Add sample and memory plugins

.mk/easyjson.mk

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+GEN_EASYJSON_FILES = $(patsubst %.go,%_easyjson.go,$(shell git grep //go:generate | grep "easyjson" | grep -v Makefile | cut -d ":" -f 1))
+
+%_easyjson.go: %.go
+	go generate -run easyjson $<
+
+.PHONY: .easyjson
+.easyjson: $(GEN_EASYJSON_FILES)
+
+.PHONY: .easyjson.clean
+.easyjson.clean:
+	find . \( -name *_easyjson.go ! -path './vendor/*' \) -exec rm {} \;
+

.mk/gendecoder.mk

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+GEN_DECODER_FILES = $(patsubst %.go,%_gendecoder.go,$(shell git grep //go:generate | grep "gendecoder" | grep -v Makefile | cut -d ":" -f 1))
+
+%_gendecoder.go: %.go
+	go generate -run gendecoder $<
+
+.PHONY: .gendecoder
+.gendecoder: $(GEN_DECODER_FILES)
+
+.PHONY: .gendecoder.clean
+.gendecoder.clean:
+	find . \( -name *_gendecoder.go \) -exec rm {} \;

Makefile

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+SUBDIRS := $(wildcard */.)
+
+all: $(SUBDIRS)
+$(SUBDIRS):
+	$(MAKE) -C $@
+
+.PHONY: all $(SUBDIRS)

README.md

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+# Skydive plugin probes repository
+
+Work In Progress
+
+This repository hosts probe plugins. Probe Plugins can be Agent and/or Analyzer
+probe, please check probe README file for more details.
+
+# Installation
+
+Just run `make` to compile all the plugins or enter to sub directory to compile specific one.
+
+# Examples
+
+You can have a look at the `sample` plugin which brings the minimal required to write a probe or the `memory` one, 
+a bit more complex but still simple registering real data structure and live updating the Skydive graph.
+
+## Contributing
+
+Your contributions are more than welcome. Please check
+https://github.com/skydive-project/skydive/blob/master/CONTRIBUTING.md
+to know about the process.
+
+## License
+
+This software is licensed under the Apache License, Version 2.0 (the
+"License"); you may not use this software except in compliance with the
+License.
+You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.

memory/Makefile

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+export GO111MODULE?=on
+
+include $(abspath ../.mk/easyjson.mk)
+include $(abspath ../.mk/gendecoder.mk)
+
+memory.so: genlocalfiles
+	go build -buildmode=plugin ./...
+
+.PHONY: genlocalfiles
+genlocalfiles: .gendecoder .easyjson

memory/go.mod

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+module github.com/skydive-project/skydive-plugins
+
+require (
+	github.com/mailru/easyjson v0.7.0
+	github.com/shirou/gopsutil v0.0.0-20180111024713-6a368fb7cd12
+	github.com/skydive-project/skydive v0.0.0-20191009170754-872a2c0bfd34
+	github.com/spf13/viper v1.4.0
+)
+
+replace (
+	github.com/skydive-project/skydive => /home/safchain/code/gocode/src/github.com/skydive-project/skydive
+	github.com/spf13/viper v1.4.0 => github.com/lebauce/viper v0.0.0-20190903114911-3b7a98e30843
+	golang.org/x/sys => golang.org/x/sys v0.0.0-20190412213103-97732733099d
+	golang.org/x/tools => golang.org/x/tools v0.0.0-20190925230517-ea99b82c7b93
+)

memory/memory.go

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+//go:generate go run github.com/skydive-project/skydive/scripts/gendecoder --package github.com/skydive-project/skydive-plugins/memory
+//go:generate go run github.com/mailru/easyjson/easyjson $GOFILE
+
+/*
+ * Copyright (C) 2019 Red Hat, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// This package implement a probe which reports memory usage to the host node.
+// This probe is fairly basic and provide a good example
+// to start writting a probe.
+package main
+
+import (
+	json "encoding/json"
+	"fmt"
+	"time"
+
+	"github.com/shirou/gopsutil/mem"
+
+	"github.com/skydive-project/skydive/common"
+	"github.com/skydive-project/skydive/graffiti/graph"
+	"github.com/skydive-project/skydive/probe"
+	"github.com/skydive-project/skydive/topology/probes"
+)
+
+// ProbeHandler describes a memory probe handler.
+// It implements the probe.Handler interface.
+type ProbeHandler struct {
+	Ctx  probes.Context
+	quit chan struct{}
+}
+
+// Usage defines how the topology metadata will look like. Tags below
+// are used in order to generate marshal/unmarshal functions and getters.
+// easyjson:json
+// gendecoder
+type Usage struct {
+	Total       int64
+	Free        int64
+	UsedPercent int64
+}
+
+// Start the handler. Implements the probe.Handler interface.
+func (p *ProbeHandler) Start() error {
+	// start a goroutine in order to update the graph
+	go func() {
+		// update the graph each five seconds
+		ticker := time.NewTicker(5 * time.Second)
+		defer ticker.Stop()
+
+		for {
+			select {
+			case <-p.quit:
+				// got a message on the quit chan
+				return
+			case <-ticker.C:
+				v, err := mem.VirtualMemory()
+				if err != nil {
+					p.Ctx.Logger.Errorf("unable to retrieve memory information: %s", err)
+					continue
+				}
+
+				usage := &Usage{
+					Total:       int64(v.Total),
+					Free:        int64(v.Free),
+					UsedPercent: int64(v.UsedPercent),
+				}
+
+				// lock the graph for modification
+				p.Ctx.Graph.Lock()
+
+				// add metadata entry to the root node
+				p.Ctx.Graph.AddMetadata(p.Ctx.RootNode, "Memory", usage)
+
+				// release the graph lock
+				p.Ctx.Graph.Unlock()
+			}
+		}
+	}()
+
+	return nil
+}
+
+// Stop the handler. Implements the probe.Handler interface.
+func (p *ProbeHandler) Stop() {
+	p.quit <- struct{}{}
+}
+
+// NewAgentProbe returns a new topology memory probe
+func NewAgentProbe(ctx probes.Context, bundle *probe.Bundle) (probes.Handler, error) {
+	return &ProbeHandler{
+		Ctx:  ctx,
+		quit: make(chan struct{}),
+	}, nil
+}
+
+// MetadataDecoder implements a json message raw decoder. It is used
+// by the analyzer to decode properly the JSON message with the proper types.
+// the Getter interface functions will be generated by the gendecoder generator.
+// See the first line and the tag at the struct declaration.
+func MetadataDecoder(raw json.RawMessage) (common.Getter, error) {
+	var usage Usage
+	if err := json.Unmarshal(raw, &usage); err != nil {
+		return nil, fmt.Errorf("unable to unmarshal routing table %s: %s", string(raw), err)
+	}
+
+	return &usage, nil
+}
+
+// RegisterDecoders registers metadata decoders
+func RegisterDecoders() {
+	// register the MemoryDecoder so that the graph knows how to decode the
+	// Memory metadata field.
+	graph.NodeMetadataDecoders["Memory"] = MetadataDecoder
+}
+
+func main() {
+}