tree 68b2640d04e0857db25125b236f663437f8f772e
parent 7cf6b7d47829942a72faf8c6525e403cd9f37e48
author Narayan Kamath <narayan@google.com> 1455281677 +0000
committer Narayan Kamath <narayan@google.com> 1455535499 +0000

ZipFile: Improve performance for ZipFile.<init>

Avoid thousands of JNI transitions in the constructor. We can
quite easily check for invalid entry names and duplicates while
parsing the central directory in native code.

The benchmarks show that the median time for opening a file with 8192
entries decreased from 488ms to 120us.

AFTER:
    Trial Report (1 of 3):
      Experiment {instrument=runtime, benchmarkMethod=timeZipFileOpen, vm=default, parameters={numEntries=128}}
      Results:
        runtime(ns): min=112794.57, 1st qu.=113238.72, median=114539.28, mean=119694.66, 3rd qu.=125191.84, max=143145.02
    Trial Report (2 of 3):
      Experiment {instrument=runtime, benchmarkMethod=timeZipFileOpen, vm=default, parameters={numEntries=1024}}
      Results:
        runtime(ns): min=112868.04, 1st qu.=113582.70, median=115180.93, mean=117760.32, 3rd qu.=118067.87, max=137760.10
    Trial Report (3 of 3):
      Experiment {instrument=runtime, benchmarkMethod=timeZipFileOpen, vm=default, parameters={numEntries=8192}}
      Results:
        runtime(ns): min=112417.27, 1st qu.=114630.16, median=117272.70, mean=119197.74, 3rd qu.=122742.84, max=135330.50

BEFORE:
    Trial Report (1 of 3):
      Experiment {instrument=runtime, benchmarkMethod=benchmarkZipFileOpen, vm=default, parameters={numEntries=128}}
      Results:
        runtime(ns): min=9360144.37, 1st qu.=9559712.86, median=9839983.50, mean=9816559.27, 3rd qu.=10057399.81, max=10170918.14
    Trial Report (2 of 3):
      Experiment {instrument=runtime, benchmarkMethod=benchmarkZipFileOpen, vm=default, parameters={numEntries=1024}}
      Results:
        runtime(ns): min=60682471.64, 1st qu.=62388598.00, median=64319977.57, mean=66545494.60, 3rd qu.=72114121.64, max=77298980.57
    Trial Report (3 of 3):
      Experiment {instrument=runtime, benchmarkMethod=benchmarkZipFileOpen, vm=default, parameters={numEntries=8192}}
      Results:
        runtime(ns): min=485804479.00, 1st qu.=487322656.00, median=488986250.00, mean=489820034.67, 3rd qu.=492383229.50, max=495372604.00

bug: 27145664

(cherry picked from commit 8c6a910cd20026c9181a46c8e800a4a566f14527)

Change-Id: Ic1bfe934548f7baf8b8789f069f654725a4b228b