Initial commit of experiment

1 files changed, 85 insertions, 0 deletions

diff --git a/plugins/http/attributes/attributes.go b/plugins/http/attributes/attributes.go
new file mode 100644
index 00000000..4c453766
--- /dev/null
+++ b/plugins/http/attributes/attributes.go
@@ -0,0 +1,85 @@
+package attributes
+
+import (
+	"context"
+	"errors"
+	"net/http"
+)
+
+// contextKey is a value for use with context.WithValue. It's used as
+// a pointer so it fits in an interface{} without allocation.
+type contextKey struct {
+	name string
+}
+
+func (k *contextKey) String() string { return k.name }
+
+var (
+	// PsrContextKey is a context key. It can be used in the http attributes
+	PsrContextKey = &contextKey{"psr_attributes"}
+)
+
+type attrs map[string]interface{}
+
+func (v attrs) get(key string) interface{} {
+	if v == nil {
+		return ""
+	}
+
+	return v[key]
+}
+
+func (v attrs) set(key string, value interface{}) {
+	v[key] = value
+}
+
+func (v attrs) del(key string) {
+	delete(v, key)
+}
+
+// Init returns request with new context and attribute bag.
+func Init(r *http.Request) *http.Request {
+	return r.WithContext(context.WithValue(r.Context(), PsrContextKey, attrs{}))
+}
+
+// All returns all context attributes.
+func All(r *http.Request) map[string]interface{} {
+	v := r.Context().Value(PsrContextKey)
+	if v == nil {
+		return attrs{}
+	}
+
+	return v.(attrs)
+}
+
+// Get gets the value from request context. It replaces any existing
+// values.
+func Get(r *http.Request, key string) interface{} {
+	v := r.Context().Value(PsrContextKey)
+	if v == nil {
+		return nil
+	}
+
+	return v.(attrs).get(key)
+}
+
+// Set sets the key to value. It replaces any existing
+// values. Context specific.
+func Set(r *http.Request, key string, value interface{}) error {
+	v := r.Context().Value(PsrContextKey)
+	if v == nil {
+		return errors.New("unable to find `psr:attributes` context key")
+	}
+
+	v.(attrs).set(key, value)
+	return nil
+}
+
+// Delete deletes values associated with attribute key.
+func (v attrs) Delete(key string) {
+	if v == nil {
+		return
+	}
+
+	v.del(key)
+}