Don't unnecessarily copy strings

Don't unnecessarily copy strings

Add a function base::SplitStringPieceUsingSubstr that splits a string
using a substring delimiter without copying the string parts. Use it in
HttpRequestHeaders::AddHeadersFromString.

BUG=572076
Committed: https://crrev.com/0e8b35ae352e71ea43bf1dc9f6b68128dc8ab187
Cr-Commit-Position: refs/heads/master@{#367504}

[Arjan van Leeuwen, 2015-12-24 12:42:42]

Description was changed from

==========
Don't unnecessarily copy strings

Add a function base::SplitStringPieceUsingSubstr that splits a string
using a substring delimiter without copying the string parts. Use it in
HttpRequestHeaders::AddHeadersFromString.

BUG=572076
==========

to

==========
Don't unnecessarily copy strings

Add a function base::SplitStringPieceUsingSubstr that splits a string
using a substring delimiter without copying the string parts. Use it in
HttpRequestHeaders::AddHeadersFromString.

BUG=572076
==========

[Arjan van Leeuwen, 2015-12-24 12:42:42]

arjanl@opera.com changed reviewers:
+ brettw@chromium.org, mef@chromium.org, xunjieli@chromium.org

[Arjan van Leeuwen, 2015-12-24 12:43:47]

We ran into this doing some testing at Opera. Looks OK?

[mef, 2015-12-28 17:29:55]

https://codereview.chromium.org/1549063003/diff/1/base/strings/string_split.cc
File base/strings/string_split.cc (right):

https://codereview.chromium.org/1549063003/diff/1/base/strings/string_split.c...
base/strings/string_split.cc:242: StringPiece16 delimiter) {
Would it make sense to take a pointer to an output vector as a parameter to
avoid copying it on the return?

[brettw, 2015-12-29 04:07:14]

https://codereview.chromium.org/1549063003/diff/1/base/strings/string_split.cc
File base/strings/string_split.cc (right):

https://codereview.chromium.org/1549063003/diff/1/base/strings/string_split.c...
base/strings/string_split.cc:242: StringPiece16 delimiter) {
On 2015/12/28 17:29:55, mef wrote:
> Would it make sense to take a pointer to an output vector as a parameter to
> avoid copying it on the return?

Return value optimization should take care of this: there should be no copy when
used in most cases.

[brettw, 2015-12-29 22:14:41]

https://codereview.chromium.org/1549063003/diff/1/base/strings/string_split.h
File base/strings/string_split.h (right):

https://codereview.chromium.org/1549063003/diff/1/base/strings/string_split.h...
base/strings/string_split.h:114: BASE_EXPORT std::vector<StringPiece16>
SplitStringPieceUsingSubstr(
I'd like to make this a mirror of SplitString[Piece] above. Can you add the
(WhitespaceHandling whitespace and SplitResult result_type) parameters as well?
This should allow you to save the comparison in the loop in net.

[mef, 2015-12-30 19:36:59]

https://codereview.chromium.org/1549063003/diff/1/base/strings/string_split.cc
File base/strings/string_split.cc (right):

https://codereview.chromium.org/1549063003/diff/1/base/strings/string_split.c...
base/strings/string_split.cc:242: StringPiece16 delimiter) {
On 2015/12/29 04:07:14, brettw wrote:
> On 2015/12/28 17:29:55, mef wrote:
> > Would it make sense to take a pointer to an output vector as a parameter to
> > avoid copying it on the return?
> 
> Return value optimization should take care of this: there should be no copy
when
> used in most cases.

Acknowledged.

[Arjan van Leeuwen, 2016-01-04 09:15:55]

+brettw added parameters as requested, could you take another look?

[mef, 2016-01-04 15:03:50]

lgtm

[brettw, 2016-01-04 18:28:56]

lgtm

[Arjan van Leeuwen, 2016-01-05 09:13:25]

The CQ bit was checked by arjanl@opera.com

[commit-bot: I haz the power, 2016-01-05 09:13:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1549063003/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1549063003/20001

[commit-bot: I haz the power, 2016-01-05 10:25:01]

Description was changed from

==========
Don't unnecessarily copy strings

Add a function base::SplitStringPieceUsingSubstr that splits a string
using a substring delimiter without copying the string parts. Use it in
HttpRequestHeaders::AddHeadersFromString.

BUG=572076
==========

to

==========
Don't unnecessarily copy strings

Add a function base::SplitStringPieceUsingSubstr that splits a string
using a substring delimiter without copying the string parts. Use it in
HttpRequestHeaders::AddHeadersFromString.

BUG=572076
==========

[commit-bot: I haz the power, 2016-01-05 10:25:02]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-01-05 10:25:51]

Description was changed from

==========
Don't unnecessarily copy strings

Add a function base::SplitStringPieceUsingSubstr that splits a string
using a substring delimiter without copying the string parts. Use it in
HttpRequestHeaders::AddHeadersFromString.

BUG=572076
==========

to

==========
Don't unnecessarily copy strings

Add a function base::SplitStringPieceUsingSubstr that splits a string
using a substring delimiter without copying the string parts. Use it in
HttpRequestHeaders::AddHeadersFromString.

BUG=572076

Committed: https://crrev.com/0e8b35ae352e71ea43bf1dc9f6b68128dc8ab187
Cr-Commit-Position: refs/heads/master@{#367504}
==========

[commit-bot: I haz the power, 2016-01-05 10:25:51]

Patchset 2 (id:??) landed as
https://crrev.com/0e8b35ae352e71ea43bf1dc9f6b68128dc8ab187
Cr-Commit-Position: refs/heads/master@{#367504}