* Use the read buffer in UploadFile for the SFTP write packets
In SftpClient.UploadFile, a buffer is allocated to read from the given stream, and for
each read, another array is allocated for the SFTP write packet (which consists of that
data prepended with headers). This change effectively leaves space at the start of the
buffer for the headers such that it can be used to assemble the packets without that
per-packet array allocation.
There are cleaner/more general ways to do this (e.g. for all packet types, leave space
for the SSH headers as well), but this gets the most impact for about as much effort as
I can be bothered with.
* Rent from pool
An SFTP download performs several reads from the server in parallel, allocating an array
to store each result until it's ready to be consumed. Since these buffers are short-lived
and normally of the same large-ish size (32KB), it seems like a good candidate for pooling.
* Build the read-ahead mechanism into SftpFileStream
This change unifies the SFTP download implementations that exist via DownloadFile and
via SftpFileStream, by rewriting SftpFileStream to perform the same "read-aheads" as
DownloadFile. This brings the performance of downloads via SftpFileStream in line with
DownloadFile, such that the latter is now effectively SftpFileStream.CopyTo. It also
brings the recently added DownloadFileAsync up to speed since that was implemented via
SftpFileStream.CopyToAsync.
The methodology is a mix of the previous one and that within OpenSSH: the first call to
SftpFileStream.Read sends one read request to the server. The second sends two and when
not interrupted by Write or similar, the number of in-flight read requests continues to
scale up in this fashion.
I have measured CopyTo to be 3-20x faster than before, depending on file size and server
round-trip time.
* Check CanSeek in ReadAllBytes
* Squeeze out some performance
* Bump the dependencies group with 4 updates
Bumps BouncyCastle.Cryptography from 2.6.1 to 2.6.2
Bumps Meziantou.Analyzer from 2.0.205 to 2.0.210
Bumps MSTest from 3.9.3 to 3.10.0
Bumps SonarAnalyzer.CSharp from 10.13.0.120203 to 10.15.0.120848
Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Rob Hague <rob.hague00@gmail.com>
Rob Hague