GODT-35: New pmapi client and manager using resty

pkg/pmapi/manager.go

@@ -0,0 +1,127 @@
+package pmapi
+
+import (
+	"context"
+	"net/http"
+	"sync"
+	"time"
+
+	"github.com/go-resty/resty/v2"
+)
+
+type manager struct {
+	rc *resty.Client
+
+	isDown    bool
+	locker    sync.Locker
+	observers []ConnectionObserver
+}
+
+func newManager(cfg Config) *manager {
+	m := &manager{
+		rc:     resty.New(),
+		locker: &sync.Mutex{},
+	}
+
+	// Set the API host.
+	m.rc.SetHostURL(cfg.HostURL)
+
+	// Set static header values.
+	m.rc.SetHeader("x-pm-appversion", cfg.AppVersion)
+
+	// Set middleware.
+	m.rc.OnAfterResponse(catchAPIError)
+
+	// Configure retry mechanism.
+	m.rc.SetRetryMaxWaitTime(time.Minute)
+	m.rc.SetRetryAfter(catchRetryAfter)
+	m.rc.AddRetryCondition(catchTooManyRequests)
+	m.rc.AddRetryCondition(catchNoResponse)
+	m.rc.AddRetryCondition(catchProxyAvailable)
+
+	// Determine what happens when requests succeed/fail.
+	m.rc.OnAfterResponse(m.handleRequestSuccess)
+	m.rc.OnError(m.handleRequestFailure)
+
+	// Set the data type of API errors.
+	m.rc.SetError(&Error{})
+
+	return m
+}
+
+func New(cfg Config) Manager {
+	return newManager(cfg)
+}
+
+func (m *manager) SetLogger(logger resty.Logger) {
+	m.rc.SetLogger(logger)
+	m.rc.SetDebug(true)
+}
+
+func (m *manager) SetTransport(transport http.RoundTripper) {
+	m.rc.SetTransport(transport)
+}
+
+func (m *manager) SetCookieJar(jar http.CookieJar) {
+	m.rc.SetCookieJar(jar)
+}
+
+func (m *manager) SetRetryCount(count int) {
+	m.rc.SetRetryCount(count)
+}
+
+func (m *manager) AddConnectionObserver(observer ConnectionObserver) {
+	m.observers = append(m.observers, observer)
+}
+
+func (m *manager) r(ctx context.Context) *resty.Request {
+	return m.rc.R().SetContext(ctx)
+}
+
+func (m *manager) handleRequestSuccess(_ *resty.Client, res *resty.Response) error {
+	m.locker.Lock()
+	defer m.locker.Unlock()
+
+	if !m.isDown {
+		return nil
+	}
+
+	// We successfully got a response; connection must be up.
+
+	m.isDown = false
+
+	for _, observer := range m.observers {
+		observer.OnUp()
+	}
+
+	return nil
+}
+
+func (m *manager) handleRequestFailure(req *resty.Request, err error) {
+	m.locker.Lock()
+	defer m.locker.Unlock()
+
+	if m.isDown {
+		return
+	}
+
+	if res, ok := err.(*resty.ResponseError); ok && res.Response.RawResponse != nil {
+		return
+	}
+
+	// We didn't get any response; connection must be down.
+
+	m.isDown = true
+
+	for _, observer := range m.observers {
+		observer.OnDown()
+	}
+
+	go m.pingUntilSuccess()
+}
+
+func (m *manager) pingUntilSuccess() {
+	for m.testPing(context.Background()) != nil {
+		time.Sleep(time.Second) // TODO: How long to sleep here?
+	}
+}