SAFTest

Android/Java Conventional File API / Storage Access Framework Performance Test

• Pre-built APK Download

This is a test application to evaluate the comparative performance of conventional Android/Java file operations vs the Android Storage Access Framework.

This project was created to demonstrate the difference in performance for file operations now that Android Q/10 will require file explorer developers to use the Storage Access Framework in lieu of conventional java.io.File access as was done with Android 1.0-9.0.

Despite being oriented toward testing Android Q/10, This application will run on any version of Android after 5.0, when Android added support for the Storage Access Framework.

The test walks the entirety of the user-accessible internal storage filesystem, i.e. that which is traditionally found at Environment.getExternalStorageDirectory(), commonly mounted at the path /storage/emulated/0 and aliased to /sdcard.

The test counts the number of files, number of folders, and total size of all files on the Internal Storage. A file manager app would perform a similar walk of a directory hierarchy if it were performing a search, checking for recently updated files, or helping the user find unnecessary items to clean-up.

This directory-walk test is performed with both conventional Java I/O (java.io.File operations) and with the Storage Access Framework.

The difference in performance shown by this app is what a user will observe after upgrading his or her device to Android Q / 10 and using a file manager which supports Android Q. (File managers which do not specifically support Q will not have access to the user's files at all.)

Setup

• Install the app.
• Run the following adb command on the device to allow it to access all files on the device using java.io.File access (on a single line):

  adb shell cmd appops set nextapp.saftest android:legacy_storage allow
  

• Open the app.
• The app will request file write access permissions (no files are actually written).
• Press the "Select SAF Target" button to select the location of the device's internal storage.
  • Tap the 3-dots menu (overflow menu) in the upper right corner of the screen.
  • If the menu contains an option, "Show internal storage", press it. I if it does not, simply continue to the next step.
  • Tap the 3-lines menu (hamburger menu) in the upper left corner of the screen.
  • Select the "Internal Storage". It may be named after the device, e.g. "Pixel"
  • Press the "Allow Access" button at the bottom of the screen.
  • Press the "Allow" button in the dialog that appears.
• Press the floating "Play" button at the bottom of the app and wait for the test to run.
  • The conventional test will run first, followed by the SAF test.
• For the test to be valid, the total folder, file, and byte counts should be similar between the two. The time, unfortunately, will not.
• The test will show a "performance factor" as a percentage representing how much longer the SAF took to perform the operation relative to conventional file access. For example, a value of 3,000% indicates SAF was 30 times slower than conventional access.

Troubleshooting

• If you're on Android Q and see very few files/folders show in the "Conventional" test, you likely haven't successfully granted legacy storage access which is required for this test to run. Try the "adb shell" command again and then force close the app (swipe it away with Android's task manager) and open it again.