
| * Copyright (C) 2020 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.internal.os; |
| |
| import android.os.StrictMode; |
| import android.os.SystemClock; |
| import android.util.Slog; |
| import android.util.SparseArray; |
| |
| import java.util.concurrent.locks.ReentrantReadWriteLock; |
| |
| /** |
| * Reads cpu time bpf maps. |
| * |
| * It is implemented as singletons for each separate set of per-UID times. Get___Instance() method |
| * returns the corresponding reader instance. In order to prevent frequent GC, it reuses the same |
| * SparseArray to store data read from BPF maps. |
| * |
| * A KernelCpuUidBpfMapReader instance keeps an error counter. When the number of read errors within |
| * that instance accumulates to 5, this instance will reject all further read requests. |
| * |
| * Data fetched within last 500ms is considered fresh, since the reading lifecycle can take up to |
| * 25ms. KernelCpuUidBpfMapReader always tries to use cache if it is fresh and valid, but it can |
| * be disabled through a parameter. |
| * |
| * A KernelCpuUidBpfMapReader instance is thread-safe. It acquires a write lock when reading the bpf |
| * map, releases it right after, then acquires a read lock before returning a BpfMapIterator. Caller |
| * is responsible for closing BpfMapIterator (also auto-closable) after reading, otherwise deadlock |
| * will occur. |
| */ |
| public abstract class KernelCpuUidBpfMapReader { |
| private static final int ERROR_THRESHOLD = 5; |
| private static final long FRESHNESS_MS = 500L; |
| |
| private static final KernelCpuUidBpfMapReader FREQ_TIME_READER = |
| new KernelCpuUidFreqTimeBpfMapReader(); |
| |
| private static final KernelCpuUidBpfMapReader ACTIVE_TIME_READER = |
| new KernelCpuUidActiveTimeBpfMapReader(); |
| |
| private static final KernelCpuUidBpfMapReader CLUSTER_TIME_READER = |
| new KernelCpuUidClusterTimeBpfMapReader(); |
| |
| static KernelCpuUidBpfMapReader getFreqTimeReaderInstance() { |
| return FREQ_TIME_READER; |
| } |
| |
| static KernelCpuUidBpfMapReader getActiveTimeReaderInstance() { |
| return ACTIVE_TIME_READER; |
| } |
| |
| static KernelCpuUidBpfMapReader getClusterTimeReaderInstance() { |
| return CLUSTER_TIME_READER; |
| } |
| |
| final String mTag = this.getClass().getSimpleName(); |
| private int mErrors = 0; |
| private boolean mTracking = false; |
| protected SparseArray<long[]> mData = new SparseArray<>(); |
| private long mLastReadTime = 0; |
| protected final ReentrantReadWriteLock mLock = new ReentrantReadWriteLock(); |
| protected final ReentrantReadWriteLock.ReadLock mReadLock = mLock.readLock(); |
| protected final ReentrantReadWriteLock.WriteLock mWriteLock = mLock.writeLock(); |
| |
| public native boolean startTrackingBpfTimes(); |
| |
| protected abstract boolean readBpfData(); |
| |
| /** |
| * Returns an array of metadata used to inform the caller of 1) the size of array required by |
| * getNextUid and 2) how to interpret the raw data copied to that array. |
| */ |
| public abstract long[] getDataDimensions(); |
| |
| public void removeUidsInRange(int startUid, int endUid) { |
| if (mErrors > ERROR_THRESHOLD) { |
| return; |
| } |
| mWriteLock.lock(); |
| int firstIndex = mData.indexOfKey(startUid); |
| int lastIndex = mData.indexOfKey(endUid); |
| mData.removeAtRange(firstIndex, lastIndex - firstIndex + 1); |
| mWriteLock.unlock(); |
| } |
| |
| public BpfMapIterator open() { |
| return open(false); |
| } |
| |
| public BpfMapIterator open(boolean ignoreCache) { |
| if (mErrors > ERROR_THRESHOLD) { |
| return null; |
| } |
| if (!mTracking && !startTrackingBpfTimes()) { |
| Slog.w(mTag, "Failed to start tracking"); |
| mErrors++; |
| return null; |
| } |
| if (ignoreCache) { |
| mWriteLock.lock(); |
| } else { |
| mReadLock.lock(); |
| if (dataValid()) { |
| return new BpfMapIterator(); |
| } |
| mReadLock.unlock(); |
| mWriteLock.lock(); |
| if (dataValid()) { |
| mReadLock.lock(); |
| mWriteLock.unlock(); |
| return new BpfMapIterator(); |
| } |
| } |
| if (readBpfData()) { |
| mLastReadTime = SystemClock.elapsedRealtime(); |
| mReadLock.lock(); |
| mWriteLock.unlock(); |
| return new BpfMapIterator(); |
| } |
| |
| mWriteLock.unlock(); |
| mErrors++; |
| Slog.w(mTag, "Failed to read bpf times"); |
| return null; |
| } |
| |
| private boolean dataValid() { |
| return mData.size() > 0 && (SystemClock.elapsedRealtime() - mLastReadTime < FRESHNESS_MS); |
| } |
| |
| public class BpfMapIterator implements AutoCloseable { |
| private int mPos; |
| |
| public BpfMapIterator() { |
| }; |
| |
| public boolean getNextUid(long[] buf) { |
| if (mPos >= mData.size()) { |
| return false; |
| } |
| buf[0] = mData.keyAt(mPos); |
| System.arraycopy(mData.valueAt(mPos), 0, buf, 1, mData.valueAt(mPos).length); |
| mPos++; |
| return true; |
| } |
| |
| public void close() { |
| mReadLock.unlock(); |
| } |
| } |
| |
| public static class KernelCpuUidFreqTimeBpfMapReader extends KernelCpuUidBpfMapReader { |
| |
| private final native boolean removeUidRange(int startUid, int endUid); |
| |
| @Override |
| protected final native boolean readBpfData(); |
| |
| @Override |
| public final native long[] getDataDimensions(); |
| |
| @Override |
| public void removeUidsInRange(int startUid, int endUid) { |
| mWriteLock.lock(); |
| super.removeUidsInRange(startUid, endUid); |
| removeUidRange(startUid, endUid); |
| mWriteLock.unlock(); |
| } |
| } |
| |
| public static class KernelCpuUidActiveTimeBpfMapReader extends KernelCpuUidBpfMapReader { |
| |
| @Override |
| protected final native boolean readBpfData(); |
| |
| @Override |
| public final native long[] getDataDimensions(); |
| } |
| |
| public static class KernelCpuUidClusterTimeBpfMapReader extends KernelCpuUidBpfMapReader { |
| |
| @Override |
| protected final native boolean readBpfData(); |
| |
| @Override |
| public final native long[] getDataDimensions(); |
| } |
| } |