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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.email.Email;
     20 
     21 import android.util.Log;
     22 
     23 import java.util.ArrayList;
     24 
     25 /**
     26  * A class to keep last N of lines sent to the server and responses received from the server.
     27  * They are sent to logcat when {@link #logLastDiscourse} is called.
     28  *
     29  * <p>This class is used to log the recent network activities when a response parser crashes.
     30  */
     31 public class DiscourseLogger {
     32     private final int mBufferSize;
     33     private String[] mBuffer;
     34     private int mPos;
     35     private final StringBuilder mReceivingLine = new StringBuilder(100);
     36 
     37     public DiscourseLogger(int bufferSize) {
     38         mBufferSize = bufferSize;
     39         initBuffer();
     40     }
     41 
     42     private void initBuffer() {
     43         mBuffer = new String[mBufferSize];
     44     }
     45 
     46     /** Add a single line to {@link #mBuffer}. */
     47     private void addLine(String s) {
     48         mBuffer[mPos] = s;
     49         mPos++;
     50         if (mPos >= mBufferSize) {
     51             mPos = 0;
     52         }
     53     }
     54 
     55     private void addReceivingLineToBuffer() {
     56         if (mReceivingLine.length() > 0) {
     57             addLine(mReceivingLine.toString());
     58             mReceivingLine.delete(0, Integer.MAX_VALUE);
     59         }
     60     }
     61 
     62     /**
     63      * Store a single byte received from the server in {@link #mReceivingLine}.  When LF is
     64      * received, the content of {@link #mReceivingLine} is added to {@link #mBuffer}.
     65      */
     66     public void addReceivedByte(int b) {
     67         if (0x20 <= b && b <= 0x7e) { // Append only printable ASCII chars.
     68             mReceivingLine.append((char) b);
     69         } else if (b == '\n') { // LF
     70             addReceivingLineToBuffer();
     71         } else if (b == '\r') { // CR
     72         } else {
     73             final String hex = "00" + Integer.toHexString(b);
     74             mReceivingLine.append("\\x" + hex.substring(hex.length() - 2, hex.length()));
     75         }
     76     }
     77 
     78     /** Add a line sent to the server to {@link #mBuffer}. */
     79     public void addSentCommand(String command) {
     80         addLine(command);
     81     }
     82 
     83     /** @return the contents of {@link #mBuffer} as a String array. */
     84     /* package for testing */ String[] getLines() {
     85         addReceivingLineToBuffer();
     86 
     87         ArrayList<String> list = new ArrayList<String>();
     88 
     89         final int start = mPos;
     90         int pos = mPos;
     91         do {
     92             String s = mBuffer[pos];
     93             if (s != null) {
     94                 list.add(s);
     95             }
     96             pos = (pos + 1) % mBufferSize;
     97         } while (pos != start);
     98 
     99         String[] ret = new String[list.size()];
    100         list.toArray(ret);
    101         return ret;
    102     }
    103 
    104     /**
    105      * Log the contents of the {@link mBuffer}, and clears it out.  (So it's okay to call this
    106      * method successively more than once.  There will be no duplicate log.)
    107      */
    108     public void logLastDiscourse() {
    109         String[] lines = getLines();
    110         if (lines.length == 0) {
    111             return;
    112         }
    113 
    114         Log.w(Email.LOG_TAG, "Last network activities:");
    115         for (String r : getLines()) {
    116             Log.w(Email.LOG_TAG, r);
    117         }
    118         initBuffer();
    119     }
    120 }
    121