1 2 /* 3 * Copyright (C) 2010 Google Inc. 4 * 5 * Licensed under the Apache License, Version 2.0 (the "License"); 6 * you may not use this file except in compliance with the License. 7 * You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 18 // This file is a copy of caliper's InterleavedReader.java 19 // (from code.google.com, last change Sep 9 2011) 20 // with Android specific changes marked with "BEGIN android-changed". 21 22 package vogar.monitor; 23 24 import com.google.gson.JsonParser; 25 26 import java.io.BufferedReader; 27 import java.io.Closeable; 28 import java.io.IOException; 29 import java.io.Reader; 30 31 /** 32 * Reads a stream containing inline JSON objects. Each JSON object is prefixed 33 * by a marker string and suffixed by a newline character. 34 */ 35 public final class InterleavedReader implements Closeable { 36 37 /** 38 * The length of the scratch buffer to search for markers in. Also acts as an 39 * upper bound on the length of returned strings. Not used as an I/O buffer. 40 */ 41 private static final int BUFFER_LENGTH = 80; 42 43 private final String marker; 44 private final BufferedReader reader; 45 private final JsonParser jsonParser = new JsonParser(); 46 47 public static final String DEFAULT_MARKER = "//ZxJ/"; 48 InterleavedReader(Reader reader)49 public InterleavedReader(Reader reader) { 50 this(DEFAULT_MARKER, reader); 51 } 52 InterleavedReader(String marker, Reader reader)53 public InterleavedReader(String marker, Reader reader) { 54 if (marker.length() > BUFFER_LENGTH) { 55 throw new IllegalArgumentException("marker.length() > BUFFER_LENGTH"); 56 } 57 this.marker = marker; 58 this.reader = reader instanceof BufferedReader 59 ? (BufferedReader) reader 60 : new BufferedReader(reader); 61 } 62 63 /** 64 * Returns the next value in the stream: either a String, a JsonElement, or 65 * null to indicate the end of the stream. Callers should use instanceof to 66 * inspect the return type. 67 */ read()68 public Object read() throws IOException { 69 char[] buffer = new char[BUFFER_LENGTH]; 70 // BEGIN android-changed: 71 // Double the lookahead size. This is a safety measure in the presence of 72 // new lines, where the line feed character is being skipped. The lookahead 73 // check in the BufferedReader class does not take these skipped characters 74 // into account. 75 reader.mark(BUFFER_LENGTH << 1); 76 // END android-changed. 77 int count = 0; 78 int textEnd; 79 80 while (true) { 81 int r = reader.read(buffer, count, buffer.length - count); 82 83 if (r == -1) { 84 // the input is exhausted; return the remaining characters 85 textEnd = count; 86 break; 87 } 88 89 count += r; 90 int possibleMarker = findPossibleMarker(buffer, count); 91 92 if (possibleMarker != 0) { 93 // return the characters that precede the marker 94 textEnd = possibleMarker; 95 break; 96 } 97 98 if (count < marker.length()) { 99 // the buffer contains only the prefix of a marker so we must read more 100 continue; 101 } 102 103 // we've read a marker so return the value that follows 104 reader.reset(); 105 String json = reader.readLine().substring(marker.length()); 106 return jsonParser.parse(json); 107 } 108 109 if (count == 0) { 110 return null; 111 } 112 113 // return characters 114 reader.reset(); 115 count = reader.read(buffer, 0, textEnd); 116 return new String(buffer, 0, count); 117 } 118 close()119 @Override public void close() throws IOException { 120 reader.close(); 121 } 122 123 /** 124 * Returns the index of marker in {@code chars}, stopping at {@code limit}. 125 * Should the chars end with a prefix of marker, the offset of that prefix 126 * is returned. 127 */ findPossibleMarker(char[] chars, int limit)128 int findPossibleMarker(char[] chars, int limit) { 129 search: 130 for (int i = 0; true; i++) { 131 for (int m = 0; m < marker.length() && i + m < limit; m++) { 132 if (chars[i + m] != marker.charAt(m)) { 133 continue search; 134 } 135 } 136 return i; 137 } 138 } 139 } 140