927407 - NS_{Input, Output}StreamIsBuffered should not cause main thread I/O when this can be avoided

Status: RESOLVED FIXED

(Core :: XPCOM, defect)

Description

[David Teller [:Yoric] - still alive but not very active]

NetUtil.asyncCopy calls ioUtil.inputStreamIsBuffered and ioUtil.outputStreamIsBuffered, both of which can cause main thread I/O for detection purposes. In particular, any attempt to read a nsIJARInputStream using NetUtil.asyncCopy will cause such main thread I/O.

While this cannot be systematically avoided, we can trivially avoid such I/O when we know that the streams implement nsIBuffered{Input, Output}Stream.

Comment 1

[David Teller [:Yoric] - still alive but not very active]

Attachment: NS_{Input, Output}IsBuffered now QI to nsIBuffered{Input, Output}Stream before resorting to main thread I/O

Comment 2

[Andrew McCreight [:mccr8]]

Comment on attachment 817840 [details] [diff] [review]
NS_{Input, Output}IsBuffered now QI to nsIBuffered{Input, Output}Stream before resorting to main thread I/O

The suggested reviewers for XPCOM bugs is not super helpful.

Comment 3

[Ed Morley [:emorley]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/af63dffeb63f

Comment 4

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/af63dffeb63f