Consider caching last toString result in RubyString, for performance
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Key: JRUBY-5370
URL: http://jira.codehaus.org/browse/JRUBY-5370
Project: JRuby
Issue Type: Improvement
Components: Core Classes/Modules
Affects Versions: JRuby 1.6RC1
Reporter: Charles Oliver Nutter
In playing with ways to speed up JRuby to Java invocation, I added a cache for
the toString result of a RubyString. RubyString normally causes a new String
object to be created for every call. In many cases, these calls are repeatedly
passed the same String object. By caching that String and flushing it on
modification, we can end up with much better call performance.
Here's the perf difference:
{noformat}
BEFORE:
~/projects/jruby ➔ jruby -rbenchmark -e "10.times { puts
Benchmark.measure { str = 'foo' * 10; dashe = Java::DashE; 1_000_000.times {
dashe.foo(str) } } }"
1.170000 0.000000 1.170000 ( 1.058000)
0.695000 0.000000 0.695000 ( 0.695000)
0.694000 0.000000 0.694000 ( 0.694000)
0.691000 0.000000 0.691000 ( 0.691000)
0.695000 0.000000 0.695000 ( 0.696000)
0.685000 0.000000 0.685000 ( 0.685000)
0.690000 0.000000 0.690000 ( 0.690000)
0.725000 0.000000 0.725000 ( 0.725000)
0.725000 0.000000 0.725000 ( 0.725000)
0.692000 0.000000 0.692000 ( 0.692000)
AFTER:
~/projects/jruby ➔ jruby -rbenchmark -e "10.times { puts
Benchmark.measure { str = 'foo' * 10; dashe = Java::DashE; 1_000_000.times {
dashe.foo(str) } } }"
0.797000 0.000000 0.797000 ( 0.684000)
0.332000 0.000000 0.332000 ( 0.332000)
0.329000 0.000000 0.329000 ( 0.329000)
0.332000 0.000000 0.332000 ( 0.332000)
0.320000 0.000000 0.320000 ( 0.320000)
0.320000 0.000000 0.320000 ( 0.320000)
0.357000 0.000000 0.357000 ( 0.357000)
0.350000 0.000000 0.350000 ( 0.350000)
0.321000 0.000000 0.321000 ( 0.321000)
0.324000 0.000000 0.324000 ( 0.324000)
{noformat}
And here's the patch:
{noformat}
diff --git a/src/org/jruby/RubyString.java b/src/org/jruby/RubyString.java
index bc8377f..04ec6f3 100644
--- a/src/org/jruby/RubyString.java
+++ b/src/org/jruby/RubyString.java
@@ -126,6 +126,8 @@ public class RubyString extends RubyObject implements
EncodingCapable {
private RString rstring;
+ private String lastString;
+
public static RubyClass createStringClass(Ruby runtime) {
RubyClass stringClass = runtime.defineClass("String",
runtime.getObject(), STRING_ALLOCATOR);
runtime.setString(stringClass);
@@ -649,7 +651,19 @@ public class RubyString extends RubyObject implements
EncodingCapable {
@Override
public String toString() {
- return value.toString();
+ String last = lastString;
+ if (last == null) {
+ try {
+ if (getRuntime().is1_9()) {
+ lastString = last = new String(value.getUnsafeBytes(),
value.begin(), value.length(), getEncoding().toString());
+ } else {
+ lastString = last =
RubyEncoding.decodeUTF8(value.getUnsafeBytes(), value.begin(), value.length());
+ }
+ } catch (UnsupportedEncodingException uee) {
+ lastString = last = value.toString();
+ }
+ }
+ return last;
}
/** rb_str_dup
@@ -731,6 +745,8 @@ public class RubyString extends RubyObject implements
EncodingCapable {
if (!isTaint() && getRuntime().getSafeLevel() >= 4) {
throw getRuntime().newSecurityError("Insecure: can't modify
string");
}
+
+ lastString = null;
}
private final void modifyCheck(byte[] b, int len) {
@@ -7292,17 +7308,7 @@ public class RubyString extends RubyObject implements
EncodingCapable {
@Override
public Object toJava(Class target) {
if (target.isAssignableFrom(String.class)) {
- try {
- // 1.9 support for encodings
- // TODO: Fix charset use for JRUBY-4553
- if (getRuntime().is1_9()) {
- return new String(value.getUnsafeBytes(), value.begin(),
value.length(), getEncoding().toString());
- }
-
- return RubyEncoding.decodeUTF8(value.getUnsafeBytes(),
value.begin(), value.length());
- } catch (UnsupportedEncodingException uee) {
- return toString();
- }
+ return toString();
} else if (target.isAssignableFrom(ByteList.class)) {
return value;
} else {
{noformat}
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