Merge "More robust read mechanism in KernelCpuProcReader" into pi-dev (f76c383f) · Commits · e / os / android_frameworks_base

core/java/com/android/internal/os/KernelCpuProcReader.java

+27 −31

Original line number	Diff line number	Diff line
		@@ -24,13 +24,14 @@ import com.android.internal.annotations.VisibleForTesting;

		import java.io.FileNotFoundException;
		import java.io.IOException;
		import java.io.InputStream;
		import java.nio.ByteBuffer;
		import java.nio.ByteOrder;
		import java.nio.channels.FileChannel;
		import java.nio.file.Files;
		import java.nio.file.NoSuchFileException;
		import java.nio.file.Path;
		import java.nio.file.Paths;
		import java.nio.file.StandardOpenOption;
		import java.util.Arrays;

		/**
		* Reads cpu time proc files with throttling (adjustable interval).
		@@ -55,7 +56,6 @@ public class KernelCpuProcReader {
		private static final int ERROR_THRESHOLD = 5;
		// Throttle interval in milliseconds
		private static final long DEFAULT_THROTTLE_INTERVAL = 3000L;
		private static final int INITIAL_BUFFER_SIZE = 8 * 1024;
		private static final int MAX_BUFFER_SIZE = 1024 * 1024;
		private static final String PROC_UID_FREQ_TIME = "/proc/uid_cpupower/time_in_state";
		private static final String PROC_UID_ACTIVE_TIME = "/proc/uid_cpupower/concurrent_active_time";
		@@ -84,13 +84,12 @@ public class KernelCpuProcReader {
		private long mThrottleInterval = DEFAULT_THROTTLE_INTERVAL;
		private long mLastReadTime = Long.MIN_VALUE;
		private final Path mProc;
		private ByteBuffer mBuffer;
		private byte[] mBuffer = new byte[8 * 1024];
		private int mContentSize;

		@VisibleForTesting
		public KernelCpuProcReader(String procFile) {
		mProc = Paths.get(procFile);
		mBuffer = ByteBuffer.allocateDirect(INITIAL_BUFFER_SIZE);
		mBuffer.clear();
		}

		/**
		@@ -108,38 +107,45 @@ public class KernelCpuProcReader {
		return null;
		}
		if (SystemClock.elapsedRealtime() < mLastReadTime + mThrottleInterval) {
		if (mBuffer.limit() > 0 && mBuffer.limit() < mBuffer.capacity()) {
		// mBuffer has data.
		return mBuffer.asReadOnlyBuffer().order(ByteOrder.nativeOrder());
		if (mContentSize > 0) {
		return ByteBuffer.wrap(mBuffer, 0, mContentSize).asReadOnlyBuffer()
		.order(ByteOrder.nativeOrder());
		}
		return null;
		}
		mLastReadTime = SystemClock.elapsedRealtime();
		mBuffer.clear();
		mContentSize = 0;
		final int oldMask = StrictMode.allowThreadDiskReadsMask();
		try (FileChannel fc = FileChannel.open(mProc, StandardOpenOption.READ)) {
		while (fc.read(mBuffer) == mBuffer.capacity()) {
		if (!resize()) {
		try (InputStream in = Files.newInputStream(mProc)) {
		int numBytes = 0;
		int curr;
		while ((curr = in.read(mBuffer, numBytes, mBuffer.length - numBytes)) >= 0) {
		numBytes += curr;
		if (numBytes == mBuffer.length) {
		// Hit the limit. Resize mBuffer.
		if (mBuffer.length == MAX_BUFFER_SIZE) {
		mErrors++;
		Slog.e(TAG, "Proc file is too large: " + mProc);
		return null;
		}
		fc.position(0);
		mBuffer = Arrays.copyOf(mBuffer,
		Math.min(mBuffer.length << 1, MAX_BUFFER_SIZE));
		}
		}
		mContentSize = numBytes;
		return ByteBuffer.wrap(mBuffer, 0, mContentSize).asReadOnlyBuffer()
		.order(ByteOrder.nativeOrder());
		} catch (NoSuchFileException \| FileNotFoundException e) {
		// Happens when the kernel does not provide this file. Not a big issue. Just log it.
		mErrors++;
		Slog.w(TAG, "File not exist: " + mProc);
		return null;
		} catch (IOException e) {
		mErrors++;
		Slog.e(TAG, "Error reading: " + mProc, e);
		return null;
		} finally {
		StrictMode.setThreadPolicyMask(oldMask);
		}
		mBuffer.flip();
		return mBuffer.asReadOnlyBuffer().order(ByteOrder.nativeOrder());
		return null;
		}

		/**
		@@ -153,14 +159,4 @@ public class KernelCpuProcReader {
		mThrottleInterval = throttleInterval;
		}
		}

		private boolean resize() {
		if (mBuffer.capacity() >= MAX_BUFFER_SIZE) {
		return false;
		}
		int newSize = Math.min(mBuffer.capacity() << 1, MAX_BUFFER_SIZE);
		// Slog.i(TAG, "Resize buffer " + mBuffer.capacity() + " => " + newSize);
		mBuffer = ByteBuffer.allocateDirect(newSize);
		return true;
		}
		}