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      1 /*
      2  * Copyright (C) 2010 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.email.mail.transport;
     18 
     19 import com.android.emailcommon.Logging;
     20 import com.android.mail.utils.LogUtils;
     21 
     22 import java.util.ArrayList;
     23 
     24 /**
     25  * A class to keep last N of lines sent to the server and responses received from the server.
     26  * They are sent to logcat when {@link #logLastDiscourse} is called.
     27  *
     28  * <p>This class is used to log the recent network activities when a response parser crashes.
     29  */
     30 public class DiscourseLogger {
     31     private final int mBufferSize;
     32     private String[] mBuffer;
     33     private int mPos;
     34     private final StringBuilder mReceivingLine = new StringBuilder(100);
     35 
     36     public DiscourseLogger(int bufferSize) {
     37         mBufferSize = bufferSize;
     38         initBuffer();
     39     }
     40 
     41     private void initBuffer() {
     42         mBuffer = new String[mBufferSize];
     43     }
     44 
     45     /** Add a single line to {@link #mBuffer}. */
     46     private void addLine(String s) {
     47         mBuffer[mPos] = s;
     48         mPos++;
     49         if (mPos >= mBufferSize) {
     50             mPos = 0;
     51         }
     52     }
     53 
     54     private void addReceivingLineToBuffer() {
     55         if (mReceivingLine.length() > 0) {
     56             addLine(mReceivingLine.toString());
     57             mReceivingLine.delete(0, Integer.MAX_VALUE);
     58         }
     59     }
     60 
     61     /**
     62      * Store a single byte received from the server in {@link #mReceivingLine}.  When LF is
     63      * received, the content of {@link #mReceivingLine} is added to {@link #mBuffer}.
     64      */
     65     public void addReceivedByte(int b) {
     66         if (0x20 <= b && b <= 0x7e) { // Append only printable ASCII chars.
     67             mReceivingLine.append((char) b);
     68         } else if (b == '\n') { // LF
     69             addReceivingLineToBuffer();
     70         } else if (b == '\r') { // CR
     71         } else {
     72             final String hex = "00" + Integer.toHexString(b);
     73             mReceivingLine.append("\\x" + hex.substring(hex.length() - 2, hex.length()));
     74         }
     75     }
     76 
     77     /** Add a line sent to the server to {@link #mBuffer}. */
     78     public void addSentCommand(String command) {
     79         addLine(command);
     80     }
     81 
     82     /** @return the contents of {@link #mBuffer} as a String array. */
     83     /* package for testing */ String[] getLines() {
     84         addReceivingLineToBuffer();
     85 
     86         ArrayList<String> list = new ArrayList<String>();
     87 
     88         final int start = mPos;
     89         int pos = mPos;
     90         do {
     91             String s = mBuffer[pos];
     92             if (s != null) {
     93                 list.add(s);
     94             }
     95             pos = (pos + 1) % mBufferSize;
     96         } while (pos != start);
     97 
     98         String[] ret = new String[list.size()];
     99         list.toArray(ret);
    100         return ret;
    101     }
    102 
    103     /**
    104      * Log the contents of the {@link mBuffer}, and clears it out.  (So it's okay to call this
    105      * method successively more than once.  There will be no duplicate log.)
    106      */
    107     public void logLastDiscourse() {
    108         String[] lines = getLines();
    109         if (lines.length == 0) {
    110             return;
    111         }
    112 
    113         LogUtils.w(Logging.LOG_TAG, "Last network activities:");
    114         for (String r : getLines()) {
    115             LogUtils.w(Logging.LOG_TAG, "%s", r);
    116         }
    117         initBuffer();
    118     }
    119 }
    120