[LANG-993] Add zero copy write method to StrBuilder

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.3.1
• Fix Version/s: 3.4
• Component/s: lang.text.*
• Assignee: Benedikt Ritter
• Reporter: Mikhail Mazursky
• Created: 31/Mar/14 15:02
• Updated: 13/Jul/14 15:15
• Resolved: 26/Apr/14 10:39

Description

Currently I have the following usecase:

StrBuilder builder = new StrBuilder();
// add lots of stuff to builder
// in multiple invocations in several classes
// writer cannot be used directly
builder.append(...);

Writer writer = ....;
CharStreams.copy(builder.asReader(), writer);

CharStreams is a class from Guava lib that copies data between reader and writer using temporary buffer.
There is a problem with such approach - two additional copies are performed:
1) data is copied from the StrBuilder in chunks into temporary buffer (CharBuffer)
2) Writer.append(CharSequence) is called that is usually implemented as write(CharSequence.toString()) - i.e. it makes another copy of data and allocates an additional String object.

I want to avoid those copies by writing the internal buffer of the StrBuilder directly to the writer. Also it is potentially more efficient because it performs one I/O call instead of many.

So I propose to add the following methods:

    public void writeTo(Writer writer) throws IOException {
        writer.write(buffer, 0, size);
    }

    public void writeTo(StringBuilder builder) {
        builder.append(buffer, 0, size);
    }

    public void writeTo(StringBuffer buffer) {
        buffer.append(this.buffer, 0, size);
    }

If there is interest I will provide patch (with JavaDocs and tests).

Issue Links

• is related to: LANG-994 Add zero copy read method to StrBuilder