Re: [PATCH JGIT] Method invokes inefficient new String(String) constructor
From: Shawn O. Pearce <hidden>
Date: 2016-06-15 22:46:25
Yann Simon [off-list ref] wrote:
quoted hunk ↗ jump to hunk
From FindBugs: Using the java.lang.String(String) constructor wastes memory because the object so constructed will be functionally indistinguishable from the String passed as a parameter. Just use the argument String directly. Signed-off-by: Yann Simon <redacted> --- .../src/org/spearce/jgit/lib/RefDatabase.java | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)diff --git a/org.spearce.jgit/src/org/spearce/jgit/lib/RefDatabase.java b/org.spearce.jgit/src/org/spearce/jgit/lib/RefDatabase.java index 87f26bf..49da538 100644 --- a/org.spearce.jgit/src/org/spearce/jgit/lib/RefDatabase.java +++ b/org.spearce.jgit/src/org/spearce/jgit/lib/RefDatabase.java@@ -447,7 +447,7 @@ private synchronized void refreshPackedRefs() { final int sp = p.indexOf(' '); final ObjectId id = ObjectId.fromString(p.substring(0, sp)); - final String name = new String(p.substring(sp + 1)); + final String name = p.substring(sp + 1); last = new Ref(Ref.Storage.PACKED, name, name, id); newPackedRefs.put(last.getName(), last);
I had a specific reason for forcing a new String object here. The line in question, p, is from the packed-refs file and contains the entire SHA-1 in hex form at the beginning of it. We've converted that into binary as an ObjectId, it uses 1/4 the space of the string portion. The Ref object, its ObjectId, and its name string, are going to be cached in a Map, probably long-term. We're better off shedding the 80 bytes of memory used to hold the hex SHA-1 then risk substring() deciding its "faster" to reuse the char[] then to make a copy of it. -- Shawn.