RFR: 8298865: Excessive memory allocation in CipherOutputStream AEAD decryption [v2]

[Anthony Scarpino]

On Thu, 15 Dec 2022 18:06:38 GMT, Daniel Jeliński <djelinski at openjdk.org> wrote:

>> This patch modifies `CipherOutputStream` to avoid pointless memory allocations when decrypting data using AEAD ciphers. This is related to #11597, which fixed a similar issue in `CipherInputStream`.
>> 
>> `Cipher.update` does not output any data when doing AEAD decryption; all data is buffered, and is later returned in one shot from `doFinal`. `Cipher.getOutputSize` returns the buffer size required by `doFinal`, which increases after every `update`, triggering new allocation in `ensureCapacity`.
>> 
>> This patch addresses the issue by calling the `update` overload that returns the output buffer until one of the update calls returns some data. When that happens, we know that the cipher does not buffer everything until `doFinal`, and revert to original behavior.
>> 
>> This PR adds a new benchmark for AES/GCM encryption and decryption using `CipherOutputStream`.
>> 
>> Benchmark results before:
>> 
>> Benchmark                         (dataSize)  (keyLength)  (provider)   Mode  Cnt       Score      Error  Units
>> AESGCMCipherOutputStream.decrypt       16384          128              thrpt   40   27949,624 ±  301,408  ops/s
>> AESGCMCipherOutputStream.decrypt     1048576          128              thrpt   40      20,730 ±    0,875  ops/s
>> AESGCMCipherOutputStream.encrypt       16384          128              thrpt   40  175358,641 ± 4235,808  ops/s
>> AESGCMCipherOutputStream.encrypt     1048576          128              thrpt   40    2588,111 ±   35,469  ops/s
>> 
>> 
>> after:
>> 
>> Benchmark                         (dataSize)  (keyLength)  (provider)   Mode  Cnt       Score      Error  Units
>> AESGCMCipherOutputStream.decrypt       16384          128              thrpt   40   69644,217 ± 1081,032  ops/s
>> AESGCMCipherOutputStream.decrypt     1048576          128              thrpt   40     949,667 ±    9,431  ops/s
>> AESGCMCipherOutputStream.encrypt       16384          128              thrpt   40  173144,038 ± 3279,149  ops/s
>> AESGCMCipherOutputStream.encrypt     1048576          128              thrpt   40    2514,840 ±   87,935  ops/s
>
> Daniel Jeliński has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix test failure

Marked as reviewed by ascarpino (Reviewer).

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PR: https://git.openjdk.org/jdk/pull/11693