RFR: 8339191: JFR: Bulk read support for ChunkInputStream

[David Schlosnagle]

On Thu, 29 Aug 2024 12:52:10 GMT, Erik Gahlin <egahlin at openjdk.org> wrote:

>> I would like to contribute an improvement to reading JFR recordings via `InputStream` by implementing `InputStream#read(byte[], int, int)` in `ChunkInputStream` to support bulk reads and avoid many expensive single byte `read()`.
>> 
>> Testing: `test/jdk/jdk/jfr/api/consumer/TestChunkInputStreamBulkRead.java`, `jdk_jfr`
>> 
>> While looking through some JFRs recently, I noticed some significant time spent in `java.io.BufferedInputStream#getBufIfOpen()` that traced back to transferring (via `InputStream#transferTo(OutputStream)` JFR profile recording being read via `InputStream` returned by `jdk.jfr.Recording#getStream(Instant , Instant)`. What caught my eye were calls to single byte `jdk.jfr.internal.ChunkInputStream#read()` rather than `read(byte[], int, int)` as seen in the stacktrace from JFR.
>> 
>> <img width="776" alt="image" src="https://github.com/user-attachments/assets/b92398cd-2761-4600-8cfe-ea1bada6efd2">
>
> src/jdk.jfr/share/classes/jdk/jfr/internal/ChunkInputStream.java line 99:
> 
>> 97:     @Override
>> 98:     public int read(byte[] buf, int off, int len) throws IOException {
>> 99:         Objects.checkFromIndexSize(off, len, buf.length);
> 
> Might want to check if buf is null, i.e. Object.requireNonNulll(buf, "buf"), to fail fast instead of later in stream.read(buf...) when a file has been opened.

If `buf` is null, `buf.length` will implicitly throw `NullPointerException` with [helpful exception message](https://openjdk.org/jeps/358)

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PR Review Comment: https://git.openjdk.org/jdk/pull/20534#discussion_r1736860366