This patch modifies `CipherInputStream` to avoid pointless memory allocations when decrypting data using AEAD ciphers.
`Cipher.update` on AEAD decryption does not output any data; instead, all data is buffered and returned in one shot from `doFinal` call. On the other hand, the value returned by `getOutputSize` increases after every `update` call, which triggers multiple allocations in the existing implementation. 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. As long as `doUpdate` returns no data, the new implementation doesn't allocate any memory. As a result, for AEAD ciphers it will only allocate once in the `doFinal` invocation. There's a similar issue in CipherOutputStream that manifests when doing many small writes; I'll file a separate bug for that. The PR adds a new benchmark for AES/GCM encryption and decryption using CipherInputStream. That benchmark shows a nice improvement on decryption and comparable results on encryption. Benchmark results before: Benchmark (dataSize) (keyLength) (provider) Mode Cnt Score Error Units AESGCMCipherInputStream.decrypt 16384 128 thrpt 40 24590,604 ± 1169,075 ops/s AESGCMCipherInputStream.decrypt 1048576 128 thrpt 40 19,159 ± 0,219 ops/s AESGCMCipherInputStream.encrypt 16384 128 thrpt 40 127135,615 ± 2322,957 ops/s AESGCMCipherInputStream.encrypt 1048576 128 thrpt 40 2138,727 ± 16,400 ops/s After: Benchmark (dataSize) (keyLength) (provider) Mode Cnt Score Error Units AESGCMCipherInputStream.decrypt 16384 128 thrpt 40 43419,355 ± 3265,238 ops/s AESGCMCipherInputStream.decrypt 1048576 128 thrpt 40 789,463 ± 89,384 ops/s AESGCMCipherInputStream.encrypt 16384 128 thrpt 40 123014,294 ± 3302,102 ops/s AESGCMCipherInputStream.encrypt 1048576 128 thrpt 40 2007,224 ± 88,347 ops/s ------------- Commit messages: - Add benchmark - Speed up CipherInputStream on AEAD decryption Changes: https://git.openjdk.org/jdk/pull/11597/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11597&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8298249 Stats: 146 lines in 2 files changed: 142 ins; 0 del; 4 mod Patch: https://git.openjdk.org/jdk/pull/11597.diff Fetch: git fetch https://git.openjdk.org/jdk pull/11597/head:pull/11597 PR: https://git.openjdk.org/jdk/pull/11597
