Author: oglueck
Date: Thu Aug 10 02:01:18 2006
New Revision: 430322
URL: http://svn.apache.org/viewvc?rev=430322&view=rev
Log:
This patch reduces the amount of intermediate garbage significantly.
PR: SANDBOX-166
Contributed by: Ortwin Glück
Reviewed by: Henri Yandell
Modified:
jakarta/commons/sandbox/csv/trunk/src/java/org/apache/commons/csv/CSVParser.java
jakarta/commons/sandbox/csv/trunk/src/java/org/apache/commons/csv/ExtendedBufferedReader.java
Modified:
jakarta/commons/sandbox/csv/trunk/src/java/org/apache/commons/csv/CSVParser.java
URL:
http://svn.apache.org/viewvc/jakarta/commons/sandbox/csv/trunk/src/java/org/apache/commons/csv/CSVParser.java?rev=430322&r1=430321&r2=430322&view=diff
==============================================================================
---
jakarta/commons/sandbox/csv/trunk/src/java/org/apache/commons/csv/CSVParser.java
(original)
+++
jakarta/commons/sandbox/csv/trunk/src/java/org/apache/commons/csv/CSVParser.java
Thu Aug 10 02:01:18 2006
@@ -19,7 +19,7 @@
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
-import java.util.Vector;
+import java.util.ArrayList;
/**
@@ -63,12 +63,23 @@
protected static final int TT_EOF = 1;
/** Token with content when end of a line is reached. */
protected static final int TT_EORECORD = 2;
+
+ /** Immutable empty String array. */
+ private static final String[] EMPTY_STRING_ARRAY = new String[0];
// the input stream
private ExtendedBufferedReader in;
private CSVStrategy strategy;
+ // the following objects are shared to reduce garbage
+ /** A record buffer for getLine(). Grows as necessary and is reused. */
+ private ArrayList record = new ArrayList();
+ private Token reusableToken = new Token();
+ private CharBuffer wsBuf = new CharBuffer();
+ private CharBuffer code = new CharBuffer(4);
+
+
/**
* Token is an internal token representation.
*
@@ -76,16 +87,17 @@
*/
class Token {
/** Token type, see TT_xxx constants. */
- int type;
+ int type = TT_INVALID;
/** The content buffer. */
- StringBuffer content;
+ CharBuffer content = new CharBuffer(INITIAL_TOKEN_LENGTH);
/** Token ready flag: indicates a valid token with content (ready for the
parser). */
boolean isReady;
- /** Initializes an empty token. */
- Token() {
- content = new StringBuffer(INITIAL_TOKEN_LENGTH);
- type = TT_INVALID;
- isReady = false;
+
+ Token reset() {
+ content.clear();
+ type = TT_INVALID;
+ isReady = false;
+ return this;
}
}
@@ -160,7 +172,7 @@
* @throws IOException on parse error or input read-failure
*/
public String[][] getAllValues() throws IOException {
- Vector records = new Vector();
+ ArrayList records = new ArrayList();
String[] values;
String[][] ret = null;
while ((values = getLine()) != null) {
@@ -211,35 +223,35 @@
* @throws IOException on parse error or input read-failure
*/
public String[] getLine() throws IOException {
- Vector record = new Vector();
- String[] ret = new String[0];
- Token tkn;
- while ((tkn = nextToken()).type == TT_TOKEN) {
- record.add(tkn.content.toString());
- }
- // did we reached eorecord or eof ?
- switch (tkn.type) {
- case TT_EORECORD:
- record.add(tkn.content.toString());
- break;
- case TT_EOF:
- if (tkn.isReady) {
- record.add(tkn.content.toString());
- } else {
- ret = null;
+ String[] ret = EMPTY_STRING_ARRAY;
+ record.clear();
+ while (true) {
+ reusableToken.reset();
+ nextToken(reusableToken);
+ switch (reusableToken.type) {
+ case TT_TOKEN:
+ record.add(reusableToken.content.toString());
+ break;
+ case TT_EORECORD:
+ record.add(reusableToken.content.toString());
+ break;
+ case TT_EOF:
+ if (reusableToken.isReady) {
+ record.add(reusableToken.content.toString());
+ } else {
+ ret = null;
+ }
+ break;
+ case TT_INVALID:
+ default:
+ // error: throw IOException
+ throw new IOException("(line " + getLineNumber() + ") invalid
parse sequence");
+ // unreachable: break;
}
- break;
- case TT_INVALID:
- default:
- // error: throw IOException
- throw new IOException(
- "(line " + getLineNumber()
- + ") invalid parse sequence");
- // unreachable: break;
+ if (reusableToken.type != TT_TOKEN) break;
}
- if (record.size() > 0) {
- ret = new String[record.size()];
- record.toArray(ret);
+ if (!record.isEmpty()) {
+ ret = (String[]) record.toArray(new String[record.size()]);
}
return ret;
}
@@ -260,18 +272,26 @@
// the lexer(s)
// ======================================================
+ /**
+ * Convenience method for <code>nextToken(null)</code>.
+ */
+ protected Token nextToken() throws IOException {
+ return nextToken(new Token());
+ }
+
/**
* Returns the next token.
*
* A token corresponds to a term, a record change or an
* end-of-file indicator.
*
+ * @param tkn an existing Token object to reuse. The caller is responsible
to initialize the
+ * Token.
* @return the next token found
* @throws IOException on stream access error
*/
- protected Token nextToken() throws IOException {
- Token tkn = new Token();
- StringBuffer wsBuf = new StringBuffer();
+ protected Token nextToken(Token tkn) throws IOException {
+ wsBuf.clear(); // resuse
// get the last read char (required for empty line detection)
int lastChar = in.readAgain();
@@ -321,14 +341,14 @@
if (!strategy.isCommentingDisabled() && c == strategy.getCommentStart())
{
// ignore everything till end of line and continue (incr linecount)
in.readLine();
- tkn = nextToken();
+ tkn = nextToken(tkn.reset());
} else if (c == strategy.getDelimiter()) {
// empty token return TT_TOKEN("")
tkn.type = TT_TOKEN;
tkn.isReady = true;
} else if (eol) {
// empty token return TT_EORECORD("")
- tkn.content.append("");
+ //noop: tkn.content.append("");
tkn.type = TT_EORECORD;
tkn.isReady = true;
} else if (c == strategy.getEncapsulator()) {
@@ -336,14 +356,14 @@
encapsulatedTokenLexer(tkn, c);
} else if (isEndOfFile(c)) {
// end of file return TT_EOF()
- tkn.content.append("");
+ //noop: tkn.content.append("");
tkn.type = TT_EOF;
tkn.isReady = true;
} else {
// next token must be a simple token
// add removed blanks when not ignoring whitespace chars...
if (!strategy.getIgnoreLeadingWhitespaces()) {
- tkn.content.append(wsBuf.toString());
+ tkn.content.append(wsBuf);
}
simpleTokenLexer(tkn, c);
}
@@ -370,7 +390,7 @@
* @throws IOException on stream access error
*/
private Token simpleTokenLexer(Token tkn, int c) throws IOException {
- StringBuffer wsBuf = new StringBuffer();
+ wsBuf.clear();
while (!tkn.isReady) {
if (isEndOfLine(c)) {
// end of record
@@ -396,9 +416,8 @@
} else {
// prepend whitespaces (if we have)
if (wsBuf.length() > 0) {
- // for J2SDK 1.3 compatibility we use toString()
- tkn.content.append(wsBuf.toString());
- wsBuf.delete(0, wsBuf.length());
+ tkn.content.append(wsBuf);
+ wsBuf.clear();
}
tkn.content.append((char) c);
}
@@ -508,7 +527,7 @@
int ret = 0;
// ignore 'u' (assume c==\ now) and read 4 hex digits
c = in.read();
- StringBuffer code = new StringBuffer(4);
+ code.clear();
try {
for (int i = 0; i < 4; i++) {
c = in.read();
Modified:
jakarta/commons/sandbox/csv/trunk/src/java/org/apache/commons/csv/ExtendedBufferedReader.java
URL:
http://svn.apache.org/viewvc/jakarta/commons/sandbox/csv/trunk/src/java/org/apache/commons/csv/ExtendedBufferedReader.java?rev=430322&r1=430321&r2=430322&view=diff
==============================================================================
---
jakarta/commons/sandbox/csv/trunk/src/java/org/apache/commons/csv/ExtendedBufferedReader.java
(original)
+++
jakarta/commons/sandbox/csv/trunk/src/java/org/apache/commons/csv/ExtendedBufferedReader.java
Thu Aug 10 02:01:18 2006
@@ -47,6 +47,8 @@
private int lastChar = UNDEFINED;
/** the line counter */
private int lineCounter = 0;
+ private CharBuffer line = new CharBuffer();
+
/**
* Created extended buffered reader using default buffer-size
*
@@ -154,16 +156,16 @@
if (lookaheadChar == UNDEFINED) {
lookaheadChar = super.read();
}
- StringBuffer ret = new StringBuffer("");
+ line.clear(); // reuse
while (lookaheadChar != c && lookaheadChar != END_OF_STREAM) {
- ret.append((char) lookaheadChar);
+ line.append((char) lookaheadChar);
if (lookaheadChar == '\n') {
lineCounter++;
}
lastChar = lookaheadChar;
lookaheadChar = super.read();
}
- return ret.toString();
+ return line.toString();
}
/**
@@ -177,7 +179,7 @@
lookaheadChar = super.read();
}
- StringBuffer ret = new StringBuffer("");
+ line.clear(); //reuse
// return null if end of stream has been reached
if (lookaheadChar == END_OF_STREAM) {
@@ -194,19 +196,19 @@
lookaheadChar = super.read();
}
lineCounter++;
- return ret.toString();
+ return line.toString();
}
// create the rest-of-line return and update the lookahead
- ret.append(String.valueOf(laChar));
- String restOfLine = super.readLine();
+ line.append(laChar);
+ String restOfLine = super.readLine(); // TODO involves copying
lastChar = lookaheadChar;
lookaheadChar = super.read();
if (restOfLine != null) {
- ret.append(restOfLine);
+ line.append(restOfLine);
}
lineCounter++;
- return ret.toString();
+ return line.toString();
}
/**
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