On Wed, 15 Nov 2023 22:15:54 GMT, Roger Riggs <[email protected]> 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 311:
> 309: }
> 310: if (i >= 1_000_000) {
> 311: System.out.printf("Unable to produce a UTF16 string
> in %d iterations: %s%n", i, original);
What I meant with my previous comment is that this leaves a trace on "success",
which is kind of unusual.
There might be good reasons to do so, but they are not apparent to me.
test/jdk/java/lang/String/StringRacyConstructor.java line 404:
> 402: }
> 403: if (i >= 1_000_000) {
> 404: System.out.printf("Unable to create a string in %d
> iterations: %s%n", i, original);
Suggestion:
System.out.printf("Unable to produce a UTF16 string in %d
iterations: %s%n", i, original);
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/16425#discussion_r1395344966
PR Review Comment: https://git.openjdk.org/jdk/pull/16425#discussion_r1395346293
