oc-lib/models/peer/peer_cache.go

package peer

import (
	"encoding/json"
	"errors"
	"fmt"
	"regexp"
	"strings"

	"cloud.o-forge.io/core/oc-lib/tools"
)

/*
* PeerExecution is a struct that represents an execution on a peer
* it defines the execution data
 */
type PeerExecution struct {
	Method   string                 `json:"method" bson:"method"`
	Url      string                 `json:"url" bson:"url"`
	Body     map[string]interface{} `json:"body" bson:"body"`
	DataType int                    `json:"data_type" bson:"data_type"`
	DataID   string                 `json:"data_id" bson:"data_id"`
}

var cache = &PeerCache{} // Singleton instance of the peer cache
// PeerCache is a struct that represents a peer cache
type PeerCache struct {
	Executions []*PeerExecution
}

// urlFormat formats the URL of the peer with the data type API function
func (p *PeerCache) urlFormat(url string, dt tools.DataType) string {
	// localhost is replaced by the local peer URL
	// because localhost must collide on a web request security protocol
	if strings.Contains(url, "localhost") || strings.Contains(url, "127.0.0.1") {
		r := regexp.MustCompile("(:[0-9]+)")
		t := r.FindString(url)
		if t != "" {
			url = strings.Replace(url, t, "", -1)
		}
		url = strings.ReplaceAll(url, "localhost", dt.API()+":8080")
		url = strings.ReplaceAll(url, "127.0.0.1", dt.API()+":8080")
	}
	return url
}

// checkPeerStatus checks the status of a peer
func (p *PeerCache) checkPeerStatus(peerID string, appName string, caller *tools.HTTPCaller) (*Peer, bool) {
	api := tools.API{}
	access := (&Peer{}).GetAccessor(nil)
	res, code, _ := access.LoadOne(peerID) // Load the peer from db
	if code != 200 {                       // no peer no party
		return nil, false
	}
	methods := caller.URLS[tools.PEER] // Get the methods url of the peer
	if methods == nil {
		return res.(*Peer), false
	}
	meth := methods[tools.POST] // Get the POST method to check status
	if meth == "" {
		return res.(*Peer), false
	}
	url := p.urlFormat(res.(*Peer).Url+meth, tools.PEER)              // Format the URL
	state, services := api.CheckRemotePeer(url)                       // Check the status of the peer
	res.(*Peer).Services = services                                   // Update the services states of the peer
	access.UpdateOne(res, peerID)                                     // Update the peer in the db
	return res.(*Peer), state != tools.DEAD && services[appName] == 0 // Return the peer and its status
}

// LaunchPeerExecution launches an execution on a peer
func (p *PeerCache) LaunchPeerExecution(peerID string, dataID string,
	dt tools.DataType, method tools.METHOD, body map[string]interface{}, caller *tools.HTTPCaller) (*PeerExecution, error) {
	methods := caller.URLS[dt] // Get the methods url of the data type
	if _, ok := methods[method]; !ok {
		return nil, errors.New("no path found")
	}
	meth := methods[method] // Get the method url to execute
	if meth == "" {
		return nil, errors.New("no path found")
	} else {
		meth = strings.ReplaceAll(meth, ":id", dataID) // Replace the id in the url in case of a DELETE / UPDATE method (it's a standard naming in OC)
	}
	url := ""
	// Check the status of the peer
	if mypeer, ok := p.checkPeerStatus(peerID, dt.API(), caller); !ok {
		// If the peer is not reachable, add the execution to the failed executions list
		pexec := &PeerExecution{
			Method:   method.String(),
			Url:      p.urlFormat((mypeer.Url)+"/"+dt.API()+meth, dt),
			Body:     body,
			DataType: dt.EnumIndex(),
			DataID:   dataID,
		}
		mypeer.AddExecution(*pexec)
		mypeer.GetAccessor(nil).UpdateOne(mypeer, peerID) // Update the peer in the db
		return nil, errors.New("peer is not reachable")
	} else {
		// If the peer is reachable, launch the execution
		url = p.urlFormat((mypeer.Url)+"/"+dt.API()+meth, dt) // Format the URL
		tmp := mypeer.FailedExecution                         // Get the failed executions list
		mypeer.FailedExecution = []PeerExecution{}            // Reset the failed executions list
		mypeer.GetAccessor(nil).UpdateOne(mypeer, peerID)     // Update the peer in the db
		for _, v := range tmp {                               // Retry the failed executions
			go p.exec(v.Url, tools.ToMethod(v.Method), v.Body, caller)
		}
	}
	return nil, p.exec(url, method, body, caller) // Execute the method
}

// exec executes the method on the peer
func (p *PeerCache) exec(url string, method tools.METHOD, body map[string]interface{}, caller *tools.HTTPCaller) error {
	var b []byte
	var err error
	if method == tools.POST { // Execute the POST method if it's a POST method
		b, err = caller.CallPost(url, "", body)
	}
	if method == tools.GET { // Execute the GET method if it's a GET method
		b, err = caller.CallGet(url, "")
	}
	if method == tools.DELETE { // Execute the DELETE method if it's a DELETE method
		b, err = caller.CallDelete(url, "")
	}
	var m map[string]interface{}
	json.Unmarshal(b, &m)
	if err != nil {
		return err
	}
	if e, ok := m["error"]; ok && e != "<nil>" { // Check if there is an error in the response
		return errors.New(fmt.Sprintf("%v", m["error"]))
	}
	return nil
}