327256 - Add ability to nsCOMArray to preallocate space

Status: RESOLVED FIXED

(Core :: XPCOM, defect)

Description

[Jonas Sicking (:sicking) No longer reading bugmail consistently]

It'd be nice to have the ability in nsCOMArray to allocate space for a set number of objects. This is useful when inserting a known number of objects since it allows both less error checking and fewer allocations.

Patch comming up.

Comment 1

[Jonas Sicking (:sicking) No longer reading bugmail consistently]

Attachment: Implement EnsureStorageFor

Not sure if the name is great. Other suggestions welcome. 

I should add that I'm going to add code that uses this function soon, so it's not dead code.

Comment 2

[Darin Fisher]

Comment on attachment 211957 [details] [diff] [review]
Implement EnsureStorageFor

I think this should be called SetCapacity to be more consistent with other container classes (e.g., nsString and nsTArray).

Comment 3

[Jonas Sicking (:sicking) No longer reading bugmail consistently]

Attachment: Better name

Comment 4

[Jonas Sicking (:sicking) No longer reading bugmail consistently]

Comment on attachment 212024 [details] [diff] [review]
Better name

Hmm.. looking at strings i'm not sure if the name is ideal as the function is implemented.

nsTSubstring::SetCapacity currently sets the capacity to
NS_MIN(mLength, aSize)
whereas this code sets it to
mLength + aSize

New patch coming up.

Comment 5

[Jonas Sicking (:sicking) No longer reading bugmail consistently]

Attachment: patch v2

So nsTSubstring::SetCapacity and nsTArray::SetCapacity behave differently. The nsTSubstring one will reduce the length of the string if it can't fit in the new capacity, nsTArray will simply never make the capacity smaller then mLength.

I made nsCOMArray behave like nsTArray

Comment 6

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

It'd be nice to have this on the 1.8 and 1.8.0 branches for bug 271669.

Comment 7

[Darin Fisher]

Comment on attachment 212151 [details] [diff] [review]
patch v2

a=darin for 1.8.1

Comment 8

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

I just landed this on MOZILLA_1_8_BRANCH and (without approval) MOZILLA_1_8_0_BRANCH so that I could land bug 271669.

Comment 9

[Jonas Sicking (:sicking) No longer reading bugmail consistently]

This was checked in some time ago