1. HAM:
Aspect Mining
Silvia Breu
University of Cambridge
Thomas Zimmermann
Saarland University
Christian Lindig
Saarland University

2. Aspects
create() connect()
close()
serve()
fork()

3. Aspects
create() connect()
close()
serve()
fork()

4. Aspects
create() connect() lock()
Typical Aspects
enter()/leave()
log()
close()
lock()/unlock()
serve()
fork()

5. Aspects
create() connect() lock()
Typical Aspects
enter()/leave()
log()
close()
AOP
lock()/unlock()
serve()
fork()

6. Aspects
create() connect() lock()
Typical Aspects
enter()/leave()
log()
close()
AOP
lock()/unlock()
serve()
fork()
Aspect Mining:
Identifying Aspects
in Legacy Code

7. Research Hypothesis
Cross-cutting concerns
emerge over time.

8. Cross-cutting concerns
emerge over time.

9. Demo #1

10. Modelling History
Transactions 142

11. Modelling History
Transactions 142
MODIFICATIONS

12. Modelling History
Transactions 142
MODIFICATIONS
DELETIONS

13. Modelling History
Transactions 142
MODIFICATIONS
DELETIONS
ADDITIONS

14. Modelling History
Transactions 142 143
MODIFICATIONS
DELETIONS
ADDITIONS

15. Code Additions
Location: _aload_0
public void _aload_0(int pc)
{
dumpPcNumber(pc);
buffer.append(OpcodeStringValues
.BYTECODE_NAMES
[IOpcodeMnemonics.ALOAD_0]);
writeNewLine();
}

16. Code Additions
Location: _aload_1
Location: println
public void _aload_0(int pc)
{
Location: _aload_0
dumpPcNumber(pc);
buffer.append(OpcodeStringValues
public void _aload_0(int pc)
.BYTECODE_NAMES
{
[IOpcodeMnemonics.ALOAD_0]);
dumpPcNumber(pc);
writeNewLine();
buffer.append(OpcodeStringValues
} .BYTECODE_NAMES
[IOpcodeMnemonics.ALOAD_0]);
writeNewLine();
}

17. Co-Addition of Calls
141 142 143
config()
connect()
serve()
close()
init()

18. Co-Addition of Calls
141 142 143
config()
connect()
serve()
close()
init()
lock()

19. Co-Addition of Calls
141 142 143
config()
connect()
serve()
close()
init()
lock()
unlock()

20. Co-Addition of Calls
141 142 143
config()
connect()
serve()
close()
init()
lock()
unlock()
“fixed bug#1234 by
adding proper locks”
Cross-Cutting Change
lock()
unlock()

21. Transaction as a Table
calls
locations

22. Transaction as a Table
t
rA
ha calls
c
runDFA
This Tx added
among others a
call to charAt in
location runDFA
locations

23. Blocks = Aspect Candidates
k lock
nc ocun
l
sy calls
d
method sync is called from
e
locations d, e, f, g, h, i, k
f
g
h
i
{sync} is an
k
aspect candidate
locations

24. Computing all Blocks

25. Computing all Blocks

26. Concept Analysis
calls
locations
Concept Analysis computes all blocks.

27. Concept Analysis
calls
locations
Concept Analysis computes all blocks.

28. Concept Analysis
calls
locations
Concept Analysis computes all blocks.

29. Concept Analysis
calls
locations
Concept Analysis computes all blocks.

30. Example from Eclipse
2004-03-01

31. Example from Eclipse
2004-03-01
nodes reflect size of
cross-cutting concern
# locations
# methods

32. Example from Eclipse
2004-03-01
nodes reflect size of
cross-cutting concern
# locations
# methods
14 locations call
unsupportedIn2()

33. Example from Eclipse
2004-03-01
nodes reflect size of
cross-cutting concern
# locations
# methods
14 locations call
unsupportedIn2()
History contains cross-cutting changes.

34. Demo #2

35. Reinforcement
Aspect Candidate Aspect Candidate
METHOD: METHOD:
lock() lock()
LOCATIONS: connect() LOCATIONS: init()
close() serve()

36. Reinforcement
Aspect Candidate Aspect Candidate
+
METHOD: METHOD:
lock() lock()
LOCATIONS: connect() LOCATIONS: init()
close() serve()
Aspect Candidate
METHOD: lock()
LOCATIONS: connect()
close()
init()
serve()

37. Locality

38. Locality
chris chris tom chris silvi silvi chris
39 40 41 42 43 44 45

39. Locality
chris chris tom chris silvi silvi chris
39 40 41 42 43 44 45

40. Locality
chris chris tom chris silvi silvi chris
39 40 41 42 43 44 45
Temporal
locality

41. Locality
chris chris tom chris silvi silvi chris
39 40 41 42 43 44 45
Temporal
locality

42. Locality
chris chris tom chris silvi silvi chris
39 40 41 42 43 44 45
Temporal
locality

43. Locality
chris chris tom chris silvi silvi chris
39 40 41 42 43 44 45
Possessional Temporal
locality locality

44. Locality
chris chris tom chris silvi silvi chris
39 40 41 42 43 44 45
Possessional Temporal
locality locality
➡ merging transactions and
running concept analysis.

45. Results for Eclipse
Transactions (43270)
max avg
The average transaction
blocks 1235 3.7
is small. It adds 5 calls
methods 1236 5.4
in 4 locations.
locations 1287 3.8

46. Results for Eclipse
Transactions (43270)
max avg
The average transaction
blocks 1235 3.7
is small. It adds 5 calls
methods 1236 5.4
in 4 locations.
locations 1287 3.8
Aspect Candidates*
112 candidates add
methods 1 2 3 ≥4
3 calls or more.
candidates 1878 362 88 24
* selected from 159448 blocks

47. Locking Mechanism
public static final native void _XFree(int address);
public static final void XFree(int /*long*/ address) {
lock.lock();
try {
_XFree(address);
} finally {
lock.unlock();
}
}

48. Locking Mechanism
public static final native void _XFree(int address);
public static final void XFree(int /*long*/ address) {
284
ts 1
lock.lock();
scu
os
cr
try {
ns
_XFree(address);
tio
oca
l
} finally {
lock.unlock();
}
}

49. Future work
• Evolution of cross-cutting concerns.
Refactor only those that actually change.
• Relation between cross-cutting concerns
• Refactoring of concerns.
• Package and ship HAM.

50. Conclusions
• Cross-cutting concerns emerge over time.
• Cross-cutting changes point to aspect
candidates.
• HAM scales to industrial-sized systems.
• http://www.st.cs.uni-sb.de/softevo/