We needed it because some of our invocations of Weave Net's `weave`
script depended on it, but that is no longer the case as of Weave Net
2.1.
Fixes#2974.
The vast majority of the cost is memory allocation, so doing a first
pass to see whether any upgrading is necessary at all, and thus
avoiding allocation when it isn't, is a massive saving.
Most maps we merge have the same keys, or at least one set of keys is
the subset of the other. Therefore, allocate a result slice capable of
holding only the max of number keys, rather than the sum.
so they can share code and are easier to run in combination.
We take advantage of the code sharing by generalising the report
rendering benchmarks to read & merge reports from a dir.
Edges between the incoming and outgoing internet nodes are typically
artifacts of imperfect connection tracking, e.g. when VIPs and NAT
traversal are in use.
So lets filter them out.
This eliminates the awkward distinction between ProcessRenderer and
ColorConnectedProcessRenderer.
It also ensures that processes resulting from direct rendering of the
process topology (/api/topology/processes is invoking
ProcessWithContainerNameRenderer and /api/topology/processes-by-name
is invoking ProcessNameRenderer) are colored and hence summarising
them correctly sets the 'linkable' property. This was the behaviour
prior to the revamping of the rendering pipeline. However, it doesn't
actually make a practical difference since process detail panels only
show other processes as connection endpoints, and these are always
marked linkable anyway.
It's now done via a special filter, once, after all other filters have
been applied.
Some tests need updating since they were relying on ordinary filters
doing that filtering.
...rather than before. That way, nodes which become unconnected during
filtering are removed, which is what we want. ATM we are depending on
some 'unconnected' filtering inside every filter, which is expensive
and largely redundant. We should soon be able to remove that.
downside: 'unconnected' filtering is no longer memoised.
Instead of three passes
1. building a 'connected' node set
2. marking nodes from that set with a LatestMap entry
3. removing unmarked nodes
we just do two
1. building a 'connected' node set
2. removing nodes not in that set
This does entail duplication of the adjecency list pruning code from
FilterFunc.Apply. We will be able to eliminate that eventually, but
not just yet.
Also, we cannot get rid of ColorConnected completely;
ColorConnectedProcessRenderer uses it to mark nodes, and that
information is required by detailed.processNodeSummary to determine
whether a process in the details panel can be rendered as a link.
All outputs of Memoise() are fixpoints to the function, i.e. feeding
them as inputs to the function just returns them.
We don't hit this optimisation in current code but have had instances
in the past.
