On Wed, 15 Nov 2023 22:15:54 GMT, Roger Riggs <rri...@openjdk.org> wrote:
>> Strings, after construction, are immutable but may be constructed from
>> mutable arrays of bytes, characters, or integers.
>> The string constructors should guard against the effects of mutating the
>> arrays during construction that might invalidate internal invariants for the
>> correct behavior of operations on the resulting strings. In particular, a
>> number of operations have optimizations for operations on pairs of latin1
>> strings and pairs of non-latin1 strings, while operations between latin1 and
>> non-latin1 strings use a more general implementation.
>>
>> The changes include:
>>
>> - Adding a warning to each constructor with an array as an argument to
>> indicate that the results are indeterminate
>> if the input array is modified before the constructor returns.
>> The resulting string may contain any combination of characters sampled
>> from the input array.
>>
>> - Ensure that strings that are represented as non-latin1 contain at least
>> one non-latin1 character.
>> For latin1 inputs, whether the arrays contain ASCII, ISO-8859-1, UTF8, or
>> another encoding decoded to latin1 the scanning and compression is unchanged.
>> If a non-latin1 character is found, the string is represented as
>> non-latin1 with the added verification that a non-latin1 character is
>> present at the same index.
>> If that character is found to be latin1, then the input array has been
>> modified and the result of the scan may be incorrect.
>> Though a ConcurrentModificationException could be thrown, the risk to an
>> existing application of an unexpected exception should be avoided.
>> Instead, the non-latin1 copy of the input is re-scanned and compressed;
>> that scan determines whether the latin1 or the non-latin1 representation is
>> returned.
>>
>> - The methods that scan for non-latin1 characters and their intrinsic
>> implementations are updated to return the index of the non-latin1 character.
>>
>> - String construction from StringBuilder and CharSequence must also be
>> guarded as their contents may be modified during construction.
>
> Roger Riggs has updated the pull request incrementally with two additional
> commits since the last revision:
>
> - Cleanup of test with review comment recommendations
> - Enable racy constructor tests iff COMPACT_STRINGS is true
> Test of string_compress intrinsic is always enabled
test/jdk/java/lang/String/StringRacyConstructor.java line 323:
> 321: */
> 322: public static String racyStringConstructionCodepoints(String
> original) throws ConcurrentModificationException {
> 323: if (original.chars().max().orElseThrow() > 256) {
The correct comparison is `>=`, as codepoint 256 is not Latin1.
test/jdk/java/lang/String/StringRacyConstructor.java line 370:
> 368: */
> 369: public static String
> racyStringConstructionCodepointsSurrogates(String original) throws
> ConcurrentModificationException {
> 370: if (original.chars().max().orElseThrow() > 256) {
Same as above
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/16425#discussion_r1395409456
PR Review Comment: https://git.openjdk.org/jdk/pull/16425#discussion_r1395410689
