This commit continues the work of taking advantage of the streaming
capabilities in go-libp2p-gorpc by improving the ipfsconnector and pintracker
components.
StatusAll and RecoverAll methods are now streaming methods, with the REST API
output changing accordingly to produce a stream of GlobalPinInfos rather than
a json array.
pin/ls request to the ipfs daemon now use ?stream=true and avoid having to
load the full pinset map on memory. StatusAllLocal and RecoverAllLocal
requests to the pin tracker stream all the way and no longer store the full
pinset, and the full PinInfo status slice before sending it out.
We have additionally switched to a pattern where streaming methods receive the
channel as an argument, allowing the caller to decide on whether to launch a
goroutine, do buffering etc.
This commit introduces the new go-libp2p-gorpc streaming capabilities for
Cluster. The main aim is to work towards heavily reducing memory usage when
working with very large pinsets.
As a side-effect, it takes the chance to revampt all types for all public
methods so that pointers to static what should be static objects are not used
anymore. This should heavily reduce heap allocations and GC activity.
The main change is that state.List now returns a channel from which to read
the pins, rather than pins being all loaded into a huge slice.
Things reading pins have been all updated to iterate on the channel rather
than on the slice. The full pinset is no longer fully loaded onto memory for
things that run regularly like StateSync().
Additionally, the /allocations endpoint of the rest API no longer returns an
array of pins, but rather streams json-encoded pin objects directly. This
change has extended to the restapi client (which puts pins into a channel as
they arrive) and to ipfs-cluster-ctl.
There are still pending improvements like StatusAll() calls which should also
stream responses, and specially BlockPut calls which should stream blocks
directly into IPFS on a single call.
These are coming up in future commits.
This is a preparatory PR to add additional APIs (Pinning Service API) easily
to cluster.
Instead of copy-pasting most of what the REST API does, I have refactored so
that the whole configuration, routing and request-handling utilities can be
re-used.
The worst part has been to divide the test between tests that test core
(common.API) functionality and tests that test specific REST API endpoint
functionality. I could not get away without an additional common/test package
to provide functions that are used from both places. This is a side effect of
testing both http and libp2p endpoints for every request etc.
