Changeset: 0fcf338ce0b4 for monetdb-java
URL: https://dev.monetdb.org/hg/monetdb-java?cmd=changeset;node=0fcf338ce0b4
Modified Files:
ChangeLog
src/main/java/nl/cwi/monetdb/mcl/parser/MCLParser.java
src/main/java/nl/cwi/monetdb/mcl/parser/TupleLineParser.java
Branch: default
Log Message:
Optimized parse method of TupleLineParser by creating less helper objects and
replacing method calls by direct operations on variables.
We now only create a StringBuilder object uesc when it is needed (when an
escaped character is detected in the tuple line).
In most tuple data lines no escape characters are used and thus the
StringBuilder object was not used/needed.
Also increased the default capacity of StringBuilder uesc such that it is not
enlarged so often.
Also made StringBuilder object uesc now part of the TupleLineParser object,
such that it can be reused by
many parse() calls, again reducing the number of created StringBuilder objects.
diffs (226 lines):
diff --git a/ChangeLog b/ChangeLog
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,10 @@
# ChangeLog file for monetdb-java
# This file is updated with Maddlog
+* Wed Sep 11 2019 Martin van Dinther <martin.van.dint...@monetdbsolutions.com>
+- Optimized parse() method of TupleLineParser by creating less helper objects
+ and replacing method calls by direct operations on variables.
+
* Wed Sep 4 2019 Martin van Dinther <martin.van.dint...@monetdbsolutions.com>
- The jar files are now named according to Java version compatibility.
For example, the monetdb-jdbc-2.29.jre7.jar file should be used with
diff --git a/src/main/java/nl/cwi/monetdb/mcl/parser/MCLParser.java
b/src/main/java/nl/cwi/monetdb/mcl/parser/MCLParser.java
--- a/src/main/java/nl/cwi/monetdb/mcl/parser/MCLParser.java
+++ b/src/main/java/nl/cwi/monetdb/mcl/parser/MCLParser.java
@@ -26,7 +26,7 @@ package nl.cwi.monetdb.mcl.parser;
public abstract class MCLParser {
/** The String values found while parsing. Public, you may touch it. */
public final String values[];
- protected int colnr;
+ protected int colnr = 0;
/**
* Creates an MCLParser targetted at a given number of field values.
diff --git a/src/main/java/nl/cwi/monetdb/mcl/parser/TupleLineParser.java
b/src/main/java/nl/cwi/monetdb/mcl/parser/TupleLineParser.java
--- a/src/main/java/nl/cwi/monetdb/mcl/parser/TupleLineParser.java
+++ b/src/main/java/nl/cwi/monetdb/mcl/parser/TupleLineParser.java
@@ -9,15 +9,21 @@
package nl.cwi.monetdb.mcl.parser;
/**
- * The TupleLineParser extracts the values from a given tuple. The
- * number of values that are expected are known upfront to speed up
+ * The TupleLineParser extracts the values from a given tuple.
+ * The number of values that are expected are known upfront to speed up
* allocation and validation.
*
* @author Fabian Groffen
+ * @author Martin van Dinther
*/
public final class TupleLineParser extends MCLParser {
+ private StringBuilder uesc = null; // used for building field
string value when an escape is present in the field value
+
/**
* Constructs a TupleLineParser which expects columncount columns.
+ * The columncount argument is used for allocation of the public values
array.
+ * While this seems illogical, the caller should know this size, since
the
+ * StartOfHeader contains this information.
*
* @param columncount the number of columns in the to be parsed string
*/
@@ -26,22 +32,22 @@ public final class TupleLineParser exten
}
/**
- * Parses the given String source as tuple line. If source cannot
- * be parsed, a ParseException is thrown. The columncount argument
- * is used for allocation of the returned array. While this seems
- * illogical, the caller should know this size, since the
- * StartOfHeader contains this information.
+ * Parses the given String source as tuple line.
+ * If source cannot be parsed, a MCLParseException is thrown.
*
- * @param source a String which should be parsed
+ * @param source a String representing a tuple line which should be
parsed
* @return 0, as there is no 'type' of TupleLine
- * @throws MCLParseException if an error occurs during parsing
+ * @throws MCLParseException if source is not compliant to expected
tuple/single value format
*/
@Override
public int parse(final String source) throws MCLParseException {
final int len = source.length();
- // first detect whether this is a single value line (=) or a
- // real tuple ([)
- if (len >= 1 && source.charAt(0) == '=') {
+ if (len <= 0)
+ throw new MCLParseException("Missing tuple data");
+
+ // first detect whether this is a single value line (=) or a
real tuple ([)
+ char chr = source.charAt(0);
+ if (chr == '=') {
if (values.length != 1)
throw new MCLParseException(values.length +
" columns expected, but only
single value found");
@@ -50,20 +56,19 @@ public final class TupleLineParser exten
values[0] = source.substring(1);
// reset colnr
- reset();
+ colnr = 0;
return 0;
}
- if (!source.startsWith("["))
+ if (chr != '[')
throw new MCLParseException("Expected a data row
starting with [");
// It is a tuple. Extract separate fields by examining the
string data char for char
- // convert whole string to char[] to avoid overhead of
source.charAt(i) calls
- // TODO: measure the source.charAt(i) overhead and whether it
is faster to eliminate the source.toCharArray(); copy
+ // For parsing it is faster to use an char[] to avoid overhead
of source.charAt(i) method calls
final char[] chrLine = source.toCharArray();
boolean inString = false, escaped = false, fieldHasEscape =
false;
- final StringBuilder uesc = new StringBuilder(128); // used
for building field string value when an escape is present in the field value
int column = 0, cursor = 2;
+ // scan the characters, when a field separator is found extract
the field value as String dealing with possible escape characters
for (int i = 2; i < len; i++) {
switch(chrLine[i]) {
case '\\':
@@ -102,14 +107,23 @@ public final class TupleLineParser exten
if (chrLine[cursor] == '"' &&
chrLine[endpos] == '"')
// field is surrounded by double quotes, so a string with possible escape codes
{
+ cursor++;
+ final int fieldlen =
endpos - cursor;
if (fieldHasEscape) {
- // reuse the
StringBuilder by cleaning it
-
uesc.setLength(0);
- // prevent
multiple capacity increments during the append()'s in the inner loop
-
uesc.ensureCapacity(endpos - (cursor + 1));
+ if (uesc ==
null) {
+ //
first time use, create it with enough capacity, minimum 1024
+ uesc =
new StringBuilder(fieldlen > 1024 ? fieldlen : 1024);
+ } else {
+ //
reuse the StringBuilder by cleaning it
+
uesc.setLength(0);
+ if
(fieldlen > 1024) {
+
// prevent multiple capacity increments during the append()'s in the inner loop
+
uesc.ensureCapacity(fieldlen);
+ }
+ }
// parse the
field value (excluding the double quotes) and convert it to a string without
any escape characters
- for (int pos =
cursor + 1; pos < endpos; pos++) {
- char
chr = chrLine[pos];
+ for (int pos =
cursor; pos < endpos; pos++) {
+ chr =
chrLine[pos];
if (chr
== '\\' && pos + 1 < endpos) {
// we detected an escape
// escapedStr and GDKstrFromStr in gdk_atoms.c only
@@ -117,9 +131,6 @@ public final class TupleLineParser exten
pos++;
chr = chrLine[pos];
switch (chr) {
-
case '\\':
-
uesc.append('\\');
-
break;
case 'f':
uesc.append('\f');
break;
@@ -132,9 +143,6 @@ public final class TupleLineParser exten
case 't':
uesc.append('\t');
break;
-
case '"':
-
uesc.append('"');
-
break;
case '0': case '1': case '2': case '3':
// this could be an octal number, let's check it out
if (pos + 2 < endpos) {
@@ -158,8 +166,16 @@ public final class TupleLineParser exten
uesc.append(chr);
}
break;
+
/* case '\\': optimisation: this code does the same as the default
case, so not needed
+
uesc.append('\\');
+
break;
+
*/
+
/* case '"': optimisation: this code does the same as the default
case, so not needed
+
uesc.append('"');
+
break;
+
*/
default:
-
// this is wrong usage of escape, just ignore the \-escape and
print the char
+
// this is wrong usage of escape (except for '\\' and '"'),
just ignore the \-escape and print the char
uesc.append(chr);
break;
}
@@ -171,23 +187,24 @@ public final class TupleLineParser exten
values[column]
= uesc.toString();
} else {
// the field is
a string surrounded by double quotes and without escape chars
- cursor++;
- final String
fieldVal = new String(chrLine, cursor, endpos - cursor);
- // if
(fieldVal.contains("\\")) {
+ values[column]
= new String(chrLine, cursor, fieldlen);
+ // if
(values[column].contains("\\")) {
// throw
new MCLParseException("Invalid parsing: detected a \\ in double quoted string:
" + fieldVal);
// }
- values[column]
= fieldVal;
}
- } else if (((i - 1 - cursor) ==
4) && source.indexOf("NULL", cursor) == cursor) {
- // the field contains
NULL, so no value
- values[column] = null;
} else {
- // the field is a
string NOT surrounded by double quotes and thus without escape chars
- final String fieldVal =
new String(chrLine, cursor, i - 1 - cursor);
- // if
(fieldVal.contains("\\")) {
- // throw new
MCLParseException("Invalid parsing: detected a \\ in unquoted string: " +
fieldVal);
- // }
- values[column] =
fieldVal;
+ final int vlen = i - 1
- cursor;
+ if (vlen == 4 &&
+ chrLine[cursor] ==
'N' && chrLine[cursor+1] == 'U' && chrLine[cursor+2] == 'L' &&
chrLine[cursor+3] == 'L') {
+ // the field
contains NULL, so no value
+ values[column]
= null;
+ } else {
+ // the field is
a string NOT surrounded by double quotes and thus without escape chars
+ values[column]
= new String(chrLine, cursor, vlen);
+ // if
(values[column].contains("\\")) {
+ // throw
new MCLParseException("Invalid parsing: detected a \\ in unquoted string: " +
fieldVal);
+ // }
+ }
}
cursor = i + 1;
fieldHasEscape = false;
// reset for next field scan
@@ -207,7 +224,7 @@ public final class TupleLineParser exten
throw new MCLParseException("illegal result length: " +
column + "\nlast read: " + (column > 0 ? values[column - 1] : "<none>"));
// reset colnr
- reset();
+ colnr = 0;
return 0;
}
}
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