public String getLine(int lineNo) throws Exception {
if (lineNo <= 0 || lineNo > mNumLines) {
return null;
}
String line = null;
Jedis jedis = pool_.getResource();
try {
String lineNoStr = Integer.toString(lineNo);
line = jedis.hget(lineNoStr, LINE_KEY);
if (line == null) {
RecordId lineId = getRecordId(lineNo);
byte[] buffer = new byte[BLOCK_SIZE];
synchronized (mDataFile) {
mDataFile.seek(lineId.pageNo() * BLOCK_SIZE);
mDataFile.read(buffer);
}
ByteBuffer bb = ByteBuffer.wrap(buffer);
int numRecords = bb.getInt(BLOCK_SIZE - INT_SIZE);
int indexPos = BLOCK_SIZE - 3 * INT_SIZE;
int curLineNo = lineNo - lineId.slotNo() + 1;
String[] recordKeys = {PAGE_NO_KEY, SLOT_NO_KEY};
for (int i = 1; i < numRecords; i++, curLineNo++) {
int offset = bb.getInt(indexPos);
int len = bb.getInt(indexPos + INT_SIZE);
ByteBuffer linebb = ByteBuffer.wrap(buffer, offset, len);
byte[] lineBuf = new byte[linebb.remaining()];
linebb.get(lineBuf);
String lineStr = new String(lineBuf);
if (i == lineId.slotNo()) {
line = lineStr;
}
// Store in cache
lineNoStr = Integer.toString(curLineNo);
jedis.hdel(lineNoStr, recordKeys);
jedis.hset(lineNoStr, LINE_KEY, lineStr);
indexPos -= 2 * INT_SIZE;
}
}
if (line == null) {
throw new Exception("LineServer: Could not find line on page");
}
} catch (IOException ioe) {
System.err.println("LineServer: IOException on line retrieval");
throw ioe;
} finally {
pool_.returnResource(jedis);
}
return line;
}
/**
* Assuming the file has an id3v2 tag, returns true if the tag can be overwritten. We cannot
* overwrite id3v2 tags not supported
*
* @param raf
* @return
* @throws IOException
*/
private boolean canOverwrite(RandomAccessFile raf) throws IOException {
raf.seek(3);
// Version du tag ID3v2.xx.xx
String versionHigh = raf.read() + "";
if (!(versionHigh.equals("4") || versionHigh.equals("3") || versionHigh.equals("2")))
return false; // only version 2.3.xx
// raf.read();
// int flag = raf.read() & 128;
// if (flag == 128)
// return false; //unsynchronised tags not supported
return true;
}
private RecordId getRecordId(int lineNo) throws IOException {
RecordId id = null;
Jedis jedis = pool_.getResource();
try {
int pageNo, slotNo;
String lineNoStr = Integer.toString(lineNo);
String pageNoStr = jedis.hget(lineNoStr, PAGE_NO_KEY);
String slotNoStr = jedis.hget(lineNoStr, SLOT_NO_KEY);
if (pageNoStr != null && slotNoStr != null) {
id = new RecordId(Integer.parseInt(pageNoStr), Integer.parseInt(slotNoStr));
} else { // Was not cached
// Read directory page containing line in question
byte[] buffer = new byte[BLOCK_SIZE];
int absIndex = (lineNo - 1) * 2 * INT_SIZE;
int relativeIndex = absIndex % BLOCK_SIZE;
int bytesRead = 0;
synchronized (mDirectoryFile) {
mDirectoryFile.seek(absIndex - relativeIndex);
bytesRead = mDirectoryFile.read(buffer);
}
ByteBuffer bb = ByteBuffer.wrap(buffer);
// Cache all entries in the page
int curLineNo = lineNo - relativeIndex / (2 * INT_SIZE);
for (int i = 0; i < bytesRead / (2 * INT_SIZE); i++, curLineNo++) {
pageNo = bb.getInt();
slotNo = bb.getInt();
if (curLineNo == lineNo) {
id = new RecordId(pageNo, slotNo);
}
lineNoStr = Integer.toString(curLineNo);
jedis.hset(lineNoStr, PAGE_NO_KEY, Integer.toString(pageNo));
jedis.hset(lineNoStr, SLOT_NO_KEY, Integer.toString(slotNo));
}
}
if (id == null) {
throw new IOException("LineServer: Could not find record id in directory");
}
} finally {
pool_.returnResource(jedis);
}
return id;
}
/**
* Read block from file.
*
* @param file - File to read.
* @param off - Marker position in file to start read from if {@code -1} read last blockSz bytes.
* @param blockSz - Maximum number of chars to read.
* @param lastModified - File last modification time.
* @return Read file block.
* @throws IOException In case of error.
*/
public static VisorFileBlock readBlock(File file, long off, int blockSz, long lastModified)
throws IOException {
RandomAccessFile raf = null;
try {
long fSz = file.length();
long fLastModified = file.lastModified();
long pos = off >= 0 ? off : Math.max(fSz - blockSz, 0);
// Try read more that file length.
if (fLastModified == lastModified && fSz != 0 && pos >= fSz)
throw new IOException(
"Trying to read file block with wrong offset: " + pos + " while file size: " + fSz);
if (fSz == 0)
return new VisorFileBlock(file.getPath(), pos, fLastModified, 0, false, EMPTY_FILE_BUF);
else {
int toRead = Math.min(blockSz, (int) (fSz - pos));
byte[] buf = new byte[toRead];
raf = new RandomAccessFile(file, "r");
raf.seek(pos);
int cntRead = raf.read(buf, 0, toRead);
if (cntRead != toRead)
throw new IOException(
"Count of requested and actually read bytes does not match [cntRead="
+ cntRead
+ ", toRead="
+ toRead
+ ']');
boolean zipped = buf.length > 512;
return new VisorFileBlock(
file.getPath(), pos, fSz, fLastModified, zipped, zipped ? zipBytes(buf) : buf);
}
} finally {
U.close(raf, null);
}
}
