Merge "First draft of StatsEvent.java"
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Treehugger Robot
331
core/java/android/util/StatsEvent.java
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331
core/java/android/util/StatsEvent.java
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/*
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* Copyright (C) 2019 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package android.util;
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import static java.nio.charset.StandardCharsets.UTF_8;
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import android.annotation.NonNull;
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import android.annotation.Nullable;
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import com.android.internal.annotations.GuardedBy;
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/**
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* StatsEvent builds and stores the buffer sent over the statsd socket.
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* This class defines and encapsulates the socket protocol.
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* @hide
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**/
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public final class StatsEvent implements AutoCloseable {
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private static final int POS_NUM_ELEMENTS = 1;
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private static final int POS_TIMESTAMP = POS_NUM_ELEMENTS + 1;
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private static final int LOGGER_ENTRY_MAX_PAYLOAD = 4068;
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// Max payload size is 4 KB less 4 bytes which are reserved for statsEventTag.
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// See android_util_StatsLog.cpp.
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private static final int MAX_EVENT_PAYLOAD = LOGGER_ENTRY_MAX_PAYLOAD - 4;
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private static final byte INT_TYPE = 0;
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private static final byte LONG_TYPE = 1;
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private static final byte STRING_TYPE = 2;
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private static final byte LIST_TYPE = 3;
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private static final byte FLOAT_TYPE = 4;
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private static final int INT_TYPE_SIZE = 5;
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private static final int FLOAT_TYPE_SIZE = 5;
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private static final int LONG_TYPE_SIZE = 9;
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private static final int STRING_TYPE_OVERHEAD = 5;
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private static final int LIST_TYPE_OVERHEAD = 2;
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public static final int SUCCESS = 0;
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public static final int ERROR_BUFFER_LIMIT_EXCEEDED = -1;
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public static final int ERROR_NO_TIMESTAMP = -2;
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public static final int ERROR_TIMESTAMP_ALREADY_WRITTEN = -3;
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public static final int ERROR_NO_ATOM_ID = -4;
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public static final int ERROR_ATOM_ID_ALREADY_WRITTEN = -5;
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public static final int ERROR_UID_TAG_COUNT_MISMATCH = -6;
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private static Object sLock = new Object();
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@GuardedBy("sLock")
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private static StatsEvent sPool;
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private final byte[] mBuffer = new byte[MAX_EVENT_PAYLOAD];
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private int mPos;
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private int mNumElements;
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private int mAtomId;
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private StatsEvent() {
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// Write LIST_TYPE to buffer
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mBuffer[0] = LIST_TYPE;
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reset();
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}
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private void reset() {
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// Reset state.
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mPos = POS_TIMESTAMP;
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mNumElements = 0;
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mAtomId = 0;
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}
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/**
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* Returns a StatsEvent object from the pool.
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**/
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@NonNull
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public static StatsEvent obtain() {
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final StatsEvent statsEvent;
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synchronized (sLock) {
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statsEvent = null == sPool ? new StatsEvent() : sPool;
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sPool = null;
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}
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statsEvent.reset();
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return statsEvent;
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}
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@Override
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public void close() {
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synchronized (sLock) {
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if (null == sPool) {
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sPool = this;
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}
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}
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}
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/**
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* Writes the event timestamp to the buffer.
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**/
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public int writeTimestampNs(final long timestampNs) {
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if (hasTimestamp()) {
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return ERROR_TIMESTAMP_ALREADY_WRITTEN;
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}
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return writeLong(timestampNs);
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}
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private boolean hasTimestamp() {
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return mPos > POS_TIMESTAMP;
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}
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private boolean hasAtomId() {
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return mAtomId != 0;
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}
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/**
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* Writes the atom id to the buffer.
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**/
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public int writeAtomId(final int atomId) {
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if (!hasTimestamp()) {
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return ERROR_NO_TIMESTAMP;
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} else if (hasAtomId()) {
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return ERROR_ATOM_ID_ALREADY_WRITTEN;
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}
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final int writeResult = writeInt(atomId);
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if (SUCCESS == writeResult) {
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mAtomId = atomId;
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}
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return writeResult;
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}
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/**
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* Appends the given int to the StatsEvent buffer.
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**/
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public int writeInt(final int value) {
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if (!hasTimestamp()) {
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return ERROR_NO_TIMESTAMP;
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} else if (!hasAtomId()) {
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return ERROR_NO_ATOM_ID;
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} else if (mPos + INT_TYPE_SIZE > MAX_EVENT_PAYLOAD) {
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return ERROR_BUFFER_LIMIT_EXCEEDED;
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}
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mBuffer[mPos] = INT_TYPE;
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copyInt(mBuffer, mPos + 1, value);
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mPos += INT_TYPE_SIZE;
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mNumElements++;
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return SUCCESS;
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}
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/**
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* Appends the given long to the StatsEvent buffer.
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**/
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public int writeLong(final long value) {
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if (!hasTimestamp()) {
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return ERROR_NO_TIMESTAMP;
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} else if (!hasAtomId()) {
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return ERROR_NO_ATOM_ID;
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} else if (mPos + LONG_TYPE_SIZE > MAX_EVENT_PAYLOAD) {
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return ERROR_BUFFER_LIMIT_EXCEEDED;
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}
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mBuffer[mPos] = LONG_TYPE;
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copyLong(mBuffer, mPos + 1, value);
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mPos += LONG_TYPE_SIZE;
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mNumElements++;
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return SUCCESS;
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}
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/**
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* Appends the given float to the StatsEvent buffer.
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**/
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public int writeFloat(final float value) {
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if (!hasTimestamp()) {
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return ERROR_NO_TIMESTAMP;
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} else if (!hasAtomId()) {
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return ERROR_NO_ATOM_ID;
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} else if (mPos + FLOAT_TYPE_SIZE > MAX_EVENT_PAYLOAD) {
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return ERROR_BUFFER_LIMIT_EXCEEDED;
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}
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mBuffer[mPos] = FLOAT_TYPE;
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copyInt(mBuffer, mPos + 1, Float.floatToIntBits(value));
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mPos += FLOAT_TYPE_SIZE;
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mNumElements++;
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return SUCCESS;
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}
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/**
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* Appends the given boolean to the StatsEvent buffer.
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**/
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public int writeBoolean(final boolean value) {
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return writeInt(value ? 1 : 0);
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}
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/**
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* Appends the given byte array to the StatsEvent buffer.
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**/
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public int writeByteArray(@NonNull final byte[] value) {
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if (!hasTimestamp()) {
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return ERROR_NO_TIMESTAMP;
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} else if (!hasAtomId()) {
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return ERROR_NO_ATOM_ID;
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} else if (mPos + STRING_TYPE_OVERHEAD + value.length > MAX_EVENT_PAYLOAD) {
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return ERROR_BUFFER_LIMIT_EXCEEDED;
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}
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mBuffer[mPos] = STRING_TYPE;
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copyInt(mBuffer, mPos + 1, value.length);
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System.arraycopy(value, 0, mBuffer, mPos + STRING_TYPE_OVERHEAD, value.length);
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mPos += STRING_TYPE_OVERHEAD + value.length;
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mNumElements++;
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return SUCCESS;
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}
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/**
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* Appends the given String to the StatsEvent buffer.
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**/
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public int writeString(@NonNull final String value) {
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final byte[] valueBytes = stringToBytes(value);
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return writeByteArray(valueBytes);
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}
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/**
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* Appends the AttributionNode specified as array of uids and array of tags.
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**/
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public int writeAttributionNode(@NonNull final int[] uids, @NonNull final String[] tags) {
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if (!hasTimestamp()) {
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return ERROR_NO_TIMESTAMP;
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} else if (!hasAtomId()) {
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return ERROR_NO_ATOM_ID;
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} else if (mPos + LIST_TYPE_OVERHEAD > MAX_EVENT_PAYLOAD) {
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return ERROR_BUFFER_LIMIT_EXCEEDED;
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}
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final int numTags = tags.length;
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final int numUids = uids.length;
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if (numTags != numUids) {
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return ERROR_UID_TAG_COUNT_MISMATCH;
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}
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int pos = mPos;
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mBuffer[pos] = LIST_TYPE;
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mBuffer[pos + 1] = (byte) numTags;
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pos += LIST_TYPE_OVERHEAD;
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for (int i = 0; i < numTags; i++) {
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final byte[] tagBytes = stringToBytes(tags[i]);
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if (pos + LIST_TYPE_OVERHEAD + INT_TYPE_SIZE
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+ STRING_TYPE_OVERHEAD + tagBytes.length > MAX_EVENT_PAYLOAD) {
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return ERROR_BUFFER_LIMIT_EXCEEDED;
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}
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mBuffer[pos] = LIST_TYPE;
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mBuffer[pos + 1] = 2;
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pos += LIST_TYPE_OVERHEAD;
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mBuffer[pos] = INT_TYPE;
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copyInt(mBuffer, pos + 1, uids[i]);
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pos += INT_TYPE_SIZE;
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mBuffer[pos] = STRING_TYPE;
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copyInt(mBuffer, pos + 1, tagBytes.length);
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System.arraycopy(tagBytes, 0, mBuffer, pos + STRING_TYPE_OVERHEAD, tagBytes.length);
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pos += STRING_TYPE_OVERHEAD + tagBytes.length;
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}
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mPos = pos;
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mNumElements++;
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return SUCCESS;
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}
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/**
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* Returns the byte array containing data in the statsd socket format.
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* @hide
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**/
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@NonNull
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public byte[] getBuffer() {
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// Encode number of elements in the buffer.
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mBuffer[POS_NUM_ELEMENTS] = (byte) mNumElements;
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return mBuffer;
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}
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/**
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* Returns number of bytes used by the buffer.
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* @hide
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**/
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public int size() {
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return mPos;
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}
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/**
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* Getter for atom id.
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* @hide
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**/
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public int getAtomId() {
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return mAtomId;
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}
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@NonNull
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private static byte[] stringToBytes(@Nullable final String value) {
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return (null == value ? "" : value).getBytes(UTF_8);
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}
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// Helper methods for copying primitives
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private static void copyInt(@NonNull byte[] buff, int pos, int value) {
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buff[pos] = (byte) (value);
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buff[pos + 1] = (byte) (value >> 8);
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buff[pos + 2] = (byte) (value >> 16);
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buff[pos + 3] = (byte) (value >> 24);
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}
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private static void copyLong(@NonNull byte[] buff, int pos, long value) {
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buff[pos] = (byte) (value);
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buff[pos + 1] = (byte) (value >> 8);
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buff[pos + 2] = (byte) (value >> 16);
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buff[pos + 3] = (byte) (value >> 24);
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buff[pos + 4] = (byte) (value >> 32);
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buff[pos + 5] = (byte) (value >> 40);
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buff[pos + 6] = (byte) (value >> 48);
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buff[pos + 7] = (byte) (value >> 56);
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}
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}
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