ipfs-cluster/allocator/descendalloc/descendalloc.go
Adrian Lanzafame 3b3f786d68
add opencensus tracing and metrics
This commit adds support for OpenCensus tracing
and metrics collection. This required support for
context.Context propogation throughout the cluster
codebase, and in particular, the ipfscluster component
interfaces.

The tracing propogates across RPC and HTTP boundaries.
The current default tracing backend is Jaeger.

The metrics currently exports the metrics exposed by
the opencensus http plugin as well as the pprof metrics
to a prometheus endpoint for scraping.
The current default metrics backend is Prometheus.

Metrics are currently exposed by default due to low
overhead, can be turned off if desired, whereas tracing
is off by default as it has a much higher performance
overhead, though the extent of the performance hit can be
adjusted with smaller sampling rates.

License: MIT
Signed-off-by: Adrian Lanzafame <adrianlanzafame92@gmail.com>
2019-02-04 18:53:21 +10:00

45 lines
1.6 KiB
Go

// Package descendalloc implements an ipfscluster.PinAllocator returns
// allocations based on sorting the metrics in descending order. Thus, peers
// with largest metrics are first in the list. This allocator can be used with a
// number of informers, as long as they provide a numeric metric value.
package descendalloc
import (
"context"
"github.com/ipfs/ipfs-cluster/allocator/util"
"github.com/ipfs/ipfs-cluster/api"
cid "github.com/ipfs/go-cid"
logging "github.com/ipfs/go-log"
rpc "github.com/libp2p/go-libp2p-gorpc"
peer "github.com/libp2p/go-libp2p-peer"
)
var logger = logging.Logger("descendalloc")
// DescendAllocator extends the SimpleAllocator
type DescendAllocator struct{}
// NewAllocator returns an initialized DescendAllocator
func NewAllocator() DescendAllocator {
return DescendAllocator{}
}
// SetClient does nothing in this allocator
func (alloc DescendAllocator) SetClient(c *rpc.Client) {}
// Shutdown does nothing in this allocator
func (alloc DescendAllocator) Shutdown(_ context.Context) error { return nil }
// Allocate returns where to allocate a pin request based on metrics which
// carry a numeric value such as "used disk". We do not pay attention to
// the metrics of the currently allocated peers and we just sort the
// candidates based on their metric values (largest to smallest).
func (alloc DescendAllocator) Allocate(ctx context.Context, c cid.Cid, current, candidates, priority map[peer.ID]api.Metric) ([]peer.ID, error) {
// sort our metrics
first := util.SortNumeric(priority, true)
last := util.SortNumeric(candidates, true)
return append(first, last...), nil
}