Source Code Cross Referenced for XByteBuffer.java in  » Sevlet-Container » tomcat-cluster » org » apache » catalina » cluster » io » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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Java Source Code / Java Documentation » Sevlet Container » tomcat cluster » org.apache.catalina.cluster.io 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


001:        /*
002:         * Copyright 1999,2004 The Apache Software Foundation.
003:         * 
004:         * Licensed under the Apache License, Version 2.0 (the "License");
005:         * you may not use this file except in compliance with the License.
006:         * You may obtain a copy of the License at
007:         * 
008:         *      http://www.apache.org/licenses/LICENSE-2.0
009:         * 
010:         * Unless required by applicable law or agreed to in writing, software
011:         * distributed under the License is distributed on an "AS IS" BASIS,
012:         * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013:         * See the License for the specific language governing permissions and
014:         * limitations under the License.
015:         */
016:
017:        package org.apache.catalina.cluster.io;
018:
019:        /**
020:         * The XByteBuffer provides a dual functionality.
021:         * One, it stores message bytes and automatically extends the byte buffer if needed.<BR>
022:         * Two, it can encode and decode packages so that they can be defined and identified
023:         * as they come in on a socket.
024:         *
025:         * @author Filip Hanik
026:         * @version $Revision: 1.8 $, $Date: 2004/05/26 16:32:59 $
027:         */
028:
029:        public class XByteBuffer {
030:
031:            public static org.apache.commons.logging.Log log = org.apache.commons.logging.LogFactory
032:                    .getLog(XByteBuffer.class);
033:
034:            /**
035:             * This is a package header, 7 bytes
036:             */
037:            public static final byte[] START_DATA = { 70, 76, 84, 50, 48, 48,
038:                    50 };
039:            /**
040:             * This is the package footer, 7 bytes
041:             */
042:            public static final byte[] END_DATA = { 84, 76, 70, 50, 48, 48, 51 };
043:            //A package looks like, always.
044:            /**
045:             * START_DATA - 7 bytes
046:             * SIZE       - 4 bytes - size of the data package
047:             * DATA       - should be as many bytes as the prev SIZE
048:             * END_DATA   - 7 bytes
049:             */
050:
051:            /**
052:             * Default size on the initial byte buffer
053:             */
054:            static final int DEF_SIZE = 1024;
055:            /**
056:             * Default size to extend the buffer with
057:             */
058:            static final int DEF_EXT = 1024;
059:            /**
060:             * Variable to hold the data
061:             */
062:            protected byte[] buf = null;
063:            /**
064:             * Current length of data in the buffer
065:             */
066:            protected int bufSize = 0;
067:
068:            /**
069:             * Constructs a new XByteBuffer
070:             * @param size - the initial size of the byte buffer
071:             */
072:            public XByteBuffer(int size) {
073:                buf = new byte[size];
074:            }//XByteBuffer
075:
076:            /**
077:             * Constructs a new XByteBuffer with an initial size of 1024 bytes
078:             */
079:            public XByteBuffer() {
080:                this (DEF_SIZE);
081:            }//XByteBuffer
082:
083:            /**
084:             * Returns the bytes in the buffer, in its exact length
085:             */
086:            public byte[] getBytes() {
087:                byte[] b = new byte[bufSize];
088:                System.arraycopy(buf, 0, b, 0, bufSize);
089:                return b;
090:            }//getBytes
091:
092:            /**
093:             * Resets the buffer
094:             */
095:            public void clear() {
096:                bufSize = 0;
097:            }
098:
099:            /**
100:             * Appends the data to the buffer. If the data is incorrectly formatted, ie, the data should always start with the
101:             * header, false will be returned and the data will be discarded.
102:             * @param b - bytes to be appended
103:             * @param off - the offset to extract data from
104:             * @param len - the number of bytes to append.
105:             * @return true if the data was appended correctly. Returns false if the package is incorrect, ie missing header or something, or the length of data is 0
106:             */
107:            public boolean append(byte[] b, int off, int len) {
108:                if ((off < 0) || (off > b.length) || (len < 0)
109:                        || ((off + len) > b.length) || ((off + len) < 0)) {
110:                    throw new IndexOutOfBoundsException();
111:                } else if (len == 0) {
112:                    return false;
113:                }//end if
114:
115:                int newcount = bufSize + len;
116:                if (newcount > buf.length) {
117:                    byte newbuf[] = new byte[Math
118:                            .max(buf.length << 1, newcount)];
119:                    System.arraycopy(buf, 0, newbuf, 0, bufSize);
120:                    buf = newbuf;
121:                }
122:                System.arraycopy(b, off, buf, bufSize, len);
123:                bufSize = newcount;
124:
125:                if (bufSize > START_DATA.length
126:                        && (firstIndexOf(buf, 0, START_DATA) == -1)) {
127:                    bufSize = 0;
128:                    log.error("Discarded the package, invalid header");
129:                    return false;
130:                }
131:                return true;
132:            }//append
133:
134:            /**
135:             * Internal mechanism to make a check if a complete package exists
136:             * within the buffer
137:             * @return - true if a complete package (header,size,data,footer) exists within the buffer
138:             */
139:            public int countPackages() {
140:                int cnt = 0;
141:                int pos = START_DATA.length;
142:                int start = 0;
143:
144:                while (start < bufSize) {
145:                    //first check start header
146:                    int index = this .firstIndexOf(buf, start, START_DATA);
147:                    //if the header (START_DATA) isn't the first thing or
148:                    //the buffer isn't even 10 bytes
149:                    if (index != start || ((bufSize - start) < 10))
150:                        break;
151:                    //then get the size 4 bytes
152:                    int size = toInt(buf, pos);
153:                    //now the total buffer has to be long enough to hold
154:                    //START_DATA.length+4+size+END_DATA.length
155:                    pos = start + START_DATA.length + 4 + size;
156:                    if ((pos + END_DATA.length) > bufSize)
157:                        break;
158:                    //and finally check the footer of the package END_DATA
159:                    int newpos = firstIndexOf(buf, pos, END_DATA);
160:                    //mismatch, there is no package
161:                    if (newpos != pos)
162:                        break;
163:                    //increase the packet count
164:                    cnt++;
165:                    //reset the values
166:                    start = pos + END_DATA.length;
167:                    pos = start + START_DATA.length;
168:                }//while
169:                return cnt;
170:            }//getSize
171:
172:            /**
173:             * Method to check if a package exists in this byte buffer.
174:             * @return - true if a complete package (header,size,data,footer) exists within the buffer
175:             */
176:            public boolean doesPackageExist() {
177:                return (countPackages() > 0);
178:            }//doesPackageExist
179:
180:            /**
181:             * Extracts the message bytes from a package.
182:             * If no package exists, a IllegalStateException will be thrown.
183:             * @param clearFromBuffer - if true, the package will be removed from the byte buffer
184:             * @return - returns the actual message bytes (header, size and footer not included).
185:             */
186:            public byte[] extractPackage(boolean clearFromBuffer)
187:                    throws java.io.IOException {
188:                int psize = countPackages();
189:                if (psize == 0)
190:                    throw new java.lang.IllegalStateException(
191:                            "No package exists in XByteBuffer");
192:                int size = toInt(buf, START_DATA.length);
193:                byte[] data = new byte[size];
194:                System.arraycopy(buf, START_DATA.length + 4, data, 0, size);
195:                if (clearFromBuffer) {
196:                    int totalsize = START_DATA.length + 4 + size
197:                            + END_DATA.length;
198:                    bufSize = bufSize - totalsize;
199:                    System.arraycopy(buf, totalsize, buf, 0, bufSize);
200:                }
201:                java.io.ByteArrayInputStream bin = new java.io.ByteArrayInputStream(
202:                        data);
203:                java.util.zip.GZIPInputStream gin = new java.util.zip.GZIPInputStream(
204:                        bin);
205:                byte[] tmp = new byte[1024];
206:                byte[] result = new byte[0];
207:                int length = gin.read(tmp);
208:                while (length > 0) {
209:                    byte[] tmpdata = result;
210:                    result = new byte[result.length + length];
211:                    System.arraycopy(tmpdata, 0, result, 0, tmpdata.length);
212:                    System.arraycopy(tmp, 0, result, tmpdata.length, length);
213:                    length = gin.read(tmp);
214:                }
215:                gin.close();
216:                return result;
217:            }//extractPackage
218:
219:            /**
220:             * Convert four bytes to an int
221:             * @param b - the byte array containing the four bytes
222:             * @param off - the offset
223:             * @return the integer value constructed from the four bytes
224:             * @exception java.lang.ArrayIndexOutOfBoundsException
225:             */
226:            public static int toInt(byte[] b, int off) {
227:                return (((int) b[off + 3]) & 0xFF)
228:                        + ((((int) b[off + 2]) & 0xFF) << 8)
229:                        + ((((int) b[off + 1]) & 0xFF) << 16)
230:                        + ((((int) b[off + 0]) & 0xFF) << 24);
231:            }//toInt
232:
233:            /**
234:             * Convert eight bytes to a long
235:             * @param b - the byte array containing the four bytes
236:             * @param off - the offset
237:             * @return the long value constructed from the eight bytes
238:             * @exception java.lang.ArrayIndexOutOfBoundsException
239:             */
240:            public static long toLong(byte[] b, int off) {
241:                return (((long) b[off + 7]) & 0xFF)
242:                        + ((((long) b[off + 6]) & 0xFF) << 8)
243:                        + ((((long) b[off + 5]) & 0xFF) << 16)
244:                        + ((((long) b[off + 4]) & 0xFF) << 24)
245:                        + ((((long) b[off + 3]) & 0xFF) << 32)
246:                        + ((((long) b[off + 2]) & 0xFF) << 40)
247:                        + ((((long) b[off + 1]) & 0xFF) << 48)
248:                        + ((((long) b[off + 0]) & 0xFF) << 56);
249:            }//toInt
250:
251:            /**
252:             * Converts an integer to four bytes
253:             * @param n - the integer
254:             * @return - four bytes in an array
255:             */
256:            public static byte[] toBytes(int n) {
257:                byte[] b = new byte[4];
258:                b[3] = (byte) (n);
259:                n >>>= 8;
260:                b[2] = (byte) (n);
261:                n >>>= 8;
262:                b[1] = (byte) (n);
263:                n >>>= 8;
264:                b[0] = (byte) (n);
265:                return b;
266:            } //toBytes
267:
268:            /**
269:             * Converts an long to eight bytes
270:             * @param n - the long
271:             * @return - eight bytes in an array
272:             */
273:            public static byte[] toBytes(long n) {
274:                byte[] b = new byte[8];
275:                b[7] = (byte) (n);
276:                n >>>= 8;
277:                b[6] = (byte) (n);
278:                n >>>= 8;
279:                b[5] = (byte) (n);
280:                n >>>= 8;
281:                b[4] = (byte) (n);
282:                n >>>= 8;
283:                b[3] = (byte) (n);
284:                n >>>= 8;
285:                b[2] = (byte) (n);
286:                n >>>= 8;
287:                b[1] = (byte) (n);
288:                n >>>= 8;
289:                b[0] = (byte) (n);
290:                return b;
291:            } //toBytes
292:
293:            /**
294:             * Similar to a String.IndexOf, but uses pure bytes
295:             * @param src - the source bytes to be searched
296:             * @param srcOff - offset on the source buffer
297:             * @param find - the string to be found within src
298:             * @return - the index of the first matching byte. -1 if the find array is not found
299:             */
300:            public static int firstIndexOf(byte[] src, int srcOff, byte[] find) {
301:                int result = -1;
302:                if (find.length > src.length)
303:                    return result;
304:                if (find.length == 0 || src.length == 0)
305:                    return result;
306:                if (srcOff >= src.length)
307:                    throw new java.lang.ArrayIndexOutOfBoundsException();
308:                boolean found = false;
309:                int srclen = src.length;
310:                int findlen = find.length;
311:                byte first = find[0];
312:                int pos = srcOff;
313:                while (!found) {
314:                    //find the first byte
315:                    while (pos < srclen) {
316:                        if (first == src[pos])
317:                            break;
318:                        pos++;
319:                    } //while
320:                    if (pos >= srclen)
321:                        return -1;
322:
323:                    //we found the first character
324:                    //match the rest of the bytes - they have to match
325:                    if ((srclen - pos) < findlen)
326:                        return -1;
327:                    //assume it does exist
328:                    found = true;
329:                    for (int i = 1; ((i < findlen) && found); i++)
330:                        found = found && (find[i] == src[pos + i]);
331:                    if (found)
332:                        result = pos;
333:                    else if ((srclen - pos) < findlen)
334:                        return -1; //no more matches possible
335:                    else
336:                        pos++;
337:                } //while
338:                return result;
339:            } //firstIndexOf
340:
341:            /**
342:             * Creates a complete data package
343:             * @param indata - the message data to be contained within the package
344:             * @return - a full package (header,size,data,footer)
345:             */
346:            public static byte[] createDataPackage(byte[] indata)
347:                    throws java.io.IOException {
348:                java.io.ByteArrayOutputStream bout = new java.io.ByteArrayOutputStream(
349:                        indata.length / 2);
350:                java.util.zip.GZIPOutputStream gout = new java.util.zip.GZIPOutputStream(
351:                        bout);
352:                gout.write(indata);
353:                gout.flush();
354:                gout.close();
355:                byte[] data = bout.toByteArray();
356:                byte[] result = new byte[START_DATA.length + 4 + data.length
357:                        + END_DATA.length];
358:                System.arraycopy(START_DATA, 0, result, 0, START_DATA.length);
359:                System.arraycopy(toBytes(data.length), 0, result,
360:                        START_DATA.length, 4);
361:                System.arraycopy(data, 0, result, START_DATA.length + 4,
362:                        data.length);
363:                System.arraycopy(END_DATA, 0, result, START_DATA.length + 4
364:                        + data.length, END_DATA.length);
365:                return result;
366:            }//createDataPackage
367:
368:            public static void main(String[] args) throws Exception {
369:                log.info("Before=" + Integer.MAX_VALUE);
370:                byte[] d = toBytes(Integer.MAX_VALUE);
371:                log.info("After=" + toInt(d, 0));
372:
373:                log.info("Before=" + Long.MAX_VALUE);
374:                d = toBytes(Long.MAX_VALUE);
375:                log.info("After=" + toLong(d, 0));
376:
377:                log.info("Before=" + 4564564);
378:                d = toBytes((long) 4564564);
379:                log.info("After=" + toLong(d, 0));
380:
381:                byte[] d1 = createDataPackage(new byte[] { 1 });
382:                byte[] d2 = createDataPackage(new byte[] { 2 });
383:                byte[] d3 = createDataPackage(new byte[] { 3 });
384:                byte[] test = new byte[d1.length + d2.length + d3.length + 5];
385:                System.arraycopy(d1, 0, test, 0, d1.length);
386:                System.arraycopy(d2, 0, test, d1.length, d2.length);
387:                System.arraycopy(d3, 0, test, d2.length + d1.length, d3.length);
388:                printBuf(d1);
389:                printBuf(d2);
390:                printBuf(d3);
391:                printBuf(test);
392:                XByteBuffer b = new XByteBuffer();
393:                b.append(test, 0, test.length);
394:                int s = b.countPackages();
395:                log.info("Nr of packages=" + s);
396:                while (s > 0) {
397:                    d = b.extractPackage(true);
398:                    System.out.print("Package d1=");
399:                    printBuf(d);
400:                    s--;
401:                }//while
402:
403:            }
404:
405:            public static void printBuf(byte[] b) {
406:                StringBuffer buf = new StringBuffer();
407:                for (int i = 0; i < b.length; i++) {
408:                    buf.append(b[i] + " ");
409:                }
410:                log.info(buf);
411:            }
412:
413:        }//class
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