The document discusses a tool called HATARI that helps identify risky locations in code based on past fix-inducing changes. HATARI calculates a risk score for each location based on the number of past fix-inducing changes compared to the total number of changes. It visualizes risk scores with annotations to show developers potentially risky areas. HATARI will be made open source on November 1st and is available at http://www.st.cs.uni-sb.de/softevo/.

1. Movie with
John Wayne
(1962)
Swahili for
“Danger”
HATARI
Raising Risk Awareness
Jacek Sliwerski, Thomas Zimmermann, and Andreas Zeller
Saarland University

2. What is Risk?

3. resolveClasspath()
/* (non-Javadoc)
* @see org.eclipse.jdt.launching.IRuntimeClasspathProvider#resolveClasspath
* (org.eclipse.jdt.launching.IRuntimeClasspathEntry[], org.eclipse.debug.core.ILaunchConfiguration)
*/
public IRuntimeClasspathEntry[] resolveClasspath(IRuntimeClasspathEntry[] entries, ILaunchConfiguration configuration)
throws CoreException {
List all = new ArrayList(entries.length);
for (int i = 0; i < entries.length; i++) {
switch (entries[i].getType()) {
case IRuntimeClasspathEntry.PROJECT:
// a project resolves to itself for source lookup (rather than the class file output locations)
9 changes,
all.add(entries[i]);
break;
case IRuntimeClasspathEntry.OTHER:
all of them fixes
IRuntimeClasspathEntry2 entry = (IRuntimeClasspathEntry2)entries[i];
if (entry.getTypeId().equals(DefaultProjectClasspathEntry.TYPE_ID)) {
// add the resolved children of the project
8 fix-inducing changes
IRuntimeClasspathEntry[] children = entry.getRuntimeClasspathEntries(configuration);
IRuntimeClasspathEntry[] res = JavaRuntime.resolveSourceLookupPath(children, configuration);
one re-implementation
for (int j = 0; j < res.length; j++) {
all.add(res[j]);
}
}
break;
default:
IRuntimeClasspathEntry[] resolved =JavaRuntime.resolveRuntimeClasspathEntry(entries[i], configuration);
for (int j = 0; j < resolved.length; j++) {
all.add(resolved[j]);
}
break;
}
}
return (IRuntimeClasspathEntry[])all.toArray(new IRuntimeClasspathEntry[all.size()]);
}

4. Fix-Inducing Changes
Fix-Inducing Changes are
Changes that lead to problems as
indicated by later fixes.
Later:
Example:
... ...
if (foo==null) { if (foo!=null) {
foo.bar(); foo.bar();
FIX-INDUCING FIX

5. How to
Locate Fix-Inducing Changes

6. How to
Locate Fix-Inducing Changes
$ cvs annotate -r 1.17 Foo.java
...
19: 1.11 (john 12-Feb-03): public int a() {
20: 1.11 (john 12-Feb-03): return i/0;
...
39: 1.10 (mary 12-Jan-03): public int b() {
40: 1.14 (kate 23-May-03): return 42;
...
59: 1.10 (mary 17-Jan-03): public void c() {
60: 1.16 (mary 10-Jun-03): int i=0;
1.18
Fixed Bug
42233
Changed:
a() b() c()
line 20 40 60

7. How to
Locate Fix-Inducing Changes
$ cvs annotate -r 1.17 Foo.java
20: 1.11 (john 12-Feb-03): return i/0;
40: 1.14 (kate 23-May-03): return 42;
60: 1.16 (mary 10-Jun-03): int i=0;
1.11 1.14 1.16 1.18
a() was b() was c() was Fixed Bug
changed changed changed 42233
Changed:
FIX-INDUCING FIX-INDUCING FIX-INDUCING
a() b() c()

8. How to
Locate Fix-Inducing Changes
$ cvs annotate -r 1.17 Foo.java
20: 1.11 (john 12-Feb-03): return i/0;
40: 1.14 (kate 23-May-03): return 42;
60: 1.16 (mary 10-Jun-03): int i=0;
Bug 42233 was reported. closed.
1.11 1.14 1.16 1.18
a() was b() was c() was Fixed Bug
changed changed changed 42233
Changed:
FIX-INDUCING FIX-INDUCING FIX-INDUCING
a() b() c()
REMOVE FALSE POSITIVES

9. A Measure for Risk
based on Fix-Inducing Changes
risk(L) is the (past) risk for a location L
“BAD” Changes
# Fix-Inducing Changes to L
risk(L) =
# Changes to L

10. How to Predict Future Risk
0.5
0.4
0.3
Correlation
0.2
0.1
0
0 1 2 3 4 5 6 7 8 9 10
Number of upcoming changes

11. How to Predict Future Risk
0.5
McCabe Cyclomatic Complexity
0.4
0.3
Correlation
0.2
0.1
0
0 1 2 3 4 5 6 7 8 9 10
Number of upcoming changes

12. How to Predict Future Risk
0.5
Nested Block Depth
McCabe Cyclomatic Complexity
0.4
0.3
Correlation
0.2
0.1
0
0 1 2 3 4 5 6 7 8 9 10
Number of upcoming changes

13. How to Predict Future Risk
0.5
Past Risk
Nested Block Depth
McCabe Cyclomatic Complexity
0.4
0.3
Correlation
0.2
0.1
0
0 1 2 3 4 5 6 7 8 9 10
Number of upcoming changes

14. Demo: HATARI

15. HATARI: Risky Locations
Granularities
Past Risk
Location
Values

16. HATARI: Annotations
“Safe” Location
(green)
Risky Location
(dark red)

17. HATARI: Risk History
Bug, fix, or both?
Change information
Bug information

18. Conclusion
Fix-inducing changes are a measure for
(past) risk.
HATARI makes risk visible for developers.
HATARI will be open source (Nov 1)
http://www.st.cs.uni-sb.de/softevo/