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duplicate-detector

This thing looks at the .jars on the classpath and identifies classes and clojure sources that might be duplicated between .jars.

Examples

Just the uberjar:

% java -jar target/duplicate-detector-0.1.0-SNAPSHOT-standalone.jar
Processing .jar file:  target/duplicate-detector-0.1.0-SNAPSHOT-standalone.jar
"Elapsed time: 107.593 msecs"
Processed 11 resources from 1 .jars

Duplicate classes between plugin jars:

This example uses the plugins-with-duplicates directory which includes multiple versions of apache commons-io.

% java -jar target/duplicate-detector-0.1.0-SNAPSHOT-standalone.jar --plugins plugins-with-duplicates
Processing .jar file:  target/duplicate-detector-0.1.0-SNAPSHOT-standalone.jar
Processing .jar file:  plugins-with-duplicates/commons-io-2.1.jar
Processing .jar file:  plugins-with-duplicates/commons-io-2.4.jar
ERROR: Class or namespace org/apache/commons/io/ByteOrderMark.class found in both plugins-with-duplicates/commons-io-2.4.jar and plugins-with-duplicates/commons-io-2.1.jar

Benchmarks

Plugins dir includes commons-io and clj-http

% java -jar target/duplicate-detector-0.1.0-SNAPSHOT-standalone.jar --plugins plugins-timing
Processing .jar file:  target/duplicate-detector-0.1.0-SNAPSHOT-standalone.jar
Processing .jar file:  plugins-timing/clj-http-0.5.3.jar
Processing .jar file:  plugins-timing/commons-io-2.4.jar
"Elapsed time: 117.502 msecs"
Processed 128 resources from 3 .jars

Plugins dir includes a handful of .jars

% java -jar target/duplicate-detector-0.1.0-SNAPSHOT-standalone.jar --plugins plugins-timing-heavy
Processing .jar file:  target/duplicate-detector-0.1.0-SNAPSHOT-standalone.jar
Processing .jar file:  plugins-timing-heavy/args4j-2.0.16.jar
Processing .jar file:  plugins-timing-heavy/clj-aws-s3-0.3.6.jar
Processing .jar file:  plugins-timing-heavy/clj-http-0.5.3.jar
Processing .jar file:  plugins-timing-heavy/clojureql-1.0.3.jar
Processing .jar file:  plugins-timing-heavy/commons-codec-1.6.jar
Processing .jar file:  plugins-timing-heavy/commons-fileupload-1.3.jar
Processing .jar file:  plugins-timing-heavy/commons-io-2.4.jar
Processing .jar file:  plugins-timing-heavy/commons-net-2.2.jar
Processing .jar file:  plugins-timing-heavy/joda-time-2.2.jar
Processing .jar file:  plugins-timing-heavy/postgresql-9.1-901-1.jdbc4.jar
"Elapsed time: 165.157 msecs"
Processed 889 resources from 11 .jars

Don't exclude the clojure sources

Interesting performance note: this example processed almost 5x as many resources as the previous example, but only took 18% longer.

% java -jar target/duplicate-detector-0.1.0-SNAPSHOT-standalone.jar --plugins plugins-timing-heavy --include-clojure-sources
Processing .jar file:  target/duplicate-detector-0.1.0-SNAPSHOT-standalone.jar
Processing .jar file:  plugins-timing-heavy/args4j-2.0.16.jar
Processing .jar file:  plugins-timing-heavy/clj-aws-s3-0.3.6.jar
Processing .jar file:  plugins-timing-heavy/clj-http-0.5.3.jar
Processing .jar file:  plugins-timing-heavy/clojureql-1.0.3.jar
Processing .jar file:  plugins-timing-heavy/commons-codec-1.6.jar
Processing .jar file:  plugins-timing-heavy/commons-fileupload-1.3.jar
Processing .jar file:  plugins-timing-heavy/commons-io-2.4.jar
Processing .jar file:  plugins-timing-heavy/commons-net-2.2.jar
Processing .jar file:  plugins-timing-heavy/joda-time-2.2.jar
Processing .jar file:  plugins-timing-heavy/postgresql-9.1-901-1.jdbc4.jar
"Elapsed time: 193.839 msecs"
Processed 4315 resources from 11 .jars

Conclusion

This approach seems to work fine. It also seems to be plenty fast - all tests so far have taken 100-200ms. Most importantly, the slowdown incurred by examining more .jars seems very minimal; processing just the uberjar (11 classes) took ~100ms, while processing the uberjar plus 10 "plugin" .jars (889 classes/namespaces) took only ~160ms. Those numbers seem to validate this approach.