Benjamin Mahler created MESOS-2438:
--------------------------------------
Summary: Improve support for streaming HTTP Responses in
libprocess.
Key: MESOS-2438
URL: https://issues.apache.org/jira/browse/MESOS-2438
Project: Mesos
Issue Type: Improvement
Components: libprocess
Reporter: Benjamin Mahler
Currently libprocess' HTTP::Response supports a PIPE construct for doing
streaming responses:
{code}
struct Response
{
...
// Either provide a "body", an absolute "path" to a file, or a
// "pipe" for streaming a response. Distinguish between the cases
// using 'type' below.
//
// BODY: Uses 'body' as the body of the response. These may be
// encoded using gzip for efficiency, if 'Content-Encoding' is not
// already specified.
//
// PATH: Attempts to perform a 'sendfile' operation on the file
// found at 'path'.
//
// PIPE: Splices data from 'pipe' using 'Transfer-Encoding=chunked'.
// Note that the read end of the pipe will be closed by libprocess
// either after the write end has been closed or if the socket the
// data is being spliced to has been closed (i.e., nobody is
// listening any longer). This can cause writes to the pipe to
// generate a SIGPIPE (which will terminate your program unless you
// explicitly ignore them or handle them).
//
// In all cases (BODY, PATH, PIPE), you are expected to properly
// specify the 'Content-Type' header, but the 'Content-Length' and
// or 'Transfer-Encoding' headers will be filled in for you.
enum {
NONE,
BODY,
PATH,
PIPE
} type;
...
};
{code}
This interface is too low level and difficult to program against:
* Connection closure is signaled with SIGPIPE, which is difficult for callers
to deal with (must suppress SIGPIPE locally or globally in order to get EPIPE
instead).
* Pipes are generally for inter-process communication, and the pipe has finite
size. With a blocking pipe the caller must deal with blocking when the pipe's
buffer limit is exceeded. With a non-blocking pipe, the caller must deal with
retrying the write.
We'll want to consider a few use cases:
# Sending an HTTP::Response with streaming data.
# Making a request with http::get and http::post in which the data is returned
in a streaming manner.
# Making a request in which the request content is streaming.
This ticket will focus on 1 as it is required for the HTTP API.
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