[LUCENE-5543] Remove Directory.fileExists

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 4.8, 6.0
• Component/s: core/store
• Lucene Fields: New
• Assignee: Michael McCandless
• Reporter: Michael McCandless
• Created: 20/Mar/14 22:27
• Updated: 09/May/16 18:32
• Resolved: 23/Mar/14 18:05

Description

Since 3.0.x/3.6.x (see LUCENE-5541), Lucene has substantially removed
its reliance on fileExists to the point where I think we can fully
remove it now.

Like the other iffy IO methods we've removed over time (touchFile,
fileModified, seeking back during write, ...), File.exists is
dangerous because a low level IO issue can cause it to return false
when it should have returned true. The fewer IO operations we rely on
the more reliable/portable Lucene is.